Thursday, June 1, 2017

Jutland at 101: Day of the Dreadnoughts

Grand Fleet at sea

A century, a year, and a day ago, giants clashed across the North Sea. It was the single grand set-piece engagement of the big gun battleship era. Nothing like it was ever seen again, or probably ever will be.

Battleships and their dreadnought cousins, battlecruisers, loom large in our collective imagination. They were and are inherently operatic. Space opera, in particular, emerged as a genre during the dreadnought era. And while it may often favor swords or space fighters, on some level space opera is really all about Dreadnoughts in SPAAACE !!!

If you doubt this, take a look once again at the opening scene of the original Star Wars movie. No lightsabers are to be seen, nor even a space fighter. What we see is a spaceship - no small one - in desperate flight ... to be overtaken by a truly looming, immense, unmistakable battlecruiser.

We know it is a battlecruiser, rather than a battleship, because of its hunting-down role, something that Jackie Fisher would have identified without hesitation as a battlecruiser mission.

And yes, franchise canon describes this majestic ship as a 'star destroyer' but we are not fooled. Perhaps George Lucas was hazy on his 20th century naval terminology, or perhaps he felt that, in those days, battlecruiser belonged to the rival Star Trek franchise.

No longer. While battlecruisers continue to have a somewhat sketchy reputation among seagoing dreadnoughts (see below), they have clearly overcome their slower if more heavily armored cousins in the battle for the stars.

Google battleship, click Images, and you get pictures of historical seagoing battleships. Google battlecruiser and you mostly get renditions of operatic spaceships, with a mere scattering of seagoing vessels. (Battle cruiser as two words brings up a slightly different sequence of images, but equally space dominated.)

It is not quite clear why, of the two dreadnought* types, battlecruisers have become so predominant in space. Perhaps, for Americans at least, Pearl Harbor looms larger than Jutland. If battleships only ever existed in order to be obsolescent sitting ducks for Japanese carrier planes, their potential as terrors of the spaceways is diminished.

* Dreadnought is used inclusively here, applied to all big-gun capital ships, though the term was not often applied to new battleships once pre-dreadnoughts had faded from the scene.


On the other hand, the US Navy never had any battlecruisers, or at least never admitted to having any. Six were under construction during World War I, but under terms of the Washington Treaty two were finished as aircraft carriers while the others were scrapped before completion. The Alaska class of World War II was described officially as mere 'large cruisers', and their wartime service was brief, uneventful, and overshadowed by the much larger Iowa class 'fast battleships'. 

Independent of their role in science fiction, dreadnoughts have their own mythology. As recently as 1991, a book with the evocative title Sacred Vessels repeated the popular (pseudo-) contrarian argument that dreadnoughts were an inherently bad idea, impressive and expensive but with little actual fighting value.

The fact that there was only ever one grand clash of dreadnoughts - Jutland - and that it was not a classically decisive battle, is often implicitly offered as evidence of this proposition. In fact, battleships and battlecruisers mixed it up on multiple occasions in World War II, though in much smaller numbers than at Jutland. Running fights with one to three capital ships ships on a side was the usual pattern.

This makes Fisher's original conception of the battlecruiser somewhat prescient. In the early 1900s he argued that the time for stately formal engagements was passing, and that future war at sea would be, in modern terms, 'kinetic' - reliant more on speed and shock than pure mass. The experience of the 1940s generally bore him out.

And - again, quite apart from science fiction - battlecruisers have their own mythology, a myth that has undergone considerable evolution.

Three British battlecruisers exploded at Jutland, and went down with nearly their entire crews. These disasters were long attributed mainly to insufficient armor protection, and the whole battlecruiser concept was often denounced on this grounds.

In recent times, however, much more of the blame for the battlecruisers' losses has been placed on operational and doctrinal errors. The British battlecruiser force put great emphasis on rapid fire of their main guns - which doctrine, like the ships' speed, was part of the emerging kinetic vision of war at sea.

But the emphasis on rapid fire led gunners to ignore safety precautions such as properly closing anti-flash doors, so that when turrets were hit the resulting internal fires spread down to the magazines - with predictably catastrophic results.

The modern source linked above perhaps overstates the conspiratorial element in the traditional story about armor. I have 'always' known that flash protection was also lacking, so the shift is less a matter of new revelations and more a re-evaluation of what was already known. (Though perhaps it wasn't clear that flash doors were already in place, but not correctly used.)

This is often how scholarship proceeds, a cycle not unlike the fashion cycle. Perhaps by the 2060s a re-re-evaluation will again say that battlecruisers blew up because they were eggshells armed with hammers.

In the meanwhile, battlecruisers may well continue to rule the spaceways - as they deserve to. And readers of this blog may continue to suspect that laserstars, for all my disclaimers to the contrary, and details of armament and configuration, are still essentially Dreadnoughts in Space.

Play the Jupiter theme from Holst's The Planets, and decide for yourself.

Discuss:





The image of the British Grand Fleet at sea comes, unsurprisingly, from a web account of the battle.

And we previously considered the last battleship, along with the proto-battleships of the (actual, historical) steampunk era.


176 comments:

Rick said...

Just testing whether Blogger is working or glitching!

 Ashley said...

Seems to be, and it has been a while. Always enjoy reading your posts.

Matter Beam said...

I've always wondered: what makes a dreadnaught? Is it the big guns? The tonnage?
That would make them mere battleships.

The principal feature is a line of uniform weaponry on top of a platform both well protected and mobile.

Now, this being a 'near mid-future' blog, let's see how this translates into a space setting. We can go about it by imagining the evolution of space warships and try to end up with a situation that led to the HMS Dreadnought being created.

The first spaceships will be scientific. Prolonged human exploration and frequent interplanetary trips will demand the use of propellant transporters between sites of production (the Moon) and departure (LEO). As human presence becomes more commercial (asteroid mining), these transporters evolves into proper tankers.

Once you have regular commerce between propellant, ISRU components, asteroid ores, spaceships parts and so on, you'll have a lot of value moving around on unprotected drones. Human transports go quickly around the Solar System on expensive nuclear-electrics, but they're not valuable.

With value comes conflict, either in the form of piracy, privateering, PMCs or military action. Either way, you're fitting one barge in ten with lasers and machine guns.

This would inevitably start an arms race on the back of trade profits.

Once everyone knows that spaceships with guns on them are running around, dedicated military ships will be created. They won't be the result of massive budgets, because they are limited to the value of the trade at risk. Refitted human transports with armor plating, guided shells, cargo bays crammed with missiles and a high-thrust nuclear rocket on the side to dodge missile waves.

These will evolve. We'll end up seeing something out of Children of a Dead Earth: multiple guns, no distinct type of weapon used over other since nothing has been really combat proven, multiple engine types for cruise/combat and small crews. They're cheap, mostly expendable and the best class distinction is how much money was spent on them.

Once we're at the point where multiple great powers need to project their influence or risk being subjugated, proper military fleets will emerge.

Each ship is a huge investment and standardization is the name of the game. Many minor conflicts will have proven one weapon type superior in most situations over others, whether it is the long-ranged laser, the gigajoule railgun or the multi-staged missile. This weapon will become magnificent. Like the 18 pounder of the Age of Sail matured into the 305mm cannons of HMS Dreadnought, we'll have low-wavelength lasers wrought like miniature suns, coilguns that blur the distinction with particle beams or missiles that are spaceships in their own right.

Armor will become significant and tailored towards countering the expected weaponry of the opposition. Human crews will become a mainstay due to the advantage their provide, even if they only occupy one ship in three.

The drive would probably have to become a one-solution-fits-all analogy to the steam turbine. Maybe we move the tech level along, such as an introduction of combat-capable gaseous core nuclear drives, or we accept that the dreadnaughts start out as lumbering mountains of propellant....

Nyrath said...

When you get right down to it, space warships are extreme examples of the concept "Weapons Platform". They are rocket propelled spacecraft with the maximum possible payload mass devoted to weapons.

I was under the impression that the term "Dreadnought" was more marketing that it was a real class of ship. And due to exposure to E.E. "Doc" Smith at a tender young age it took me a long time to stop spelling it as Dreadnaught

You can find my tentative groping towards a theory of warship classes here:
http://www.projectrho.com/public_html/rocket/spacewarship.php#id--Ship_Types--Winchell_Chung's_Ship_Types

Matter Beam said...

@Nyrath:

I would tend to disagree. Space warships do have to balance between propulsion and weapon mass, and armor does play a role. A space-going weapons platform would be some sort of missile bus. A 'warship' is usually understood as somewhat protected from enemy fire at the intended engagement distance.

Nyrath said...

@Matter Beam
Agreed, you have a point there

Anonymous said...

Ok, battleships vs battlecruisers. Usually the difference is amount of armor. However, if you removed one of the secondary weapons, or reduced the number of rounds (or missiles) that the ship carried and replaced it with more powerful engines or more propellent (or both), you would have a battleship sized spacecraft able to out boost a regular battleship...it just wouldn't be able to pound away as long as a regular battleship. But that's ok, because you'd need interceptors with battleship level firepower, just not for very long. Regular battleships could stay in orbit around whatever valuable target destination you want to protect. Maul the incoming ships, then pound away once they get close. Those attacking ships are probably mostly battlecruisers anyway.

Ferrell

Anonymous said...

Something occurs to me.
Torpedo boat destroyer + time = destroyer
Combat Spacecraft destroyer + time = destroyer

Ferrell

Jon Brase said...

As for the combat-worthiness of battlecruisers, I'd say that it's really Hood's fate, more than that of the BCs at Jutland, that draws into question the wisdom of the battlecruiser (though I will qualify this later).

It is generally agreed that Hood was destroyed by direct penetration of a magazine by incoming fire. Now, British powder was notoriously volatile, and it may be that Hood would not have been lost if she was using American or German powder (at Dogger Bank, an ammunition fire on Seydlitz spread *into the magazine*, but only set off fore charges in transport, and none of the main charges, see http://webpages.charter.net/abacus/news/jutland/18/CHAPTER%2018.htm), but then again, Arizona was destroyed by a direct magazine penetration, and was using American powder. In any case, the British had learned their lessons about powder handling, but Hood was sunk because enemy fire defeated her armor and set off a magazine directly. It could be argued that Bismark was a more modern ship, but her guns were, I think, in reach of German technology at the end of WWI (the muzzle velocity was similar to German WWI-era guns, the shell weight somewhat heavier than German WWI 15-inchers, but still short of that for the Hood's guns), and practically every other aspect of the Bismark's design, other than propulsion, shows little advancement over the WWI state-of-the-art (she had far too little deck armor for a WWII design, and that silly, old fashioned 4x2 turret arrangement), which is to be expected, as the German warship industry had been obliterated by Versailles, so they hadn't gained much experience since WWI. As such, I think it quite likely that, had Hood ended up in combat against a contemporary capital ship from some other nation in the 20s, she would have suffered the same fate.

All that said, it is specifically the British conception of the battlecruiser that I think was problematic. The German conception (trading gun caliber, rather than armor, for speed) is on a much more solid footing, but still suboptimal.

The battlecrusier concept I would use is one that trades gun count, rather than caliber or armor, for speed. The battlecruisers of WWI on both sides already did this to some degree, mostly by using more efficient gun arrangements in which every main gun could fire on both broadsides (whereas with the early dreadnoughts, a good chunk of the main armament was mounted in wing turrets that could only fire to one side, but I think that a solid battlecruiser could have been made by starting with the New Mexico class, for example, and eliminating the aft turrets, using the weight savings for propulsion. The resulting design would have six guns, all forward. I might make light sacrifices in armor, but nowhere near as deeply as the British did.

BTW, Rick, are you aware of the game "Rule the Waves"?

AlexT said...

Battlecruisers and battleships had fundamentally different roles. BBs were meant to stand and fight, take punishment and keep fighting. BCs were never supposed to go up against BBs, and always beat a hasty retreat when they encountered them. At Dogger Bank and Jutland, both sides' battlecruiser squadrons carefully followed this principle, although they were quite eager to duke it out with each other.

AND IN SPACE! I would imagine military space ships will also evolve to fill particular roles. To stand and fight would probably mean controlling a body's orbital space (ie being able to blow up anything in the vicinity) and resisting any dislodgement attempts; also, to dislodge enemies doing same. Whether this is done by giant 'dreadnoughts' or by swarms of remote-controlled drones or whatever else, will depend on weaponry, defenses, propulsion, ship construction technology etc. The cruiser's role is to hunt down unarmed opponents and the battlecruiser-counterpart is the cruiser killer.

In the dreadnought days, battlecruisers and battleships were of similar size simply because the best hunter-killer design happened to be of comparable size with the best stand-and-fight configuration. Their Age of Sail counterparts, frigates and ships-of-the-line, were quite different. What a cruiser and cruiser-killer would look like, assuming a given technology level, is a huge and hugely interesting discussion.

I think there are even more reasons for battlecruisers' appeal in current pop culture, besides the one in the article. Not only, as Rick says, are 'battleships' popularly mostly known for sinking at Pearl Harbor. Also, in their heyday, battlecruisers had a kind of panache and audacious aura about them, a reputation for devil-may-care bravery and fighting spirit. At Jutland, Jellicoe was the big boss who won the battle, but Beatty was the popular hero. The (mis-)perception might have endured ever since.

The word even SOUNDS awesome: BAT-tle CRUIS-er ! BAT-tle CRUIS-er ! it's like war drums..

Finally: Thanks Rick & commenters for a hugely interesting blog and conversations that often are just as fascinating !

Tony said...

The battlecruiser was a reaction to the armored cruiser, which was in turn a reaction to the protected cruiser. Basically there was an arms race between Britain and France in anti-trade and trade protection cruisers. The Germans got involved in the race not for trade/counter-trade reasons, but because cruisers also had battle fleet roles, and the Germans had to counter with similar capabilities.

So the British developed the battle cruiser as the ultimate armored cruiser, up to and including armored cruiser level armor. The Germans developed the battlecruiser from the other direction, as a fast battleship, with only a little less armor than the battleship. It was convergent evolution, in a way.

As battlecruisers evolved -- and this all happened in the eight years between 1906 and 1914; not very long at all -- they becaame longer and displaced more than battleships. Even with less armor and fewer/smaller guns, battlecruisers required very large propulsion plants and finer hulls to achieve just 4-5 more knots than the battleships. Translating to space warfare types, a higher acceleration/delta-v ship with a similar armament to a battleship would need larger engines and more fuel/reaction mass.

WRT the loss of British battlecruisers at Jutland, it appears that battlecruiser turret roofs on both sides just didn't handle each other's main armament projectiles very well, where battleship turret roofs did. In German ships, due to better ammunition handling and more robust propellant storage/protection, it only led to the loss of the turret crew (including those in the ammunition supply column). On British ships, where ammunition handling was slipshod, and the propellant unpacked in large quantities, ammunition fires produced a lot more high pressure gas -- enough to tear the ships appart.

I don't think what happened to Hood had anything to do with that. Sometimes you just have bad luck.

Tony said...

Hipper ran at Dogger Bank because the odds were against him. Scheer broke off at Jutland for the same reason. Similar things happened in WW2. The Italians, for example, were notorious for avoiding decisive combat.

The reason for these developments -- unexpected developments in the case of Jutland, where the British genuinely believed that the Germans would have wanted to fight it out -- was that Dreadnought Era battleships and battlecruisers were too big to fail. They represented so much naval (and indeed national) capital that admirals didn't want to risk losing them except in the case of overwhelming advantage. Even Jellicoe, who knew he had the larger, more capable fleet, shied away from a torpedo attack covering the withdrawal of the German High Seas Fleet. He can't be blamed for cowardice on the day -- he said when he took command that he wouldn't pursue a retiring German fleet, because they might be trying to draw him onto mines dropped in their wake. He knew what he would and wouldn't risk with the Empire's greatest military asset.

Thucydides said...

The Battlecruiser idea hasn't died quite yet. The former Soviet Union built 4 of the massive Kirov class ships, which are often portrayed as battlecruisers, and they combined the idea of speed, long range and firepower in a modern idiom (carrying a massive battery of missiles rather than gun armament). The American idea of an Arsenal ship was actually an evolution of the so called "Strike Cruiser" concept from the late 1980's as well, which can be conceptually thought of as an Arleigh Burke class hull stripped of its superstructure and filled with VLS missile cells and surface mounted AESA radar panels.

Having a large, fast ship with a considerable amount of firepower will always be an advantage, even in an age where we look at swarms of smart weapons and active "kill webs" of sensors and shooters linked together across platforms and even services (A USMC F-35 recently conducted a test where it detected a target, then cued and fired a missile from a nearby destroyer to destroy it). Getting a large number of weapons rapidly to the battle zone will be advantageous even in a space setting.

While I have advocated in the past for RBoDs as the premier weapons system for constellations in a space fleet, I have been changing my mind based on the need for enormous auxiliary systems for target tracking, cooling and so on. I now feel a space warship will be carrying a belly full of nuclear weapons that drive advanced systems ranging from Casaba Howitzers shooting energetic plasma to nuclear "shotgun shells" driving pellets at a target at 100km/sec. RBoDs are the "coastal artillery" buried in asteroids, planted on the surfaces of moons and inside gigantic space stations orbiting the home planet, where the massive support systems is less of an issue.

Tony said...

Calling the Kirov class "battlecruiser" shows something of a lack of imagination. One can almost see a bunch of naval intelligence analysts sitting around, trying to figure out how to categorize the latest, largest Soviet missile cruiser. They think, well, it's a cruiser, but it's the size of a battleship. I know, let's call it a battlecruiser. Yeah, brilliant guys.

Except that unlike the original battlecruisers -- particularly if you're talking about the British conception of the type -- the Kirov class ships were meant to be fleet command ships and the main offensive punch of a task group. Also, while the classic battlecruiser was almost ridiculously weighted towards offensive firepower, the Kirov class ships were in large part given over to defensive sensors and weapons. The whole point was for the ship to survive heavy air attack and enemy submarines until it got close enough to launch its offensive cruise missiles at a carrier battle group.

In this last respect, the Kirov illustrates the basic difficulty with the laserstar. (Or kinetistar, or any highly optimized single-capability platform.) They're designed to work against a doctrinally unsophisticated enemy. If an enemy has the wherewithal to identify and attack the laserstar's weakness, then defeating the laserstar becomes nothing but an exercise in military engineering. That is unless the laserstar possesses the means of defending itself against the broad array of possible enemy counters. But such systems would degrade the main armament's effectiveness and power, to the point that it's not exactly overwhelming in size or even effect.

Well, Tony, I can hear you say, you don't have to put all of the necessary systems on the same platform. That's true. But resources are limited. Multiple single-capability platforms, with multiple propulsion systems, sensor suites, and other forms of overhead, are less efficient for a given amount of tonnage than fewer, multi-capability platforms. In any case, one may be able to afford only a few RBoD platforms, for the need to protect them well enough to survive a reasonable amount of time in combat. Then they become less and less dominant.

Even as defensive systems in orbital or surface stations, RBoDs have the disadvantage of being targets of military engineering, rather than maneuverable operational assets. They do require the attacker to plan for them and expend resources on their neutralization. And that may be useful, if the attacker has limited time and/or material resources, or if the defender has supporting maneuver forces that can take advantage of the imposed delays. But if the body that the RBoDs are defending becomes isolated by a sufficient attacking force, then it's just a matter of time.

Bill said...

Interesting discussion, I would just like to reflect on the Star Destroyer from Star Wars for just a moment. Often fans of Star Wars and the expanded Universe have tried to take the Destroyer term as suggesting it was a small class of Warship and have added numerous larger ships. But of course that doesn't show up in the movies where only 1 significantly larger ship is shown, and there is every reason to believe that it was not meant to be built in large numbers. Further, every use of the Star Destroyer in the movies suggests that it is a multi-purpose capital ship filling the role of carrier, cruiser and even battleship.

So why call it a destroyer? Why not? Too many people tend to think of these nautical terms as being fixed, but in fact they can be very fluid. Sloops of war were once a small sailing war ships that might not even have three masts (in civilian terminology, a sloop could only have one mast, but naval sloops could have more), by the Civil War however, sloops of war could be large enough that the Second USS Constellation was confused by a later generation with the original Frigate (Which, was essentially the early 19th century version of a cruiser). Frigates likewise went from being large sailing warships in the early 19th century (second in size and prestige only to ships of the line) to being the smallest dedicated ocean going warship in the 20th century. Meanwhile, America's latest generation of Destroyers are as large as WWII cruisers and considerably more deadly and certainly do not take a back seat to America's aging cruisers which in fact share more in common with American Destroyers than earlier cruisers.

In other words, nautical terms get used, reused, and often abused.

Thucydides said...

The Kirov was certainly designed for a much different era of naval warfare than the HMS Hood, but still comes pretty close to Fisher's (admittedly imprecise) definition: "A ship big enough to fight almost anything, and fast enough to run from what it can't fight". As a large, fast and well armed capital ship, it certainly comes much closer to the conception of a battlecruiser than anything else built in the modern era.

The Kirov, much like the USN's carriers, is designed to operate as part of a task force, and thinking back to the discussions of laser vs kinetic stars, I don't recall anyone ever thinking that either type of platform would be operating independently, but rather as part of a constellation of ships. How it would work is probably dependent on the flavour of the month the author is drinking, a constellation designed around the USN's "Kill web" concept would be built and operate differently than one designed around the sort of thinking that led to big gun Dreadnoughts in the first place.

It is interesting to think of how a "kill web" constellation might look and operate. The modern USN version might have Marine F-35b's flying ahead to seek out and identify targets, then engage them with everything from on board weapons to bombs and missiles from USAF "arsenal planes" to the guns and missiles of the task force ships themselves. In space, there might be lots of sensor drones to identify targets and cue the weapons of other drones or the accompanying ships of the constellation, perhaps instead of huge RBoDs, they might have multiple smaller laser weapons gang up on high value targets until they get into the kill range of kinetic stars launching clouds of SCoDs. (Since there is no stealth in space, there is no actual equivalent of a stealthy F-35 slipping ahead to mark targets unseen by the enemy). The huge disadvantage of this model is the engagement range is shortened considerably; A RBoD can attack targets one light second away and effectively carve through steel, ceramic and carbon fibre, while even gangs of smaller lasers might not have that effect until closer in. This also changes the nature of the space warships to something similar to arsenal ships and aircraft than to destroyers, cruisers or battleships, huge "missile trucks" and "laser trucks" which generally operate under the guidance or even command of remote sensor platforms and without a great deal of independence of their own.

YMMV

Tony said...

The attractive thing about cruisers is that they existed in a sweet spot between capital ships and escorts. Escorts work in flotillas. Similarly, capital ships worked in squadrons. Cruisers, on the other hand, could be assigned independent missions, in ones or twos. That's very romance friendly. Even more romance-friendly is the battlecruiser, imagined not as a fleet reconnaissance unit, but just as a super-badass cruiser.

Tony said...

Battlecruisers were not in fact capable of running from something that could defeat them. They couldn't run from other battlecruisers. Fisher's lack of vision on this point was and is ridiculous.

Likewise, Kirov class ships couldn't run from a carrier air group strike.

Aircraft spotting for other assets at sea is an old story. In fact, the Soviets were relying on their maritime reconnaissance aircraft to locate US carrier groups for cruise missile strikes.

WRT space warfare constellation, I'm just not convinced that highly specialized sensor and weapon platforms would be worthwhile. Once again, the inefficiency of large numbers of duplicated capabilities argues against it.

I also don't think for one second that a laser weapon could be effective at more than a small fraction of a light second. Yeah, I know what Luke Campbell says about that. The problem is that there are mechanical and combat environment factors that make it highly, highly unlikely.

And, BTW, we really need to walk back this no-stealth-in-space trope. There certainly is no absolute invisibility, as in hiding behind a hill. But there are relative levels of observability. If you're not maneuvering under power, and you keep your other power uses to a minimum, you're going to be hard to see by military grade sensor systems.

Thucydides said...

Unless the scout drones or spacecraft are on an entirely ballistic course throughout their lifespan, then the odds are they will reveal themselves to watching sensors. While it is entirely possible to launch sensors on ballistic paths, any movement by the constellation will gradually see the drones slipping out of position to provide high quality information to the constellation. Since we all seem to have read the same source documents, then I don't have to go into why one light second is the "optimal" distance for warships to engage in combat, and any sensor drone which slips outside of the one light second "bubble" surrounding the constellation will become less efficient and provide less accurate "real time" information.

Your objection to using specialized weapons and sensor platforms is a bit strange, since virtually every military machine on Earth is a "specialized weapons and sensor platform", and have been since WWI, if not before. Even civilian machines purchased for military usage get various things bolted on to become militarized, from a heavy machine gun on the back of a pickup truck to a sensor pod and Hellfire missiles mounted on Cessna Caravans over Iraq. Given the unique demands of the space environment, I actually find it less likely that commercial space craft will be militarized by bolting on military hardware, the hit to deltaV due to increased mass will be quite significant. Bulk cargo may be sent via mass driver on unpowered ballistic trajectories to the customer, which makes weaponizing them tough (unless you aim off and use the container itself as the weapon).

The real question is similar to the McGuffin on why colonize space in the first place: what is worth fighting over that makes it essential to build space warships or other military hardware? In this case, the answer may be as simple as planetary defense. Being able to spot and deflect or destroy incoming asteroids and space debris will be highly desirable, while settling disagreement might result in flinging ISO containers full of rock at interplanetary speeds at the offending party. Colonists on asteroids, moons and free flying space stations will have the same imperatives, indeed it will be more urgent since they will have much smaller margins of survival due to smaller populations and resource bases.

Tony said...

"Unless the scout drones or spacecraft are on an entirely ballistic course throughout their lifespan..."

Who ever said I was talking about scouts only? I think that a whole fleet would approach under emission controls until within detection range.

"Since we all seem to have read the same source documents, then I don't have to go into why one light second is the "optimal" distance for warships to engage in combat..."

I don't think that's been demonstrated at all. Those sources concern themselves only with the pure optical theory. They don't take into account all of the things which would actually affect the platform:

mechanical noise
differential heating
heat distortion of aiming mirrors
vibration in mirrors caused by coolant flows
noise caused by coolant flows throughout the system
imprecision in observation and measurement of targets

...and a bunch of other things. All of those are very real things that make fighting at more than a few tens of thousands -- or maybe only a few thousand -- miles not very likely at all.

"Your objection to using specialized weapons and sensor platforms is a bit strange, since virtually every military machine on Earth is a 'specialized weapons and sensor platform', and have been since WWI, if not before."

Except that I said "highly specialized sensor and weapon platforms". In the context of "constellations" and "RBoDs", it should be obvious that doesn't mean ordinary weapon systems. It means systems that only do one thing each. Like, for example, a tank that had no machine guns and only fired armor piercing projectiles out of its cannon. The problem is that systems like that are vulnerable to relatively simple counters, even if used in groups of complimentary capabilities. And, as already mentioned, they represent an inefficient use of assets. Propulsion systems, sensor suites, structures, etc are not perfectly scalable. There is an inescapable overhead for each unique unit. SO it makes sense to have fewer units with fewer increments of overhead across the fleet.

Thucydides said...

An interesting coincidence, I came across this in Quora:

https://www.quora.com/How-mightve-the-Battle-of-the-Denmark-Strait-gone-had-the-HMS-Hood-not-been-destroyed-by-an-unlucky-hit/answer/Nate-Carmody

How might've the Battle of the Denmark Strait gone had the HMS Hood not been destroyed by an unlucky hit?

Just curious as to how well the two forces matched up, if Hood might’ve landed some hits on Bismarck, or if Prinz Eugen’s torpedoes came into play, alternate ways the battle may have turned out?
Nate Carmody

The conventional wisdom on the HMS Hood is that she was hit by a “lucky” plunging shot that penetrated her weak deck armor and exploded in one of her magazines. As an upgraded battlecruiser, she was not originally designed to slug it out with another battleship. She had been upgraded in many regards, but still had deck armor of only a few inches thick. This was a well known flaw, and her captain fought the Battle of the Denmark Strait appropriately for this - closing quickly to eliminate plunging fire as an issue.

In reality, she was not destroyed by a plunging shot through her weak deck armor, the ballistics of the range and the Bismark’s guns don’t work out that way. She was only ~16,000 yards away at that point, and her guns were capable of penetrating the Hood’s thickest armored belt at ranges out past 25,000 yards (the HMS Hood had a maximum of 12″ belt armor). However, at that 16,000 yards range, the Bismark’s shells were only going about 10 degrees off of horizontal - they would not be able to penetrate the Hood’s deck armor, but would skip off.

The inescapable conclusion is that the Bismark’s shell penetrated the main armor of the Hood and exploded a magazine. The US Navy calculated that there is a 1 in 6 chance of each penetrating shot exploding either a magazine or the ship’s boilers. Given that the Hood was hit twice like this, she was a little unlucky, but not a lot unlucky. Given how weak her belt armor was, she was not going to last long in a prolonged fight. She was a 1920s design as her core, she had been passed by better more modern ships. Admiral Holland, though a gunnery expert, had bad information about how to fight the Bismark, and it cost him the lives of almost all of his crew along with his ship.
[snip]

The rest of the answer is interesting as speculation, but too long to post here

Geoffrey S H said...

