Monday, June 4, 2012

The Last Battleship

Over the Memorial Day weekend, USS Iowa left San Francisco Bay, presumably for the last time,on its way to become a historical exhibit in, apparently, San Pedro. (She should have become a historical exhibit here, in San Francisco. That she didn't is a travesty for which the political side I generally agree with was to blame, but has roots in an episode that was not the Navy's best moment. See the Wikipedia page on the ship. But watching her leave was a rather moving experience I otherwise would not have had.)

I am not sure in what sense Iowa is the 'last battleship.' It does not seem to have been the very last in commission, but more likely was the last to be 'striken' from the navy list. This came after it rusticated for some years in the Suisun Bay mothball fleet, out of commission but at least nominally available for refurbishment and return to service. (In fact, it seems that even as a museum ship it is in some theoretical sense still available. But its next berth will almost certainly be its last.)

By exquisite coincidence Iowa passed under the Golden Gate Bridge on the day before the bridge's 75th anniversary celibration, and also happened to coincide with the commemoration of Memorial Day, the 'Murrican counterpart to Remembrance Day.

It all lends itself to any number of reflections. Swords and plowshares: After a lifetime of honorable service (70 years since launch, less a few months), Iowa is headed for a twilight afterlife as a waterfront exhibit, while the bridge remains a major regional traffic artery.

The transience of grandeur: The battleship era still conveys a powerful image, but it was remarkably brief, and Iowa's career belongs almost entirely to its epilogue. None of its class was ever seriously tested as a battleship, i.e. in action against enemy battleships.

In World War II the Iowas were used primarily as carrier escorts. During the Cold War era they were periodically recommissioned for offshore fire support. Functionally they were no longer capital ships, though size and impressiveness certainly qualified them for maintaining a presence, one of the most fundamental naval missions.

The first battleship is considerably harder to identify. The last generation of sailing 2-deckers and 3-deckers were called 'line of battle ships' in place of the older 'ships of the line.' But this usage disappeared when ironclads came along.

The first generation of ironclads had an amazing variety of armament layouts and general configurations. No one knew what the capital ship of the future would be like, which gives the era a wonderfully steampunkish flavor. Russia's Admiral Popov was a radical design even for the era, but shows how unsettled the design possibilities were.

By the 1880s the more bizarrely creative designs were set aside. A relatively standard type of capital ship emerged, exemplified by HMS Royal Sovereign, laid down 1889, and the term 'battle ship' came into use to describe them.

Today we mainly know them as pre-dreadnoughts. Let us pause to admire the meta-ness of that term. Pre-dreadnoughts ruled the waves for a generation, but for nearly all of that time absolutely no one thought of them as 'pre-dreadnoughts.' Our ideas about these ships are inevitably filtered through their successors, and for half the battleship era retrospective time flows backward.

The last engagement between battleships - there were never very many - was Surigao Strait in 1944, so that the battleship era lasted just 55 years. If we take Pearl Harbor as the end of battleship supremacy, 52 years. Thus the battleship epilogue, exemplified by Iowa's career, lasted considerably longer than the battleship era itself did.

In fact the battleship era was transitory, not really an 'era' at all. This may be kept in mind when thinking - and most of you are inevitably thinking - of battleships' possible future spacegoing counterparts. Relatively short periods can stand out in our minds and become nearly timeless 'eras,' when in fact they only lasted a few decades.

That said, in an an age of post-industrial technological maturity the overall configuration of capital vehicles might be as stable as it was in the age of sail.

Capital vehicles - how is that for a colorless expression? I have argued before in this blog, more than once, that the familiar and time-honored naval analogy may be misleading when it comes to space forces. Laser stars, as I have speculated about them, have only a fairly tenuous similarity to 'battleships.' If kinetics are dominant, the platforms from which they are deployed might be even more remote from the battleship image.

On the other hand, the similarities might turn out to be greater, if only because impressive weapon systems have power-political significance that extends well beyond their purely military characteristics.

Discuss.




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My phone camera image of Iowa passing under the Golden Gate Bridge was too low-res to be worth posting. The Tumblr image above comes from this naval history page.

1,169 comments:

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Locki said...


Its a battle between a guy with Flamethrower and a myopic guy with a Cigarette Lighter and you are suggesting the hot air coming off the Cigarette lighter is going to cause the Flamethrower to malfunction.


Geez. Thats a bit rough. I never suggested I'd be mounting a series of laser pointers and 4-cell Maglites as counter-battery lasers.

To be fair I was thinking more along the lines of a huge laserstar been countered by 3 frigates/cruisers with a decent size laser but primarily relying on kinetic kill weapons. I was not envisaging taking on a laserstar with thousands of drones packing my old lecturer's left over laser pointers.

I am seeing where you are coming from about intensity of the laser beam. But I think you are overlooking quite a few things.

If you have a 30m wide laser the chances are that laser occupies more than 60% of your frontal cross section. I don't have to increase my spot size to hit the laser. I've got a 60% chance of hitting it anyway even with a small spot size.

Whichever way you cut the math the laserstar can be countered by a laser much smaller than itself because an unshuttered laser is easily the most vulnerable, delicate thing on a warship.

As soon as the laserstar begins firing every laser on my fleet within blinding (defanging) range will open fire and either destroy your laser or suppress it. If the lasers are not within blinding range they stay shuttered.

To borrow from your own modern war analogy. Modern 155mm howitzers have to scoot and shoot because every enemy 155mm howitzers within 30km can quickly counter battery fire.

A laserstar is so vulnerable to counterbattery fire it is effectively a howitzer that can be suppressed by every 20mm cannon within a 60km radius of your position. (NOTE: 20mm cannon not spitball gun!)

Laserstar Filters:

With regards to filters I actually think they will increase the vulnerability of your laserstar.

To be effective the filter has to first possess the virtually handwavium properties of being able to block 80-90% of undesired EM radiation whilst also possessing exactly 100% efficiency in letting your own laser energy pass through. 100% efficient is just not something you come across in real life.

Furthermore, the filter will work by absorbing the hostile laser fire and converting it all to heat. If I hit your filter with a laser that can heat it up by 30-100 celsius (something your hull can easily handle) it will need to be able to retain that self-same magitech property of being 100% efficient in letting through your own laser.

If the filter material distorts by even 0.00000001% then the next time your laserstar fires you'll only succeed in destroying your own laser cannon.

I am positive 0.000001% of the energy of the death ray of doom at pointblank range is going to be deadly to your own ship.

jollyreaper said...

There have been many weapons systems that made sense on paper but never worked in practice. I could buy a scenario where there's not been a real war for generations and laserstars are the pride of the fleet but have never fought. The imagined battle is fighting light seconds away and doing this and that. Kinetics are seen as only for use against bulky targets like orbitals or digging out bases buried on celestial bodies. In practice the laserstars get knocked out too quickly and the telling damage is done with cheap missile buses scattering kinetics.