A laserstar sounds more like an artillery weapon than a battleship. Fire at a mirror in the constellation and use that to hit the enemy. The laserstar stays out of effective range the whole time. Depends on mirror vibration, etc so not likely in plausible mid-future.

I would imagine a few specialised craft (the new British carriers seem to lack all capabilities other than aircraft), but otherwise within a constellation of generalised craft. A generalised craft can start out with missiles and switch to either shells or lasers (depending on enemy armour capabilities) as the effective range closed.Easier to handle logistically.

Things also depend on how big your military industrial complex is, how big your budget is, and how difficult it is to procure equipment. You could end up with specialised craft instead of the better generalised rockets you origionaly asked for, or your civil servants could do things properly and get a few well-armed general rockets.

As for names... I have thought of some candidates.

For specialised craft:

kinetic carrier- carries missiles and gun-satellites. Possesses a small reactor due to low power requirements.

Kinetistar- carriers missiles, gun-sats and possesses a railgun/ coil gun. Large reactor.

Laserstar - What it says on the tin.

For generalised craft:

fighter- gunship. Can use mirrors to redirect beams from laser craft to targets, inspect habs and do the small dirty work in a planetary system.

shieldstar- cheap frigate type craft. shields larger craft from kinetic attacks. uses mirrors to aid firepower from laser armaments of larger craft.

Striker- independent craft that works outside main formation.

Assault striker- larger striker that can supplement battlegroups of larger craft if need be.

Dominator- large craft armed with a variety of weapons most effective for the task.

Battlestar-Carrier with some self-defence capability. basically a mobile station that deploys craft to occupy a planetary system.



P.s.: People talk about battlecruisers, but no one ever mentions the Razees a century earlier..... Always thought those demonstrated Fisher's principles a little better.


Matter Beam said...

I don't think we should trap ourselves by thinking in classes and ranges.

As Rick pointed out, space warships will be built like trains. Each 'wagon' is an otherwise independent spaceship, but are put together to accomplish a task.

So, we'll have a propulsion unit, a power unit, an appropriate radiator unit, a crew unit, an armored nose unit...

A laserstar would be a huge honking power generator attached to an array of radiators and a laser generator at the end. You can stick a large lens in front, an armored nose cone or extra tanks of propellant. Swap all this out for hollow boxes of missiles and you've got yourself a missile carrier.

The modularity would extend to the battlefield. Dedicated interplanetary sections propel the rest of the stack at the target... then detach an retreat. Propellant sections are ejected as they are emptied, to be recovered and assembled into a empty tender ship that awaits a tanker arriving after the battle is over. The armored nose cones can be swapped out after being damaged.

I don't believe range is a factor either. The laser weapon web can be deployed by any laser star to massively increase its strike range, or allow it to attack from multiple angles. A web can replace a large lens and allows a laserstar to take full advantage of armored noses. At the same time, an independent laser star (without a web) might find itself completely unable to cut down smaller targets because it cannot keep the beam on the same spot, or because its thermodynamics increase the M2 factor to uselessness.

The same goes for kinetics. The most important measure for kinetics' range is relative acceleration vs relative velocity, or more accurately the relative deltaV that can be expended during the time-to-target.

If stealth is a factor, it really changes things. I strongly believe that infrared and radio stealth can be achieved during manoeuvring using 'midfuture' tech this blog assumes. It would allow, for example, small, cold, slow kinetics to defeat hot RBoDs blazing across the sky, of for laser webs to set up 'terminals' behind the targets and zap them up the nozzle...

AlexT said...

"no stealth in space" certainly starts to sound a lot like "two legs bad, four legs good"

Is this thesis corroborated, anywhere at all, by someone familiar with telescopes, the cost of making and orbiting them, probable detection ranges, likely kill distances against enemy detectors etc ? Obviously, assuming current/plausible technology and physics as we know it, otherwise all bets are off.

Maybe I've not looked well enough, but arguments I've come across postulate huge numbers of superb detection systems working perfectly well all the time, as well as being perfectly protected against any enemy action. The predictable result being, of course, a cosmic game of perfect information where the (probable) loser is predetermined and might as well give up immediately.

My point is that deception and concealment have been and will remain the key to winning wars, however technically cumbersome they may be.

Thucydides said...

No stealth in space is simply a result of thermodynamics, whatever you do is against a very cold background. Life support, computation, basic hotel services all produce waste heat, which is displayed against a 3 k background. Weapons, reactors, rocket exhaust and other high energy devices mean you are producing far more heat, which shines like a bacon against the cosmic background.

Sensors don't have to be large and elaborate, indeed, there are many reasons to have a multitude of small, distributed sensors (even outside the military) and build up a picture using a multitude of elements. This also allows for graceful degradation and makes putting out the enemy's eyes very difficult. A multitude of sensors to detect asteroids and other possible space threats, help aim laser power beams and communications systems can obviously be pressed into service, and constellations will also be carrying a multitude of sensors of their own.

As for single system ships, while Tony is correct that extreme specialization is not a great way to go, the rocket equation tells us every gram counts. A general purpose "Frigate" mounting missiles, lasers and railguns will have much less capable systems than an equivalent ship which only carries one system, or alternatively the ship with one system will have much more deltaV than one lugging around extra mass of multiple systems.

Matter Beam said...

@AlexT:

No, no need for large numbers of sensors or incredibly sensitive telescopes. Regular spaceships are hot enough against their background to be detected quite easily. Turning a sensors to cover the entire sky and processing the data before the start of the next sweep can be done cheaply.

By easily and cheaply, I mean that a hobby-grade infrared telescope (10cm lens?) hooked up to a gamer's desktop can scan the entire solar system in less than 4 hours and pick out 300K radiators from life support out to the orbit of Pluto. Of course, it won't give you the position of the target within +/- 100 million kilometers or worse, but it would be good enough to sound the alarm and get one of your two high-resolution expensive orbital AWACS platforms to have a look at that section of the sky.

You won't even really need to dedicate a budget to these hobby-grade sensors. By the time we're shooting tons of metal at each other at several kilometers per second and call it transport, we'll need a decent traffic control system that avoids turning spaceships into manned projectiles. This traffic control system relies on mandatory sensors installed on all civilian craft and additional ones orbiting vulnerable space stations and critical junctions in space, such as the Lagrange points.

Naturally, by the time we have space warships, we'll have thousands or more eyes scanning space with enough sensitivity to detect anything operating at room temperature across the entire solar system.

Serious militaries only need one, or two for redundancy, expensive platforms to focus on suspicious detections.

HOWEVER,

Even the best military lookouts won't spot a spaceship cooling a carbon nanotube (VantaBlack) hull to 20K using hydrogen boiloff ...beyond 100000km, even in the far future with advanaced detection technology, because it simply does not emit enough photons. Use a helium-hydrogen heat pump to drive down your surface temperature to 4K, and your can remain undetected until you bump into your target. Physics.

@Thucydides:
Agreed. A specialized ship will exploit their advantage to beat any multi-purpose opponent, whether it be laser range, number of missiles or projectile velocity. The great thing about realistic space warfare, contrary to say the WWII battleship era, is that there is not just one single advantage to play with. It isn't just gun range vs gun range, or reload rate vs reload rate, but many interesting and non-directly-comparable characteristics such as beam quality and missile deltaV!

AlexT said...

@Thucydides

Obviously ships are much hotter than their background. So are stars, and they're still hard to see if they're reasonably far away. If I remember my physics correctly, detectability (as per apparent magnitude) drops with distance squared.

Sure, constellations of little cheap sensors sound better than single large installations. But it's not clear how effective they will be, how easy to turn synchronously so you can scan the sky or track a target, how difficult to maintain.. Also, would making 1 million cheap sensors be cheaper than making one big telescope ? Also, while a constellation would indeed be harder to take out with a single kinetic impactor, the components would presumably be more vulnerable to other kinds of attack, eg EMP, high-velocity dust etc. Bear in mind that putting out the enemy's eyes would rank very high on an enemy's priority list.

@Matter Beam

"...a hobby-grade infrared telescope (10cm lens?) hooked up to a gamer's desktop can scan the entire solar system in less than 4 hours and pick out 300K radiators from life support out to the orbit of Pluto."

Not sure where your numbers came from, could you link some specs ? I've had trouble finding this sort of quantitative analysis.
300K radiators of how many watts please ? Or am I seriously mis-remembering basic physics ?


With perfect detection ruled out, you'd use various stealth techniques for various missions, bearing in mind you only need to stay hidden a limited time in any case. And even if they see you coming, you want to give them as little time as possible to counter the nasty surprises coming their way.

Geoffrey S H said...

You need a 'class' for a spacecraft so that you have an easy to remember name. Doesn't stop it from being highly moduler, and I don't believe that that the millions of potential combinations of modules mean that they will all be used. Certain common combinations will emerge as space warfare develops.

Thucydides said...

To answer Matter Beam and by extension Tony, single purpose spacecraft will be individually more capable than multi purpose frigates, but since they will be operating in constellations of ships, each with different properties, then you would almost have to think of the constellation as the "ship" and a Kineticstar, Laserstar or support ship as one of the modular units that make up the constellation. Taking this to extremes, Geoffrey would then be talking about a "frigate" Constellations of small, high ISP ships, or a Dreadnaught Constellations of massive ships carrying huge weapons arrays (RBoDs, batteries of SCoDs, scores of CASABA Howitzers or railguns firing hypervelocity projectiles).

As an aside from space war, but keeping with the topic of naval evolution, the US Navy was recently started rethinking itself for the 21rst century: Thinking outside the hull 9https://www.usni.org/magazines/proceedings/2017-06/think-outside-hull). Taking this conception to its logical conclusion, ISO type containers with hypersonic missiles could be placed on any hull (or installed ashore on trucks and fixed platforms) and networked together to launch deadly firepower at any target in range. The Admiral's job would then be to keep his platforms dispersed enough to avoid a devastating strike while being able to concentrate his forces at the right time and place to deliver a devastating strike of his own. Would it be worthwhile to build missile armed "battlecruisers", or have a large fleet of "Liberty Ships" with deck space for landing and utilizing missile containers instead?

Rick said...

Lots to chew on ... for which thank you all, returning and first time commenters!

So E E 'Doc" Smith is to blame for the 'dreadnaught' spelling of the word! Didn't know that. As for the marketing quality of the word, the blame for that goes to the Royal Navy, which is unique in the modern era for giving Cool Names to its ships. Victory! Dreadnought! Invincible!

If the first 'all big gun battleship' had been USS Michigan or Germany's Rheinland, there might never have been an evocative generic name for the type, or even a distinct popular image. We would just know that battleships after c. 1906 had more main battery guns, and became bigger overall.


Matter Beam's historical sketch reminds me of the 16th century development of the Atlantic sailing man-of-war, as haphazardly armed ships gave way to purpose built warships. But interplanetary trade warfare has a couple of interesting complications. If most cargo goes on slow orbits, either the escorts are robotic or their crews are in for a very long and probably boring mission.

On the other hand, I think that the fast-orbit passenger ships, far from being 'not valuable', are the highest value trade targets. Apart from the hostage aspect, human skills are likely the most valuable trade item. Of course, the fast passenger ships are also the hardest to catch.


Regarding HMS Hood, bad luck *does* happen, and her deficiencies did not automatically make her a floating coffin. When built she was a pretty well balanced fast battleship, not a 'pure' battlecruiser - for her era, an Iowa equivalent.

Also note that while Bismarck proved as hard to sink as earlier German battleships, she was mission killed pretty quickly, and never landed a punch on Force H. So an alternate world might not have to be too alternate for Hood and Prince of Wales to put Bismarck away. In that world, Hood might well be remembered for having 'avenged' the Jutland battlecruisers.

Alas, I don't know the game 'Rule the Waves'. The description sounds interesting, and I would love to play with the ship design engine.

Nice point from AlexT that the very term 'battlecruiser' has a high coolness quotent. The word itself had very much a marketing flavor, since it was a journalistic coinage for what the RN originally called 'dreadnought armored cruisers'. And jumping ahead to Bill's remark about star destroyers, 'destroyer' is just plain a badass term. So it is understandable that Lucas et al did not feel obligated to confine it to light escort craft!

Rick said...

Continued ...

Tony points out an entire ship type that I tend to forget, namely the fleet scout. And in fact these ships tend to be widely forgotten, I believe, in that you don't often see them mentioned in conceptual discussions of fleets, the way for example that flotilla-type escorts get discussed. (Even if to doubt their applicability in a space scenario.)

One reason, IMHO, is that while the fleet scout mission is conceptually unrelated to the classic cruiser mission of commerce warfare (raiding / raider-hunting), the actual scout ships of the battleship era were similar enough to cruisers that they were designated as cruisers (including battlecruisers), and could be built as dual-capable without too much compromise.

Fleet scouts of the battleship era even shared a romance element with cruisers, as the dashing 'cavalry' of the battle fleet - driving through the North Sea rain and fog ... glimpsing the enemy battle line through the mist ... pushing onward to gain a clearer view ...

Sailing frigates also had this dual role, as when Nelson talked about sweating 'want of frigates'. He meant as eyes of the fleet, not the commerce war mission.

Battlecruisers were not in fact capable of running from something that could defeat them. They couldn't run from other battlecruisers.

LOL! But this was true of cruisers in general, since they were rarely armored against their own main guns. In this respect sailing frigates were more robust!

WRT space warfare constellation, I'm just not convinced that highly specialized sensor and weapon platforms would be worthwhile.

OTOH, weren't scout cruisers and battleships also, respectively, 'highly specialized sensor and weapon platforms'? A 'sensor platform' might well be armed (or not; AWACS aircraft aren't armed). But the armament would be intended to support its sensor mission, not to fight it out with enemy 'weapon platforms'.

Rick said...

Re dreadnoughts and laserstars, without needing to get into the practical merits/demerits of the laserstar idea, it would lend itself to a setting analogous to the dreadnought revolution. Suppose that the previous 'capital platform' in space combat has multiple turreted laser mirrors (a fairly familiar image). Effective laser ranges are then limited by the various devils in the details.

Technical progress then overcomes many of the devils, allowing potential laser range to extend to a decent fraction of a light second. And perhaps the effective range of kinetics is also growing (as with torpedoes in the 1900 era), making long range zapping more important. You could then see interest in arming laser ships with one jumbo mirror capable of exploiting maximum potential range.

On one level the development is just opposite to dreadnoughts - reducing rather than increasing the number of main battery weapons. But functionally, dreadnoughts were associated with more centralized fire control, the whole main battery serving as a single (multi-barrelled) weapon, rather than each turret firing on its own.


In other naval/space analogies/contrasts, sad to say that cruisers, in general, may not translate into space as well as either battleships or flotilla craft. Capital-force constellations have a plausible mission, being dispatched to dominate or contest a planet's orbital space (or whatever region of local space).

But even if the overall strategy is trade warfare, the place to intercept cargo craft - or protect them from interception - is also in or near orbital space. Chasing them down along the high spaceways is probably harder in delta v terms, without much compensating advantage.
A case might be made for firing long range missiles to intercept en route, which could call for escorts. But this scenario does not have much in common with either raiding cruisers nor raider hunters.

Nor, alas, would sensor platforms of a battle constellation seem to behave, or fight each other, the way battleship era fleet scout and screening forces did. Thus no true battlecruiser analogs, even if you have spacecraft called battlecruisers. :-(


But all this really goes to an overall point that space forces may not particularly resemble navies, which is why I tend to push back against the automatic assumption of 'space navy' analogies.

Rick said...

I should perhaps emphasize *may*. I'm not arguing that naval analogies are inherently wrong, only that they are also not inherently valid.

AlexT said...

@Rick:

"sad to say that cruisers, in general, may not translate into space as well"

Commerce raiders might get sent to the waypoints in the Interplanetary Transport Network. With near-future tech, cheap large-scale transport within the Solar System would make heavy use of various Lagrange points, gravity slingshots etc. which would be prime locations for commerce raiders (at least while both sides' Grand Fleet analogues are stuck guarding homeworld).

And then battlecruiser-analogues would be needed, to hunt down raiders. This would require them to have very good strategic mobility (ie isp) and to be able to kill raiders without too much trouble. Sounds more and more like battlecruisers.

Obviously, once these ships are available, they'd get used for all sorts of things beside their intended mission. They might even get used in fleet engagements, where the heavy hitters would tear them to pieces. History does have a way..

Matter Beam said...

@Rick:

Hi! I'm glad this blog is up and running again.
You are correct about space complicating analogies, so here's another: I do not think escort missions will be routine. Think about how a slow robotic merchant fleet will travel. It boosts off from the departure point, riding its own jets or a laser beam network, and is sent on a long, slow journey through empty space.

The trajectory is extremely predictable and it goes through the space equivalent of clear water: any attack on the robot barges will be bright, visible and unequivocal in intent.

So, to defend the robot barges, you don't necessarily need to be 'already there', as the escorts in an escort mission, but only to intercept the attackers before they reach the fleet. This should be easy to do, since the interceptor fleet should have better equipment than the rogue attackers and only need to perform a single high-speed pass to destroy the attackers while the attackers need to reserve enough deltaV to rendezvous with the fleet.

What is comes down to is a race between the attackers and interceptors, which the interceptors cannot win under equal circumstances.

As for fleet scouts, I'm hesitant to fill that role with a dedicated spaceship. Compare the benefits of driving a spaceship closer to the target with staying back and simply installing a better and bigger sensor to your warship. Perhaps the role is justified, just that it would not act as we would expect it. A sensor works best when mounted independently in an environment with as little disturbances, vibrations and heating as possible. This would justify having a drone that is nothing more than the biggest, coldest and widest CCD and lens combination riding piggyback on the warships, to be deployed before an engagement and meant to stay back and not get up close to the enemy.

(to be continued)

Tony said...

Geoffrey S H:

"A laserstar sounds more like an artillery weapon than a battleship."

Totally agreed.

"Fire at a mirror in the constellation and use that to hit the enemy. The laserstar stays out of effective range the whole time. Depends on mirror vibration, etc so not likely in plausible mid-future."

IMO not plausible period, for any imaginable future. Combat mirrors are, almost by definition, lesser elements -- much lesser ones. Aside from issues of coordination in aiming, It seems to me that they would be almost impossible to defend and relatively easy to neutralize.

"I would imagine a few specialized craft...as the effective range closed. Easier to handle logistically."

Even patrol corvettes of modern navies have a selection of weapons -- guns, missiles, machine guns, maybe even some ASW equipment. While space may not be an ocean, I can't see why that would lead to warships of almost any type not needing a range of capabilities for self-sufficiency purposes.


"P.s.: People talk about battlecruisers, but no one ever mentions the Razees a century earlier..... Always thought those demonstrated Fisher's principles a little better."

Razeeing took a ship of the line down to a heavy frigate. It was in some senses an economy measure. A ship was no longer useful in the line for age or technology reasons, but it was still useful as a cruiser. Whatever battlecruisers were, they were not economy measures. They cost as much or more than battleships of the same design year and, apart from the British ones hunting down some German cruisers at the beginning of the war, they became premier assets of the fleet. It was just not the same thing.

Tony said...

Matter Beam:

"I don't think we should trap ourselves by thinking in classes and ranges."

Not classes, which are specific implementations, no. But there will be types. And speculation about the useful types seems like something interesting to do.

WRT ranges, I think that the range at which one can fight will have a lot to do with the necessary types. SO we need to pay attention to plausible ranges of plausible weapons.

"As Rick pointed out, space warships will be built like trains. Each 'wagon' is an otherwise independent spaceship, but are put together to accomplish a task.

So, we'll have a propulsion unit, a power unit, an appropriate radiator unit, a crew unit, an armored nose unit..."


I don't think Rick ever pointed that out. He has considered in writing the potential advantages of modularity. But I don't remember him stating that modularity would naturally dominate other considerations.

"A laserstar would be a huge honking power generator attached to an array of radiators and a laser generator at the end. You can stick a large lens in front, an armored nose cone or extra tanks of propellant. Swap all this out for hollow boxes of missiles and you've got yourself a missile carrier."

Ummm...sensors? And how well integrated would sensors be with command facilities and those facilities with weapons, in a modular structure? what kind of structural integrity would modular craft have under maneuver? Even with the high modularity of weapons and some sensors in modern combat aircraft, for example, we still find it advantageous to integrate propulsion, main fuel supply, command, and the most powerful sensors into one package. Now some of that does have to do with the constraints of aerodynamics, ut still, one could imagine putting the main radar in a module, or the guns, or more of the fuel. But we don't, because integrated systems work best when they're...wait for it...integrated.

"Dedicated interplanetary sections propel the rest of the stack at the target... then detach an retreat."

Once they get the "stack" on the way, they're not just going to stop and turn around. The best they could do is miss the target space by some hundreds of thousands or millions of klicks, then recover at the launch point some years or months later. Seems like a pretty wasteful way of managing equipment, putting whole complex, expensive -- and thus relatively rare -- systems out of useful position for a long time for the purpose of one operation.

Tony said...

Matter Beam:

"Propellant sections are ejected as they are emptied, to be recovered and assembled into a empty tender ship that awaits a tanker arriving after the battle is over."

Propellant tanks that are abandoned on orbit just keep on going. If your interplanetary speeds are high enough, they just keep on going out into interstellar space, hardly worth tracking down and recovering. Even if they stay in-system, the orbits that they might be on might make them too expensive to recover.

"The armored nose cones can be swapped out after being damaged."

Where, in the battle space? Do we have a tender that does nothing but carry spare armor sections?

And in reality people rarely consider the logistics problems of interplanetary warfare. It's not likely you can compel your enemy to replenish your supplies. One of the tactical objectives would probably be to drive him out of space, including his surface to orbit capabilities. So once you win, everything necessary still has to come from home. Basically all you achieve is the necessity to establish an expensive, hard to maintain, and open ended orbital guard commitment over the enemy planet.

"I don't believe range is a factor either. The laser weapon web can be deployed by any laser star to massively increase its strike range..."

Range with lasers is necessarily more a function of being able to hit the target, and maybe even keep the beam on target, if one quick pulse isn't enough. As already mentioned, combat mirrors are probably not going to be useful.

"The same goes for kinetics. The most important measure for kinetics' range is relative acceleration vs relative velocity, or more accurately the relative deltaV that can be expended during the time-to-target."

That's why kinetics would be relatively short ranged weapons, and why guided missiles would have utility. They can adjust their trajectory after launch. But, once again, there's a range limitation. In space there's no reason to have cruise missiles, so a guided missile would likely expend most of its fuel on getting up to speed, then separate the warhead (explosive or inert) so that the maneuvering thrusters have as little mass to work on as possible, thus maximizing the value of maneuvering propellant. But of course maneuvering capability is still finite, so past a certain consumption of fuel, the enemy target can dodge. Note that there is a range associated with this. It's not the range at which the enemy can be detected and targeted reliably, which is probably well past the distance over which a missile warhead would travel while still able to maneuver, probably far past. So the effective range is the distance the missile warhead can fly before being detected, plus the distance over which it can travel while maneuvering to hit a dodging enemy.

Tony said...

Matter Beam:

"If stealth is a factor, it really changes things. I strongly believe that infrared and radio stealth can be achieved during manoeuvring using 'midfuture' tech this blog assumes. It would allow, for example, small, cold, slow kinetics to defeat hot RBoDs blazing across the sky, of for laser webs to set up 'terminals' behind the targets and zap them up the nozzle..."

Nope, because the enemy can use radar to detect combat mirrors within range. This is practical because I don't think emission controls mean much at ranges that lasers would be actually capable of hitting anything, especially with the added complication of using combat mirrors. One would light up radars before coming into laser range, because it's likely that one would already be detected at that point.

The real deal is not stealth, but low observability while on transfer orbit between planets. Even then you're just widening the possible window you could come out of, not causing any great mystery about the general direction you're coming from. After all, even without the ability to monitor the whole sky -- and I don't think that kind of thing is likely -- powers could still afford to observer enemy planets and bases. So they could detect and monitor departures, and at least figure out when the attack is likely to arrive. About all the attackers can do is make low energy maneuvers as far away from the objective as possible, so that they could slightly adjust arrival time, arrival angle, or the configuration of their attack formation.

Tony said...

AlexT:

"Maybe I've not looked well enough, but arguments I've come across postulate huge numbers of superb detection systems working perfectly well all the time, as well as being perfectly protected against any enemy action. The predictable result being, of course, a cosmic game of perfect information where the (probable) loser is predetermined and might as well give up immediately."

This is why I've always been dubious of the idea. There is, by the inescapable workings of optics, a practical detection horizon for a given intensity of energy. The problem with detecting non-maneuvering spacecraft at interplanetary distances is that one needs something like an IR Hubble to do it. But such instruments create the effect of trying to watch a baseball game through a soda straw. What are you really going to see? and it's even worse than that, because such instrument's have to be slewed slowly, then allowed to settle down before collecting light. Try to do even a plane of the ecliptic scan under those constraints. But even a plane scan wouldn't be enough. Enemy ships might be as high as ten degrees off of the ecliptic, because they could be coming from asteroids at high inclinations.

What one might reasonably achieve is close observation of known enemy planets and bases, so that departures and arrivals could be detected. One might also manage an all-sky scan of space close to defended bodies, to detect the enemy when they come. But that would be only good for a few million klicks, maybe.

"My point is that deception and concealment have been and will remain the key to winning wars, however technically cumbersome they may be."

Yep. And this is where space would be like an ocean -- your enemy can be over the observability horizon and practically detectable only when he crosses that horizon, or decides to emit.

Tony said...

Thucydides:

"No stealth in space is simply a result of thermodynamics, whatever you do is against a very cold background..."

If any of that were absolutely true, you could see the galaxies in the Hubble Deep Field with just any old telescope. But it turns out that there is an inverse square law and instruments have limited sensitivity. This establishes a practical observability horizon, based on object energy, instrument sensitivity, and the ability to scan the whole area of sky that the enemy might be in. And, I'm sorry, but past a few million klicks, several thousand kilowatts, at a couple of hundred degrees* takes a pretty good instrument with a limited field of view.

*What housekeeping waste heat might be for a medium sized warship on interplanetary transfer orbit.

"As for single system ships, while Tony is correct that extreme specialization is not a great way to go, the rocket equation tells us every gram counts. A general purpose "Frigate" mounting missiles, lasers and railguns will have much less capable systems than an equivalent ship which only carries one system, or alternatively the ship with one system will have much more deltaV than one lugging around extra mass of multiple systems."

All other things being equal, yeah, sure. But all other things aren't equal. You have to have the weapons, sensors, and propulsion that you need when you need it. Patrol ships -- the majority of your ships, in any likely fleet -- certainly need a variety of capabilities, because any mission they might be on might require any one of them immediately, not after the right capabilities can be assembled.

Now, the battleships that fought at Jutland might have gotten away with just their main armament, for all that they fought in large formations surrounded by cruiser squadrons and destroyer flotillas. Those cruisers and destroyers each needed a variety of weapons -- guns to fight each other and torpedoes to attack larger ships. (Because their guns couldn't be effective against the next larger class of ship before the larger ship could defeat them.) But the battleships, because they were so big, and so heavily armed, had their own limits. They were basically designed to fight each other. If they carried no anti-destroyer/cruiser armament, they wouldn't have been able to go anywhere without escorts. Even with close-in defensive armament, battleships and battlecruisers still didn't go anywhere without escort.

I'm not seeing how space is so different that similar -- or perhaps even effectively the same -- rules wouldn't apply. Patrol ships will need multiple capabilities. Escorts will need multiple capabilities. And capital units may only be able to fight each other.

Tony said...

Matter Beam:

...a hobby-grade infrared telescope (10cm lens?) hooked up to a gamer's desktop can scan the entire solar system in less than 4 hours and pick out 300K radiators from life support out to the orbit of Pluto.

300K is 80F. On a summer evening in most of North America, the air in front of the telescope is hotter than that. Much of the time in the winter the sky is covered with clouds that can block significant amounts of energy from even the Sun.

Okay, let's move things out into space. You still have the inverse square law. Hobby telescopes have how much sensitivity exactly?

AlexT:

"Not sure where your numbers came from, could you link some specs ? I've had trouble finding this sort of quantitative analysis.
300K radiators of how many watts please ? Or am I seriously mis-remembering basic physics ?"


AFAICT, his numbers come from nowhere. No you haven't mis-remembered basic physics. But I think some people could benefit from an undergraduate level astronomy class...

Tony said...

Geoffrey S H:

"You need a 'class' for a spacecraft so that you have an easy to remember name."

You need types, as in "battlecruiser", "destroyer", etc, so that people can know what you're talking about in general terms. A class is a specific implementation, like Iowa class, or Mogami class.

"Doesn't stop it from being highly moduler, and I don't believe that that the millions of potential combinations of modules mean that they will all be used. Certain common combinations will emerge as space warfare develops."

Still don't see the superiority (or even parity) of modularity over purposeful integration.

Tony said...

Thucydides:

"To answer Matter Beam and by extension Tony, single purpose spacecraft will be individually more capable than multi purpose frigates, but since they will be operating in constellations of ships, each with different properties, then you would almost have to think of the constellation as the "ship" and a Kineticstar, Laserstar or support ship as one of the modular units that make up the constellation. Taking this to extremes, Geoffrey would then be talking about a "frigate" Constellations of small, high ISP ships, or a Dreadnaught Constellations of massive ships carrying huge weapons arrays (RBoDs, batteries of SCoDs, scores of CASABA Howitzers or railguns firing hypervelocity projectiles)."

Still not convincingly realistic. Most ships, at most times, need a variety of capabilities in order to function. Piecing out all of those functions individually to elements just makes things inefficient as h3ll. There's no reason to have a frigate constellation when a frigate will do. Why have all of the overhead for six individual ships, let's say, when we can have one set of overheads for a single ship? Why pay the cost of coordinating all of those units, when one unit can coordinate within itself much more effectively within itself? I'm sure a few runs of fiber optics on one ship is cheaper and more reliable than several laser comms emitter/receivers on each and every constellation element. And that's just the most obvious, off-the-top-of-the-head example of single integrated unit efficiency. One could speculate about building and maintaining a single propulsion plant instead of several. The same goes for sensor systems, command and control facilities, life support, etc.

In short, T, it might be a little bit more realistic to think in terms of economics and logistics, instead of letting the imagination run away with neat seeming ideas.

"As an aside from space war, but keeping with the topic of naval evolution, the US Navy was recently started rethinking itself for the 21rst century: Thinking outside the hull...Would it be worthwhile to build missile armed "battlecruisers", or have a large fleet of "Liberty Ships" with deck space for landing and utilizing missile containers instead?"

The big difficulty with unsophisticated missile shooters is that they can be detected and identified as such, and removed from the order of battle relatively quickly and easily. Just like destroyers and cruisers that could threaten dreadnoughts with torpedoes, future space missile shooters will need the ability to fight to defend themselves, or they'll never get close enough to shoot.

Tony said...

Rick:

"Tony points out an entire ship type that I tend to forget, namely the fleet scout."

I did?

"LOL! But this was true of cruisers in general, since they were rarely armored against their own main guns. In this respect sailing frigates were more robust!"

Sailing era warships weren't all that robust. They got suddenly very fragile when shell guns came around. Turns out they were robust against inert shot, but not against chemical energy projectiles.

"OTOH, weren't scout cruisers and battleships also, respectively, 'highly specialized sensor and weapon platforms'? A 'sensor platform' might well be armed (or not; AWACS aircraft aren't armed)."

Without a doubt. But let's keep in mind that unarmed scout aircraft either possess very long range sensors (AWACS) or they rely on some kind of surprise or speed to make their missions happen. AWACS might translate into space warfare, but would SR-71 or a reconnaissance fighter?

"But the armament would be intended to support its sensor mission, not to fight it out with enemy 'weapon platforms'."

Well...depends on your assumptions. At Jutland, Beatty had to fight it out with Hipper in order to get close enough to the German main body to locate and identify it. Conversely, the damage Hipper's battlecruisers took during that fight made them so weak and that they couldn't resist Beatty shoving them away from the Grand Fleet, leaving Scheer to be surprised by its appearance in front of him. So if horizons of some kind exist, and the enemy can make you fight to cross them, then scouting becomes all about shooting it out.

Tony said...

Rick:

"Re dreadnoughts and laserstars..."

All good points. but let's never forget that capital units of this type tend to get specialized to fight each other and become very limited in what they're actually good for. They tend to become enablers of the rest of the fleet, by protecting them against their opposite numbers in the enemy array.

"In other naval/space analogies/contrasts, sad to say that cruisers, in general, may not translate into space as well as either battleships or flotilla craft."

There will always be a need for patrolling craft. And cruisers tend to accomplish their missions near land, or in the vicinity of the fleet base or the fleet itself. I'm sure the same would be true in space. Cruisers would visit outposts and provide a police/deterrent service. They might shadow enemy outposts at a distance. Even if they're seen, as they likely would be in space, the rules would very probably be that you can't shoot them just cause they're there. On the other hand, they are there, and if shooting starts they have to be dealt with -- probably by your own cruisers. And of course there's the use they would be in the battle fleet, carrying whatever weapons might most be effective against the enemy fleet, his orbital facilities, and maybe even his assets on the ground.

"But all this really goes to an overall point that space forces may not particularly resemble navies, which is why I tend to push back against the automatic assumption of 'space navy' analogies.?"

Seems to me that a lot of the same missions would exist, requiring analogous capabilities. The requirement for analogous capabilities might not lead to similar solutions, but I tend to come down on the side of "show me why not".

And, to be honest, I haven't seen much to convince me that space warships wouldn't have a lot in common with naval vessels of some era, simply because we are dealing with humans and the constraints of human societies and economies. You just can't send nuke drones or RBoDs to do the job. Capabilities have to be flexible. Missions will be long -- as in shipboard capabilities long, not aircraft flight long. People will have to stay in the near-real time loop, meaning manned capabilities will have to be provided for in each potential conflict space. Marines (sorry, "espatier" is way too contrived for me) will have to board vessels and land at facilities, to police or fight in situations where bombing or burning just isn't the thing to do. Patrolling and policing in general will have to be done. Hard to see how all of this wouldn't be more naval in character than air force or army.

Thucydides said...

WRT the issue of sensors, megapixel sensors currently exist and are often built using the components of cheap cell phone cameras. The general plan is to assemble a multitude of these camera components in a "fly eye" arrangement yet the results are startling, allowing for wide angle coverage, almost infinite zoom and depth of field (a typical example is to shoot a cityscape, then enlarge a view down a street and pick out and read the licence plate of a particular car in the background, which is not even visible in the overall shot). It seems a natural progression to build units like this "on a chip", and in space, sending these things out in the hundreds or thousands on drones in a sphere out to one light second in diameter to provide a finely grained 3D representation of the space around you is almost a no brainer. "Sensor arrays" of almost any arbitrary size can be created using this technique.

Places which already deal with space traffic (orbital space ports, planetary mass drivers, momentum transfer devices like tethers) would have these sorts of sensor arrays almost as a matter of course, and any space fleet would be very keen to tap into this existing infrastructure to do the long term surveillance, as well as providing a sort of long range baseline when combined with the deployed sensor array of a constellation in flight. As a bit of an aside a way to really get the jump on potential opponents would be to use the "Server Sky" technique to fill large areas with a multitude of inexpensive sensors. Since individual units are potentially the size of postage stamps, it will be exceedingly difficult to identify, much less blind all the sensors. Slowly moving clouds drifting towards the expected trouble spots would provide the detailed intelligence picture in a multitude of wavelengths long before the constellation arrives.

In a way this is an inversion of Rick's observation that battleships used centralized fire control systems (optical rangefinders until the development of radar) to control a multitude of cannons. With the rocket equation ruthlessly stripping away ancillary systems so the platform can have the maximum performance, you have one "big gun" surrounded and directed by the information of a multitude of sensors.

This is why I disagree with Tony on the utility of "single purpose" ships, the hit you take by adding extra equipment makes your ship more vulnerable and less able to maneuver, or alternatively you make each ancillary system smaller and less capable compared to a single purpose ship of the same mass. You can also work the other way, a ship with a single small laser/railgun/missile battery will have much better performance (to a point) than a much larger ship. Being able to dodge is about the only performance factor that counts once you get into weapons range, or being able to use more deltaV to do things like change orbits (especially when doing it "out of sight" like making a burn on the far side of Jupiter, making the enemy cover a much wider possible range of orbits when you reappear).

As a final thought, Constellations might resemble something like an Aldrin Cycler for much of their lives, keeping everything in a large, armoured "shell" while on patrol, but dispersing small "battle riders" and sensor drones when it is time for action.

Rick said...

Hi all -- RM suffered a hosting glitch, but it seems to be fixed now.

So carry on!

AlexT said...

@Thucydides
"Sensor arrays" of almost any arbitrary size can be created using this technique.

The sensor swarm is a cool idea. But the fact remains that you need to detect very very small amounts of radiation, and the sensors in individual swarm elements would be pretty low-quality. Meaning the ship would be effectively invisible to the swarm, because its photons aren't enough to flip any of those megapixels from 0 to 1. Feel free to point me to where this is discussed and analyzed using actual numbers.

Other problems with the swarm:
Each element needs to survive in outer space: solar wind, flares, cosmic rays.
Each element needs to survive enemy action. Would nuking the swarm work ? Neutron bombs ? Shining a bomb-pumped laser in the general direction of the swarm, to fry their sensors ?
Would they need to maneuver at all ? That would mean more mass, more things that can break..

Thucydides said...

The sensor swarm is simply an extension of optical interferometry, an already well established technique right here on Earth. A swarm of sensors a light second across would be the equivalent to a mirror one light second across While such a huge mirror would be rather unwieldy, it certainly can be subdivided into a multitude of of smaller mirrors to allow 360 degree coverage of the sky.

And don't forget the navy might want to coopt existing mirror swarms around space stations, launch facilities and other installations to create even greater sensor coverage. The future of a space enabled civilization is going to be full sensor coverage of everything. Even if there was only a "space guard" on the lookout for stray asteroids, then there still is an incentive for an all sky surveillance network based on thee principles.

Anonymous said...

Another problem with these sensor swarms is communicating with them and the signal processing and information integration. Both of those requires massive computer power and a huge antenna array. Power, cost, mass, heat...accessing these arrays may be more difficult than building them. About multi-purpose warships vs. single weapon types: if every gram counts, then you might want a limited number of dual-purpose weapons. You might wind up with a ship that has a massive energy weapon and scores of tiny point defense rockets; or a ship with a couple of medium-small energy weapons and a few Scary-As-Hell missiles; or you could just put a few point defense weapons on a sensor ship and have it carry a few combat drones. Besides, when the only difference in firepower between corvettes and battleships is the number of salvos and the number per salvo they can shoot, you might want to rethink your ship and fleet design.

Ferrell

Thucydides said...

We live in a society today where Amazon can rent you hundreds to tens of thousands of cores to build your own virtual supercomputers, so I doubt the amount of computational power available will be a limiting factor. Given the current generation of megapixel sensors is built from cellphone parts, cost isn't a factor either.

Server sky is a conceptual means of creating million of sensors "on a chip" with their own built in sensor array, solar cells and processor, demonstrating one way that this could be instantiated. Drones carrying megapixel arrays and ballistic clouds of server sky units provide the conceptual model of how it can be done.

Matter Beam said...

@Tony

-Ranges: I meant that the effective range of each weapon is quite variable and depends on the mission. A 'long-range' laser might only have a short range against small targets such as missiles, while slow kinetics might become long-range weapons when fired from an interplanetary intercept trajectory.
This means we cannot compare ranges in a 1:1 ratio.

-Sensors: Considering how easily detected spacecraft are once a battle starts, what with their drive plumes and hot radiators, sensor packages so small as to become negligible in mass and energy requirements are more than sufficient.

-Modularity: The point of modularity is to have the best possible spaceship for each situation, from interplanetary travel to defense or offensive tasks. There are external advantages, such as economical savings from producing modular components or increased survivability from investing in self-sustaining ship sections, and I am not denying that some systems work best when integrated together (such as a laser generator and heat management system) but even those can just be made into larger and less flexible modules.

As for the propellant tanks, they would detach along with the interplanetary drive section after the braking burn into orbit. The interplanetary drive sections and the propellant sections slowly reassemble to be refuelled while the combat sections go into the battle with reduced deltaV but higher performance engines.

Replacing armor... no, not a dedicated tender, but more like an exchange between spaceships in battle. If lasers and kinetics are in play, we'd have armor rated in 'laser hours' which indicate how long they can stand up to laser fire, much like battleship armor was classed by immunity to certain calibers, plus or minus some specifics. One spaceship could be a kinetics craft that made close pass to the targets, dropped its load and retreated. Its buddy is a laser spaceship. The kinetics craft detaches its partially depleted armor, gives it to the laser craft, and the latter can now drive in for a close range strike. This way you only need one armor plate for two ships.

-Laser ranges: A valid point made here is that telescopes and lasers are aimed equally well. If you can hold a steady image on the target, you can lay down laser fire equally accurately. For reasonable lasers, the diffraction limit is a bigger problem than mechanical ability to point at a target. So, a laser web would vastly increase range by both overcoming the diffraction limit and by replacing the large, hot, vibrating laser ship with a lightweight, cold adaptive lens close to the target for better accuracy.

-Kinetics range: I was trying to come up with the most general description of kinetics performance with that quote.
If use insist on using 'range', consider this - a defensive missile that doesn't accelerate towards its target, just matches 1km/s of lateral motion for an intercept vs a missile with 10km/s of deltav being fired at a target leaving LEO at 9km/s. Which one has more 'range'?

-Mirror detection: The stealth I always refer to is a supercooled shell surrounding the vehicle while it manoeuvres with thrusters that produce an equally cool stream of exhaust. By supercool, I mean under 20 Kelvin, approaching 4K temperatures using active pumping. It is physically impossible to detect the emissions of such objects.

A mirror can move into position using cold gas thrusters while staying inside its shell until its hydrogen reserve is all boiled off. When it needs to be used, it inflates the mylar balloon, delivers the strike and retreats after either deflating the balloon and scooting away... or just dropping the balloon. Balloons are lightweight and it could carry many of them after all.

I would talk more about stealth, but I would not want to derail the thread. Unless, it is what you want?

Rick said...

A few random zaps ...

Mirror drones - My beef with these is that a mirror able to be a useful range extender will probably be fairly big, thus fairly heavy. I suspect you'd be better off just adding a laser and having a full laser platform in its own right.


Modularity - I don't regard modularity as a given, but as something to think about. And more in terms of transport missions than space warcraft. See the links below for more of my thinking on this:

http://www.projectrho.com/public_html/rocket/basicdesign.php
(about 1/5 down the page)
http://www.rocketpunk-manifesto.com/2009/10/spaceship-design-101.html

My impression is that recent efforts to build modular drop-ins for naval craft (such as Scandinavian corvettes?) have been something of a bust. In part because there's not much actual occasion for swapping out a ship's fit, and in part because doing so is a pain, requiring special facilities.

But if a high level of modularity, a la trains, is the general norm, military planners will come out of that mindset. (And clamping a module onto a spacecraft is simpler than hoisting it aboard a sea ship. That said, a couple of military specific considerations. A laser and its optics pretty much need to be a single rigid structure, though an electric power supply (eg reactor) can be separate. At the other extreme, drop tanks are a gimme. If you can leave them on a recovery orbit, fine; if not, you kiss off the tank, but that is also fine.

Box type VLS launchers for missiles also seem fairly straightforward, and I could see defensive armament pods attachable to cargo craft as viable against relatively simple threats, especially if there's no need for independent tactical maneuver by 'convoy escorts'.


Logistics - @Tony, people rarely consider the logistics problems of interplanetary warfare
This strikes me as a vast understatement! At the most basic level, an expeditionary force needs to carry round trip delta v, *plus* whatever you need for combat, as well as operational maneuvers in the local space around the objective. This could end up being effectively a deal breaker, because local defending forces would have such an enormous delta v advantage.

Basically all you achieve is the necessity to establish an expensive, hard to maintain, and open ended orbital guard commitment over the enemy planet.
And this! Interplanetary warfare could end up never happening, because no offensive operation is practical to carry out.


Stealth - @Matter Beam, I would talk more about stealth, but I would not want to derail the thread. Unless, it is what you want?
This thread seems pretty broad focus, so I'm not sure anything would be derailed! But I'd suggest that 'stealth' is not a thing unto itself, but rather just one form of military deception. The objectives are surprise and/or confusion, which might be achieved in a variety of ways.

Geoffrey S H said...

@ Tony:

"Still don't see the superiority (or even parity) of modularity over purposeful integration."

I was effectively agreeing with you there. Modularity can only go so far. There's nothing stopping an integrated weapon from firing multiple ammunition types anyway.

That said,thankyou for correcting me on type v class. Memory got hazy there.

"people rarely consider the logistics problems of interplanetary warfare"

They never consider procurement either!

Regarding specialisation, it's easier to leave a multi-mission warcraft around, say, Callisto, than suddenly find that that laserstar orbiting that moon is in a heating up warzone without kinetic support.
Even when imagining over-the-top RBOD laserstars some years ago, I always made sure they had two smaller pds mirrors and the ability to fire lightcraft kinetic ammunition as a backup.

@ Rick:

"And this! Interplanetary warfare could end up never happening, because no offensive operation is practical to carry out."

Frankly, I'm beginning to think conflict wouldn't happen at all unless each nation is completely secure against planetary assault (that includes all planetary colonies). You don't want to lose a war and find laser sats overhead enforcing a regime that is impossible to throw off. A comparatively limited war is the only possibility.



Regarding logistics- might laserstars send lightcraft between formations, loaded with supplies? Is that feasible? Or would the supply loads require RBOD power levels (and thus unfeasible power levels)?

Thucydides said...

Given the extreme costs and specializations of either individual warships or fleshed out constellations, we might see something like WWI, where mighty battle fleets remain in secure asteroid bases or orbiting moons under the watchful gaze of gigawatt laser launchers on the surface, because to send them into battle is to risk destruction and total defeat. Of course, you can ask Imperial Germany or Tzarist Russia the consequences of leaving the fleets and their crews idle for prolonged periods of time......

It isn't really clear what would break the stalemate. since most of the same factors would apply to any sort of spaceship. Building fleets of Corvettes simply substitutes small, low value targets for large, high value targets. Maybe instead of Space Operatic fleets we will need to look at economic sabotage, "Hybrid Warfare", Special Operations Forces and other asymmetric means of carrying out "politics by other means". Space warfare will indeed be vary different from what we know and understand today.

Matter Beam said...

@AlexT:
Sensory Arrays: The array can function as a very high resolution camera that takes in the whole sky at once. It must be paired with a narrow-angle high sensitivity sensor that is directed by the array to focus on specific parts of the sky where a spaceship is expected to be.
Communication between elements in the array can be accomplished by simple radio. Unless your target is much closer to the elements than they are with each other, radio can serve to communication while dissipating enough to not leak to the target.

If you try to attack the swarm with a powerful enough attack to wipe it all out, like a nuclear warhead... you've wasted a multi-ton expensive weapon to have a chance at removing kilogram-sized sensors of which you have thousands of.

@Ferrell:
I strongly doubt that massive computer power is going to be that expensive on a technologically advanced spaceship... because the sensor's array's job is to find anomalous sectors of the sky that the sensitive sensors should be directed at. It therefore only has to assemble images of relatively low resolution into a single high virtual resolution image. This is something modern GPUs do today relatively efficiently.

The second argument is that if spaceships are 'hard' to detect from a single sky scan, then they're not torchships shining like continuous nuclear detonations. Conversely, low energy means they are not zooming across the sky. You'll have more than enough time to complete your full sky scans before the potential targets have time to move outside of one pixel of your wide-angle scan.

Multi-weapon warships:
I think we must distinguish between a 'weapon' used offensively or defensively. Offensive weapons must be min-maxed to defeat the opponent's offensive capabilities in a critical characteristic such as accuracy, diffraction limit, output heat tolerance ect. Defensive weaponry aren't necessarily the same technology as used in the offensive weapon and don't have the same requirements. While the offensive weapon must be a specialized, extreme tool, the defensive weapon must counter all threats in all situations. The defensive capabilities do not have to mass very much or consume much energy either. Consider the point defense CIWS weapons mounted on guided missile frigates. They are literal bolt-on equipment that does not really cut into the frigate's main offensive missile capacity.

@Rick:
-An adaptive reflective surface isn't too heavy. One of the main advantages of a mirror swarm is that the beam can be bounced and re-focused from reflector to reflector up to the target, hence the 'web' in laser web. This means that the mirrors only need to be effective over inter-reflector distances instead of the distance to your target.

For example, if you currently need a 10m radius mirror to do damage to a target at 4000km, you can instead use a series of 1m mirrors. The spot size needs to remain within 1m radius to be fully refocused. A 400nm/10m radius laser blooms to 1m radius spot size at about 4000km. At this distance, you are not doing any damage to your target. However, a 1m radius refocusing mirror at this distance will either transport the beam another 4000km or focus it into a deadly beam within 400km.

Initial set-up: deals damage at 4000km, requires 314m^2 mirror.
Laser web set-up: deals damage at 400km, beam can be transported for 4000km per refocusing mirror, requires 2 or more 3.14m^2 mirrors.

-Stealth is not a monolithic present or not concept, and doesn't necessarily rely on contrived circumstances or specific settings. There is a technological, physics-backed and mathematically certain method of reducing all emissions to near zero. I only hope this fact is considered more often when discussing a 'plausible mid-future' where vast quantities of liquid hydrogen, compact nuclear thrusters and massive first-strike advantages are all in play.


AlexT said...

About a swarm of cheap little sensors using interferometry to detect enemy ships:

There's obviously a confusion between resolution and sensitivity. Interferometry is great for picking out high-resolution details of very bright, very far-away objects such as galaxies etc. The swarm could have comparable resolution with a mirror of comparable size but it would actually have lower sensitivity. Great for mapping the stars in distant galaxies. Spotting ships in-system - not so much. There is a significant difference in apparent magnitude.

@Matter Beam
"If you try to attack the swarm with a powerful enough attack to wipe it all out, like a nuclear warhead... you've wasted a multi-ton expensive weapon to have a chance at removing kilogram-sized sensors of which you have thousands of."

If the swarm elements are small and cheap, the enemy doesn't need many costly weapons to burn the lot. If they're hardened, they're expensive enough to warrant spending even more nukes on them. Besides, blinding one's enemy is never too expensive.

"The second argument is that if spaceships are 'hard' to detect from a single sky scan, then they're not torchships shining like continuous nuclear detonations. Conversely, low energy means they are not zooming across the sky. You'll have more than enough time to complete your full sky scans before the potential targets have time to move outside of one pixel of your wide-angle scan."

Torchship camouflage would be difficult while thrusting. So you launch them quietly, they coast towards the target and only turn on their drives when it's too late for the other side to react effectively. Valid both for attacking enemy static targets and for intercepting attackers foolish enough to approach with engines blazing. And the "full sky scans" that detect every speck of dust continue to sound like fantasy.

AlexT said...

Dreadnoughts:

I think the most significant feature of dreadnought battleships was the ability to resist weaponry similar to that which they themselves carried. Not indefinitely and not without some damage to less-important parts and areas; but they ought not to be knocked out in a couple of salvos. The British tried to deviate from this principle and paid the price at Jutland and with the Hood.

In space, with near-future tech, this becomes difficult. Defense would be more a matter of hiding (the stealth thing again..) or point-defense interception against missiles and dumb kinetics. Which is more like submarines or modern destroyers than battleships.

The most dreadnought-ish defense would be some sort of armor. Some kind of ablation shielding against lasers, high-strength plates against kinetics.. well-spent mass if the ship can stay in action.

But if something is called a dreadnought, it had better be able to take punishment and keep shooting.


Logistics in space:

Armies and fleets have always been huge wastes of resources and that never stopped anyone. The combat fleet will probably be accompanied by a vast fleet of supply ships (probably automated) possibly with more being continuously sent from home. The defenders have a shorter supply line, but that's not enough to win against a logistically competent attacker.

Hugh said...

One of the advantages of both battleships and battlecruisers over a swarm of smaller ships is that they're just so damn impressive. It may be even more important in peacetime than in war to have monster ships.

One of the points O'Connell makes in "Sacred Vessels" (which for those who haven't read it, is entertaining and interesting even if you don't agree with the author) is that the emotional appeal of dreadnoughts led entire organisations or even countries into finding excuses to have them regardless of military usefulness. Even a more sympathetic author like Peter Padfield wrote that the pre-WWI dreadnought mania could be compared to medieval cathedral building. Brazil, Argentina, and Chile all spent fortunes buying dreadnoughts.

In space, prestige will still be a factor. I'm sure the Empire in Star Wars had critics both inside and outside the military asking why so much was being invested in giant Star Destroyers without support vessels. The opening scene of Star Wars is a pretty good advertisement for just why the Empire would find them useful. No-one seeing that pursuit and capture, even from a distance, would have any doubt about who is the biggest and baddest.

Matter Beam said...

@AlexT:

Drone sensor arrays are necessarily widely spaced apart. You cannot take out a lot of them at once because your nuclear explosions aren't big enough and lasers would either have to diffuse their beam to uselessness or spend an inordinate amount of time tracking, targeting and focusing down individual sensors.

Torchships: Launching them quietly is the hard part. How do you impart enough deltaV for them to leave orbit on a trajectory that intercepts their target? It requires a lot of energy expended over a short time frame. If the deltaV involved is tiny, it can be achieved with cold thrusters. If the torchships are tiny, they can be externally propelled with heatsinks absorbing the waste heat. If it is neither, then we have a blazing hot exhaust plume lighting up the solar system's sensors.

Fully sky scans: These wide-angle scans only need to pick up sectors of the sky which have more than expected photons or photons of specific wavelengths. They do not need the resolution to spot specks of dust, only enough to distinguish a planet from a star. Once the anomalous sector is flagged, more sensitive telescopes will focus their attention it and repeat with ever more finely-tuned narrow-field sensors until the spaceship is picked up with excruciating detail. Set a laser tag to illuminate the target and you can return to full sky scans for the next target.

Logistics: Military fleets are an expense leveraged out of trading income. A fleet goes to places where your trade interests are under attack, otherwise you'd just build orbital defenses at lower cost.

So, military fleets can be seen as a percentage tax on trade profit. They are necessary to protect trade, and a protected trade earns more and increases fleet size in a positive feedback loop.

However, fleet costs can balloon when your rivals have fleets of their own that can ruin your entire investment unless you drop a lot of cash on new designs. That's the age-old arms race that breaks the trade-military relationship.

AlexT said...

On-topic (dreadnoughts):
WW1 dreadnoughts were big and intimidating, sure, but they weren't just vanity projects. Whenever lighter ships like destroyers or even cruisers came up against dreadnoughts, they fled or were obliterated. At the time, at that tech level, if you were serious about controlling the sea, you had to have them.

Off-topic (stealth):
The NIRCam is the infrared imager on NASA's next space-based infrared telescope. I think it's fair to say this is near today's state of the art. It is said to pick up 29-magnitude sources if it stares at them for about 10,000 seconds, so roughly 2,8 hours. It so happens that 29 is about the apparent magnitude of a 20 kW radiator at 1 AU. For comparison, NASA had a design for a Mars-going crew compartment for 6 people radiating about 15 kW of heat in cruise mode.

Now, with its 2.2 x 2.2 arcmin^2 view angle, NIRCam it needs about 743 snapshots to cover one square degree, of which there are about 41,252.96. So, it should complete a whole-sky survey in about 85,820,660 hours. That's about 9,700 years, give or take a few decades.

And this is the state-of-the-art. Any sensors cheap enough to spray the whole solar system with them would be many orders of magnitude worse.

Telescopes keep improving, sure. Then again, that Mars lander wasn't meant to stay hidden from anyone either.

If we're sticking to near-future tech and if the numbers aren't way off, the demise of stealth has been greatly exaggerated. Much more likely, there'd be no space battles because a competent enemy would be nearly impossible to find.

Matter Beam said...

@AlexT:

Dreadnaughts: Exactly! They were revolutionary ships that immediately made everything before them seem small.

Stealth: The NIRCam would be an example of a narrow-angle high sensitivity camera you would employ to investigate anomalies detected by wide-angle low sensitivity sky scans.
It is also poorly suited for detecting in-system objects. It can detect objects with an accuracy far greater than what is required to track spaceships.

AlexT said...

@Matter Beam: "The NIRCam would be an example of a narrow-angle high sensitivity camera you would employ to investigate anomalies detected by wide-angle low sensitivity sky scans."

The quick low-sensitivity scan will not pick up an "anomaly" in that direction. It simply can't tell there's something there.

Rick said...

I love the crunch of numbers! Hat tip to AlexT for the NIRCam example, which gives us something to work from. But now I get to zap back :-D

NIRCam combines ueber sensitivity (apparent mag 29) with ueber precision (0.07 arcsec) But we don't need such high precision for full sky search, just the sensitivity. Change the telescope focal length so that resolution (= precision) is 10 arcsec instead of 0.07 arcsec. The field of view of the full array will be larger in proportion, ~5 deg, and the number of snapshots needed to cover the sky falls by a factor of ~20,400.

Which means that the time for a full sky search falls to not quite six months. Provide an array of 180 units and you perform a coarse resolution full sky search (mag 29, precision 10 arcsec) once a day. Yes, 180 James Webb Space Telescopes is a lot, but a) we are implicitly assuming that space hardware in general is a LOT cheaper than today, and b) we are throwing Pentagon money at the problem, not NASA money.

To be sure, there are other complications. You need high enough resolution that most individual pixel elements won't register a bright enough natural source to overwhelm the target signal. I do not know the number of apparent mag 29 IR objects in the sky, but you are dividing it into ~60 billion bins.

But in any case the real problem for stealth is concealing the enormous power output of propulsion. Not all propulsion systems are as bad as nuclear electric, dumping 75+ percent of their total power output from radiators, but pushing big spaceships around at multiple km/s requires beaucoup energy, and some significant part of that is going to be detectable waste heat. Cold gas only gets you so far!


On a separate note, if something is called a dreadnought, it had better be able to take punishment and keep shooting.