Later in the war more practical laserstars are deployed but their optics are built for far shorter engagement ranges and the primary design constraint is cheap repair because they will bs damaged and have to input back into service in the field.

In terms of operatics, all that's required is relatively short ranges for drama's sake and the ability of a single commander to swing the course of a battle. It's not so interesting when a head of cabbage sitting in the chair could have about as much influence on the battle.

Anonymous said...

Locki,

To be fair I was thinking more along the lines of a huge laserstar been countered by 3 frigates/cruisers with a decent size laser but primarily relying on kinetic kill weapons. I was not envisaging taking on a laserstar with thousands of drones packing my old lecturer's left over laser pointers.

===========

I saw 30-100 Laser-Fighters with Lasers that were an order of magnitude smaller.

3 frigates with Lasers that are 1/2 as good as the Laser-Star's is not really the same ball park.

3 frigates with lasers that have Lasers that are an order of magnitude smaller are still likely just carrying cigarette lighters they can't aim well at the kill range the Laser-Star has.

(SA Phil)

Anonymous said...

Locki,

If you have a 30m wide laser the chances are that laser occupies more than 60% of your frontal cross section. I don't have to increase my spot size to hit the laser. I've got a 60% chance of hitting it anyway even with a small spot size.

===============

You are assuming you dont need to increase your spot size to hit at all at a range greater than the Laser-Star's kill range.

The Laser-Star has superior targetting.

(SA Phil)

Thucydides said...

It dosn't matter about how long your small lasers are shuttered if you are trying to approach a firing enemy laser (I will use the general case, because the same argument applies regardless if you have an astronaut with a laser pointer or a massive ground based installation), since once the enemy weapon opens up at scorch range, it is blinding your exposed sensors. If it is a weponized system capable of engaging hundreds of KKVs in an oncoming cloud, it will also rapidly take out your off board sensors within scorch range as well.

While you may have a sensor cloud far enough back to be outside of scorch range, they may still be in dazzle range, and if they are too far back, you will have a highly degraded and light lagged picture of what is going on (worst case scenario is the enemy laser platform has moved away from your target solution without you being aware of this).

As you get closer, the enemy laser now has the advantage of beig able to dump more and more energy on your platform, degrading harder systems, creating thermal stress on your heat rejection systems and making it dangerous for the ratings to go EVA and fix things; while you are approaching blind.

Even when you on board computer announces it is time to unshutter and fire a blinding shot, you will have a poor fire control solution, a ship which is already suffering from damage and potentially within the killing range of the enemy laser. And we havn't even discussed the enemy firing KKV clouds at you during the time your sensors were first degraded, or the fact that in a military scenario, it would be unlikely for there to be only one enemy laser.

Best place for the fuel and remass tankage is around the center of gravity/balance, so the ship can change orientation on all axis rapidly and with minimal thruster power, and to minimize shifts in the center of balance as fuel and remass are expended.

Anonymous said...

Laser,

If the filter material distorts by even 0.00000001% then the next time your laserstar fires you'll only succeed in destroying your own laser cannon.
==========

First you are speculating on numbers of a speculative technology. The lens/mirror without the filter is presumably able to survive its ineffieicencies. The filter would have a similar requirement.

Second the filter isn't next to the Laser it is on the other side of the mirror/lens, so it wont destroy the laser - it will destroy the filter.

(SA Phil)

Anonymous said...

Locki-

A laserstar is so vulnerable to counterbattery fire it is effectively a howitzer that can be suppressed by every 20mm cannon within a 60km radius of your position. (NOTE: 20mm cannon not spitball gun!)
------

But what if it is more like a sniper with a .50 cal and a 10X scope vs a group of near sighted guys armed with handguns at a range of 1000 years.

(SA Phil)

Anonymous said...

1000 yards*

Tony said...

jollyreaper:

"I also agree with the notion that size is not an ultimate defense and a force with a striking power of x is stronger split among four hulls than concentrated in two or one."

Only in an eggshells and hammers world. If larger ships have disproportionate survivability, you would have a mix of types for a given mass total.

Also, the cost of multiple propulsion and sensor systems might make it impossible to practically have a steady firepower per unit mass ratio.

Finally, weapons aren't continuous and perfectly divisible. They're made up of discrete units. It may take a minimum size ship to carry a given unit of firepower.

Tony said...

SA Phil:

"The Laser's can have exactly the same power level at the source ..But at the target if the spot size of the Big Laser is 1 and the spot size of the Small Laser is 10-- then the Big Laser has 10 times the relative power at the target as the Small Laser as far as blinding/burning through something."

If all you're trying to do is pump heat into the target, and regardless of your spot size you're target is bigger than your spot, then the above is irrelevant. In fact, a larger spot give's you a marginal advantage in cases of a near miss, in that a small spot may miss totally, while a larger spot may get at least some effect.

Tony said...

And where's the best place to put the propellant? Clustered around the ship's CG, in as near a spherical configuration as possible. It makes the most efficient use of RCS propellant when rotating the ship.

Eth said...

I'm surprised no-one evoked nuke-pumped laser warheads yet. After all, if you can build 10m lasers, you can probably build them. Throw some of them in your KKV cloud and you would make it far deadlier, as they could score a hit from dozens, if not thousands of km instead of upon impact.
Would it be enough to make laserstars obsolete, though, I have no idea.

Anonymous said...

Tony,

If all you're trying to do is pump heat into the target, and regardless of your spot size you're target is bigger than your spot, then the above is irrelevant. In fact, a larger spot give's you a marginal advantage in cases of a near miss, in that a small spot may miss totally, while a larger spot may get at least some effect.
-------

True - I suppose I was envisioning a filter that would fail less from distributed heat (as in it would take a whole lot of it) but more from concentrated heat - causing a melting of the lens.

(SA Phil)

Tony said...

Eth:

"I'm surprised no-one evoked nuke-pumped laser warheads yet. After all, if you can build 10m lasers, you can probably build them. Throw some of them in your KKV cloud and you would make it far deadlier, as they could score a hit from dozens, if not thousands of km instead of upon impact.
Would it be enough to make laserstars obsolete, though, I have no idea."


It turns out that nuclear pumping probably won't work at the scales we're discussing. They only have an effective range of about 100 km.

Anonymous said...

RE: Tony

Why is that - Targetting problems or focus?

(SA Phil)

Rick said...

First of all, welcome to new commenters!

Vigorous debate is most certainly in order here, and new commenters can play. As a general reminder, playing and working well with the other children is helpful.

Now, to the substance of the thread ... yikes! I had to skim 250+ messages to kinda sorta catch up.