Quibble that battlecruisers were also dreadnoughts! But the underlying challenge is a huge one, and not unrelated to the stealth problem. Space travel just plain takes lots of energy, meaning that a) you can really throw a punch, but b) it is hard to be subtle about it.

Rick said...

On showboats and prestige -

@Hugh: One of the advantages of both battleships and battlecruisers over a swarm of smaller ships is that they're just so damn impressive. It may be even more important in peacetime than in war to have monster ships.

This. The value of sheer impressiveness tends to be underrated because, in a utilitarian aesthetic, it is rated as frivolous. See this post:

http://www.rocketpunk-manifesto.com/2011/10/showboats-in-space.html

Geoffrey S H said...

Always preferred learning about 18th c naval warfare because the mix of elegant and utilitarian was obvious. Battleships with gilded sterns, prestige objects (see: Namur, Orient, both Victories), yet the best tools for the job of sea-superiority.

Eth said...

About launching quietly, one solution is a shrouded catapult. The catapult itself is a Verne/light gas gun or a long electromagnetic accelerator (railgun, coilgun). It is surrounded by an opaque shell, probably with random ports opening and closing in addition to the actual exit port, so the enemy cannot tell when and where you are firing.
The installation itself is very visible, and the enemy can probably tell when it is powered up and down. More advanced observations may give a rough idea about its firing operations, though there may be other counter-measures.

A big difficulty is that either your payload has to resist excessively high g forces or your gun is extremely long.
A novel from Alastair Reynolds features such stealth launcher (I won't say which one to avoid spoilers), which goes for the second solution as it is (barely) crewable. The gun itself is a megaengeenering project built for quite some length through a planetary crust and whose construction was kept secret only thanks to particular circumstances (exploited through counter-intelligence).
Conversely, a shorter launcher would be similar to guided gun artillery today: the sturdy, low-performance projectile is mostly accelerated by the gun, but still has some ability to manoeuvre and track the target/increase precision. The shortest-ranged ones may not even need to shroud the launch.

we are throwing Pentagon money at the problem
Now I have a vision of Rick throwing pentagon-shaped coins at the telescope...

To go back to an earlier comment from Tony, we do see modular pods in aviation. Gun pods, laser targeting pods, IR pods, reconnaissance pods, jamming pods, fuel tanks... They are often considered inferior because of decreased aerodynamic performances (and increased vibrations) and increased radar cross-section, which wouldn't be present on a spaceship.

Eth said...

But in any case the real problem for stealth is concealing the enormous power output of propulsion. Not all propulsion systems are as bad as nuclear electric, dumping 75+ percent of their total power output from radiators, but pushing big spaceships around at multiple km/s requires beaucoup energy, and some significant part of that is going to be detectable waste heat. Cold gas only gets you so far!

A sufficiently large nozzle allows you to cool your exhaust down to 20 K. Nuclear-thermal would be used to avoid the huge waste heat problem. In idle mode, you would need some more hydrogen to get rid of its waste heat, but a large hydrogen steamer has plenty anyway.
The problem is that anyone looking down your nozzle would see the still-hot hydrogen emerging from the reactor chamber, so you would need a non-conventional nozzle where the inner parts aren't visible from the outside. This is probably feasible in exchange for some performance cost, but definitely not trivial to develop.

On the other hand, I wonder how far neutrino detectors will evolve. Could they be used to detect stealth nuclear ships?

Thucydides said...

The two defining factors in Stealth technology are "what are you hiding from?' and "what are you willing to give up to do that?".

For combat aircraft, the defining factor is disappearing from short wavelength radar, since this is the sort of thing that is the most threatening. High performance fighters and missiles have small cross sections and therefore only have small radar antenna, which limits the wavelengths they can emit and receive. As well, short wavelengths provide for much sharper definition of the targets, which is why despite apocalyptic warnings about VHF and longer frequency radars, stealth aircraft are not optimized to defeat these threats, it simply isn't considered a problem until something with a much higher frequency radar gets into position.

What you give up is quite different. The F-117 "Wobbly Goblin" gave up a lot with its first generation design, in order to be able to penetrate heavily defended airspace and dispatch targets with two bombs. Modern 5th generation designs like the F-22 and F-35 have managed to overcome lots of aerodynamic limits, and are perhaps the premier air superiority and air dominance platforms on the planet right now, but are costly and apparently difficult to maintain. The costs of blazing performance, low observability and highly integrated sensor fusion are fiscal and O&M costs, rather than dodgy performance.

How this translates into space is difficult to determine. Horizons, "clutter" and other means of evading detection are largely absent, and everything is done against a 3K background. Distances are so great that you must expend a great deal of energy just to get places in any reasonable amount of time, and this is the case regardless of what you are sending.

The rocket equation means that high performance generally comes at a steep penalty (every gram counts), and interplanetary velocities are so great that even a box of used kitty litter would be a devastating warhead, so the incentives to identify, target and intercept at long range is extremely high. The idea of surrounding a single spacecraft with a cloud of sensors makes perfect sense in that environment, and arming with something like a CASABA howitzer or a RBoD to deal with hypervelocity threats inbound is also a reasonable extrapolation of what is necessary.

Carrying vast tanks of hydrogen to "steam" off heat implies a huge performance penalty (lugging all the extra mass around), so a very complex calculus will have to be done to determine if it is going to be worth the cost. As a bonus, many people touting the concept think it is going to be useful around planetary orbit, but now you have to look at being seen against the cold background of space from some angles, but the hot background of the planet from others. A very interesting (and complex) problem to address, especially if you don't know where the sensors actually are.

Anonymous said...

I think that we have all gotten so hung up on stealth (or the lack thereof), in space that we tend to forget another question: even though we can see it, are we sure we can intercept a ship before it reaches it's destination, does whatever, then leaves? Just because we can see that a ship is leaving Callesto and headed for Ceres, are we capable of launching a ship that can intercept it before it reaches Ceres? Oh, and if it is an Imperial Joven vessel of battlecruiser class or better, can we launch something to intercept it that's more than a corvette class?

Ferrell

Tony said...

Let's see...

Sensor swarms. I think people are totally ignoring the infrastructure required. If you're out to 2 million or more klicks with your sensor units, then you're going to have to have powerful radios, power for them, powerful reaction wheels to keep things pointed right, power for them, etc. You're not going to have thousands of them, maybe not even hundreds, even with Rick's Pentagon shaped shekels.

Also, the further out you expand a cooperative sensor net, the less responsive you make it. Remember, a true picture of conditions has to be consistent in time. Each observation, with each instrument, has to be at a definite time hack. That means the more light seconds your sensor net is in radius, the more seconds you add to each observation.

Grrr...weapons and ranges. Just sign me up with the Team Kinetics, Explosives, and Terminal Guidance.

Horizons in space. Of course they exist. They're defined by planets, most obviously. They're also defined by detection range. Can't escape Captain Inverse Square. He's out there, and he's gonna get ya.

Dreadnaughts and battlecruisers. Yes, battlecruisers were indeed dreadnaughts, dreadnaughts optimized for speed, at the cost of protection and guns. Battlecruisers in space would be dreadnaughts optimized for delta-v, at the cost of weapons and armor. And yes, if you're going to call it a "dreadnaught", let's have some durability under fire.

Geoffrey S H said...

"Sensor swarms. I think people are totally ignoring the infrastructure required. If you're out to 2 million or more klicks with your sensor units, then you're going to have to have powerful radios, power for them, powerful reaction wheels to keep things pointed right, power for them, etc. You're not going to have thousands of them, maybe not even hundreds, even with Rick's Pentagon shaped shekels."

Drat! You got there before me.

The one thing people don't seem to consider with 'swarms' is whether they are thrown out and collected later, or whether they have engines themselves.

This has huge implications. If they have manouvering thrusters and little else, they're only useful when you aren't manouvering and take up time to throw out and collect. Or they get left behind when you burn. Oh, and you have to carry them with you.

If they have engines, then they need alot of infrastructure to essentially be proper spacecraft.

You think you can afford thousands of those?

It's essentially the decoy spacecraft paradox, only for detection instead of evasion. I'd imagine these would only be useful for defence of a planetary body. Think of them as a type of mine.

AlexT said...

"Change the telescope focal length so that resolution (= precision) is 10 arcsec instead of 0.07 arcsec."
I have no idea what consequences that would have. The sensor would be bombarded with more radiation than previously. The presence or absence of a faint radiation source would presumably register as a variance in detector output. No idea what the stats are for wide-field astronomical cameras currently in operation and no idea what the histogram of brightness of sky objects (heavenly brightness?) looks like.

"we are throwing Pentagon money at the problem, not NASA money"
In 2016, the US military budget was about $580E+9. NASA's budget was about $19.3E+9. So NASA got about 29 times less, call it 30 to spare a few neurons. Arguably, thus, it would take the Pentagon 6 times longer to make 180 James Webb telescopes, than it took NASA for the one. Just kidding.

Accelerating sneakily: It would depend on the drive, of course. A torchship has a big plume of hot plasma that it wants to conceal, so it can only thrust behind a planet or in low solar orbit. If the drive technology allows, it might use quick, small, randomly timed thrusts, hoping to register as noise on any detector that happened to be watching.

With near-future technology, where the heat comes from energy generation, you could have energy beamed to the ship by orbiting powersats, at least during departure. Unmanned ships could get catapulted. Powersat beamers and catapults would also be handy for civilian use. The sneaking ship could carry 'some' open-cycle coolant for a little delta-V before it has to drop its mask.

These won't be cloaked Warbirds, just regular ships that try their damnedest not to be spotted too early.

Re: battlecruisers are also dreadnaughts. Indeed, and the British were shocked by the losses of the Battlecruiser Squadron and of the Hood. Those ships were expected to survive, not to blow up in seconds. Because they were.. Dreadnoughts! qed

Re: swarms. Maintaining a swarm of 10k+ microsats? Forget it, they're cheapo anyway, just let them drift. There's surely an automated factory that churns them out by the million. The trouble is, being so cheap, are they any good ?

Geoffrey S H said...

At the very least I can imagine swarms as a 'tripwire' for high-traffic hot spots.

Thucydides said...

Present day sensor drones, which model how the sensor drone swarm surrounding a ship or constellation may operate:
https://www.nextbigfuture.com/2017/06/israeli-gigapixel-camera-on-drones-with-30-hours-of-endurance-provide-persistant-surveillance-of-80-square-kilometers.html#more-133859

Large scale computing power and communications across a swarm (up to a maximum one light second distance) are not going to be show stoppers for this sort of thing, we already have demonstrated scalable power at low cost (renting cores from Amazon.com and other commercial vendors), and establishing a "mesh" network between the various parts of the sensor swarm is hardly going to be challenging either. The network can conduct whole sky scans, or be subdivided and focused on areas of interest, and ultimately hand off target data to the main mirror of a laser weapon or missile/railgun battery.

Anonymous said...

Two things: One; when I spoke of 'cost' (processors, multiplexers, communications arrays, radios, display, etc) I was talking about the cost of the mass and time-lag; where are you going to put your user equipment? is it on a planet or orbital station? is it on board a spaceship? Even if it's dirt cheap, it still costs volume and mass and power and heat rejection.
Two; in astronomy, a 'whole sky scan' means photographing the night sky from horizon to horizon, east to west, north to south, in one night. If your detector swarm is in orbit, a whole sky scan will take a year, due to that ginormous unshielded fusion reactor that sits in the middle of the solar system. You can certainly observe a great deal of the sky, but not all of it at one go. It's probably just me being old and cranky, but it annoyed me so I thought I'd say something.

Thinking about space-going dreadnoughts: big, heavily armed and armored...but most space battles would be fought in a planet or moon's orbit and not (with few exceptions) deep space intercepts. So while the space dreadnought might have a staggering amount of Delta-V, probably not much in the way of acceleration. So, space dreadnoughts are likely to be more like asteroid bases that have a very slow interplanetary capability. So your dreadnoughts aren't just battleships and battlecruisers, but monitors as well. Interplanetary Heavy attack, heavy intercept, very heavy orbital defense; all with similar sizes and weapons, but optimized for interplanetary cruise, fast intercept, or orbital defense; guns, engines, or armor.

Ferrell

Hugh said...

Thucydides, Tony is right about the infrastructure overhead. It doesn't make a swarm impossible, but it does push the cost up.

Amazon and similar companies selling computer power are not comparable. The only reason they can sell processing so cheaply is that all the computation hardware is packed as tightly as possible into giant data centres to share infrastructure. One big air conditioner beats a lot of little ones, one big AC to DC converter replaces individual power supplies on the computers, etc.

Rick said...

On sensor swarms, I suspect you'd rather have a smaller number of more powerful sensor platforms. But if they are small enough, and deployable well before the enemy arrives, it is possible that they could be stealthed, even if little else can be. (They need to report in, but this can be by tight beam.) It would be handy to have eyes that cannot readily be detected and blinded.
But --
Places which already deal with space traffic (orbital space ports, planetary mass drivers, momentum transfer devices like tethers) would have these sorts of sensor arrays almost as a matter of course
I don't think you want a swarm of anything drifting around near civil traffic lanes!

On stealth in general -

@AlexT ... No idea what the stats are for wide-field astronomical cameras currently in operation and no idea what the histogram of brightness of sky objects (heavenly brightness?) looks like.

Nor do I, and this is a case where general principles don't get very far, the devils are in the details. (But I overstated the number of 'bins' for my example, since resolution specified is 10 arcsec, not 1, making the detection challenge almost certainly tougher.

That said, I still think the deep space environment is unfriendly to stealth, especially of the energy output needed for ships to maneuver, for values of 'maneuver' that include leaving your home base to go anywhere. But note that the strategic/operational problem of detecting big ships at interplanetary distances, and the tactical problem of detecting small target seekers, etc, at tactical ranges, are two distinct issues.

Also note the proviso deep space. Planets (and moons etc) are a whole nother ball game. In multiple ways, deep space forces are none too well suited to the 'inshore waters' of space, and vice versa for aerospace or other local-space forces. Space armadas will need to exercise due precautions when operating in the vicinity of large plot complications.

Thucydides said...

The tightly packed server rooms are on board the spacecraft in the constellation, with much of the processor power being used to examine the inputs from the sensor swarm and convert that to effective targeting information. I would imagine each spacecraft would have its own "server room" for redundancy and to allow the constellation to function even with lots of battle damage.

Looking again at the idea of the ship itself, and in particular the "Battlecruiser", there is indeed a Rocketpunk counterpart to its Steampunk ancestor: the USAF "ORION" battleship proposal dating back to the Kennedy Administration. This 4000 tom monster would be packing Minuteman ICBMs, 5" naval cannon, CASABA howitzers and several hypersonic reentry vehicles. While not exactly the same, the Michael from "Footfall" might also serve as conceptual battlecruiser design as well. Both ships are very fast, have high ISP and loads of deltaV by the nature of their ORION nuclear pulse drive and pack impressive amounts of weaponry (in the case of the Micheal, real battleship turrets.

Like a battlecruiser, even a massive ORION spacecraft will be relatively unarmored, since the amount of kinetic energy that even a SCoD can deliver at interplanetary speed exceeds the strength of any real world materials. Using the ORION's superior deltaV to "sidestep" kinetic energy attacks is about the only realistic defense (outside of trying to intercept a sky full of incoming kinetic energy weapons), and as long as you are at least a light second away from giant lasers, particle beams or plasma weapons like massive CASABA howitzers, you have some chance to evade being hit as well.

Some diagrams of the proposed USAF ORION battleship can be found here: http://up-ship.com/blog/?p=27691

Thucydides said...

Given the "one light second" rule, I would not think that planets or moons would actually be a big deal for an interplanetary armada. The Hill Sphere makes a great demarkation point, and you can observe the vast majority of a system or planet's orbital space with your constellation deployed out there, yet have the manoeuvre room needed to evade any effects that the planet or moon will send against you. Dispatching some drones around the sphere will give you effecitve coverage of all orbital space, although at a much lower resolution.

And your own weapons will be effective down to LEO, and kinetic weapons will be capable of attacking ground targets as well. Operating in the region of the Hill Sphere gives you another advantage as well, breaking off the engagement, for military or political reasons, is also easy, since you are pretty much at the top of the opponent's gravity well.

Rick said...

Stepping back from stealth -

@Tony ... And yes, if you're going to call it a "dreadnaught", let's have some durability under fire.

I would certainly prefer some durability, but it could be hard to come by. Space encounter speeds are generally faster than bullet speed (~1 km/s), often *much* faster, making kinetic hits inherently devastating. And if laser zaps are effective enough to put lasers in the mix, they must also be devastating. Not good news for taking a punch.


@Ferrell ... are we sure we can intercept a ship before it reaches it's destination, does whatever, then leaves?

This is a big, big question. And a big, big reason why you might want to dispatch a missile strike, not a task force. If the intercept force is expendable it can use its entire delta v to take the fastest orbit, with no need for get-home propellant. To first approximation you can get there twice as fast - which could make all the difference.

Also an example of a way in which deep space operations and forces might be utterly unlike naval counterparts, even if the war is 'maritime' on a grand strategic level.

Rick said...

@Thucydides ...

I would not think that planets or moons would actually be a big deal for an interplanetary armada.

It depends on your war objectives. If it is 'maritime' - blockade or blockade-busting, or some equivalent of guerre de course - you need never enter inner orbital space. Or if you want to simply slag a planet, or at least flatten cities. But if you want to, say, impose a no fly zone over part of the surface, you probably can't do that effectively from a light second away.

In spite of the questions I raise about 'navies' or especially 'warships', my bias is that power exerted across deep space would indeed be broadly maritime. Your all conquering space legions won't conquer anyone if they get zapped en route, whether by battlecruisers or by forces that don't quite fit any familiar analogy.

But even maritime polities may sometimes need to project power inward/downward, probably with force components distinct from your deep space armadas, whatever form those constellations take.

AlexT said...

Stealth: this could go on and on, but better do it when the starting topic isn't Dreadnoughts, of all things. February 1st 1917 was the resumption date of unrestricted submarine warfare and there was no RPM thread for that, more's the pity.

"If you're going to call it a dreadnought"
The name carries overtones: big, lots of firepower, resilience under fire. Pretty expensive, too. Whether these can be achieved in space depends on many things. But if they can't be achieved, I would personally prefer to name the ships something other than Dreadnought or Battleship. Then again, I'm sure the first time somebody bolts a railgun to an ion drive, it'll be called everything from Battlecruiser to Death Star.

Durability: assuming an impact at about 10 km/s, that means a 1kg kinetic impactor hits at 100 MJ. Current anti-tank rounds have in the ballpark of 10 MJ and tank armor is intended to give *some* survivability against that. Armoring a ship with 10 times the amount on a tank sounds like a lot of mass. Then again, there's nothing inherently wrong with that, as long as it keeps the ship that much more protected. Just add more engines.

The ship would travel accompanied by tankers, like modern warships did on long cruises. Assuming the tankers are big, cheap, automated and the propellant cost is negligible, you can have as many tankers as the mission profile requires. Then, delta-V is not a relevant parameter in the ship's design. The dreadnought refuels before going into combat, spends propellant like crazy to dodge big strikes and shrugs off smaller impacts. After the job is done, it refuels, rearms and paints over the scratches on the frontal plate.


"If the intercept force is expendable it can use its entire delta v to take the fastest orbit, with no need for get-home propellant. To first approximation you can get there twice as fast - which could make all the difference."

1.41 times faster iirc, but even so the interceptors don't need to be expendable. You can brake AFTER the fight, assuming you can fight at high delta-v. Which is preferable, if you're using kinetics. Combat ships would probably try to fight with the tanks almost empty, to maximize maneuverability. Tankers follow them around and refuel any survivors post-action.


Re: deep space vs orbit. Planets in space warfare sound much like cities in modern warfare: you can't move and shoot properly, low situational awareness.. A big difference is, ground forces can avoid entering cities, whereas gravity assists are inevitable unless you assume torchships. Plot complications, indeed !

AlexT said...

To clarify: "1.41 times faster" etc. assumes some sane form of propulsion where thrust is continuously applied over the whole duration of transit, not kick & coast. So the interceptor would accelerate continuously until the encounter and decelerate afterwards.

Thucydides said...

Just getting back to sensor swarms for a moment, here is a link to a real life space based sensor swarm proposal that will give high resolution coverage of Earth from LEO: https://www.nextbigfuture.com/2017/06/near-term-technology-for-global-big-brother.html#more-133927. There is also some discussion of hundred plus megapixel sensors in the article as well (NBF often has ....interesting.....juxtopositions inside the same story).

Since Rick has often said that space environments will be very different and lead to different solutions for problems, I wondered what sort of non spaceship/spacefleet/constellation ideas would have military utility for at least the "maritime" portion of the war. For close in work, there would be a separate fleet analogous to what the Marines use to perform amphibious landings, but even then futuristic "San Antonio" class LPD would be escorted by the constellation and work under cover of the fighting platforms orbiting around the Hill Sphere as they move to and from low orbit. I suppose there will be specialist constellations to provide sensor and fire coverage in low orbit, which would seem to be ships optimized for this sort of environment (and perhaps carried separately in some sort of mobile hanger or carrier en route to the AO). So we now have at least three distinct constellations in play, a deep space constellation to get there and back, a "Marine" constellation for bringing force to bear directly on a surface and a "Littoral" constellation optimized for LEO to cover the Mariens.

As for deep space operations, there have been proposals to provide momentum to spacecraft by using micro lightsails, which can accelerate very quickly and impact the spacecraft's pusher plate or be reflected off a magnetic field to provide momentum (See http://www.foresight.org/Conferences/MNT05/Papers/Bishop/index.html). If clouds of tiny sails can be focused in a "beam" and accelerated at high velocity using a laser, you could essentially send a "sandblaster" at the enemy, using millions of postage stamp sized elements to erode exposed structures or even cause damage through kinetic energy attacks (although millions of very small impacts as opposed to one big one). By varying the intensity of the laser beam at launch, you can send clouds of these microsails on different orbits, complicating the ability of the enemy to determine where and when the attacks will occur. Even if they can determine the laser is being fired due to heat emissions, local spies or other means, they still won't necessarily know what is being launched or where or when it will arrive. This is one of those cases where a "space guard" or some sort of orbital inspection regime not affiliated with any Power would be useful to monitor these facilities. Perhaps insurance companies will do this to protect the massive underwriting risks they take on these facilities.

Anonymous said...

Thucydides said: "Perhaps insurance companies will do this to protect the massive underwriting risks they take on these facilities." ...and the dreadnought class orbital monitors "Progressive" and "State Farm" square off against the invading space fleet in defense of their insured satellites...That's a great inspiration for a story.

Ferrell

Tony said...

Gonna lay some cards on the table here. IMO swarms and "constellations" are not susceptible to analysis. IMO they're pure ideology.

Rick said...

@AlexT ... To clarify: "1.41 times faster" etc. assumes some sane form of propulsion where thrust is continuously applied
+1
Except that, other things equal, an expeditionary force not only has to slow down, it also needs to return to base, requiring additional delta v (though the return can be on a slower orbit, at the cost of being unavailable for the duration).

On reserve delta v carried by tankers, since they accompany the fighting constellation they need comparable propulsion, so they won't be all that cheap. Providing adequate delta v for expeditionary forces is just plain difficult, and a huge constraint on deep space ambitions.

Armor. I used to think of armor in space as futile, but SCODs could change that calculation. Other things equal, if you force the enemy to use heavier kinetics, they can launch fewer of them, helping point defense. And, presumably, making laser zaps take longer to burn through is also a good thing.

That said, spacecraft armor is likely to be more like WW II aircraft armor than sea battleship or even tank armor. The stuff is heavy, and spaceship performance doesn't do well with penalty weight.

And for newcomers, SCOD = soda can of death (a small guided kinetic); RBOD = ravening beam of death (fairly self explanatory, but with a connotation of *really* Stupendous Range).


@Thucydides ...
If clouds of tiny sails can be focused in a "beam" and accelerated at high velocity using a laser, you could essentially send a "sandblaster"

'Sandblasting' has the range limit problem of unguided kinetics in general (including my original conception of a killer bus). You need to throw too much mass to hit anything at even moderately long range.


@Tony ...
The ideology part eludes me. I'm not a fan of swarms for technical reasons, but that's a tech question. 'Constellation' is current space usage for satellites in coordinated orbits. Using it for spacecraft in formation seems reasonable enough, but so is 'formation' for anyone who prefers it!

Thucydides said...

@Rick
I have been seeking other papers or description of the "beam" of small sails concept. The implication seems to be that the beam will remain fairly tight for substantial distances, but for now I have no idea exactly how great the effective range wold be. IF we are talking interplanetary ranges (for example accelerating and aiming a beam from Lunar orbit to Mars), then we have a very serious killing device on our hands, while if the beam dissipates after a few thousand kilometres, then it might serve as a short range CIWS type weapon against incoming missiles.

@Tony
Swarms, constellation and other forms of distributed weapon and sensor platforms are the way the military is evolving today, so extending the idea into space is hardly ideological or even ground shaking. Looking at the idea of a USMC F-35B tracking an incoming drone and then cuing, firing and directing a SAM from a nearby USN warship is a simple example of what is possible, and evolving to a web of sensors and shooters is not even plausible mid future, it is literally just a few years down the road: https://www.nextbigfuture.com/2016/11/f-35b-controls-missiles-on-aegis.html

@Anonymous
I was thinking more of insurance companies installing or stationing monitors and agents aboard launch facilities and other high energy devices to ensure they were NOT being used for military purposes and therefore not going to become targets.

AlexT said...

"tankers, since they accompany the fighting constellation they need comparable propulsion, so they won't be all that cheap"

It depends, I think. Compared to warships, supply ships need no weapons, no defenses, no sensors, minimal command&control (no human crew obviously), no radiation shielding, structural strength just enough not to break apart under thrust.. Only if the engines are disproportionately expensive compared with all the rest, will tanker cost be a problem.

Also, if combat maneuvers are a thing then warships would require a high-thrust capability. Tanker engines only have to run in high-isp mode, presumably reducing their complexity and cost.


"a real life space based sensor swarm"

Cool stuff. Prime Kessler syndrome material, too. Well, surely they'll have thought about that..


"at least three distinct constellations in play, a deep space constellation to get there and back, a "Marine" constellation for bringing force to bear directly on a surface and a "Littoral" constellation optimized for LEO to cover the Mariens"

I think any invasion troops would arrive in specialized deep-space transports that would hold back with the battle fleet, while the troops drop in specialized, small craft, meant to zoom through low orbit and crash through the atmosphere. WW2 gliders might be a better analogy than D-day landing ships.


"micro lightsails, which can accelerate very quickly and impact the spacecraft's pusher plate or be reflected off a magnetic field to provide momentum"

Trouble is, when you're using them to accelerate a bigger ship, the target is cooperating. Not sure how effective it would be against an enemy that's doing his best to dodge the stream. I think they'd fare badly against planets with an atmosphere, since they'd need to be pretty sturdy to survive reentry. Would probably make one helluva light show over the target city.


"spacecraft armor is likely to be more like WW II aircraft armor than sea battleship or even tank armor"
I think the nearest analogy is WW1 battleship armor - reasonable defense against stuff that's likely to hit you. Torpedoes were a deadly threat that armor couldn't help against, and their equivalents would be big kinetics that you *really* want to dodge.

Thucydides said...

@ AlexT
Based on the descriptions I have come across, the stream is relatively tight and accurate, so the cooperative target does not have to expend a lot of time or energy matching the beam. If that is the case, then (up to the limit where the beam disperses) you have a stream of kinetic energy which is dispersed enough to be difficult to disrupt or avoid, but still capable of depositing a great deal of energy against solid surfaces and fittings of any ship unfortunate enough to get caught up in it. "Sandblasting" airless moons, asteroids and space stations seems to be a valid way to sue this sort of technology if the beam can be maintained for sufficient distances, or "sandblasting" incoming ships and missiles if the beam is only available for relatively short ranges.

Another example of swarming drone technology, this time from China: http://www.janes.com/article/71624/china-launches-record-breaking-uav-swarm

Matter Beam said...

A few notes:

-Insurance companies building dreadnoughts to protect their investments perfectly fits into the megacorp dysotopia so popular in SF.

-Armor: An all-or-nothing internal armor scheme is most likely the only mass-efficient defense against kinetic impacts. Basically, most of the spacecraft, such as rockets, propellant tanks, radiators and so on are protected only against lasers using ablative nitrile rubber coating. Kinetic impacts fly right through... but you have a lot of propellant and many radiators. You can afford to lose a lot of them. Your core components, such as crew and power generator, are protected by a thick layer of armor INSIDE the spaceship. Using bulkheads instead of complete spherical protection further reduces the mass dedicated to armor until it becomes a handful of 'hardpoints' dedicated to preventing a hard kill of the spaceship.

I did a mockup of this armor scheme for my Space Warship design series of posts. I came up with this: https://toughsf.blogspot.com/2016/09/space-warship-design-iii-final.html

A highly angled rotating nose to protect against a small arc of laser fire, and angled internal armor belts to prevent projectiles from ripping through the spaceship nose to tail.

Nuclear Explosively Formed Penetrators would certainly make it a requirement.

Armor belts, all-or-nothing... fit well with the battleship theme too!