As usual, IMHO, there is an awful lot of people talking past each other. (Not 'are' a lot of people - just 3-4 of you max. :-)

But also some interesting stuff ...

* The human factor in war. This really needs a front pager, which I am reluctant to do. Volatile topic, plus I really mean for this to be a blog about more than blowing up / zapping spaceships.

But to a narrower question, I don't think it matters, morally, whether every individual weapon platform has an onboard crew. To me the fighting unit is the constellation, and it has human decision makers. They may be distributed, they may all be aboard a command ship, or they may all be in a bunker underneath their capital city.

If the latter, they are in effect using their own civilians as human shields. And the attacker will have to weigh the moral issue of flattening the city to take out the bunker and decapitate the defending force.

But whoever is directing the constellation is a fighting crew and generally a legitimate target.

As a practical matter I can certainly see a case for distributing the human crew(s) of a constellation among several spacecraft, these need not be the constellation's primary weapon platforms, and indeed might have only purely defensive armament.


* Laser blinding. I have puzzled over this for a long time; I think some of the Space Warfare posts talk about it.

But the most powerful laser installation in the show also has the longest sensor-blinding range, much greater than its blowtorch range.

I won't go into battle shuttered. I'll fire up through that big main mirror as soon as we're approaching my scorch range.

It seems to me that any laser battle turns into an eyeball frying contest between two lasers zapping straight at each other. That geometry maximizes damage both ways, because each beam is being focused by the other's optics, right onto the laser elements.

Note that this is most effective between two lasers zapping each other. An off-axis zap by a third laser is not focused by the target telescope, so is less effective.

Which is why one big laser (more precisely laser telescope) defeats two or more smaller ones of similar total power. At least in this scenario, constellations engaging at long range, away from clutter.

Close to a planet with an extensive surrounding space infrastructure is a whole nother matter.

Tony said...

On eyeball frying...

I wouldn't be so worried about damage to the weapon itself. I wouldn't be so worried about damage to the fire control sensors. What I would worry about is damage to the target acquisition sensors, which by definition have to be wide angle and sensitive.

Tony said...

SA Phil:

"Why is that - Targetting problems or focus?"

100km was the range quoted for Excalibur in Atomic Rockets. No reason given, but considering it was a totally conceptual system to begin with, its notional operational constraints have to come out of pure physics.

Tony said...

Rick:

"Note that this is most effective between two lasers zapping each other. An off-axis zap by a third laser is not focused by the target telescope, so is less effective."

The unstated presumption here is that the flank of the laserstar is no more vulnerable to laser attack than the weapon's optics. I wouldn't be so sure of that.

Locki said...

3 frigates with lasers that have Lasers that are an order of magnitude smaller are still likely just carrying cigarette lighters they can't aim well at the kill range the Laser-Star has.

===============

Finally progress!

I hereby accept your challenge to a duel! I choose a Zippo lighter and a rapier. And wait. Gee. I see you've chosen a slightly non-traditional flame-thrower.

OK then. Well as long as you solemnly promise, as a gentleman, to only target me through your starlight scope, looking through a 30m diameter cylopean magnifying glass I guess its still a fair fight.

If you still somehow manage to scorch my top hat and tails I'd humbly request to upgrade my Zippo to a flare.

If this isn't enough I'd also like to be accompanied by my good friends Odysseus and Telemachus - also armed with flares and rapiers.


..... ok enough fun.

I'll try to address the barrage of criticism directly and succintly.

Scorching range on any laser exceeds burning range.

A laser is unique amongst weapon systems in that it is a high precision, highly fragile component that is itself exquisitely sensitive to laser damage. In fact its the component most susceptible to laser damage.

It is too easy to suppress with a cheaper, smaller laser. This makes it a bad investment since I can neutralise you for less money. This makes it a very bad primary weapon system.

I'll let someone else do the math but Byron reasonable suggested a laser 1/30th the size may be able to suppress a larger laser.

A Laserstar dare not fire if there are any lasers within scorching range.


With regards to Thucydides and Rick:

Even if the the laserstar begins firing as fast as it can at extreme scorching range the attacking ships can stay shuttered up (including sensors!) on the approach run. As soon as my own lasers get within their scorching range the laserstar must stop firing or risk being mission killed. As long as my secondary lasers have a scorch range which exceeds the burn range of the target laserstar it will be a sitting duck.

jollyreaper said...

Can we crunch the numbers for counter battery to see how effective that would really be? Ranges? If the laserstar has a range advantage on a laser destroyer then counter-battery doesn't mean much. Also, the first person to fire is vulnerable to counterfire like a sniper being exposed by a muzzle flash. The first target could lose a sensor while it's laser is shuttered but relay counter-battery directions to a constellation mate.

Can we crunch these numbers for sure?

Anonymous said...

Locki,


With regards to Thucydides and Rick:

Even if the the laserstar begins firing as fast as it can at extreme scorching range the attacking ships can stay shuttered up (including sensors!) on the approach run. As soon as my own lasers get within their scorching range the laserstar must stop firing or risk being mission killed. As long as my secondary lasers have a scorch range which exceeds the burn range of the target laserstar it will be a sitting duck.
============

I think Rick's point was you can only blind the Laser-Star effectively fron one specific angle. And it can shoot out from the reciprocal of that same angle. (with better range, power, and accuracy)

With that assumption then the blind the laser strategy is going to be tricky.

(SA Phil)

jollyreaper said...

How do the numbers work out, hammers and eggshells? The modern world of destroyers and cruise missiles is exactly that. A single solid hit is going to mission-kill any ship if not sink it outright. Therefore much effort is put into active defense.

Modern fighters aren't considered to be all that durable vs. missiles so the emphasis is on avoiding the hit. Tanks are armored because they will be hit and there's no avoiding it. They have to take those hits while effectively returning fire. Infantry fighting vehicles may have antitank weapons but their primary defense is not engaging tanks in the first place.

Kinetics seem like they should be pretty definitive but I don't know how the damage scales for the lasers. Would a heavy warship be trading deathblows vs an opponent for a half hour?

Can we determine what it would be like?

Tony said...

jollyreaper:

"Also, the first person to fire is vulnerable to counterfire like a sniper being exposed by a muzzle flash. The first target could lose a sensor while it's laser is shuttered but relay counter-battery directions to a constellation mate."

If the target acquisition sensors are burned out before they can gather enough data, no targeting information would be forthcoming.

"How do the numbers work out, hammers and eggshells? The modern world of destroyers and cruise missiles is exactly that. A single solid hit is going to mission-kill any ship if not sink it outright. Therefore much effort is put into active defense.

Modern fighters aren't considered to be all that durable vs. missiles so the emphasis is on avoiding the hit. Tanks are armored because they will be hit and there's no avoiding it. They have to take those hits while effectively returning fire. Infantry fighting vehicles may have antitank weapons but their primary defense is not engaging tanks in the first place.

Kinetics seem like they should be pretty definitive but I don't know how the damage scales for the lasers. Would a heavy warship be trading deathblows vs an opponent for a half hour?

Can we determine what it would be like?"


Good analysis. Who are you, and what have you done with my jollyreaper? ;)

In any case, if we are in the hammers and eggshells world, then no ship is safe simply through sheer mass, by definition. Kinetics or lasers would be as effective, hit for hit. Or, if they weren't, all other things being equal, one would prevail over the other pretty decisively. If things weren't equal, such that the heaviest hitter didn't stand much of a chance of getting a hit, then maybe the lighter hitter would prevail for reasons of practicality.

Nota bene: The heavy hitter is likely to be the kinetic weapon. If you can't get hits with a kinetic weapon, then it's possible that the laser-armed ships would trade shots until one ship was beat up so much that it couldn't continue. Even in the eggshells and hammers world this might be true, if ships naturally tried to fight at the longest possible ranges, making getting hits hard and holding spots on targets even harder.

How long ships would be trading shots would depend on how much of the target area contained stuff that could be damaged easily, the cycle times between shots, and how many shots it takes to get a hit. I don't think we could rationally put numbers on that. It could be seconds, minutes, even days.

Thucydides said...

Loki

If you want to approach with all your weapons and sensors shuttered then you are approaching blind; you will not even know if I am still in the area when you reach your projected firing solution.

To be technical, you will have to search a spherical volume "x" the moment you unshutter for each and every one of the potential targets you have identified, with "x" being defined as the distance I could potentially move from my last recorded position during the time it takes you to make your approach.

During this time (since there is no way to determine what exactly you are doing), I will still be opening up at scorch range to cripple any sensors you may potentially have operating, and still launching waves of KKVs under the cover of my blinding laser(s) from the various ships in the constellation.

You will still reach your scorch range suffering from thermal damage from the ever increasing amount of laser energy you are receiving, and you will be shooting blind when you unshutter. To be nice, I have not assumed that the KKV cloud has reached you yet, nor that you are within "kill" range of the high powered lasers. (If we assume that, you are dead already).

Nuclear pumped warheads are an interesting addition to the incoming weapons cloud, since nuclear weapons need to be virtually in contact with the target in the space environment to deliver their energy. A sudden dazzeling burst of x-rays will certainly make things difficult for the defender, and incoming nuclear warheads could also be fitted out like Orion pulse units and shoot a directed cloud of high energy plasma at the enemy ship. One thing I remember reading was the plasma would "pile up" on the surface of the pusher plate and essentially be recompressed, momentarily increassing the temperature to several thousand K. The sudden thermal load on exterior parts would not be giving the chief engineer happy thoughts, even as the plasma begins rebounding from the glowing surfaces, imposing off axis mechanical loads as well.

The ORION pusher plate was engineered for this, surface plates and radiator panels are not.

Anonymous said...

To be fair to Locki - nothing stops him from having backward observers reporting to his shuttered lasers letting his blinder squadron know where they are,

(SA Phil)

Locki said...

I had actually made the assumption that if the laserstar (outnumbered 3:1) has begun desperately firing at extreme scorching range then really its broadcasting its exact position like a lighthouse in a storm. I've also stolen the idea of an offboard IR sensors swarm, complete with shutters. The laserstar can only blind one target at a time and my sensors can alternately "take a peak" to give me full 3d situational awareness. I can certainly afford more sensor drones then you can laserstars. If the laserstar elects not to fire for fear of giving away its position whilst futiley trying to scorch armored shutters then its being suppressed.

I think the protection from being off-axis is being badly overestimated by the forum. Being slightly off-axis will reduce the efficacy of a blinding laser not render it 100% ineffective as soon as you are firing at a few degrees off centre. My modern medical lasers can burn out a person's retina even if they aren't looking directly at it. It can even blind you by scattering off a white wall. All this well before my laser gets into "burning range".

Besides if you are being pedantic and insist you can only blind a laser whilst on axis I can just line up all my ships in a row.

Say what. I think I've just come up with a use for that Laserstar George W Bush the 12th saddled me with so he could build it in Space California win the next election. I could always place USSN White Elephant at well behind at extreme standoff scorch ranges whilst the rest of the fleet, with the real men onboard, shutter up their lasers and sensors and ride through the death rays of doom to deliver the KKVs.

Thucydides said...

Remember we are talking about a weaponized system that is designed to cut through clouds of incoming KKV's. For a ravening beam of death the overmatch needed is in the thousands of KKV's.

So a large cloud of sensors, decoys and even "stayback" sensors will be needed to operate, and unless the differential in ranges is relatively small or your closing distance is incredibly fast; you will be hammered by the long range laser before you come into range. The stayback cloud will suffer the least damage (being in dazzle range) while the leading edge of your cloud (depending on how big your cloud is and the range of the enely laser) may already be inside kill range.

So given enough investment in resources your small laser platforms may still be able to close with the big laser platform, and may still have enough operating sensors to find the target. You may even get lucky and score a hit (although if the enemy has a rough idea as to your scorch range, they will already have one or more lasers already focused on the shutters of your weapon. Once again, it is quite possible you are unshuttering inside kill range for the enemy laser, or at least the incoming pulse will be more than sufficient to blind your laser weapon).

jollyreaper said...

With all the talk of blinding and dazzling, how do kkv's fare?

With modern sensors in missile combat we've yet to kill IR with defensive lasers but I hear there's been research. Radar-guided missiles can be jammed but some models can home on jam. That goes for air-to-air and air-to-surface.

We assume that since space has no stealth that visual sensors are king, correct? Passive, can see a distance. Radar is of intermediate range at the moment, barring new developments, correct?

If lasers are burning out optics left and right then radar is probably more durable. How far is it good for with targeting resolutions? I'm guessing it's good enough for terminal guidance for kkv's.

So, attacker fires kkv bus. It bursts to scatter the payload along the most likely approach vector. Maybe 5% of the projectiles will have a suitable trajectory for intercept. The earlier the burst, the less likely the bus is killed. Individual kkv's are a much smaller target than the bus.

The defender radiates to detect incoming kkv's. They see where he is. Defensive lasers fire back. What would it take to mission-kill the kkv? No optics to blind. Kill the radar emitter? Once the weapon goes ballistic, evasion is more than likely. Would the kkv try to hit intact or burst into shrapnel at the last second? Maybe secondary burst if direct impact won't happen?

There's also the thought that there are only x many kkv attacks a formation can make and there may be more arrows in the laser quiver (to abuse a metaphor.)

As for a laserstar, could a successful tactic be charging the enemy up his throat with targeting observation relayed from other units? The charger goes in blind taking hits and then opens up at scorch range.