Tankers: Their main advantage actually is that they don't have to arrive alongside the combat fleet. If the combat fleet survives the engagement, it has most likely won. If it has won, then it can sit around for weeks waiting for tankers on slow, low-velocity trajectories to arrive and fill them up for a trip back home.

It becomes even easier when we consider warships that can detach their crew compartiments, or if they are drones controlled by a manned spaceships. The manned spaceships can vampirize the propellant in the drone warships tanks for their trip back home, leaving behind an empty fleet that can loiter for months until the tankers arrive.

A constellation of damaged warships drained of their propellant and in low-power mode, without authorization to shoot incoming spaceships willy-nilly... would make the absolute perfect SF setting for pirates to acquire their ships and have pirate wars over the loot.


Geoffrey S H said...

Rick's expendable interlanetary missiles, RBODs, light-sail sandblasters. These all feel like artillery. Use them to soften up constellations before you send forces to occupy orbits, etc.

Really, I think we need to walk back the ''space is not an ocean'' trope. Trying to be different is a sensible course of action drawing on military history, but we risk going too far and ignoring certain commonalities in warfare.

We may not have aerodreadnoughts bombing cities (after 1918 that is) but we do still have aerial command posts and small groups of mobile missile platforms (fighters) that hunt for enemy groups and fire massed missile volleys. Is that somewhat similar to land warfare with its many small units, and similar to sea warfare with its constant manouvre and lack of territorial gains?

If you showed a soft-sf sci-fi fan, what we're debating, they'd see something completely different to naval warfare. Yet we are still worried about being 'too similer'.

Think about it: space 'artillery', mobile command posts (something Rick was keen on), mobile armed units, either small/light or heavily armoured/large. High velocity passes or matching orbits for slugging matches. It's not an exact copy of any other style of warfare... but it does contain elements from others.

Basically, I think that space warfare will be a mixture of land, air, and naval warfare with its own flavours thrown in.

Thucydides said...

Given the iron laws of physics, the rocket equation and orbital mechanics, one you are committed to a particular orbit between planets or moons you have pretty much committed yourself. Yes, you can expend an insane amount of energy to claw your way out of that orbit and into a new one, but that is hardly going to surprise the enemy or anyone else in the Solar System (if you are using torch ships, any observer in Alpha Centauri will be aware of your actions in 4 years or so).

Given that, I was always taken by Ricks vision of a fully realized constellation unfolding and deploying like some sort of mobile Vauban fortress, with different types of vehicles in the formation forming overlapping arcs of observation and fire (much like the bastion structures of a "Star" fort provided mutually overlapping arcs of fire swept ground the enemy had to cross, and even taking one part of the fort wasn't usually enough to be able to breach to defences), with particular vehicles optimized for long range fire (the RBoD equipped laserstars), while Kineticstars complicated the calculus and filled the spaces between with hypervelocity railgun fire, or dumped swarms of SCoDs at enemy laser emplacements to overwhelm them before they could use their RBoDs to slice through your constellation.

Given the extreme speeds and distances involved in "hard" SF space warfare, the idea that military space vehicles would evolve to become essentially artillery platforms is hardly surprising, really the only thing which has changed in the way I think about this is I now tend to believe future space navies (constrained as they are by mass, deltaV and so on) will likely use nuclear pulse units to drive weaponry to avoid carrying massive power plants, radiators and other items which would cause too much of a hit to performance. YMMV.

The only real way to get around this is to essentially change the tropes, so future polities are contesting with economic weapons, cyber attacks, propaganda and possibly extremely limited applications of force like assassins or SoF teams infiltrated into enemy habitats. Since even "civilian" spacecraft could be incredibly dangerous if they somehow got out of control (essentially becoming massive guided missiles or Kamikaze ships), there will be a need for massive installations capable of deflecting or destroying anything which is not approaching the habitat at the approved velocity and vector (which once again brings us back to artillery), with a possibility of a "SpaceGuard" type force to board and inspect or even take over ships which are arousing suspicion due to their activities.

AlexT said...

"Insurance companies building dreadnoughts to protect their investments perfectly fits into the megacorp dysotopia so popular in SF"
More likely, insurance premiums become vastly increased for undefended installations. The responsability for defense falls to the owner. Who would employ specialized security contractors. Space mercenaries !

"drones controlled by a manned spaceships"
If the ship is big enough, adding life-support for a small crew wouldn't be such a big deal, and worth the mass cost to eliminate the complexity and failure modes associated with remote control. Then again, having crew on extended missions would require a centrifuge and more space than an Apollo Command Module.. Maybe the warship flies on autopilot most of the time and the crew transfers from a hotel ship before combat.

"mobile Vauban fortress"
Sounds cool etc, but there's that age-old saying about plans surviving contact with the enemy.. The flying formation of death reminds me of hoplite phalanxes - invulnerable if you fight their way, deathtraps against a flexible enemy who doesn't play by the (assumed) rules.

Geoffrey S H said...

Apologies for the double post, it won’t let me post it all in one piece.
Zoomed out, you have the naval analogy of large forces needing to cross a hostile area, with ‘terrain’ which is difficult to hold. Orbits are difficult to change and partially reflect 18th c sea-lanes. This, as Rick said, is ‘naval’.
Zoom in a bit more, and you have ‘mobile forts’. Formations that can move and change position, but comprise a whole that is hard to split off once it commits to manoeuvres.
Let’s go into that Vauban formation in more detail.

At the rear you have logistics craft and command craft. These are similar to ocean going ships in their make-up- engines and cargo/payload modules. Reasonably specialised for their tasks, but can carry defensive payloads if necessary.
Then you have the artillery- laserstars, sandblasters, InterPlanetary Ballistic Missiles. These also have some defensive measures, but generally focus on their primary purpose.
The IPBMs are offensive, sent out when an overwhelming fast response is needed. Presumably they might have some armour, but wouldn’t have too much in the way of sophisticated/expensive sensors and defences—they are expendable after all.
The laserstars are defensive- due to their overwhelming power, you don’t want to send a laserstar against another laserstar as one will vaporise the other in short order. It’s too much of a risk. These hang back and vaporise SCODs and any other kinetic assaults.
Amongst them and slightly ahead are other command posts designed to filter data and provide real-time communications to the outer edges of the formation. These, like posts at the rear, have good manoeuvrability, good armour/defences, but minimal offensive weapons.

Also slightly ahead are the kinetic carriers- armed with missiles/SCODs and whatever kinetic weapons that can soak up laserstar fire. They are the primary threat to enemy formations. Generalised defensive laser turrets are common on these craft- lose them and you lose the battle.

Continued below:

Geoffrey S H said...

Continued:

It’s when you look ahead of THESE that you see naval analogies. Escort craft that try to shoot down incoming SCODs whilst threatening enemy escort craft of the other formation. These would have some manoeuvrability to avoid kinetics, and would be able to spin to lessen laser impacts. Armed with a variety of weapons, with good armour and defensive capability. Capable of carrying out many types of mission. As close to dreadnoughts [or infantry] as you can get.

Some would have a toned down (but not removed) offensive loadout to provide space for crew modules. These variants serve as front line command posts.

The largest of these escorts would have substancial offensive weaponry, and the smallest/most numerous would be more orientated towards defensive weapons. The largest can form formations to ‘dominate’ anything short of a RBOD. These are thus called Dominators. The smallest shields the entire constellation, hence ‘shieldstar’.

There might be a middle-weight type that can range ahead of the constellation. Given that once an orbit is chosen a constellation is locked into it, there is thus room for a craft to skim an enemy formation, nibbling away at the escorts, whilst staying as far from the kinetistars as possible. While it too would be locked into a course after a burn, one may assume that efforts to intercept it would be difficult without an immense expenditure of energy. These would be called ‘Strikers’. Depending on your preference, you can call these battlecruisers, skirmishers or mobile artillery. Whatever.

How do you use all these craft? Well, if a formation is locked on whatever course it chooses, then sending two constellations hurtling through each other is madness. You’ll want to have them ‘brushing’ each other, with only the outer edges coming into direct contact. Having the escorts fight among each other while IPBMs and SCODs are sent through them, directly at the heart of the enemy constellation seems to be the best bet. You could also send ‘strikers’ before and after to harry the escorts.

That said, if you manage to eliminate a constellation’s laserstars, all bets are off. THEN you can use your own laserstars to hoover up resistance without fear of getting vaporised.

I could go on, but I don’t want to get bogged down in detail. Does anyone agree with any of this? Does it work for you? I probably cannot get a consensus, but I think all of you have a lot of merit in what you say. It’s just a question of synthesising the best bits.

Tony said...

Rick:

The ideology part eludes me. I'm not a fan of swarms for technical reasons, but that's a tech question. 'Constellation' is current space usage for satellites in coordinated orbits. Using it for spacecraft in formation seems reasonable enough, but so is 'formation' for anyone who prefers it!

Note that you can in fact not be a fan of swarms because they don't seem technologically likely. The same can probably be said of constellations made up of nothing but single-capability units. The ideology is where you cannot be convinced for rational reasons. A Thucydides eloquently puts it, one can be "taken" by a "vision". That describes ideology that is insusceptible to reason.


Thucydides:

Swarms, constellation and other forms of distributed weapon and sensor platforms are the way the military is evolving today, so extending the idea into space is hardly ideological or even ground shaking. Looking at the idea of a USMC F-35B tracking an incoming drone and then cuing, firing and directing a SAM from a nearby USN warship is a simple example of what is possible, and evolving to a web of sensors and shooters is not even plausible mid future, it is literally just a few years down the road: https://www.nextbigfuture.com/2016/11/f-35b-controls-missiles-on-aegis.html

Ummm...not anything new at all, in principle. Back in the day -- and we're talking over forty years ago -- droppers of laser guided bombs didn't illuminate the target for themselves. Another aircraft did it for them. Soon after that, they developed equipment and procedures for observers on the ground to illuminate targets. A fighter identifying and guiding in a missile from a ship? Neat application, but nothing really new in concept.

Also, this application presumes horizons or at least target concealment. How is that going to be applicable in the space environment that you imagine?

Rick said...

A couple of conceptual points -

@Tony ...
... don't seem technologically likely. The same can probably be said of constellations made up of nothing but single-capability units. The ideology is where you cannot be convinced for rational reasons.

Fair enough! I would say that there is a distinction - which I should perhaps emphasize more - between 'pure' conceptual models and stuff I would actually want to build.

Case in point, the conceptual laserstar is indeed aptly described as a mobile artillery piece. This might apply (or not!) to a 'monitor' type intended for defense of local space against deep space attack, that would only operate near extensive support bases and forces.

For expeditionary service I would want something more flexible, presumably with some equivalent to secondaries, in whatever form and however provided for. For cruiser-esque independent operation, more so.

Extending to the other end of the spectrum, there is a conceptual place for the maid of all work that is not particularly optimized to anything, but with some ability to mix it up with whatever threat comes along. With the constraint that the 'pure' maid of all work is probably equally abstract, and for most if not all real missions should probably be somewhat optimized against the more likely threats.


@Geoffrey ...
Really, I think we need to walk back the ''space is not an ocean'' trope. Trying to be different is a sensible course of action drawing on military history, but we risk going too far and ignoring certain commonalities in warfare.

I don't really disagree! Per above, my apparent self appointed task, WRT demi-operatic space warfare, has been to push back against the common habit of simply imitating some favorite era of naval warfare. Especially since the biggest fave, for obvious historical reasons, tends to be WW II. Which gives you space fleets provided with air cover and ASW escorts.

Ideally, the forces and their operations should flow organically from the intersection of war objectives with physics/tech/economic constraints. And, for purposes of opera, should provide a suitable admixture of surprise, familiar echoes, and plain old thud and blunder.

A setting of serene peace among worlds (because they cannot effectively attack each other) and a setting of planet-slagging missile strikes have very different moral implications, but neither one is particularly well suited to space opera.

On a side note, 'striker' as a term for capital ships gives me a big, big smile. When I was in college, a *long* time ago (though not in a galaxy far away), that was my term of preference for what amounted to a space battlecruiser. It neatly conveys a badass flavor while not evoking any specific historical type.

Alas, a quick google indicates that it has been used for some kind of Star Wars space fighter. But screw it. I think it's a good term especially for missile ships, since they launch strikes, and 'kineticstar' is a bit clunky to my ear. (Whereas 'laserstar' rolls off the tongue, and stars *are* associated with light.)

Rick said...

Wow, did I just have a wonderiffic little moment of synchronicity. I just hit 'post' on my last when the classical station I stream struck up Elgar's Pomp & Circumstances #4

Perfect *pass in review* music!

AlexT said...

Terminology: "constellation" refers to a group of similar satellites that serve the same purpose. Not quite similar to giant, stable formations of mutually supporting, complementing spaceships who move and fight in lockstep. I'd call them phalanxes, because that's what they resemble most, rather than naval fleets or squadrons.

On a side note, what would be the effect of orbits on such formations ? How large could a formation grow, with different orbital velocities slowly tearing it apart ? Or is the concept only applicable to ships who thrust continuously to maintain formation ?

Dumb question: whence the 'star' in 'laserstar' ?

Tony said...

Rick:

Case in point, the conceptual laserstar is indeed aptly described as a mobile artillery piece. This might apply (or not!) to a 'monitor' type intended for defense of local space against deep space attack, that would only operate near extensive support bases and forces.

I have never conceived of them as mobile. In what seems to be the most commonly held conception -- Light second range, with nearly instantaneous ship killing power -- they would be so big and fragile that they couldn't be mobile. And they would wind up being primarily self-defensive, because they would be the first thing any attacker would target, in the most overwhelming manner possible.

For expeditionary service I would want something more flexible, presumably with some equivalent to secondaries, in whatever form and however provided for. For cruiser-esque independent operation, more so.

Well, one would naturally want something as balanced as possible. With the exception of systems intended for fleet confrontation in total war, you can't really predict what missions a ship might have to undertake within its service lifetime. Even within the scope of a single cruise the possible missions can be hard to predict. (Which is why modularity isn't as good an idea as it first might appear.)

On the other hand, balance is not the only design objective...

Extending to the other end of the spectrum, there is a conceptual place for the maid of all work that is not particularly optimized to anything, but with some ability to mix it up with whatever threat comes along. With the constraint that the 'pure' maid of all work is probably equally abstract, and for most if not all real missions should probably be somewhat optimized against the more likely threats.

Oddly enough, the notionally general purpose cruiser could be optimized only so far. Their primary mission, as expressed in armament, was to fight and defeat enemy cruisers they might encounter. They could only address their other missions if enemy forces couldn't intervene. Or it might be that on a specific cruise their primary operational mission would be to neutralize enemy cruisers that were threatening their own commerce.

Conversely, the large, Pacific Ocean, fleet escort destroyers of the US and Japanese navies were well balanced between surface, anti-air, and anti-submarine warfare. They needed to be, because they formed the outer perimeter of fleet task groups and had to be ready to fight all of those threats. Cruisers, battleships, and aircraft carriers could be more offensively specialized, because they had general purpose destroyers to help in fleet defense.

Tony said...

AlexT:

Dumb question: whence the 'star' in 'laserstar' ?

I always took it to be a riff on "battlestar".

Tony said...

Rick:

I don't really disagree! Per above, my apparent self appointed task, WRT demi-operatic space warfare, has been to push back against the common habit of simply imitating some favorite era of naval warfare. Especially since the biggest fave, for obvious historical reasons, tends to be WW II. Which gives you space fleets provided with air cover and ASW escorts.

But it says something maybe not so complimentary about how you envision your audience. (From both the perspective of who you think they are, and what that says about you.) Push back is one thing. Even the most thoughtful person needs push back from time to time. But is the absolutism really necessary? It seems to me that you attract only thoughtful people. It should be enough to just point out to them that they may not have though of everything, then let them come to their own conclusions.

Ideally, the forces and their operations should flow organically from the intersection of war objectives with physics/tech/economic constraints. And, for purposes of opera, should provide a suitable admixture of surprise, familiar echoes, and plain old thud and blunder.

But that never really happens, ever. Wars are, for the most part, and certainly for the first couple of years, fought with stuff made or at least designed before the war. Those forces are the product of untested (once again, for the most part) theory, unrealistic exercises, politics, and peacetime (whatever that means, within a given context) economics. It takes real work as an author to imagine and describe the overall strategic and economic environment in which a war is fought, and how it is fought. The authors that do that work write good stuff. The authors that lean on standard tropes may not write the best stuff, but they can from time to time write entertaining Romance. There's room for both.

A setting of serene peace among worlds (because they cannot effectively attack each other) and a setting of planet-slagging missile strikes have very different moral implications, but neither one is particularly well suited to space opera.

Seren peace between worlds in no way guarantees serene peace upon a given world. Drake, for example, never goes into whether there are interstellar wars within his Slammers universe, or how they might or might not be fought. But planetary wars of almost any description seem to be happening all of the time.

And I'm not sure that planet-slagging missile capabilities automatically lead to planet-slagging missile strikes. There is plenty of room for Romance in a universe where its possible to slag a planet, but also to forcefully resist such slaggings. Interstellar warfare, and even, under the right circumstances, interplanetary warfare imply planet slagability. But we're still interested in the stories of those times nad places, precisley because it brings out the most heroic in humans (and I don't even believe in heroes, as normally conceived) to fight the Good Fight.

On a side note, 'striker' as a term for capital ships gives me a big, big smile. When I was in college, a *long* time ago (though not in a galaxy far away), that was my term of preference for what amounted to a space battlecruiser. It neatly conveys a badass flavor while not evoking any specific historical type.

Certainly less contrived that "espatier" or "constellation".

Thucydides said...

Since there seems to be some misunderstandings about how I am describing things, I'll go back to first principles.

There is no "horizon" or ground clutter in space, so the limiting factor in detection is distance. In order to see and evaluate what sorts of threats or possibilities are "out there" at interplanetary distances, very large mirrors would be needed, but from a military perspective, giant mirrors wold be impractical for mobile use. I would not doubt that there would be huge telescopes mounted in or near an orbital base or on a moon, but to maximize the light gathering while reducing the threat of being blinded, or to allow for graceful degradation of the system, using a multitude of sensors and combining the images using optical interferometry makes sense. For various reasons outlined in the Atomic Rockets site, I agree that a cloud of sensors extending to a disc or sphere one light second in diameter is about the practical limit, ensuring that the information from the various sensors does not get too badly out of sync. The other advantage is the system is inherently flexible in that it can be subdivided into smaller virtual mirrors to provide sensor data to individual ships in the constellation.

As for single purpose ships, once again, this simply falls from the rocket equation. Since every gram counts, and your ability in a demi operatic space war depends on being able to have superior ability to engage than your enemy, then your ship must ruthlessly strip away every extraneous system. If I can mount a laser, railgun or missile launcher with superior range, rate of fire or other attribute, then I will have a potentially unbeatable edge compared to a ship with smaller, less capable systems. This even shows up in a weird way in the battleship era, battleships and battlecruisers kept increasing the size and power of their main guns to outrange their potential opponents or have the capability of penetrating their armour. While only the IJN actually built battleships with 18' guns, this didn't stop other navies from seriously considering this (the British "N3" concept is a good example of that sort of thinking). On Earth, it became possible to carry greater weight of fire over longer distances using airplanes, hence the modern aircraft carrier displacing the battleship. It is not clear to me what the analogous system in a demi operatic setting would be to an aircraft carrier.

While a laserstar mounting a RBoD may well be the primary target of any enemy capital ship, the ability to strike at long range at light speed is a capability that will be highly desirable to sweep the sky of missiles and kinetic weapons. The advantages are so great that every effort will be expended to create that sort of capability (some possible substitutes like CASABA howitzers or high energy particle beams might take the place of lasers, but the effects and desired outcome will be similar). Ships carrying a belly full of nuclear driven CASABA howitzers would not have the inherent mass penalties of an actual RBoD, and the Atomic Rockets site and Tough SF both suggest that in advanced form this would essentially have the sort of power we associate with RBoD weapons, a Megaton "lance" which can convert 20% of its energy into the plasma stream can slice through 291mm of aluminum at 10,000km, and can still penetrate 2mm of aluminum at 50,000km. Nuclear driven EFP devices can have similar ranges (the first time I read through the section I was incredibly startled at how effective they could be) although the mechanism of injury is quite different.

Eth said...

Tony:
Certainly less contrived that "espatier" or "constellation".

As a French-speaking native, "espatier" never sat with me that well either.
I now go for "spationaut", as it is the actual term coined by France when they were searching for a word to describe space-operating personnel (due to quirky historical reasons, and it has been now dropped for the more common "astronaut").

Similarly, I go for "astrale" for the space equivalent of "navy". Obviously, its personnel are "astronauts" - which also convey the interplanetary/interstallar nature of their tasks, where spationauts do operate in space but in a much smaller environment (orbital/aerospace assault, ship boarding...).
Maritime law becomes "astral law".

If we do want to use "cosmonaut", it could be used for scouts/explorators, as "cosmos" is more about the greater Universe, and is more associated with its immensity.

"Constellation" is a bit clunky, but is an actual term used for satellites, so I give it a pass. Then again, "formation" also works and is shorter.
What would you use?

Rick said...

A few random laserstar zaps -

On the origin of the term, what Tony said: it is a riff on 'battlestar'. I'd have to look through old comment threads to see whether I adopted it on my own or swiped it from a commenter. In any case it has a nice ring to my ear.

As for what a laserstar IS, no one owns the word, but in my usage it means a spacecraft armed with, and more or less built around, a laser bank zapping through the largest practical telescope mirror, keel mounted on account of aperture and bulk. And by connotation big all around, though I suppose a small spacecraft with a big mirror relative to its size would be a sort of mini laserstar.

A couple of assumptions/implications in my usage. I see electric propulsion as much the likeliest option for regular human deep space travel, meaning that ships have beaucoup electric power available. YMMV. For example, if I read Matter Beam's blog correctly, in his setting he favors gaseous core nuke thermal, at least in part to avoid the implication of gigawatt 'free' electric power.

But if your ships DO have nuke (or solar) electric drive, it is friendly to sustained laser zapping (whether CW or pulsed). So no nearly instantaneous ship killing power is required - instead the requirement is the ability to hold a beam on target well enough that if you keep zapping away, the target will presently feel the pain. If you can burn through armor at 0.1 mm/sec, and keep doing it, an hour of steady zapping defeats Yamato thickness armor.

If your tech does not allow sustained precision zapping, laserstars are not for you. If technology does allow them, the main military constraints are 1) you can't maneuver while zapping, and 2) you can only engage one target at a time, or at least targets with only slight angular separation. (No rule says laserstars can't have turreted 'secondary' mirrors, but I'm talking about the big, long range main mirror.)

If effective zapping range is a few hundred km, these constraints pretty much rule out laserstars. But if the big main mirror allows you to effectively zap at, say, a tenth of a light second = 30,000 km, you have quite a lot of zapping time before an enemy can close with you.

And multi-axis attacks, with substantial angular separation, and timed well enough that you must deal with both at once, are likely easier said than done. Though this gets into the whole question of tactical maneuver ....

Rick said...

Nothing to do with laserstars, or even space, but in my day gig I have been doing blog-style articles for Northrop Grumman, the stealth bomber guys. Including a piece on Midway:

http://now.northropgrumman.com/the-battle-of-midway-a-victory-of-information/

Tony said...

Rick:

http://now.northropgrumman.com/the-battle-of-midway-a-victory-of-information/

I think you should read Shattered Sword by Parshall and Tully.

Tony said...

Thucydides:

There is no "horizon" or ground clutter in space, so the limiting factor in detection is distance.

The distance limitations create a horizon, for tactical purposes.

In order to see and evaluate what sorts of threats or possibilities are "out there" at interplanetary distances, very large mirrors would be needed, but from a military perspective, giant mirrors wold be impractical for mobile use. I would not doubt that there would be huge telescopes mounted in or near an orbital base or on a moon, but to maximize the light gathering while reducing the threat of being blinded, or to allow for graceful degradation of the system, using a multitude of sensors and combining the images using optical interferometry makes sense. For various reasons outlined in the Atomic Rockets site, I agree that a cloud of sensors extending to a disc or sphere one light second in diameter is about the practical limit, ensuring that the information from the various sensors does not get too badly out of sync. The other advantage is the system is inherently flexible in that it can be subdivided into smaller virtual mirrors to provide sensor data to individual ships in the constellation.

What you don't seem to understand is that a constellation of sensors spread over such a large space is not at all a trivial exercise. It is in fact a monumental undertaking. Since you want to use interferometry, you have to be able to coordinate the pointing of multiple elements to very fine degrees in real time. That means the highest spec reaction wheels and control systems. (And by control systems I'm not talking about computing power, but mechanical control systems.) Because you seem to want real time data transmission, you will have to design a chassis that allows accurate pointing of the comms antenna(s), while at the same time managing to hyper-accurately point the observation package. Transmitting data at such high bandwidth, implies a high power directional transmitter on each element. All of this is going to need a lot of power. That makes the overall spacecraft very heavy, very complicated, and very expensive. If you have the economy of an entire planet...maybe.

For strategic surveillance I think I'd rely on a relatively few high power instruments observing key strategic competitor spaces. I'd use a few more to track spacecraft under thrust. This of course depends on your technological assumptions. If you have short bursts of high thrust to enter transfer orbits, then observing the competitor spaces should be adequate. If you have, at the opposite extreme, operatic torchships, any good medium powered technical instruments should be able to do the job. In between, with long duration, low thrust propulsion, one would have to have some pretty good instrumentation, but periodic observation should be sufficient.

For local tactical surveillance, I think I'd use relatively unsophisticated passive IR sensors to detect objects large enough to be dangerous within a few million km. I'd also use powerful radar.

Tony said...

Thucydides:

As for single purpose ships, once again, this simply falls from the rocket equation. Since every gram counts, and your ability in a demi operatic space war depends on being able to have superior ability to engage than your enemy, then your ship must ruthlessly strip away every extraneous system. If I can mount a laser, railgun or missile launcher with superior range, rate of fire or other attribute, then I will have a potentially unbeatable edge compared to a ship with smaller, less capable systems. This even shows up in a weird way in the battleship era, battleships and battlecruisers kept increasing the size and power of their main guns to outrange their potential opponents or have the capability of penetrating their armour. While only the IJN actually built battleships with 18' guns, this didn't stop other navies from seriously considering this (the British "N3" concept is a good example of that sort of thinking). On Earth, it became possible to carry greater weight of fire over longer distances using airplanes, hence the modern aircraft carrier displacing the battleship. It is not clear to me what the analogous system in a demi operatic setting would be to an aircraft carrier.

Even the largest battleships needed their own self-defense sensors and weapons. And then on top of that they needed general-purpose escorts to help. The only was that the above makes any sense at all is if only weapon system, at its fullest power, can accomplish all missions, all of the time. IMO that's so unlikely as to be not worth considering. Yes, there are constraints on how much you can do with so much mass. But that's true of any combat platform. And, I'm sorry, I don't believe for one minute that space is so flat that only beam weapons need be employed. I think missiles and guns will have a place -- likely a dominant place, because the claims made for lasers strike me as unrealistic nonsense.

While a laserstar mounting a RBoD may well be the primary target of any enemy capital ship, the ability to strike at long range at light speed is a capability that will be highly desirable to sweep the sky of missiles and kinetic weapons.

"[S]weep the sky"? Comes across as hyperbolic noise, T. A small number of very expensive platforms are going to be ridiculously vulnerable to neutralizing attack. The more effective they are, the fewer there will be, and the more resources that can be dedicated to each one. fighting them wouldn't be a tactical problem, where combining maneuver and firepower matters. They will be the targets of military engineering operations, just like any other immobile fortress. And they would be immobile...and fragile. The more power you spit out one end, at higher and higher rates of fire, the more heat rejection you will need. That leads to larger and larger radiators that are less and less durable under attack, and makes the spacecraft less and less maneuverable.

This is all basic military theory and engineering tradeoff stuff, T. It's not speculation. It's not something you can handwave away,

Tony said...

Eth:

As a French-speaking native, "espatier" never sat with me that well either.

My observation is that "espatier" seems to have come out of a conversation where "marine" was a priori bad because it was too naval and space, as we all know, is NOT an ocean. But just because English speakers used half-@ssed French cognates 200 years ago, apparently we have to use them now. Right...

To tell you the truth, I think "marine" is just fine for expeditionary close combat operators closely associated with the fleet. It's kind of like "frigate". It means something approximating a certain role, and its usefulness has outlived its original strict meaning.

(Truth in advertising: I was a US Marine myself. But I think I'm being reasonably objective here.)

'Constellation' is a bit clunky, but is an actual term used for satellites, so I give it a pass. Then again, 'formation' also works and is shorter.
What would you use?"


Nothing wrong with "constellation", per se. But it comes across as contrived when one can just as easily call a fleet a "fleet". Once again, people seem to have assumed this ideological duty to remind themselves at every turn that this is SPAAACE. Seems a bit overwrought to me.

Tony said...

Rick:

But if your ships DO have nuke (or solar) electric drive, it is friendly to sustained laser zapping (whether CW or pulsed). So no nearly instantaneous ship killing power is required - instead the requirement is the ability to hold a beam on target well enough that if you keep zapping away, the target will presently feel the pain.