One assumption being made is that lasers in blind mode can stay on like a spotlight. But at max range isn't blind mode requiring full power shots? So limits of duty cycle for the weapon?

Anonymous said...

Locki,

My modern medical lasers can burn out a person's retina even if they aren't looking directly at it. It can even blind you by scattering off a white wall. All this well before my laser gets into "burning range".
-----------------

I am not sure that the lens or mirror of a Laser-Star weapon will function exactly like the lens of an eye. For one thing peripheral focus is really unimportant.

Also we may need to be careful comparing weapon lasers to other lasers in exact function. We cut steel with an industrial laser where I work but that same laser can't cut through a thin polyester tape.

If I were to use that as anecdotal evidence I could armor my ship with cheap tape and laugh as the Laser-Star fires at me.

(SA Phil)

Anonymous said...

Jollyreaper,

So, attacker fires kkv bus. It bursts to scatter the payload along the most likely approach vector. Maybe 5% of the projectiles will have a suitable trajectory for intercept. The earlier the burst, the less likely the bus is killed. Individual kkv's are a much smaller target than the bus.

======================

I would think you would want to design for a better threat than 5%.

You would at least want all kinetics to appear to be threats for some portion of the Laser-Star's kill range.

If nothing else but to make the Laser-Star shoot at as many kinetics as you can.

If the Laser-Star can filter out 95% the incoming cloud - you would probably have been better off having 1/20th as many missiles with 20 times the mass budget (and presumably much better DeltaV)

(SA Phil)

jollyreaper said...

How does that laser not make it through tape?

Anonymous said...

I wonder if even soda cans of death are too big.

What if you had a guided chemical missile about the size of a cigarette?

Instead of hundreds of KKVs you could send hundreds of thousands.

Each one separated by hundreds of meters - meaning the laser would have to shoot once per missile.

While they couldn't penetrate the front armor very well, they would damage the Whipple shields, mirrors, sensors, radiators.

That cloud could be followed by larger missiles once the defenses of the target had been substantially degraded.

(SA Phil)

jollyreaper said...

My 5% kkv intercept rate was guessing that part of the targeting will be like a WWII sub skipper firing his spread. He has to guess where the targets are. With guided weapons the kkv bus has an intercept envelope but low delta-v. That's an assumption since performance is never what we would like it to be. So if the defender is running his engines at full thrust, it seems possible that he could add uncertainty to his trajectory. If the kkv has to burst very far out, there are only so many potential trajectories it can cover. If it was following a ballistic trajectory with no surprises, then the bus would burst shortly before the scorch range and each kkv would have a 100% chance of intercept and only be degraded by being a dud or destruction by defensive weapons.

That's my thinking. All assumptions subject to tweaking.

Anonymous said...

Jollyreaper,

How does that laser not make it through tape?

-------

I wish I knew.

Maybe it has something to do with the fact that the tape doesn't conduct heat very well.

So far we just have some phds and laser techs obviously making explanations up.

(SA Phil)

jollyreaper said...

Laser-proof tape. Heh. Must be made out of the same stuff they use for black boxes. Why don't they make the whole plane out of it? Lol

Anonymous said...

Jollyreaper

So if the defender is running his engines at full thrust, it seems possible that he could add uncertainty to his trajectory

=================

I suppose it depends on closing velocities, acceleration rates and DeltaV

I envision something more like that sub-skipper firing from halfway across the ocean but the torpedo is going 500 mph and the target battleship has a broken rudder with one guy using a paddle to try and change course.

(SA Phil)

Anonymous said...

"Laser-proof tape. Heh. Must be made out of the same stuff they use for black boxes. Why don't they make the whole plane out of it? Lol"

The tape isn't laser-proof; it is invisable to the frequency of the laser; if you built your ship from tape, the laser would go streight through and fry everything inside.

So, if I start shooting my constant-wave laser at the enemy's pulse-laser ship at several times the pulse-laser's max effective range and just keep it firing until I get close enough to hit you with a railgun...or just throw a rock at it.

I'll have to check out that referance to bomb-pumped lasers; the only thing I'm totally sure about them is that the USAF still classifies the aunnual update of the concept. I'll get back to you on that; oh, and by-the-way, that article about the table top gamma ray source neither refutes nor supports bomb-pumped lasers.

Ferrell

Anonymous said...

Ok, I think I see the problem: 'Excaliber' was a massive weapon that detonated a bomb inside a circle of individually aimed laser emitter-rods; this was a first gen. concept of a weapon; most speculations of modern concepts of the weapon are much more compact and focused, being based on the Orion pulse-unit; In the next paragraph after the one that states that 'Excaliber' would have a 100 km range, it says that at 10 megameters (10,000 km) it would deposit ~300 MJ over a 200 square meter circle. A little confusing, but I think that the first statement was speculation and the second was a crunch of the numbers (or an attempt). Due to the fact that most things related to weapons employing nuclear explosions is usually classified, discussions about them is generally reduced to more-or-less educated guess-work.

Ferrell

Anonymous said...

Ferrell

The tape isn't laser-proof; it is invisible to the frequency of the laser; if you built your ship from tape, the laser would go straight through and fry everything inside.

==============

That was one speculation - however it couldn't cut the opaque tape either. Nor could it cut the steel under the tape (either clear or opaque)

Of course it may be reflective, we have trouble with materials that don't absorb the laser such as copper.

I think a weapon laser would not only cut the tape but flash it away with no problem.

I think even a 400 watt of the same type of industrial laser would do that.

I doubt that tape armor would work - I was more suggesting that it would not - and that anecdotal examples can be flawed.

(SA Phil)

Anonymous said...

RE: Bomb pumped lasers

If the scenario assumes the only way to make a superior targeting system is on a big Laser-star..

Then the bomb pumped laser might run into problems.

I don't know though. If you had a "Hubble" attached to a giant battle-star would the Hubble work better?

What about a device like the Hubble on the surface of the moon?

And if big mass does offer you a targeting advantage - why not put a few Laser Batteries on the moon instead of bothering with Laser-Stars? (or Mountain Tops, Near Earth Asteroids .. w/e)

(SA Phil)

Locki said...

I think Rick's point was you can only blind the Laser-Star effectively fron one specific angle. And it can shoot out from the reciprocal of that same angle. (with better range, power, and accuracy)

With that assumption then the blind the laser strategy is going to be tricky.



I’ve finally pulled out my old trigonometry textbook. At the extreme ranges we are talking (many thousands kms), assuming my fleet is clustered within a a few kilometres of each other – then realisitically any counter-battery blinding lasers will only be firing at a minuscle fraction of a degree off axis. Laserstars are still dreadfully vulnerable to blinding lasers from any non-suppressed ships in my fleet that have a laser that has a scorching range that exceeds the laserstars burning range.



Thucydides said...

So given enough investment in resources your small laser platforms may still be able to close with the big laser platform, and may still have enough operating sensors to find the target. You may even get lucky and score a hit (although if the enemy has a rough idea as to your scorch range, they will already have one or more lasers already focused on the shutters of your weapon. Once again, it is quite possible you are unshuttering inside kill range for the enemy laser, or at least the incoming pulse will be more than sufficient to blind your laser weapon) .

True. But have you considered what happens if I approach your n laserstars with n+1 sensors that remain shuttered until we are within scorch range. The problem is the Laserstar has bet the house on a singular, admittably imposing, weapon system. You can only blind one sensor at a time. So the 3 frigates approach with shutters down. The laserstar starts dazzling at extreme range. I slam all my shutters down. I make sure I have a laser whose scorch range exceeds your burn range. This won’t be hard considering how vulnerable lasers are to blinding. At the instant my fleet brings your laserstar into scorch range the 2 frigates that aren’t been suppressed open up their shutters, get a target lock and send counter-battery laser fire straight back and mission kill the laserstar. I suspect the scenario is weighted even more heavily against the Laserstar since you can probably afford a lot more than 3 frigates for every laserstar


jollyreaper said...
With all the talk of blinding and dazzling, how do kkv's fare?

With modern sensors in missile combat we've yet to kill IR with defensive lasers but I hear there's been research.



AFAIK blinding lasers for both humans and sensors are very possible but there are some serious issues with the Geneva convention. There is this conspiracy theory that keeps popping up on strategypage.com that the chinese have a boat loadof IR “jammers” that will be accidentally let loose on soldiers/pilots in the event of a full scale war.
Similarly there’s been rumours for ages the Russians either blinded a recon satellite or have the ability to do so. The circumstantial evidence is the Americans blew a crap load of hot air and made it painfully clear any laser attack on a satellite would be considered an act of war. So the Americans at the very least think it is theoretically, if not practically, possible. Note the weird way international treaties work means a recon plane can be legitimately shot down but a flyover with a satellite is considered kosher.

Geoffrey S H said...

Taking in the arguments of as many posters as I can read without getting swamped, here is a sketch of a potential battle. Lets say that they are on a direct course for each other, with programming technicians possibly on board or a command module nearby providing instructions for drones.

The formations are in a rough wall to allow all craft to fire at their respective maximum ranges. Large laserstars and kineticstars make up the main centrepieces, with middle-weight craft that can be sent off to other tasks but match them in firepower when teamed up with a sister-craft also are present,. Small, “disposable” craft also accompany them to provide extra CIWs and blinding support. Stubbier craft, with the same engine modules of the largest craft in the formation, but less weapons/ payload modules (with thus an ability to spin faster and accelerate quicker) can accompany the formation, rushing up and down the wall/line whenever attempts to lessen the incoming swarm of missiles appears to be going badly for one part of the constellation.

When battle is joined, constellations of laserstars open up at extreme range to blind the other side, with sub-constellations of blinder frigates aiding them, these will continue this work when the laserstars are attempting to knock out and mission kill the other laser stars and kineticstars when the range is suitable.
Accompanying them are the kinticstars, who fire buses of of kinetic warheads in a single salvo. These will have smaller shrapnel-bust cigarette sized missiles as the first volley when they are in appropriate range, while holding back larger missiles for after the first volley has overwhelmed the lasers.

This swarm will cross the swarm fired by the opposing side, the cigarette missiles on each side's buses being used as an anti-bus munition as the swarms pass. Lasers, when possible, and not beign blinded will attempt to add to the kill-rate of buses.

Interspersed with this will be volleys of bomb-pumped warheads that will attempt to eliminate incoming buses, suppress lasers further and attempt mission kills, while aiming to damage the other war-craft in the constellation. This is only possible under the cover of the blinding lasers, but even with the short range of the warheads, gives each side a source of cheap “expendable” lenses that if mission killed are a less serious loss than the lenses on the laserstar constellations.

With the line of warheads no reaching either side, the warcraft, all equipped with some form of point-defence laser weaponry, all open up, perhaps with some submunitions also. Smaller escort craft will add to the fire-power, being less valuable than the larger capital craft and thus more expendable. Some manoeuvring to avoid mission-killed shrapnel will take place. With the impacts, both sides can survey their damage (if any) and proceed to either manoeuvre to avoid the other side if possible, or open up with lasers at the appropriate range. The loser then is either destroyed or consists of survivors that band together and improvise a survival strategy, or are picked up by rescue craft that were launched by their home base some time before battle was joined.

The victors get tea and medals.

jollyreaper said...

Seems reasonable in broad strokes. There's a whole pile of variables that would need put in a spreadsheet to see how the details change with assumptions. For example, you mention ships moving up and down the wall to shore up weak points. I think that would only be likely with Demi-operatic drives.

Likewise, I think kinetics only have a place where lasers have performance limitations. If they are capable of operating as ravening beams of death, kinetics would be destroyed en route. The only way to take out a laserstar in that case is with another laserstar and by definition they would have to be armored up to hell and back to stay in the fight.

Also, if laserstars are glass cannons whose offense no one can withstand, even other laserstars, then wars could be a bit stilted. Both sides might keep their ships in port to preserve the threat they represent rather than risk their destruction. The Germans kept a lot of British ships tied up in WWI because they never knew if or when the fleet would sortie. A "fleet in being" it's called. But if they do go to war and start losing ships quickly, there could be lulls in the war where neither side possesses the means to push forward one way or the other, left waiting for new ships and training new crews.

The presence of ships with various capabilities can alter the shape of a war without firing a shot as planners try to take every variable into account.


If the ravening beam of death is the strongest case version of the laserstar, the reletavistic kill vehicle is the supreme kinetistar. Of course, that's only if the spreadsheet allows for that kind of performance.

If the kkv's are fast enough, even the best laser can be affordably saturated. If the laser is fast and powerful enough, it would take a stupendous number of kkv's to saturate. But it's all variable. In a low-thrust setting, a mediocre laser might qualify as the RBOD. If it's a high-thrust setting, even a laser that can vaporize anything in range in a millisecond is insufficient when a target can cross the kill zone in seconds and there's a hundred more following behind.

Eth said...

Even with 100 km range (low hypothesis), it still gives a big advantage to 'dumb' kinetics, who have to make contact to cause damage. It means that you can target a 100 km radius circle around the enemy and still hit it, and no amount of manoeuvres will make it miss.
If they are expensive, just add some of them to a KKV cloud, and the enemy craft will have to burn them all, not knowing which one is a decoy.