Okay, I've studied naval weapons pretty thoroughly, guns in particular. (Yes, they were the most romantic weapons during the most romantic periods of naval history. They were also some of the most technically fascinating, when taking their fire control systems into account as well.) For my sins I was a naval gun crew member for almost two years. (The two 5"/38 mounts on USS Long Beach were crewed by the Marine Detachment.) The devil with any gun type weapon -- and lasers are, or should be, pretty obviously gun-type weapons -- is in a bazillion details. I just don't see the RBoD being a real practical weapon that can do more than make random hits at anything over a few thousand (or, if tech gets really snazzy, a few tens of thousands) of kilometers. That means for really long ranges one is going to have to get a lot of effect in a little time. Which means shooting very high power, very short bursts, observing effects, then going again. Kind of like long range naval gunnery in the first half of the 20th Century. (But don't tell anyone...)

And multi-axis attacks, with substantial angular separation, and timed well enough that you must deal with both at once, are likely easier said than done. Though this gets into the whole question of tactical maneuver ....

Attacking a well designed fortress was never an easy thing. It can take years just to neutralize a fortress so that you can safely bypass it. (See Rabaul in WW2.) Coordinating a multi-axis attack likely to beat a laserstar would be a feat of military engineering, no doubt. But not an impossible one. Just a fair-to-midlin tough one.

Matter Beam said...

Quick note on detection and data handling:
I dug up some calculations I made in A Constellation of Warships II (http://toughsf.blogspot.com/2016/07/a-constellation-of-warships-ii.html). Here's the quote:


Your opponent will be forced to scan the entire section of the sky your spaceships are possibly in. This means that the sensors cannot continuously cover your spaceships' likely positions. For example, if a 0.5 degree FOV sensor was looking at targets approximately 10 million km away, then it can only cover a section of the sky 87260 by 87260km across. If the spaceships in a fleet are distributed over an area 150000km in radius, then the sensor can only ever see 10.8% of the fleet at any one time. If the sensor wishes to pick up details 10m across, then it requires 76 trillion pixels, or a CCD plate 8.7 meters wide, consisting of 1 micron sized pixels.

A 10 GPU stack of Nvidia's GTX1080 can handle 100GB/s. The CCD will produce 152 TB images of its FOV. Therefore, full scans of the fleet's mid-remote distributed signals area will be completed every four hours ... and this is without any further analysis of the data. Entire insertion burns can go unseen. Even a gentle 0.01G acceleration for 4 hours will push a spaceship to 1412m/s. If it is travelling at a closing velocity of 20km/s, and it performs no other burns, by the time it is detected by wide-angle sensors at a distance of 1 million km, it would be out of position by 635000km. It would evade any pre-positioned kinetics, and would attack at a 32.4 degree angle.


What do you think?

AlexT said...

It seems to me that space is very much like an ocean, as far as human travel is concerned. Currently plausible technology implies long-duration travel using complex, expensive machinery. It is also an inherently hostile environment where we need to carry along everything we need in order to survive for any extended period. And humans do need to go out there, unless the mission is extremely simple, predictable and unimportant to boot. Whether the ships are the size of triremes or nuclear carriers, to my mind the commonalities greatly outweigh the differences.


Concerning laserstars:

"a riff on 'battlestar'"
Without Vipers ?! Blasphemy..

I believe lasers as weapons need to prove themselves in an actual conflict before they can be taken seriously. There's the concept of a laser in orbit, or on a 747, that would burn ICBMs while they're boosting. Is there any other serious concept for a practical laser weapon ? And those ICBMs aren't designed to withstand laser attack (or any attack at all), quite unlike any space warships worth their salt.

I do agree the concept sounds cool. Assuming laserstars do everything imagined of them, the biggest laser pretty much always wins, right ? So tactical combat is pretty much done for and winning is about strategic maneuvering and deception.

Thucydides said...

@ AlexT
Laser weaponry has been under investigation for decades, but the difference between the current crop of 50-100kW lasers that are in the advance prototype stage for air and naval deployment and previous ones (think of the SDI program of the 1980's) is that modern laser weapons are "electric" and solid state rather than chemical lasers.

For the high power outputs needed back then, the only feasible way to generate intense bursts of energy to drive the laser was a chemical reaction, often using exotic and toxic or corrosive chemicals. While this had certain advantages (much of the laser weapon was actually low tech plumbing and tankage, highly energetic reactions could be created in a very short time frame and wast heat could be vented with the chemical exhaust), the fundamental issues of dealing with the chemicals, and the limitation of the lasers due to the amount of chemical fuel you could carry pretty much ended that line of experimentation. The Boeing ALL (Airborne Laser Lab) was relatively successful in demonstrating the principles in a flight ready article, but having to fly back, land and refuel the laser after burning one ICBM generally limited the feasibility of the concept.

Modern weapons are driven directly by electrical energy, so the only limitation in that regard is how much continuous power can your generator deliver? (This is a factor even if it is a pulsed weapon being driven by capacitor banks, how fast you can recharge the banks is a critical limitation). One of the "selling points" of the F-35 was the huge space for the lift fan could be substituted for a generator driven by the engine drive shaft for a future laser weapon. While I doubt this is going to happen, the USAF is testing the use of laser "pods" attached to fighter aircraft to dazzle or shoot down enemy missiles, drones and aircraft. The USN has already done testing with 100kW laser weapons at sea burning things like drones and speedboats, and previous testing by the Army has focused on using laser weapons to shoot down incoming artillery and mortar shells, as well as artillery rockets (not theatre ballistic missiles but much smaller and shorter range rockets). The IDF is also working on layering "Iron Dome" with laser weapons to shoot down unguided artillery rockets fired from Gaza, the West Bank and Lebanon.

So laser weapons are literally a year away from limited deployment for testing and developing tactics, techniques and procedures (TTPs). The next generations of weapons will likely "gang" several smaller units together to create modular emitters of higher power, while Free Electron Lasers (FEL) is likely the generation after next, since FELs have much greater efficiency and can be "tuned" to provide a wider range of energies to zap targets, evade countermeasures and find "windows" to limit atmospheric absorption.

So laser weapons are already capable of operating in high stress environments like a warship at sea or a high performance jet fighter, and can deposit enough energy on non cooperative targets like incoming artillery to destroy incoming shells. Obviously this is the dawn of practical laser weaponry, and we should see immense improvements in things like recharge rates and the ability to deal with multiple targets in the coming decades here on Earth, lessons which will be taken into the Space environment when the time comes.

Eth said...

Tony:
My observation is that "espatier" seems to have come out of a conversation where "marine" was a priori bad because it was too naval and space, as we all know, is NOT an ocean. But just because English speakers used half-@ssed French cognates 200 years ago, apparently we have to use them now. Right...

To tell you the truth, I think "marine" is just fine for expeditionary close combat operators closely associated with the fleet. It's kind of like "frigate". It means something approximating a certain role, and its usefulness has outlived its original strict meaning.


The problem with "marine" is that etymologically, it is very, very wet. It is literally the adjective for things related to the sea. So "space marine" makes about as much sense as "space submarine" would for a hydrogen steamer.
Originally, I tried to find what term would have actually been obtained instead of "espatier" by following the same logic, which is how I got "spationaut". But beyond its (quirky) history, it is a surprisingly good term for describing "space infantry" forces.

"Navy" is not quite as wet, but still sort of dripping. It does mean "fleet of sea-ships", basically. I got "Astrale" from similar reasoning, but again it feels to me like a surprisingly good fit, particularly with the existing "Astronaut" being useful (and sometimes used) for starship personnel.

The big advantage is that those make perfect sense etymologically-wise, so they can be integrated to the existing language with ease - which is even more important for use in fiction. Here is what the terms say by themselves:
"Spationaut": those who travel through space
"Astronaut": those who travel among asters (celestial bodies)
"Astrale": the force related to asters (celestial bodies), composed of astronauts. Merchant astrale. Astral law. (The final "e" is not strictly necessary, but I like how it differentiate from the adjective, and it does give an echo to "marine")
"Cosmonaut": those who travel through the cosmos

And I may not be objective, but I feel those also sound just right.

"Spacer" could still be used, as it fits the more general concept of any space-borne personnel (military, civilian, on ships, stations, in orbit, in deep space...)

As for "fleet", well, it does come from "to float", so again a bit weird for space. Then again it is used for civilian airplanes(/cars/drones...) - but it is for the whole inventory of planes a company has, and has a "bigger" connotation than "constellation".
So constellation would be more the equivalent of a task force/squadron/battalion/flotilla, a smaller subdivision than the fleet. Then again, we could also call it a task force/squadron/battalion/flotilla.

Also, could you give some examples of those devils in details of naval guns? Even if it doesn't translate directly, parallels would be interesting.

Eth said...

AlexT:

Indeed, lasers have been over-promised and under-delivered for decades, but since a few years ago, it seems progress really picked up pace. Fibre lasers (combining several small lasers into a big one with not too much decrease in beam quality) are the last hotness, but not the only nor the final one.
While the current ship- and aircraft/helicopter-borne lasers tested by the US military were rather underwhelming once you cut through the PR (the USS Ponce laser was supposed to neutralise Iran-style swarm tactics, but is barely more effective than a heavy machine gun), there are already some effective niche use. Despite facing varied criticisms, it seems Iron Dome proved the effectiveness of the concept in anti-projectile defence. Several nations are developing rather effective anti-drone lasers.
If progress continues as expected, in a few decades they may be able to shoot aircraft down.

So building a big and strong enough beam for a laserstar should be possible by the time those are asked for. The problems of power generation, heat management, vibration dampening and aiming are different, though, and may or may not still cripple laserstars.

AlexT said...

@Thucydides @Eth
My understanding of the state of military high-energy lasers is that they're promising but not yet operational. I'm rather skeptical about the testing that they went through, since it was carried out by the people implementing the laser. Cost and complexity will surely be big issues: laser, mirror, power generator and cooling system all seem very high-tech systems that could be defeated by very low-tech means. My feeling, for what it's worth, is that lasers will be enormously useful for jamming, dazzling, blinding etc long before they are effective weapons.


Switching to a completely different subject, it would be rather useful to continue the Tech readiness level scale downwards to encompass imaginary technologies. This would help clarify discussions about science fiction topics, should this seem desirable. I'm thinking something like this:

Level 0: The underlying science is accepted and proven. The details aren't worked out, but are expected to present few difficulties if seriously researched. E.g. a automated probe to Alpha Centauri.

Level -1: The technology doesn't contradict current science, but lacks detailed understanding of its basic functionality. E.g. fusion power.

Level -2: The tech assumes major leaps in science which allow it to function. It contradicts current science, similar to black holes or radioactivity in the context of Newtonian physics. It assumes future advances will reveal its plausibility under special conditions, in which current theories are no longer valid. E.g. faster-than-light travel.

Level -3: The tech contradicts current understanding of science and, were it possible, would disprove commonly accepted and throughly tested theories. E.g. a ship that accelerates to light speed and beyond, simply by using a big engine.

Level -4: Theories that contradict themselves, never mind science. Essentially, pure nonsense. I'm currently having a hard time envisioning such, probably because I've tuned them out whenever I've encountered them.

This isn't quite the same as the Mohs scale of sci-fi hardness since it doesn't refer to works of fiction. Rather it's a way to specify, about a certain piece of technology, how far ahead of our time it is.

Thucydides said...

The NextBigFuture blog has three interesting articles today, one expanding on current laser technology (a demonstration of using a high power laser on an AH-64 attack helicopter), the use of optical phased arrays to create "lensless" cameras and improvements in the state of the art of stable laser propelled sails for space probes (and other uses).

The state of the art is advancing very quickly in a multitude of areas, and probably a lot faster than we are thinking or conceptualizing. It would seem that some sort of critical mass of science, technologies and trained manpower has been reached.

https://www.nextbigfuture.com/2017/06/high-energy-combat-laser-fired-from-an-apache-ah-64-helicopter.html
https://www.nextbigfuture.com/2017/06/ultra-thin-camera-without-lenses-uses-optical-phased-array.html
https://www.nextbigfuture.com/2017/06/progress-to-stable-laser-propelled-sails.html

Rick said...

Nomenclature zaps -

'Espatier' was devised, so far as I know, by a native speaker of Swedish. :-)

My terminology biases have more than one root, and are not always consistent. I certainly have no problem with 'spaceship' or simply 'ship', but I hate 'boat' for small spacecraft. Because a boat gets you really up close and personal with the water, in a way a ship does not, or at least *should* not.

Regarding marines, you can certainly say that 'space marines' are no more incongruous than 'air cavalry', a term used with no hint of irony. My grump is a bit more subtle, albeit era and culture bound. Growing up with WW II movies, US Marines didn't seem functionally all that much different than ordinary Army grunts, except for snappier dress uniforms. More landing craft and fewer tanks, maybe. And in the wars of my lifetime, their deployment and service hasn't seemed dramatically different.

In a space context, that seems to make 'marines' simply an expeditionary army. And what other army would a star empire even have, other than militia/constabulary forces on individual planets? Whereas if the requirement is more or less 'boots in the airlock', that is a mission that looks more analogous in contemporary terms to Navy SEALs than US Marines. (And SEALs even use naval ranks: chief petty officers rather than master sergeants.)

So it is not just the splashy thing that makes 'marines' seem not quite right for space grunts. OTOH, 'navy' is not an issue for me - precisely because I am so maritime that I would simply call it the service.

'Fleet' is yet another issue. In modern times, even at sea, it has nearly fallen into abeyance for a group of warships in company, applying instead to the totality of a state's naval force (or a trucking company's trucks, etc). Or administrative units, like the US Seventh Fleet. The actual language reflects this; I have more than once seen a naval force underway described as an 'armada' - a remarkable linguistic throwback to 1588.

So if I were writing a story, the Martian fleet would comprise all the ships (and drone or lesser craft) of the Martian service. The ones coming your way would be a Martian constellation.


But my biases aren't just about wetness, but also the fact that the story focus of my old future history was around the 28th century - much farther into the future than the widely popular 23rd-24th century era. And with a long intervening period of a 'universal state' without peer competitors or major regular warfare.

Such a future would have more the flavor of Firefly than Babylon 5 (or Battlestar Galactica), and much of our familiar military vocabulary might well have faded into the past. Haven't seen many cohorts or centurions around lately!

On the other hand, 'frigates' have been around for 500 years. On the third hand, the English language usage of 'armada' for a naval force deployment - with neither a galleon nor a Spanish flag to be seen - shows the odd ways that words can evolve over time.

Geoffrey S H said...

Astronaut, spacionaut... is there any room for rocketeer?

Maybe it could be the name of a specific regiment or something... 'Her Majesty's Honourable Company of Rocketeers'.

Speaking of Marines, I've been doing work on what ground forces would look like, and I keep finding that small expendable soccer-ball sized drones would be useful. In the event of a stalemate, where some but-not-enough of your kinetics get through defence lasers, fit the drones in a missile, somehow get them to ground during a bombardment (using the incoming kinetics as a distraction) and have them flit out to do lot's of nuisance sabotage work for above-surface installations. At worst they'll divert resources to find them that could have been better used making more anti-orbital defences. It doesn't seem impossible, but it is a bit weird to think of them as 'marines'.

Rick said...

More laserstar zaps -

Regarding the real world military potential of laser weapons, I am agnostic. We have reached a threshold point where the navy is ready to service test them aboard ships, as a close in defense against aircraft and speedboats. This gets us to the starting gate. (Combat testing is another matter, but that requires, well, combat.)

Where things go from here depends on devils in the details that may or may not emerge to bedevil such weapons. CIWS lasers may turn out to be not quite as good as short range missiles or plain old miniguns. Or the technology may prove capable of future development right up to laserstar standards. We. Just. Don't. Know. And because devils in the details are so complex, we can't even make a really informed guess.

The good news, from story perspective, is that you are pretty much free to set whatever capability level you want. Laserstars, as I have described them, are an effort to picture what you could get if laser optical performance turns out to be near the high end, a 'decent fraction' of diffraction limited performance.

@Tony ... The devil with any gun type weapon -- and lasers are, or should be, pretty obviously gun-type weapons -- is in a bazillion details. I certainly agree with the overall points!
Which means shooting very high power, very short bursts, observing effects, then going again. Kind of like long range naval gunnery in the first half of the 20th Century. (But don't tell anyone...)

One difference, though. Range matters in long range gunnery, which is why spotting and rangefinders were so important. But at distances below a light second, and encounter speeds no more than a few dozen km/s, lasers are close to point & shoot. Poor beam quality and beam jitter could rule out long range zapping, and beam wander could make holding on target difficult. But if you can handle that, sustained precision should be viable once you make initial adjustments.

Cooling issues could produce an effect like you describe, if in a different way. If coolant flow turbulence produces beam jitter, the laser cannot keep up steady precision zapping, but must pause between zaps to cool down. This will degrade the effectiveness of long range fire, since it takes longer to deposit energy onto the target.

Again, nothing I say should be taken as saying that Stupendous Range zapping is a given, only that it is not inherently ruled out.

Rick said...

Assorted zaps -

[Me] Ideally, the forces and their operations should flow organically from the intersection of war objectives with physics/tech/economic constraints ...
[Tony] But that never really happens, ever. Wars are, for the most part, and certainly for the first couple of years, fought with stuff made or at least designed before the war.

Oops, this is a meta-ness collision. I meant from the author's perspective, not the characters'. If your tech uses gigawatt electric drive engines for general deep space travel, then they can reasonably carry megawatt weapons. You might not carry such weapons for other reasons (eg, aiming a megawatt laser turns out to be like aiming a firehose), but lack of plug power shouldn't be a huge issue for those ships.

Practically anything can be gotten away with, but some combinations require deft footwork if they are to be convincing, like smoothbore cannons on gas turbine ships. Though story *always* rules. Great characters with unconvincing physics make for some reader grumbling; great physics with cardboard characters makes for unread books.


Serene peace between worlds in no way guarantees serene peace upon a given world.

Fair enough! My maritime bias was showing, no? Catching me out doubly, emdemic on-planet warfare could be eminently consistent with a hegemonic power that rules the spaceways, but generally avoids getting itself bogged down in penny ante local disputes.


@Geoffrey ...
The laserstars are defensive- due to their overwhelming power, you don’t want to send a laserstar against another laserstar as one will vaporise the other in short order. It’s too much of a risk

This is an interesting situation. A laserstar is in practice mainly a volume denial weapon. No lesser ship can enter its zapping range and expect to survive long - while it dares not enter the zap radius of a more powerful laserstar. Laserstars that appear well matched will show mutual wary respect. I'm still not quite sure what happens when two equal laserstars get in an eyeball frying contest, but probably not so good for either one.

Other than that, laserstars mainly use their zapping power to engage kinetic salvoes, protecting the entire constellation. A bit like WW II battleships in the Pacific, which protected against aircraft more often than they engaged enemy battleships.

sending two constellations hurtling through each other is madness. You’ll want to have them ‘brushing’ each other, with only the outer edges coming into direct contact.

Yes. Welcome to vector motion. Once committed to a vector it is difficult to change it. Commanders who forget this can get themselves into worlds of hurt.

And all of this leads toward the question of maneuver tactics, something I've never really addressed here. I think there is a widespread general assumption in geekdom that ships with milligee drives are so sluggish that tactical maneuver is a nonstarter. My own Vauban fort analogy does not exactly challenge that perception.

But I suspect it is really more a question of time scale. One day of steady burn at one milligee will scoot you along at jet fighter speed, and carry you more than 37,000 km. (Both relative, of course.) And you can keep it up for weeks. It may not be 'quick', but it is plenty fast.

So a battle would unfold at a pace we associate with 'operational' rather than 'tactical' maneuver, unfolding over days or even weeks. And in a general way I think the goal is to catch the enemy between two fires, while avoiding the risk of getting too spread out and open to defeat in detail.

If, as I still think likely, there is 'no stealth in space', you won't be able to sneak up in a literal sense. OTOH, there is no stealth on a chessboard, either - except at the level of players' intentions.

Matter Beam said...

Artillery:
I find the comparison poor. Laserstars, despite the extreme distances and low manoeuvrability, directly face enemy fire. They are armored and can dodge or out-accelerate missiles and ships. These all sound like the characteristics of war-ships...
I do not think interplanetary missiles make their launch site artillery either, much like ICBMs do not make their silos artillery.

Orbits:
Well, even with delta-V limited chemical rockets, a small difference of 10m/s in the departure burn can put the spaceship in polar, equatorial, low, high, retrograde, elliptic, closed or open orbit. The probability cloud for the positions it can take at the closest point to its target is technically as wide as the planet's entire Hill sphere.

If we use the interplanetary capture deltaV map, we can see that the deltaV costs are measured in between 1 to 4km/s for most planets. (http://hopsblog-hop.blogspot.co.uk/2012/06/inflated-delta-vs.html)

Even a milligee electric rocket would take only a few hours to escape an elliptic capture orbit.

Hotel ship:
Nice name!

Nomenclature:
I think the X-'star' name came from satellite formations being called constellations, and the components of a constellation are stars. Hence, kinetics-star (gunstar?), laserstar and so on.

Likely propulsion:
I do not think military spaceships will ever use one single engine type. If they had to, they'd use staged nuclear thermal engines (of all levels of fuel consistency) and just add propellant stages to get the necessary deltaV, because the ability to just drop your tanks and escape a missile wave the nuke-electric drive would have fallen to is priceless.

Sensor swarms:
I'm adamant that a sensor swarm is the best detection tactic available, but I think most of the problems being raised here stem from the idea that the swarm's elements are spaced apart on ranges measured in light-seconds. That's crazy! You don't need such resolution to target spaceships with a laser! If we use infrared (2000nm) sensors, we can define a 10m ship at 1 lightsecond using a sensor array spaced by just 60km.

A lightsecond baseline just increases this distance to a pointless... wait, my calculator gives a few dozen million AU.

Any thoughts on my data handling quote?

Rick said...

A quick extra laser zap -

@Tony ... don't see the RBoD being a real practical weapon that can do more than make random hits at anything over a few thousand (or, if tech gets really snazzy, a few tens of thousands) of kilometers

@Me ... If effective zapping range is a few hundred km, these constraints pretty much rule out laserstars. But if the big main mirror allows you to effectively zap at, say, a tenth of a light second = 30,000 km, you have quite a lot of zapping time before an enemy can close with you

A meeting of minds! Or at least getting into the same broad range zone. :-)

Tony said...

Thucydides:

So laser weapons are already capable of operating in high stress environments like a warship at sea or a high performance jet fighter, and can deposit enough energy on non cooperative targets like incoming artillery to destroy incoming shells. Obviously this is the dawn of practical laser weaponry, and we should see immense improvements in things like recharge rates and the ability to deal with multiple targets in the coming decades here on Earth, lessons which will be taken into the Space environment when the time comes.

None of which necessitates or even validates RBoDs.

Tony said...

Eth:

Also, could you give some examples of those devils in details of naval guns? Even if it doesn't translate directly, parallels would be interesting.

So, for about the last 120 years, ever since shooting at thousands of yards became practical, knowing the range to the target, its speed of advance, and the directional components of its motion, at the time of firing has been quite a requirement of gunnery. It governs how you point the gun and how you set time fuses. While lasers won't have fuses to set, they will have to know the rest. You can't just point at some light in the sky and pull the trigger. If you do, the target will be long gone when your zap gets there.

For guns, radar became -- and still is AFAIK -- the premier means of determining range (and rate of change of range). I don't see that being any different with laser weapons in space. So most of the means of spoofing radar that work in modern naval gunnery should work in space.

A possible exception to the above would be long baseline triangulation. But baselines would have to be pretty long, and instruments many to deal with a large attack at fractions of a light second or greater. Also, communication and processing lags would cause issues too. So, maybe radar is still better. You can mount it on the weapon platform, reducing delays and coordination uncertainties.

Going back to gunner principles in general, on US ships in WW2 the relative positions of various observation devices and gun mounts had to be accounted for, or accuracy would go right out the window. And by "accounted for", the reader is meant to understand that the location of the positions were precisely surveyed in relation to a single datum point, in 3 dimensions. Once again, I see no reason to think it would be different with laser weapons and fire control sensors. A parallax error of a fraction of an arc second could really pile up at fractions of a light second.

Platform motion would be more controlled in space, but it would have to be accounted for just like the motion of a ship was. For example, a platform sitting "still" in orbit is actually rotating WRT the solar reference system in which spacecraft are moving. The slightest error in accounting for that motion in the firing solution would affect accuracy.

I think you probably get the idea by now...

Tony said...

Rick:

Regarding marines, you can certainly say that 'space marines' are no more incongruous than 'air cavalry', a term used with no hint of irony. My grump is a bit more subtle, albeit era and culture bound. Growing up with WW II movies, US Marines didn't seem functionally all that much different than ordinary Army grunts, except for snappier dress uniforms. More landing craft and fewer tanks, maybe. And in the wars of my lifetime, their deployment and service hasn't seemed dramatically different.

In a space context, that seems to make 'marines' simply an expeditionary army. And what other army would a star empire even have, other than militia/constabulary forces on individual planets? Whereas if the requirement is more or less 'boots in the airlock', that is a mission that looks more analogous in contemporary terms to Navy SEALs than US Marines. (And SEALs even use naval ranks: chief petty officers rather than master sergeants.)

So it is not just the splashy thing that makes 'marines' seem not quite right for space grunts.


Marines, aside from being shipboard security, were traditionally the on-hand landing force of navies. I think an interplanetary or interstellar environment with long reach back lead times would be very friendly to such a force. They would also constitute a form of mobile constabulary force.

When ships went from firing at musket range to firing at hundreds, then thousands of yards, marines went from manning the tops to manning guns. WRT Jutland, there were plenty of marines in the RN capital ships manning guns. That feature of marine duties didn't go away in the US service until the 1990s, when the last battleship Marine detachments were disbanded. As I mentioned above, when I was a US Marine on the USS Long Beach, Marines (including yours truly) manned two 5-inch gun mounts.

Of course, marines also participate in general purpose land warfare, but that's been a thing for almost exactly 100 years. And while US Marines went for the big, aesthetically pleasing ground operations, the British Royal Marines did the Commando thing. (Though often as part of big, aesthetically pleasing ground operations.)

So, I don't see a problem with space marines, and by that name. Missions analogous to traditional marine missions would exist, and specialized grunts would be needed for them.

Tony said...

Rick:

One difference, though. Range matters in long range gunnery, which is why spotting and rangefinders were so important. But at distances below a light second, and encounter speeds no more than a few dozen km/s, lasers are close to point & shoot.

Ummm...nope. Range and target motion matter. If you shoot at something at 1/10 of a light second, and it's travelling at a velocity of 30 kps, it's gone 6 km by the time your beam gets there. (3 km while the target image that you're pointing at gets to you, 3 km while your beam travels back out.) To have any chance of hitting something a hundred meters long (let's say) with a beam a few meters in radius, you're going to have to know target distance and motion to a fine degree.

Poor beam quality and beam jitter could rule out long range zapping, and beam wander could make holding on target difficult. But if you can handle that, sustained precision should be viable once you make initial adjustments.

Problem is, everything in an RBoD militates against fine beam control. You're generating so much heat that all of the machinery and fluids needed to move it away from the laser generator and pointing mirror are going to really make things bounce and jiggle. I don't see any way of avoiding it, because you can't just reject vibrations to an outside medium like submarines do. (Event the quietest submarine is only "quiet" in the sense that all of its equipment installations are designed to efficiently smooth out vibrations before they meet the hull-water interface.)

Again, nothing I say should be taken as saying that Stupendous Range zapping is a given, only that it is not inherently ruled out.

I would say that it is practically ruled out, for any technological tool set I can imagine. IOW, if you have it in your story, I'm going to think you're invoking magic where you don't need to. (I know its personal prejudice, bt the only magic allowable IMO are hyperdrive, artificial gravity, and torch drives.)

Tony said...

Matter Beam:

Artillery:
I find the comparison poor. Laserstars, despite the extreme distances and low manoeuvrability, directly face enemy fire. They are armored and can dodge or out-accelerate missiles and ships. These all sound like the characteristics of war-ships...


Until almost 100 years ago, artillery was a direct fire weapon. Ships' guns, which still fire directly at their targets, are classed as artillery, for technical and engineering purposes.

I'm not sure how you figure a laserstar can dodge anything. The more powerful it is, the more immobile it becomes. All those radiators are fragile and hard to move safely.

I do not think interplanetary missiles make their launch site artillery either, much like ICBMs do not make their silos artillery.

Gun positions aren't the artillery. The guns themselves are. V-2 was an army program because the missiles were rocket propelled artillery. ICBMs, because of the strategic nature of their mission and capabilities, are air force weapons, but that doesn't keep them from being artillery in the prely technical sense of a missile being projected at a target.

Tony said...

Rick:

A meeting of minds! Or at least getting into the same broad range zone. :-)

I certainly don't see lasers being effective at more than 1/10 ls. But I'm still not buying-in to the laserstar paradigm. Just too much specialization to be practical. Ya gotta be able to maneuver to be able to fight effectively, and RBoDs strike me as being inherently unmaneuverable.

AlexT said...

@Thucydides
"demonstration of using a high power laser on an AH-64 attack helicopter"
I've read the article, read the post from Raytheon's site, watched the video.. They made the target shine (brightly) for a few seconds. Doth not a weapon make.