It also means that a craft would have to consider far more unidentified objects as threatening. With dumb kinetics, they can only consider those who will come very close as potential threats. With bomb-pulsed lasers, everything coming in range of 100 km is a potential threat.
And if the range is 10 000 km instead, then almost anything in orbit around the same body becomes a potential threat.
And as evoked above, also, their blinding range in a fleet duel would be even greater than that.

Thucydides:
A sudden dazzeling burst of x-rays will certainly make things difficult for the defender, and incoming nuclear warheads could also be fitted out like Orion pulse units and shoot a directed cloud of high energy plasma at the enemy ship. One thing I remember reading was the plasma would "pile up" on the surface of the pusher plate and essentially be recompressed, momentarily increassing the temperature to several thousand K. The sudden thermal load on exterior parts would not be giving the chief engineer happy thoughts, even as the plasma begins rebounding from the glowing surfaces, imposing off axis mechanical loads as well.

Wait, did you just describe a realistic plasma weapon? I hear the joyous clamour of many SF writers.

Eth said...

(Read the first 'it' as 'bomb-pumped laser warhead' in the post above)

Locki said...

Geoffrey S H said...

Taking in the arguments of as many posters as I can read without getting swamped, here is a sketch of a potential battle ...

======

Sounds like a semi-plausible fun space battle scenario. Nice work (especially summarising the 446 posts!).

I would only add that the advancing fleets would try to hold off firing their KKVs and submunitions until they can at least bring their own lasers into scorch range. Which if fleet intelligence did their job properly is still outside the kill range of the enemy Laserstars. That way the lasers can effectively cover the KKVs whilst they accellerate and attempt to close the distance. No point letting go of the KKVs too early and getting them blinded.

The big laserstars hang back as far as usefully possible and use their laser primarily as a blinding weapon. Or they can stand back even further, totally out of harms way, and radio in precise targetting data with their unrivalled optics. :)

Re: Bomb Pumped Lasers

I read a heap into these. I thought given modern tech the primary problem was the impossibility of targetting the X-ray Laser. The problem is the fission explosion is itself triggered by conventional explosives to achieve critical mass. This triggering explosion makes aiming the rods impossible as it shakes the rods (and destroys your targetting optics) well before you have lasing of the x-rays.

Of course in a higher tech setting I guess you could have a laser triggered fusion bomb which should solve the targetting issue.

I started reading quite a bit deeper into the bomb pumped x-ray lasers (best way to counter a laserstar) and was getting the impression the laws of physics might preclude harnessing the power of a nuclear explosion and obtaining beams of lasing x-rays. The physics was well above my pay grade though so I'll leave someone else to discuss that.

Rick said...

One problem with bomb pumped X-ray lasers is that they are relatively big - certainly much bigger than SCODs, let alone killer cigarettes AKA coffin nails. So they are easy for point defense to pick out of the incoming clutter and engage.

I’ve finally pulled out my old trigonometry textbook. At the extreme ranges we are talking (many thousands kms), assuming my fleet is clustered within a a few kilometres of each other – then realisitically any counter-battery blinding lasers will only be firing at a minuscle fraction of a degree off axis.

In that case I can (probably) keep them all under 'rotating' fire without physically pivoting the laser star.

They are all in my field of view, and I only need fine adjustments in the optical train to shift the beam from one closely grouped target to the next, (probably) on a time scale shorter than it takes to open your shutters.

To clarify another important point, I don't argue that off-axis zaps are ineffectual - only that down-the-barrel zaps are *more* effectual (thus effectual to a greater range), because they are concentrated onto the target's laser elements by its own optics.

More broadly, a laser is either shuttered (and thus unable to zap), or unshuttered, thus able to zap but also vulnerable to zaps, especially end-on zaps.


Geoffrey SH - That description sounds like a good starting point for thinking about the problem.

But if (as I think is most likely) both lasers and kinetics are viable, the interesting challenge will be combining them effectively. They are highly asymmetrical.


Lasers are 'durable' weapons. (Except for bomb pumped.) Set aside all the debate about laserstars. If you have laser-armed spacecraft, the implied expectation is that they can zap, and zap again. If your lasers use solar or nuke power, you won't run out of ammo.

On the other hand, kinetics are inherently expendable: To use them is to lose them. Trying to recover the buses usually isn't worth it; you would get more for the money by letting the buses use all their delta v for higher closing speed.

This has implications for patrolling some region of local space. Zaps are cheap. Kinetics are more expensive, and more final. You don't want to use them up, other than a symbolic few, and if you have to go beyond that, depleted magazines may cripple the patrol mission.

Or make it depend almost entirely on its laser component, until resupplied.*


* Never mind where the propellant for maintaining a standing orbital patrol comes from.

Anonymous said...

Locki,

I’ve finally pulled out my old trigonometry textbook. At the extreme ranges we are talking (many thousands kms), assuming my fleet is clustered within a a few kilometres of each other – then realisitically any counter-battery blinding lasers will only be firing at a minuscle fraction of a degree off axis. Laserstars are still dreadfully vulnerable to blinding lasers from any non-suppressed ships in my fleet that have a laser that has a scorching range that exceeds the laserstars burning range.

============

I have to give you that point since it agrees pretty well with how I see the small angles involved. Two passing trains fighting in a railway tunnel.

None of the ships will have enough DeltaV to come from crazy off angles - and none will have operatic enough accelerations for long enough to massively change their vectors.

Whether those angles are small enough for the optical effects - that is another thing - someone would have to figure out what angle is close enough to "head on" and still effect the Laser visavis the geometry of the lens/mirror.

--------

These small angles is also why I dont think it will take much Delta V to get missiles into the "threat" region of any target.

(SA Phil)

Anonymous said...

Nice post Geoffrey S H.


==========================
---------
Rick,

In that case I can (probably) keep them all under 'rotating' fire without physically pivoting the laser star.

They are all in my field of view, and I only need fine adjustments in the optical train to shift the beam from one closely grouped target to the next, (probably) on a time scale shorter than it takes to open your shutters.

--------------------
-------------------

Which might argue for even Bigger Laser-Stars -- ones that can fire much more often, hopefully faster than the attempting to offend frigates.

Or a supply of ejectable coolant, intended for a rapid fire mode - to allow the Laser-Star to better deal with that threat.

The Frigates though might have some KKV busses to deal with the rapid fire, forcing the Laser-Star to deal with SCOD/CNODs at the least opportune time.

(SA Phil)

jollyreaper said...

The kkv bus could be a spaceship outright. Flies with the fleet with a big tank and tagging along. No fight, heads back to base for servicing. Big fight? Gets orders from command ship, max thrust to target. Resupply constellation with kinetics? Load and fuel a bus drone, send it on intercept vector.

While the fleet will still have limited shots with kinetics regardless of whether they are drones or on warships, the resupply situation might be simpler.

There's also the possibility that the bus could be recovered at a much later date. Fight battle, six months later buses trickle back in having used solar sails to kill delta-v and head to collection point.