I'm left with the same impression about current laser CIWS systems of various sorts: prototypes with doubtful performance, cumbersome and expensive as hell.

When discussing kinetics vs lasers, kinetics are at a major disadvantage because they're already mature tech. We know pretty well what you can do with a cannonball, also what rockets and missiles are capable of, both in- and out-of-atmosphere. So there are no fantasy performance characteristics allowed, cost is predictable, the launch platform holds no major surprises (even railguns), multiple generations (& defenses) have been researched, tried and tested.. Whereas lazorz can be anything at all. Particle beams and other directed-energy weapons even more so. Nor does the one thing we know about them (they're really cool) help with expectations management.

Not saying lasers don't work, just that kinetics do the same job more cheaply, simply and on high heels.

AlexT said...

I think there would appear a new class of combat infantry: zero-g specialists, fighting in vacuum and inside ships. Those would be the real space infantry and their training and skills would be of dubious use ground-side.

Terminology: I like the word "gropo" (ground pounder) when referring to space-borne ground-assault troops. Or just go with the cool factor and call them stormtroopers. But ultimately, only if you say "marine" does everybody know exactly what you're talking about.

Specialized land forces (not marines) have a place in a future setting, assuming a planet-based force can defend itself successfully against space forces in direct line-of-sight. The invader establishes a bridgehead (using marines, presumably) beyond the horizon. Ground-based specialist forces can then reduce the enemy strong-point without needing (and risking) dreadnoughts in a direct assault from above. Essentially, Gallipoli with better leadership and planning.

AlexT said...

Assuming lasers are useful as weapons:

"A laserstar is in practice mainly a volume denial weapon. No lesser ship can enter its zapping range and expect to survive long - while it dares not enter the zap radius of a more powerful laserstar."

A sweet spot will probably emerge between cost and effectiveness, where making bigger ships would be inefficient because they'd be a little more powerful but much more expensive.

There will probably also emerge configurations specialized in killing enemy laser ships (rugged mirrors, heat-resistant materials, good at dodging, whatever). If these are poor at shooting down incoming kinetics, both types end up being necessary in a fleet.

AlexT said...

WRT to maneuverability, I fully agree with Matter Beam that combat ships will need the ability to maneuver (ie high thrust). Unless they are juggernauts who can shrug off any attack, they will need to dodge at least the worst of incoming strikes.

With current tech, that means chemical rockets for combat maneuvers and high-isp propulsion for cruise mode. Probably not both on the same ship: combat ships could dock to a large ion-drive mothership for long-duration acceleration. Or maybe they each have their little ion drive which they decouple from before combat.


@Rick:
"If, as I still think likely, there is 'no stealth in space', you won't be able to sneak up in a literal sense. OTOH, there is no stealth on a chessboard, either - except at the level of players' intentions."
At that point, the winner in any war is the one with the most advanced fleet command computer, no ? Battles don't need to be fought at all beyond the point where the winner's computer can prove to the loser's that he will be checkmated in N seconds. Even better: why build ships at all ? Make the best computer, match it against the other side's and, if yours is better, dictate the terms of surrender.

Eth said...

Duelling laserstars don't necessarily have to expose each-other to direct fire, with long enough range. Even in the absence of long-range relay mirrors, they can use independent shutter drones: those open in succession to let the outgoing laser pulse, but an incoming laser pulse would hit one shutter or another.
Short-range relay mirrors may then be used to try and get more angles on the enemy, while needing their own shutters. In fact, with several targets on each side, the number of shutters needed may increase very fast, particularly as those would probably be cheap and light compared to giant laser generators.

I don't know the minimal range for usable shutters, nor what tactics would emerge from it, but it would probably have significant impact in a scenario where laserstars start being a thing. They may use laser propulsion from the laserstars themselves for manoeuvre.
Interestingly, it may bring back a Jutland-like battle: laserstars themselves are the main damage-dealers, well-protected and have a very hard time to destroy each-other. However, they may be crippled (even with its own on-board shutters closed, a hit may damage heat management system, for example), and escorts may suffer much higher causalities.


Tony has a point about position and velocity acquisition problems for long-range laserstars. Targeting a passive target, say a civilian ship, should be well within the capabilities of anyone building those laserstars.
Targeting a military system actively trying to spoof or blind you may become something else entirely.

Eth said...

Nomenclature:

Gunstars?
A stock ship from Children of a Dead Earth can deploy "Shooting Star" gun drones.

Air cavalry
It makes sense so far as it is basically doing the same thing with light armour and helicopters as it did with horses: hard-punching, fast-moving units that are good at flank or cross distances fast (but are rather fragile against entrenched enemies or dedicated counter-measures, so be careful with it).
Basically, the unit kept the same role while switching equipment.

Space marines are a somewhat different cases.
Depending on militaries, they range from dedicated amphibious assault infantry to commando and expeditionary forces with tradition of sea-based projection, which may or may not include ship security. It may also be independent, part of the navy or the (land) army.

When those militaries will start having the need for space-borne infantry and overspace expeditionary infantry, they may or may not give that role to their existing marine infantry.
Some, like the US, may give them the role, and the marines would in turn create dedicated units for the job. Others would create new units outside of the existing marines, and attach them to whatever corps ends up in charge of that role, which could be the Navy, the (land) Army, the Air Force, a new Space Force or Astrale, or even an independent corps.
I expect most militaries, both present and future, to do the latter, and thus not call them "Marines". Even in the case, like the US may, where those are part of the Marines, it would at least start as dedicated forces instead of changing the core role of the entire corps, and as such would probably have its own denominations - which I doubt would be "Space Marines", though again who knows how many W40K there are among US general and PR officers.

From there, I would expect nascent militaries, who may not necessarily have links to the sea (like, say, the new Democratic Jovian Free Forces or the People's Republican Mercury Liberation Army) to skip marines entirely.
But this is not a given, so if you want your story to have Space Marines, it would easily make sense. It's simply that I don't see it as the best generic term for space-borne infantry.

As for rocketeers, it sounds like something more specialised (like Cavalry vs Marines), so Spationauts may have, say, Rocketeer companies. As with cavalry, if the role is kept while switching equipment, they could keep the name despite not using rockets anymore.
That said, what role would be specified by its primary use of rockets?

Eth said...

@AlexT:
About laserstar manoeuvrability, they have a big honking generator, so they would probably use electric propulsion, particularly as they would not use propulsion and laser at the same time due to the inability to aim under thrust.
This would probably mean low-thrust high-Isp ion drive for cruise, and high-thrust meh-Isp resistojets or arcjets for tactical manoeuvre. Bonus points if both can use the same propellant and/or if they have variable thrust/Isp.

In Children of a Dead Earth, this is actually a popular design (though aiming problems are currently not modelled so some use nuclear-thermal instead to be able to thrust while firing).

The battle may be decided by who has the better algorithms indeed, but even then it would be "interesting": neither side has perfect data on the other, so enemy weapon specs may be misidentified. Then it becomes a story intelligence collection, spying, sabotage or politics...
As the result cannot be perfectly predicted, there may still be combat. If both sides think they will win, there will be combat. Even if one side evaluates its chances as poor but the alternative is unacceptable ("regime change", enslavement, extermination...), they will still take their chances and there will be combat.
If both sides see the result as uncertain and aren't desperate enough to take chances, we have more of a Cold War scenario, possibly with a more unstable balance of terror (as the winning side may escape annihilation)

Anonymous said...

AlexT said:"At that point, the winner in any war is the one with the most advanced fleet command computer, no ? Battles don't need to be fought at all beyond the point where the winner's computer can prove to the loser's that he will be checkmated in N seconds. Even better: why build ships at all ? Make the best computer, match it against the other side's and, if yours is better, dictate the terms of surrender." You should watch the TOS Star Trek episode "A Taste of Armageddon".
I agree that combat spacecraft should have more than one engine (or have their primary have 'gears'), but leaving your ride home unattended seems a bit risky to me. Take the penalty and have chemical rockets for maneuvering in battle, ion thrusters for interplanetary, and maybe something for dire emergencies.
Having to build two or three ships due to extreme specialization, when you can build one ship that does all three tasks (even if not quite so well), does give you more ships to use. And for a given amount of resources and cash, will probably get you a larger number of ships.

Ferrell

AlexT said...

@Eth
"Duelling laserstars don't necessarily have to expose each-other to direct fire, with long enough range. Even in the absence of long-range relay mirrors, they can use independent shutter drones: those open in succession to let the outgoing laser pulse, but an incoming laser pulse would hit one shutter or another."
Shutters depend on the laser's parameters, especially pulse duration. So, fantasy stuff - can be anything. Bearing in mind, also, that the shutters must be able to open and close (mechanically) in comparable time. Say 1ms pulses, assuming 10m shutters that can open and close that fast. That means the shutters must be 300km apart, and you need 2 of them. So you need to aim a 600 km long gun barrel made of independent pieces at a moving and/or accelerating target. Tricky, tricky and more tricky !

Also, the shutters must be able to withstand enemy fire or the whole thing is pointless. Assuming such shutters existed, I'd bolt them straight on top of the main mirror and open/close them quickly synchronized with the laser pulses. If the pulses are randomly timed, the enemy would have to be lucky to get even a single hit at the mirror. And a laser kill happens over time, it's not zap! and done.

"Targeting a military system actively trying to spoof or blind you may become something else entirely."
Indeed.

"About laserstar manoeuvrability, they have a big honking generator, so they would probably use electric propulsion <...> This would probably mean low-thrust high-Isp ion drive for cruise, and high-thrust meh-Isp resistojets or arcjets for tactical manoeuvre. Bonus points if both can use the same propellant and/or if they have variable thrust/Isp."
For mega-Newton level thrust, chemical or nuclear thermal rockets are required. Or fusion torches, but those are out in fantasy land, one step below warp drives.

@Ferrell
"leaving your ride home unattended seems a bit risky to me. Take the penalty and have chemical rockets for maneuvering in battle, ion thrusters for interplanetary, and maybe something for dire emergencies."

Indeed, it depends on the technology level. If you've got to carry a nuclear reactor to feed the lazor, the ion drive will probably not matter. Crew accommodations are heavy and bulky, maybe it'd be worth the mass cost, maybe not.

The non-fantasy deal is chemical and electrical propulsion and kinetic weapons. In this case, carrying around ion drives in a space battle is doubtful. Instead, there would be rocket-driven combat ships and ion-drive tugs that carry everything you don't need to fight directly. There could be specialized hotel ships for the crews, supply ships, repair ships etc. or everything could just get lumped together into carrier-analogues. Personally, I'd go with several small support ships, so that one lucky shot won't cripple the whole task force.

"Having to build two or three ships due to extreme specialization, when you can build one ship that does all three tasks (even if not quite so well), does give you more ships to use. And for a given amount of resources and cash, will probably get you a larger number of ships."
I don't see the hull as the most expensive part of a ship. Especially in space. In fact, cost is the primary argument for chemical rocket-powered combat ships: rocket engines are fairly cheap compared with nuclear reactors. So you could have more pure rockets for combat.

Rick said...

Yikes ... More great stuff than I could possibly comment on. For the record, another hearty thanks to the commenter community!

Nomenclature - Still not sure what to call space grunts. To my ear, spationaut, rocketeer, et al, have a true rocketpunk flavor in the original sense that I've hardly used here - a 1950s Dawn of the Space Age feel. (Stormtroopers can only be bad guys, for a good long time to come - meaning author era, not story era.) Astrale for a space service is rather elegant, but (alas) in English it is all too close to 'astral' with its new agey mystical connotation.

And speaking of rocketpunk era SF, a curious little note on space marines. Heinlein mentioned Marines, by that name, in several of his classic 50s YAs, notably *Space Patrol* and *Starman Jones*. But in *Starship Troopers* he called them Mobile Infantry, with what seemed more like plain old army than marine roots.

I am tempted to just call them Boots ... in the airlock, on the ground, wherever you need them.


Magic - @Tony ... the only magic allowable IMO are hyperdrive, artificial gravity, and torch drives
Okay, I'll bite. FTL for sure; it is *really* hard to to have star empires and similar cool stuff without it. Torch drives also help ships move at the speed of plot. But all artificial gravity does is get rid of spin habs, which IMHO doesn't really seem a magic-justifying priority. What am I missing?


More laser zaps - Okay, I understated the leading-the-target issue. But if you can achieve ueber precision in the first place (small enough sustained spot size to deliver an effective zap), leading the target is probably not *that* much harder.

Another way to look at the whole zapping question is this: What is the minimum laser performance needed to make a space laser weapon effective at all? I see two basic things you might want to do: Engage enemy ships (or large drones/missiles) before they can let off a salvo of SCODs, or as point defense against the incoming SCODs.

Consider a salvo of 100 SCODs, incoming at 10 km/s. Suppose that each one is about 10 cm in diameter - comparable to a 4-in shell - with a faceplate of Super Carbon Nano Stuff 5 cm thick. So to defeat the salvo you need to burn through (or shatter with impulsive shock) a total 2 meters of laser armor. Put another way, each faceplate is about 1 kg mass, and takes ~50 MJ to burn through. To use beam energy efficiently the spot size must also be not much more than 10 cm in diameter - a 20 cm spot would waste 75 percent of its energy; a 1 meter spot would waste 99 percent (!) of its energy.

Starting at 1000 km, you have 100 seconds before you get smacked. A 500 nanometer beam will need a mirror about 1 m in diameter (more or less). With 50 MW of beam power you will nominally take out one SCOD each second, and just barely defeat the salvo. Initial required aim precision is 0.1 microradian, about 50 milliarcseconds.

In practice, as the salvo gets closer your spot size gets smaller, and burns through the faceplates faster - if you hold the beam steady on that smaller spot. That favors the laser defense. OTOH, you need to confirm each kill, then shift to the next target. And at some point the salvo is close enough that even burned-out SCODs still smack you.

These are VERY rough numbers, done in my head. If your zaps deliver impulsive shock, advantage laser. If beam performance is much below the diffraction limited ideal, advantage SCODs.

The overall point is that basic laser point defense is not all that much easier than the 'laserstar standard' of laser capability. This is not an argument for laserstars as such, it is more that laserstars are what came out of my attempt to estimate what it would take for lasers and kinetic missiles to both be viable in more than niche applications.

http://www.rocketpunk-manifesto.com/2009/09/battle-of-spherical-war-cows-purple-v.html

http://www.rocketpunk-manifesto.com/2009/09/further-battles-of-spherical-war-cows.html

Make of it what you will!

Rick said...

Oops, the mirror diameter should be more or less 5 meters - I forgot the spot size was 10 cm. Hey, I warned you it was quick & dirty! If anyone once to check these numbers, thanks in advance!

Thucydides said...

I would not get to wrapped around the axle about terminology, since a lot of it is based on historical or traditional factors which generally only make sense in historical context. In the Canadian Army, for example, we have several units (Regular and Reserve) styled as "light Infantry" and "Rifles". In the 17 and 1800's, these distinctions were quite important, and things like uniforms and even the drill was different to reflect the different roles of a light infantry or rifle regiment compared to a line infantry unit.

Today, the Princes Patricia's Canadian Light Infantry (PPCLI) ride around in LAV's (similar but larger than US Army Strykers) just like everyone else, and the remaining "Rifle" units do not march around at 140 paces to the minute, nor carry specialized firearms. Indeed the only remaining reminder they are rifle units is they have traditional black buttons on their dress uniforms rather than brass buttons. Armoured units still mostly have Cavalry origins in the Canadian Forces, but the only functional difference between the Dragoons and the "Strathcona's Horse" is the government bought so few tanks that only one unit is fully equipped (the remaining squadrons using another version of the LAV). An even more extreme historical mutation was the evolution of the "Canadian Mounted Rifles" from horse mounted infantry in the Boer War to plain dismounted infantry in the trenches of WWI. (Mounted Rifles were disbanded as an actual arm and unit post WWI, but had they survived into the present day, might conceivably have been airmobile on helicopters. OTOH, they might be riding around on LAVs was well, like everyone else).

So space troops may have names and traditions dictated by some sort of historical circumstance, which is no longer reflected in their current role. If there is a "British" flavour to the back story, unit name and even regimental affiliations might have been merged and changed over the years as units were formed, amalgamated or even disbanded.

The USMC is actually instructive in this regard as well. Traditional ships Marines were not an assault force, but the ships own security force. Even in the modern day, few nations even have Marine forces dedicated to amphibious assault, or enough Marines to make that their exclusive task. In the Falkland Islands War, the British assaulted the islands with Royal Marine Commandos, Paras, Guards and other assorted units in order to have enough troops to do the job. Divisional sized Marine units belong to the United States. Even in the former Soviet Union, the amphibious landing job was handled by a component called Naval Infantry.

So for anyone writing a setting or a story, you can call your troops whatever you want.

WRT laserstars, Rick has demonstrated why there will be a drive to create the most extreme devices possible. The greater the range the laser can reach, the more time there is to dwell on individual targets. The worked example only gives 100 seconds to deal with the salvo, but a beam with twice the effective range now has 200 seconds, and so on. Even at very extreme ranges, the "scorch" poser of the beam should be considered, since blinding sensors or causing radiation damage to internal computers and systems could be a very significant part of the battle.. Even just heating the SCoDs so they stand out more clearly so subsequent layers of defensive systems can engage more quickly can be a big win for your side, if you can sweep enough of them away.

Rick said...

Nomenclature again, @Thucydides ... I would not get to wrapped around the axle about terminology, since a lot of it is based on historical or traditional factors

Very much true. But that is also what makes the nomenclature question interesting! 'Marines' are a perfect case in point. Calling space troops by that name is a feature if you want to evoke the USMC or Royal Marines, but may be a bug for a setting where it would be, say, comparable to calling troops 'Legionaries'. (And yes, you might *want* Space Legions, because the good old SPQR has cast a very long shadow.)

Similarly, in a somewhat far future setting I would be more comfortable with 'frigate' than 'cruiser' for a powerful, long range patrol craft, because frigates have been around for so long.

Rick said...

Propulsion -

@Ferrell ... combat spacecraft should have more than one engine (or have their primary have 'gears')

Hmm. There seem to be three distinct mission requirements, which somewhat correspond to three viable propulsion modes.

* Cruise, for interplanetary travel (including, by common SF convention, to FTL jump points). Requires delta v of dozens of km/s. Time scale of weeks to months. All but requires electric drive - which can more evocatively/romantically be called ion drive (even if not 'true' ion drive in the technical sense), but limited to milligee acceleration. Even the lowest 'gear' is still in the milligee range.

* Tactical, for orbit changes to shape the engagement geometry. Probably needs delta v of several km/s. Time scale of minutes to a day or so. Moderate acceleration (10-100 milligee) called for; more if you can get it. Well suited to nuke thermal; ion drive is very sluggish, while chemfuel has lousy gas mileage.

* Jinking, to dodge kinetics or throw off laser aiming precision. (Though you don't really dodge zaps at sub lightsecond range.) Time scale of seconds. High acceleration (1 g range) desirable. Nicely suited to chemfuel, especially since engine thrust/mass ratio is very high. Ships may jink 'sideways'.

The correspondence of mission role to drive type is pretty neat, but may be too neat. Jinking may or may not be useful in practice. Nuke thermal specific impulse is not all that high, so the advantage over chemfuel may be limited. Also mainly suited to fairly large craft due to radiation shielding mass. But dual mode nuke thermal may be viable, producing electric power for cruise and direct thrust for combat.

And yes, for those who like being shot out of a cannon, there is Orion drive. I'm not sure, though, that it has the specific impulse for deep space travel. And there may be problems with operating it anywhere but the middle of nowhere, since it puts out *lots* of radiation. Combat is one thing, but where do you base it and deploy it for routine training missions?


Something else to think about is that for long duration human spaceflight - civil or military - we probably need to bite the bullet and provide spin habs with 'career standard' radiation shielding. Meaning enough that people can serve an active career without retiring early due to hitting the lifetime radiation limit.

At a guess, this probably means a minimum 1000 ton hab for about 100 passengers in transport configuration, or working crew of a few dozen. Larger habs benefit: perhaps 3000 tons for 500 passengers or 200-300 crew, 5000 tons for 1000 passengers or 400-600 crew. The 'dry' mass of the whole ship might range from 2-5 times hab mass, and with full propellant load, departure mass about 2-5 times dry mass.

This gives a range of departure mass from about 4000 tons to 100,000 tons plus - more or less the same mass range as oceangoing ships. Smaller craft are not necessarily 'riders', since some may have their own deep space drive, but for deep space service they would not have a permanant onboard crew. Either they are drones, at least during transit, or the crew rotates in and out from larger 'hotel' ships.

Rick said...

@Ferrell ... but leaving your ride home unattended seems a bit risky to me

It would make me uneasy, too. And it invites a defender to engage you far out along your approach track, before you have fully decelerated from transfer speed. All I need to do is force you to detach from your logistic craft, and keep you hopping enough that you can't hook up again. Your combatants don't have enough delta v to slow down, so your whole task force will hurtle past my planet and into the void, a complete mission fail even if I never laid a glove on you.

And another general thought. If lasers (or coilguns, etc) are a Big Deal, it makes sense to mount them on your ion drive ships, which have plenty of juice. Which produces something like capital ships. But if missiles are dominant, the actual combatants may be much smaller craft, often expendable killer buses, with the big ships being only vulnerable targets you need to protect.

Geoffrey S H said...

Three engine types. Lot's of different spare parts to carry around. Hmm... Unless you have multiple carriers with ion engines for strategic transit, wouldn't it be better to simply use nuclear thermal for transit as well? I feel like we're delving a little too far into specialisation again here. YMMV

Battle riders sound like dragoons... can bring multiple assets to the table on one carrier, but aren't the dominant part of the constellation. 'Topping up' numbers alongside more independent craft if the battle plan allows it.

"And yes, for those who like being shot out of a cannon, there is Orion drive."

Argh! Now I have this terrible/ridiculous idea for a far future setting involving Orion cruisers shot out of Jules Verne-style cannons on the moon. E. E Doc Smith, eat your heart out!

R.E: infantry: I do keep thinking of infantry sent to capture asteroids and airless moons that you don't want to vapourise. Could be robotic, would be equipped with vanta-black helium tanks. Minimal thermal emissions as they approach the surface... Dark Infantry?

Tony said...

Rick:

And speaking of rocketpunk era SF, a curious little note on space marines. Heinlein mentioned Marines, by that name, in several of his classic 50s YAs, notably *Space Patrol* and *Starman Jones*. But in *Starship Troopers* he called them Mobile Infantry, with what seemed more like plain old army than marine roots.

Well, it takes a little remembering to recall just how Marine-y the Mobile Infantry was. The Mobile Infantry had "Ship's Sergeants" and "Fleet Sergeants". This suggests that they were at least as institutionally tied to the fleet as the US Marines, who only got as close as Gunnery Sergeant to acknowledging their shipboard duties. Knowing a little bit about historical Marine rank structure helps too. Just prior to Heinlein writing Starship Troopers,the US services reformed their enlisted rank structures, going from seven pay grades to nine. The Marine Corps elected to assign pay grade E-3 the rank of Lance Corporal. As one may recall, that rank was used in the book, at the same level in the grade structure as the Marines were using in 1959.

Also, while having administrative units and formations like battalion, regiment, brigade, and division, and while using formations up to division sized in ground combat, the Mobile Infantry deployed from and returned to fleet transports that they were closely associated with. The longest missions were counted in days and resembled WW2 island fighting in the Pacific in a lot of ways. Historically, a lot of that was done by Marines.

I am tempted to just call them Boots ... in the airlock, on the ground, wherever you need them.

Jeepers, open source license that term before somebody trademarks it! It could very well be the basis of a great trope.


Magic - @Tony ... the only magic allowable IMO are hyperdrive, artificial gravity, and torch drives
Okay, I'll bite. FTL for sure; it is *really* hard to to have star empires and similar cool stuff without it. Torch drives also help ships move at the speed of plot. But all artificial gravity does is get rid of spin habs, which IMHO doesn't really seem a magic-justifying priority. What am I missing?


Artificial gravity is pretty optional, but allowable for a few reasons. If you have it, you presumably have space warping STL drives that allow you to come and go on planets a lot easier. Also, while (thanks to Atomic Rockets) the upright cylinder has become almost a litmus test of SF hardness in spaceship design, a few large decks of a saucer or laid-down cylinder are operationally much easier to manage. Artificial gravity gives you those options. (Or at least gives you those options much more organically.) No switching from spin to acceleration orientation either. If you want to call it a plot convenience go right ahead -- same-same torch drives and FTL.

More laser zaps...

If I were using literally 12 oz can sized SCoDs, I would be launching thousands of them at each target laser star. Remember, the longer ranged and more powerful the laser, the less mobile it becomes, and the more like military engineering operations against them become. SO you have time to gather the necessary resources to make overwhelming attacks.

Tony said...

Thucydides:

The USMC is actually instructive in this regard as well. Traditional ships Marines were not an assault force, but the ships own security force. Even in the modern day, few nations even have Marine forces dedicated to amphibious assault, or enough Marines to make that their exclusive task. In the Falkland Islands War, the British assaulted the islands with Royal Marine Commandos, Paras, Guards and other assorted units in order to have enough troops to do the job. Divisional sized Marine units belong to the United States. Even in the former Soviet Union, the amphibious landing job was handled by a component called Naval Infantry.

The US Marines were originally authorized as "two Battalions" in 1775, and had already completed an Amphibious raid in the Bahamas four months before the Declaration of Independence. The us of ships' troops as landing forces occurred from time to time throughout the history of the Marine Corps. Even as late as 1987, Marine Detachments on US Navy ships were armed and equipped for short duration landings.

The greater the range the laser can reach, the more time there is to dwell on individual targets.

The greater the range, the less likelihood of being able to dwell on a target at all.

Tony said...

Ferrell:

Having to build two or three ships due to extreme specialization, when you can build one ship that does all three tasks (even if not quite so well), does give you more ships to use. And for a given amount of resources and cash, will probably get you a larger number of ships.

It won't give you more ships, and it will give you fewer fleet units.

It won't give you more ships, because each ship has to have a complete set of communications and surveillance apparatus. Even if you dedicate one ship to enemy surveillance, the other ships have to maintain surveillance on each other and the surveillance ship, in order to have good position data so that the surveillance ship's enemy data can be put to meaningful use. You also need some kind of backup capability in case the surveillance ship gets neutralized. So, for example, having three single-purpose ships to replace a more general purpose ship requires three times the critical sensro and communications gear. The same story goes for other types of overhead. So what you might manage is the same number of ships, but having a large dose of a single capability in each one.

It will give you fewer fleet units because while you may have the same number of ships, you have to send them out in stereotyped groupings, so that each mission has the complete array of capabilities. That means you can't be as flexible, as in sending out one or two ships on a small mission, instead of the required three (of four, or whatever).

Single-purpose ships also create unnecessary vulnerabilities to targeted attacks the break up the integrity of the combat unit. If the enemy can figure out a way to make one ship in the fleet unit excessively vulnerable, the loss of its capabilities may handicap the entire unit. With multi purpose ships, the neutralization of any set of ships neutralizes just those ships, it doesn't neutralize an entire capability.

Anonymous said...

I said: "Having to build two or three ships due to extreme specialization, when you can build one ship that does all three tasks (even if not quite so well), does give you more ships to use. And for a given amount of resources and cash, will probably get you a larger number of ships."
Tony said :"It won't give you more ships, and it will give you fewer fleet units"

Tony, you completely misunderstood what I said, getting it totally opposite of what I meant.
I was arguing that building less expensive multi-role ships would be better than very expensive single purpose ships. Your arguments support my own. Even if you only build, say, X number of multi-role ships and your adversary builds 1/4X laserstars, 1/4X kineticstars, 1/4X missile cruisers, and 1/4X command ships, you can still deploy your ships to four times the places your opponent can or achieve local numerical superiority much easier due to his having to deploy four ships to have the full range of capabilities your one ship does. One of these units of four specialized ships would be at a disadvantage to a unit of four multi-role ships.

Ferrell

Rick said...

@Geoffrey ... wouldn't it be better to simply use nuclear thermal for transit as well?

Poor gas mileage. Solid core is in the neighborhood of 10 km/s (1000 seconds isp). Liquid core is somewhat better (1500 sec isp), but not awesome, and tricky to handle. Gaseous core is *so* tricky to handle - effectively containing a fizzle yield nuclear explosion - as to be demimagical.

The rocket equation, combined with planetary distances, is just plain a bad tempered bear. I don't favor ion drive because I love hauling around gigawatt power generators and massive radiators, or solar wings the size of a farm. But a million tons of lower stages or drop tanks are even worse.

@Tony ... a little remembering to recall just how Marine-y the Mobile Infantry was

I do remember fleet sergeants and such. Perhaps Heinlein didn't want to touch interservice rivalry with the proverbial three meter pole, so avoided explicitly calling 'em gyrenes.

Boots ... Jeepers, open source license that term before somebody trademarks it!

I will interpret that as a 'like'. Works for me, so Boots they are.

Artificial gravity ... If you have it, you presumably have space warping STL drives that allow you to come and go on planets a lot easier.

Well, artificial gravity and antigravity plausibly go together, and antigravity drive would be *really* convenient for planetary landings.

And contrary to popular perception, it need not imply 'inertialess' drive. Conceptually it is just like an elevator car, minus the 40,000 km physical cable. Feed in power to go up, get it back (ideally) when you go down.

Regarding deck orientation, truth to be told the convention of crosswise decks only really applies to torchships, which sustain prolonged high acceleration. (And tail landers, if you expect to spend a long time on the surface.)

Chemfuel or nuke thermal ships are only under thrust for brief intervals, so if you want to strap yourself to a bulkhead, no problem. Ion drive is so gentle that you can ignore it (stuff left floating will slowly drift aft). I assume that spin habs of ion ships just go on spinning while under under cruise thrust.

If I were using literally 12 oz can sized SCoDs, I would be launching thousands of them

Actually, so would I, at least against heavily defended targets. The practical limit to how many SCODs you carry is probably not their mass (even including magazine) but their individual cost. The cost of thrusters and such probably scales roughly to mass, but the guidance system does not - a small target seeker needs as much precision to score a hit as a big one does. So the guidance package sets the lower limit to unit cost.

All the same, even 'magnum bottles of death' tip the purple/green balance massively (so to speak!) toward kinetics. You pretty much need to assume Awesome lasers to make point defense meaningful.

And I think there is a bias in geekdom toward more than one major weapon system. And that massive kinetic salvos make space battles into crude, inelegant slugfests. OTOH, you could argue that at this level of generality, battles between sailing ships armed with smoothbores are also crude slugfests ...


As a side note, I often notice people using 'kinetics' and 'missiles' as distinct weapon systems. Which seems odd to me, because when I speak of kinetics I generally mean target seekers (or at least their fragments).

Rick said...

On single or multipurpose ships, I'll own some blame for often discussing 'pure' cases here. On the few occasions on which I've described individual warcraft, they have been more balanced, such as here:

http://www.rocketpunk-manifesto.com/2010/11/space-patrols.html

(Though I'd now call that ship much too small for prolonged missions, by about a factor of 10.)

I see two distinct aspects to how specialized ships can or cannot be. One is that you generally want some minimum of ability to handle the unexpected. Your capital unit is intended to operate within a substantial constellation, but you probably don't want it to be helpless if, in rendezvous with a neutral station, a space taxi makes a 'speedboat' attack.

(And speaking of unguided kinetics
, a plain old minigun may be as good a close in defense as any.)

Distinct from that minimum level of flexibility, there are some missions that go well together and some that don't. HMS Dreadnought sank a U-boat by ramming, but battleships were generally not very good ASW platforms. OTOH they turned out to be excellent AAW platforms, able to carry scores of antiaircraft guns and shrug off a couple of kamakaze hits.

To take another case, as I noted upthread, trade warfare raiders and fleet scouts have entirely unrelated missions, but the mission requirements were similar enough that both called for cruiser types, and individual cruisers could often serve in either role as needed.

A possible similar case suggests itself. Even without stealth as an issue, you want to know as much as possible about an approaching hostile force, which means getting a powerful scan suite as close as possible. You may also want a deep space strategic reconnaissance capability, observing hostile centers. Again, a powerful scan suite is called for.

Depending on other requirements - notably mission duration and need for independent decision making, the strategic and tactical reconnaissance missions may or may not call for cruiser or frigate types that can perform both.

AlexT said...

Instead of trying to burn through armor, wouldn't lasers be better for heating up the enemy's radiator array ? Lower precision required since radiators are big, lower beam focus and intensity required since you don't need to heat up a small area very quickly. So you could do it from further away, possibly with a smaller laser and/or optics. Just a thought with no numbers to back it up..

Another thought on laser ships: since can't thrust while shooting, I'd just keep them busy shooting down guided kinetics, one at a time, while an unguided, cold (hence undetected) kinetic strike is hurtling on an intercept trajectory. To make up for inaccuracies and/or small maneuvers, the killer could use its engine on final approach, or it could be a shrapnel burst, a nuclear shaped charge.. or it could simply be a cloud of 10 gram ball bearings.

"I would be more comfortable with 'frigate' than 'cruiser' for a powerful, long range patrol craft, because frigates have been around for so long"
Weren't frigates in the Age of Sail actually called cruisers ?

Re space magic: Artificial gravity has so many possible consequences ! It just gets slipped by quietly in movies etc when people don't really want to think about it..

"And I think there is a bias in geekdom toward more than one major weapon system. And that massive kinetic salvos make space battles into crude, inelegant slugfests."
Purely aesthetically, I find lasers are an extremely impersonal and "unskilled" means of destruction. Point, push button, wait a few hours. Kinetics have trajectories, intercept solutions, they can turn on the engine only on final approach so surprises are possible, you can send them where you think the enemy will be, you can use them against each other.. far more opportunity for human foolishness and/or brilliance.

"And another general thought. If lasers (or coilguns, etc) are a Big Deal, it makes sense to mount them on your ion drive ships, which have plenty of juice. Which produces something like capital ships. But if missiles are dominant, the actual combatants may be much smaller craft, often expendable killer buses, with the big ships being only vulnerable targets you need to protect."
Spot on. Considering habitats are huge, probably those need to be separated out in any case into hotel (barracks?) ships. There may even emerge an (unwritten?) consensus that nobody shoots the spin habs. That would be enforced by the fact that each round/kilowatt fired at an unarmed target is NOT fired at a dangerous one. Of course, if you put guns on the cruise ship, you deserve what's coming to you.

Eth said...

Nomenclature:

About the Russian naval infantry, according to Wikipedia, Russian Marines is an alternate name. Which makes sense, as Marine infantry means naval infantry. Case in point, the French Infanterie de Marine, where "Marine" comes from in the first place, would be literally translated by "naval infantry".
About "Legionnaires", while it does call back to the Roman Empire, which may be intentional from the force's creators, it also evokes modern forces like the French Foreign Legion or the Spanish Legion as an extra bonus - which have a similar expeditionary/shock troops role.
Rick, I am surprised that Spationauts and Rocketeers feel '50: Spationaut is a more recent term, and Rocketeer evokes Musketeer, so more of a Clock Punk (case in point, the tabletop RPG The Three Rocketeers, which is more or less exactly what you imagine it to be).
Too bad about the "Astral projection" & cie evocation. Surprisingly, astronauts don't seem to be hit by that. Though I'll personally keep using Astrale - Starfleet is too Star Trek-chained, and Star Navy doesn't feel right to me.

That said, "Boots" is a good generic name indeed. Most probably not what the actual force would be called, but it seems that this one would be heavily dependent on the force's history and choices.


Dual drives:
My rather limited knowledge of ion drives mostly comes from Children of a Dead Earth, but it appeared to me that such drives are rather light, so the drive itself would not call for a dedicated bus. The massive powerplant might, but why would it be left behind when it can be used for powering weapons in the first place?

Also, while thermal-electric drives have had a limited history so far, their performances are better than directly nuclear-thermal drives, as they can heat the propellant at higher temperatures. And you have the huge aforementioned powerplant.


About external laser shutters, have there been studies about those? I would expect shutters coordinated with lasers (as opposed to actively hostile targets), though coordinated aiming at long distance becomes a problem - there, secondary mirrors may help, though.
If a shutter can open and close in, say, 50ms, this gives a 15000km long beam, which seems manageable for moderately strong laserstars.

But reasonable laserstars do seem vulnerable to swarms of SCoD (like Tony, I imagine any such projectile with guidance - unguided slugthrowers are strictly short range). Rick's 10 km/s even appears conservative depending on the engagement: interception of/with an interplanetary force could attain much higher velocities.
Using stealth projectiles is a good idea, and may make point defence irrelevant in serious engagements. A tiny, simple Hydrogen Steamer design would have limited autonomy but it would be enough, and even simply supercooling projectiles before firing may be enough.

Also I don't see how projectile swarms are unromantic. Throwing hailstorms of hypervelocity projectiles at each-other while trying to avoid/shoot down/survive longer than the other side has a rather badass - and familiar - feel.
Even more so if the (probably romanticised) Chivalrous Rules of Space War saying that:
- you don't fire at crewed ships (recognisable at their spinning habitats)
- you don't put offensive weapons on crewed ships (or fire offensively with defensive weapons)
- you don't fire at celestial bodies and avoid positioning yourself so shooting at your forces would put celestial bodies in possible trajectory
- you rescue everyone regardless of sides
(of course, reality is often much less romantic...)

Lasers could still be useful for laser-thermal projectiles, though, particularly for light interceptors: a tiny telemetry package can help with laser aiming, the sensor suite can be lighter as the defending ship can complete it, so it can still be much cheaper and lighter than a dedicated anti-ship SCoD.

Thucydides said...

One drive which everyone (myself included) is studiously ignoring is the ORION nuclear pulse drive in its various forms. An ORION battleship, cruiser or frigate has both high thrust (for combat manoeuvres) and high ISP (for economical long range cruising). The USAF ur design concept form the 1960s was a 4000 ton vessel which carried a battery of ICBMs, 5" naval cannon and CASABA howitzers (as well as several landing craft). It is really difficult to characterize this as anything less than a battleship, since it carries a main battery designed to vaporize cities, and the self defence systems can deal with pretty much anything outside of a similarly armed and equipped vessel. ASATS, space mines (unless the Captain and crew are careless) and even 1960 vintage SDI concepts like BAMBI would all be vulnerable to the USAF space battleship.

(not very good summary here: http://www.defenceaviation.com/2013/04/usaf-nuclear-powered-doomsday-machines.html)

Conceptually, the ICBMs can become long range missile busses for warheads of various types, or replaced by railguns or coilguns. There is no issue in carrying a large and powerful nuclear reactor aboard an ORION, and if the propulsion system is an implosion type fusion reaction (like Dadelus), then lots of electrical energy can be tapped from that source as well. Using large lasers will be problematic in an ORION style ship with the drive engaged, since it is difficult to imagine a "raft" with sufficient ability to damp out the vibrations for the optical train (although we should never say never, nuclear submarines can isolate the noise and vibration of very powerful turbines and transmission systems to gear down the rotation speed for the drive shafts), ORIONS might have to be "sprint and drift" laser platforms if that is the way you want to go.

ORION drive ships are conceptually the ones needed for multi purpose vessels, since you are far less bound by the tyranny of the rocket equation. Instead of taking barber chairs to Mars and Saturn, as Freeman Dyson cheekily suggested, the extra carrying capability can be used to mount primary and secondary batteries. The level of performance also lends itself to more "naval" tactics, since the ship has the thrust and ISP to perform long cruises in reasonable timeframes, move in and out of gravity wells quite quickly and potentially sidestep incoming enemy rounds or zaps with sufficient warning. Turning the pusher plate towards the enemy and firing a few pulse units or igniting a stream of fusion pellets will also create difficulties for the enemy, ranging from a cloud of tungsten plasma in an ORION to a star hot stream of charged particles with a fusion drive.

YMMV, but this might eventually mutate into essentially a giant missile bus, bringing missiles just out of range of enemy defences and dispensing them in a heavy salvo designed to overwhelm potential defences. I could also see them as kinetic firing platforms to strip away incoming missiles and bombard surface and orbital targets which are either not worth the expense of a missile, or maybe need to be engaged by hypervelocity rounds in a shorter time frame than a missile could get there.

Matter Beam said...

Multiple engines:
Project Timberwind's nuclear rockets achieved over 1GW/ton, so placing small engines that can shunt around a huge spaceship doesn't cost a lot of mass.

Laserstar firing on the move:

If propulsion is so 'dirty' that it creates vibrations the laserstar cannot cancel out using dampers, anti-frequency devices and other stabilization techniques, then there is always the option of dropping your massive mirror as an independent spaceship. This targeting drone does not have to follow your spaceship - all your laser star has to do is hit the mirror across the short distance between it and the drone, and let the motionless stable drone handle focusing the beam across the long distance between drone and target.

Extending this method to several drone is the start of a laser weapon web, where laser generator, focusing array and target can all be manoeuvring independently.

Also, pulsed lasers can cut the engines, drift for a few seconds to stabilize the main mirror and shoot a volley of laser fire, like an archer shooting from horseback.

Big generators and electric rockets:

Again, you can separate power source from power consumers. Using beamed power, you can deliver the watts of a large, vulnerable generator to a nimble warship. You will accept an efficiency hit, but it might be an acceptable trade-off if you don't have to lug around hundreds of tons of reactor and football fields of glowing radiators.

The disadvantages of such a system can be mitigated by using high-efficiency masers that are easy to focus with massive yet lightweight metal mesh arrays and be absorbed by water-based heat exchangers. You can deliver the energy to your friendlies because unlike enemies, they are reporting their positions and your generator/friendly distance can be much lower than your generator/enemy distance... or not. If we have laser webs, we can energy webs.

A fully distributed 'network' fleet would have generators sitting far back, feeding laser stars that pump beams at focusing drones while they dodge incoming kinetics from independently power gunstars. Missile waves would have the choice of making a long shot at the generators through a wall of defensive laser fire, or try to hit the laserstars themselves. Focusing drones are a low-value target. Add in Hydrogen Steamers trying to slip through for a behind-the-lines strike, pellet gun 'snipers' that are a hard counter to soft-skinned laserstars (a barrage of fast kinetics that cannot reasonably be shot down in time) and goalkeeper ships that can easily intercept fast kinetics with cheap plate drones... and you have an exciting and diverse mix of warships that would liven up any post-midfuture setting.

Matter Beam said...

SCoD sensors:
You can group and share targeting information across the entire missile swarm, and computers will (probably already can) handle the manoeuvring of hundreds of individual units out of a single SCoD. Slave units with a simple receiver is extremely cheap and lightweight.

If you place one sensor per five SCoDs and have ten computers distributed among the swarm, you can reasonably expect the swarm to always track its target unless the majority of the swarm is destroyed.

Orion:
A gamechanging technology for sure... but it has certain pre-requisites such as massive amounts of fissile fuel being available in neatly packaged 'pulse units' that require that the setting run along specific lines that not all authors want to adhere to. There are consequences to those setting requirements that maybe do not fit certain future histories or do not answer certain social questions the way the author wants.

For example, a large supply of fissile fuels implies that some cheap way of mining fissile ores has been developed. The only few I can think of is deep mining of several rocky bodies or mature seawater extraction of uranium. Maybe I don't want the solar system to be so well developed. In that case, a handful of Orions would deplete the current world's nuclear reserves in a few days of thrusting.

Another example: how would governments justify the risk of hundreds of small pulse units landing in the wrong hands, either through theft, sabotage or an accident? Its a proliferation risk at an existential level. Accepting these risks implies a worthwhile benefit, which is usually beating the enemy.

Nuclear proliferation, Orion battleships, existential nuclear threats... these are themes strongly attached to Cold War history, which might not always be an attractive theme.

Geoffrey S H said...

Matterbeam:

When it comes to propulsion, where do you stand on gun-fusion these days?

Rick said...

A new front page post is up, 'Republics and Maritime Hegemonies'. (Remember the date!)

http://www.rocketpunk-manifesto.com/2017/07/republics-and-maritime-hegemonies.html

Only fair to note that I do make passing mention of contemporary politics. You have been cautioned!

Matter Beam said...

@Geoffrey:

I find gun-fusion to be the quick and dirty solution to making a fusion engine work. It doesn't require a lot of energy, doesn't burn much of the fuel and has low overall efficiency, but you don't have to tinker with keeping your megaAmpere superconducting wires at cryogenic temperatures while being blasted by heat and neutrons.

My stance is that if you need high performance low tech drives that aren't Orion, use gun fusion.

However, there are some very interesting alternatives I'm looking into. One relies on the info I gathered for nuclear EFPs: explosive lenses can create conditions suitable for fusion without a fission primary. The biggest drawback is the mass of explosives required. Replace those with an inert metal heated rapidly through inductive heating or simple explosive resistance heating and you can do away with the explosives! It doesn't even have to be the extremely rapid heating in inertially confined fusion, just the combined collapsing wavefront from multiple chemical-explosive shockwave velocities coming together.

Another is magnetically collapsing metal liners. Very strong coupling between a sheet of metal and a magnetic field allows a metal target to implode and compress a propellant to fusion temperatures. It is quite efficient and only requires strong magnetic fields in pulses.

@Rick: Will look it up.

Rick said...

Orion et al ... of course we'd have a volunteer to be shot out of a cannon!

The USAF Orion battleship with the 5-inch guns and Polaris missiles sounds so much like a Dr Strangelove era parody that it is *even more awesome* as an actual proposal.

As quoted at Atomic Rockets, 'Mathematician Richard Courant viewed an Orion test and said "Zis is not nuts, zis is super-nuts."'

That said, it was rather ahead of its time with the gun armament - the 1960 era was the golden age of 'missiles only'. As Tony doubtless already knows, the USS Long Beach was originally designed without the 5-inch guns its Marine contingent served.

One constraint: Plain vanilla Orion has a listed exhaust velocity of 39 km/s, which is borderline for practical interplanetary travel. Fine for Mars, but a slow boat to Saturn. A 'second generation' version is listed with 120 km/s, but I don't know what additional bells & whistles are required.

What is gun fusion? Is it the same thing as 'magnetized target fusion', discussed here?

https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20030065965.pdf

Unfortunately that link says nada about the underlying performance of the engine, much less the actual prospects of achieving 'easy' fusion. Which I have to be doubtful of, simply because fusion has proved so damn hard. Except the H-bomb kind, of course.

Matter Beam said...

@Rick:
The higher exhaust velocity Orion comes from higher temperature resistance pusher plates. The first design used a very thick tungsten propellant in each unit to greatly reduce the temperature of the gas that impacts the pusher plate. I'm guessing later designs protected the plate with oil films and used less propellant or lighter propellants, like polyethylene.

I don't want to link to my own blog too often on Rocketpunk Manifesto, so I'll give a short description here. Gun-fusion involves shooting two fusion fuel pellets at each other. Their momentum compresses them enough for fusion ignition temperatures and pressures to be achieved.

Naked fusion fuel pellets need incredible velocities to achieve this, on the order of 3000km/s. The fuel burnup ratio is also extremely low, as only the 'face' of each pellet is contained in the high pressure zone and undergoes fusion.

The solution I found in a patent was to confine the fusion fuel to the tips of dense bullets. The bullets act as pistons that continue compressing the fusion fuel at the collision point. Several hundred km/s is still required.

An advanced concept allows impact velocities as low as 20km/s for achieving fusion. It uses multiple staged compression and preheating of the fusion fuel with a laser just before impact.

These are velocities and technologies that are within reach today and unlock high-isp, high energy propulsion for rapid travel around the solar system.

What do you think of the fleet combat model I described a few posts up?

Thucydides said...

One of the other issues of Orion is that it scales "up" very well, but does not scale "down" easily. High efficiency ORIONs tended to have huge pusher plates that could absorb a lot of the incoming energy, and utilize larger pulse units. I may be a bit backwards here, but I seem to recall that the initial versions of ORION used lightweight materials like polyethylene, and only later switched to high molecular weight materials like tungsten because the smaller pusher plates could not handle the high velocity, high temperature plasmas.

There is also the issue of drive plate interactions to consider. Polyethylene and Tungsten plasmas probably don't interact with the material of the plate, but star hot ionized iron (a common material you could mine in space) would interact with the plate. I also suspect water would be dangerous to use, with ionized oxygen interacting with the spacecraft, something to be avoided.

Rick said...

@Matter Beam ... I don't want to link to my own blog too often on Rocketpunk Manifesto

Never hesitate to do that! Your blog does make my head explode, but that is a feature, not a bug.

Gun-fusion involves shooting two fusion fuel pellets at each other ... Naked fusion fuel pellets need incredible velocities to achieve this, on the order of 3000km/s.

Yikes! But I did see the part about how pellet velocity might be brought down. Don't know that I'd *quite* call it 'technologies in reach today.' Truth to be told, it will be hard to beat nuke/solar electric propulsion for general travel, until you have something that allows torch level power output.

Something not fully appreciated is that for brachistochrone type orbits, average travel time is the inverse cube root of power output - ie, you need 8x the drive power to cut travel time by half ... or 1000x to speed up by a factor of 10. Not pretty.

What do you think of the fleet combat model I described a few posts up?

Is this the one with a discussion of beamed power? This is something I know almost nothing about, but what is the size/power relationship of the transmitting and receiving antennae?

The only context for beamed power I'm vaguely familiar with is powersats, and I seem to recall that the ground antenna farm would be a couple of miles across. Which doesn't sound compact enough for ship propulsion, unless it can be really lightweight. Put another way, how does this power density compare to solar electric kites?


@Thucydides ... One of the other issues of Orion is that it scales "up" very well, but does not scale "down" easily.

Yeah, the smaller the scale, the bumpier the ride.

There is also the issue of drive plate interactions to consider.

This, too. No matter what the material, it is impacting the plate at very high velocity, and the corresponding temperature is in the millions of degrees. I'm not entirely convinced that you won't get serious plate erosion under sustained power. Nuking yourself once is one thing, but nuking yourself hundreds of times ...

Matter Beam said...

Rick!

Explode in which way? In the 'I never realized this' way or the 'this isn't being explained clearly and simply' way?

I think gun fusion is a step above Orion propulsion but much less complex than fusion Tokamaks or even ICF fusion such as the Z-pinch. It opens up terawatts of propulsive power however, and that might just provide the x1000 factor needed for ten times faster travel...

Beamed power using shorter wavelengths such as infrared and operating over combat ranges (10000km) only needed transmitters and receivers of a few meters across. 1000nm laser at 10000km only needs a 10m wide mirror to deliver energy to a 1.22m wide receiver. You might have an overall efficiency of 0.6*0.9=54% for direct laser-thermal propulsion, or 0.6*0.3=18% of laser-photovoltaic energy.

Thucydides said...

I would actually put gun fusion, ICF, Z pinch and similar systems in the"Pulse Drive" category, and are conceptually very similar to ORION. With a bit of tweaking (throwing extra reaction mass in the mix to be accelerated by the high energy plasma) you can move roughly into ORION's high thrust/high ISP performance. If we are talking about military space vehicles, this will be quite desirable for combat manoeuvres, but even civil "packets" carrying people can take advantage of this when operating in the gravity wells of planets or other places where a burst of high thrust would be desirable.

The other huge advantage of this sort of drive is you can tap it for a great deal of on board electrical energy, which can be channeled into such things as magnetic shielding against cosmic radiation or other high energy applications (using it for "hotel" power generation is a pretty trivial use considering the massive amounts of energy you are dealing with. Not having to lug around a separate nuclear reactor or kilometres of rectenna to receive beamed power would radically cut back the amount of mass being carried and improve performance considerably.

AlexT said...

@Rick
"Truth to be told, it will be hard to beat nuke/solar electric propulsion for general travel, until you have something that allows torch level power output."

Fusion propulsion can take two distinctly different forms, as far as I can tell. Either a fusion reactor generates electricity which powers some form of mass driver, or the fusion plasma is directly ejected to generate thrust. The former is theoretically possible, but might prove to be as impractical as flapping wings on airplanes. The latter is possible with current technology, by shooting Teller-Ulam thermonuclear bombs behind an Orion-type floating juggernaut. Which is insane for multiple obvious reasons.

The good news seems to be that if we can do fusion reactors, we can also do pulsed fusion drives and vice-versa. My question is, wouldn't a mass driver powered by a fusion reactor be better, isp-wise, than direct drive ? Obviously, not as energy-efficient and with far less thrust, but with far greater delta v. Maybe enough for interstellar travel.

The outcome would then be two different classes of fusion ships: straight-up torches that shoot fusion plasma out the back, and true long-range ships that use the power output of a fusion reactor to hurl tiny masses at c-fractional velocities.

Eth said...

A mass-driver, Isp-wise, would be better only if said mass is ejected faster than the fusion plasma would. This may be possible with ion drives, maybe with thermal-electric drives (resistojets or arcjets) if the plasma is for some reason particularly low, but probably not with a slugthrower, which is what we think about for "conventional" mass drivers.

AlexT said...

@Eth: yeah, by 'mass driver' I meant some form of electrical propulsion which can accelerate a tiny amount of propellant to extreme velocity. I'd rather not go into specific propulsion methods because, if we have fusion power, we probably know lots of clever new tricks for working with magnetic fields, accelerating small masses etc.

Applied to military ships, physics being what it is, we'll still end up with high-thrust low delta-v "fighters" and low-thrust long-range "motherships"; the fighters are either chemfuel / nuclear-thermal or fusion torches, and the motherships fission or fusion-powered.

Eth said...

Taking the Atomic Rocket numbers for VASIMR (for ion drive) and MIC (for direct fusion), high-gear VASIMR has a much better specific impulse. So, assuming you have both access to MIC and a fusion generator (and its mass isn't too important), it may be worth it to use generator+ion drive instead of direct fusion in this case.
This may change depending on what ion drives, fusion generators and fusion drives are available. You may have fusion drives that have better Isp or that make it otherwise more interesting.
I would expect ion drives to end up with less acceleration in general, as a generator introduces inefficiencies (and as such, waste heat) and you end up with less energy going to accelerating propellant.


I am also working on a rocketpunk setting, but Rick probably won't like it.
Taking the idea of "the Galaxy is full of black-powder conquistadors who discovered gravity drive/FTL and stopped tech evolution (only Terrans were too stupid to miss it and had to do with that complicated stuff like high-power gunpowder, antibiotics and computers)" from a Harry Turtledove novella - but while they land in about 2050 in the novella (a Mars manned mission is en route), I have them land in 1928. That way, I can revive the romantic tropes of analog computers, slide rules and good old space naval ships full of space sailors.
But this is essencially dropping tech-disrupting magic onto the Interwar period (though WWII will probably go completely off the rails, so they won't call it Interwar).
I'll have to check the theoretical performances of mechanical digital computers, though.

AlexT said...

Re torch vs electrical: It would certainly depend on the particulars. It might be that electrical drive is so inefficient that the ship runs out of fusion fuel before reaction mass. Or that all the mass for radiators etc makes electrical drive totally useless, even over long periods.

Your black-powder and FTL setting reminded me of a Van Vogt novel. It was set in a post-nuclear holocaust future where humanity still knew how to make some kind of nuclear-thermal rockets (if I remember correctly) although they didn't have the foggiest about why they worked. But most other tech didn't survive the cataclysm, so they went to war in starships, disembarked and fought with swords, pikes and bows. It was fun.

Elukka said...

@Matterbeam:
The higher exhaust velocity Orion comes from higher temperature resistance pusher plates. The first design used a very thick tungsten propellant in each unit to greatly reduce the temperature of the gas that impacts the pusher plate. I'm guessing later designs protected the plate with oil films and used less propellant or lighter propellants, like polyethylene.

It's not really temperature that's the limiting factor. Effective exhaust velocity/isp is related to the velocity of the plasma from the pulse unit, and the limiting factor for that is pusher ablation. That lower exhaust velocity figure is about right for a large, later type Orion using a steel pusher with ablative oil. If you can find a pusher material that can withstand a higher speed impact with the plasma, you can get higher isp. These numbers weren't intended to represent any sort of ultimate limit, rather they were considered adequate for initial operating capability. They threw out an educated guess of 100-200 km/s exhaust velocities a couple decades and vehicle generations down the line, but I wouldn't put too much stock in that particular number.

Physics conspires to make temperature less of an issue. The environment around an Orion's pusher is really weird. What you've got is a 120 000 K plasma at a pressure of about 1 atmosphere. It's hot enough to radiate ultraviolet, and dense enough to be opaque to it. I don't know quite how that works out, but apparently it prevents much of the heat from reaching the pusher. Even if it did not, the temperature issue would be mitigated by the extremely short time the plasma is in contact with the pusher:

"For about one three-thousandth of a second the plasma stagnates against the pusher plate at a temperature of about 120,000 degrees. The time is too short for heat to penetrate the pusher; so the ship is able to survive an extended series of pulses, the way someone can run barefoot across a bed of coals without getting burned. Even on ambitious interplanetary mission, involving several thousand explosions, the total plasma-pusher interaction time amounts to less than one second. The high temperatures are safely isolated, in both time and distance, from the ship."
(From Project Orion - The Atomic Spaceship)

@Rick
Yeah, the smaller the scale, the bumpier the ride.

Yup, and the worse the performance and the economics. Check out how the isp scales with size with the underlying technology being the same:
http://i.imgur.com/DlmOKMr.png

They also worked out how pulse unit costs scale, and though that is probably more speculative, this is still illustrative:
http://i.imgur.com/Tadtsxh.png

When you pay twice as much for a pulse unit, you get over sixteen times as much thrust! Economics will heavily favor very large ships. By going big, you can get twice the isp at a fraction of the propellant costs relative to ship size.

You'll also want high acceleration. Pulse units are expensive regardless of their size, so you want to minimize their number - which means maximizing delta-v per pulse unit, which means a high acceleration.

So, if Orion drives are in, our midfuture craft have rather different design considerations. We get big and nimble battleships that can figuratively (or, I suppose, literally) run circles around nuclear electric rockets and handily out-dV nuclear thermal rockets. I don't see it obsoleting other types of propulsion, though. Given the nature of the system, Orion ships are likely cheap to build, but flying them is very expensive. Not an everyday patrol ship, then, but an asset that stays at port until a shooting war happens. (And now we've got a fleet with drastically different types of propulsion depending on role.)

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