Thucydides said...

Kudos for your battle summary, Geoffrey S H.

Laser and kinetic weapons are complimentary, any spacefleet would be equipped with both. The faster the KKV's can be delivered, the more useful they will be, but it is hard to imagine how small missile busses will be able to get substantially better performance than the main engines of the carrier vessels. Perhaps we can adopt the convention from Atomic Rockets, where a weapon with similar performance to the ship is a "torpedo", while one with less performance is a "missile".

Obviously a "torpedo" would be the most dangerous weapon out there, with missile busses carrying SCoDs coming in as number two. I have some doubts about "coffin nails"; they seem too small to be able to make course corrections at high closing speeds (unless the propellent is degenerate matter, in which case the defender has a lot more to worry about). For the time and effort needed to make "coffin nails" I could just disperse ball bearings, delivering the same amount of kinetic energy at a fraction of the cost.

Nuclear pumped Xray lasers and shaped charge plasma warheads give nuclear weapons a lot more utility than a straight nuclear bomb in the space environment, so I do expect to see something like that deployed alongside the SCoDs to give the enemy targeting computers the vapours. For a nuclear pumped Xaser in this environment, the laseing rods would only have to be in a bundle and pointed at the last moment at the target; any vibration caused by the firing sequence would be overtaken by the wave of nuclear energy being converted to x-ray photons in the bundles; a slight divergence of the various beams could be allowed and even encouraged to ensure at least some to the beams strike the target.

Tony said...

Rick:

"Lasers are 'durable' weapons. (Except for bomb pumped.) Set aside all the debate about laserstars. If you have laser-armed spacecraft, the implied expectation is that they can zap, and zap again. If your lasers use solar or nuke power, you won't run out of ammo."

It's an implied expectation, but it's not a realistic one.

Using a realistic (for a mobile vessel) fission power reactor, one would have to charge up a limited number of capacitors over a long time, then live with the limited number of shots in tactical time. Otherwise you have an essentially immobile laser battle station that can draw on a huge power reactor.

There is also the likelihood of thermal control systems becoming saturated by rapid fire, shutting down the whole show until enough cooling can be affected.

TANSTAAFL.

Anonymous said...

Rick said: "To clarify another important point, I don't argue that off-axis zaps are ineffectual - only that down-the-barrel zaps are *more* effectual (thus effectual to a greater range), because they are concentrated onto the target's laser elements by its own optics."

That last sentence always bothered me- so I looked up some websites about the ABL; most of them made mention of 'thermal protective' devices (most were a little vague, and several out-of-date), in the front end, or optics turret, that will purposely fail and keep any laser light from shining into the laser elements and damaging those elements; the protective devices can be switched out in an hour or two...on the ground. Even if Laserstars are equiped the same way, You won't be switching out failed protective devices during battle.

Ferrell

Anonymous said...

Thinking about kinetics, here's one; a weapon (call it a 'torpedo') that has three sections, each one the size and shape of a 55-gallon drum; the first section is the drive section and has two sets of engines; a small, liquid fueled rocket for primary launch/manuvering, and a set of solid-fueled rockets for terminal stage flight. The second, or middle, section contains fuel tanks for the manuvering engines, electronics(both for sensor/navigation and jamming); the last, or front, section contains the submunitions, either scads of ballbearings, clouds of SCoD's, several dumb rocket impactors, or a single heavy smart impactor the same size, shape, and mass of a nuclear-powered weapon (Shaped Nuclear Charges, Bomb Pumped Lasers, Nuclear Explosive Forged Projectiles). A 'bus' for these weapons would be a large fuel tank, various engines, a guidence package, powerplant, sensor/navigation/communication booms, and radiator panels, and mounting four to nine of these torpedoes; they're launched from the transport bus, that then 'retires' from the battle by a relatively long burn to put it on a slighly different trajectory. Otherwise the battle goes on much like Geoffery SH's scenario.

Ferrell

Anonymous said...

Thucydides said...

I have some doubts about "coffin nails"; they seem too small to be able to make course corrections at high closing speeds (unless the propellent is degenerate matter, in which case the defender has a lot more to worry about). For the time and effort needed to make "coffin nails" I could just disperse ball bearings, delivering the same amount of kinetic energy at a fraction of the cost.

--------------

The idea behind the cigarette/coffin nails - at least from my perspective - was the smallest fully functional guided rocket you could manufacture.

It would not take much propellant, even with chem fuel efficiencies- to move a rocket that was only a couple hundred grams including remass.

I suppose I imagine that machine miniaturization and electronics will make some small improvements into the 100MJ laser future.

I suppose the idea occurred to me when I started thinking about SCOD and then about the model rocket engines I bought my kid 10 years ago. Those only weighed less than an ounce.

(SA Phil)

Anonymous said...

It could be that the development might start with Map Case Missiles moving to 40 ouncers of death, moving to Soda Cans of Death, to Cigarettes of Harm - As the requirements for the number of guided kinetics per unit of mass carried increased.

I don't think the expense would be the killer problem. Just the motivation to build them. If we used the apparent expense argument visavis miniaturization we would still be renting rotary phones and room sized computers.

(SA Phil)

Anonymous said...

RE: Ferrell's modular kinetics delivery -

I agree with that- I see things being largely standardized up to a point where the diversity is needed.

So the SCOD /CNOH delivery vehicle, a Sensor Blinder Vehicle, and a Bomb pumped Laser Vehicle might all look identical when loaded on the Kinetic Star.

------------
-------------

As to propulsion for the Kinetic busses - I wonder if since we have high performance laser technology, if Laser Thermal might be better than chemical or NTR.

With Nuke Electric being used for the Bus Carrier / Kinetic Star (whatever the configuration)

(SA Phil)

Rick said...

Using a realistic (for a mobile vessel) fission power reactor, one would have to charge up a limited number of capacitors over a long time, then live with the limited number of shots in tactical time. Otherwise you have an essentially immobile laser battle station that can draw on a huge power reactor.


Heavy artillery does not move and shoot at the same time.

If you have transport-class interplanetary ships with electric drive, then you have drive buses with electric output at least in the tens of megawatts, probably 100+ MW. (Because you are pushing large ships at a milligee or so.)

And these drive units are capable of radiating off the waste heat during sustained full power operation.

A 100-MW power plant should be good for ~20 MW average beam power. Probably the beam is not CW, but a train of pulses with much higher peak power. but the point is that I am hitting the target with 20 MJ per second, for as long as I want to hold down the trigger.

I cannot use my main main drive while zapping, but so what? A minute is a very long time for a sustained zap train(and puts over 1 GJ of energy onto the target), but the maneuver power of an electric drive on a scale of minutes is trivial.

If I have a tactical evasion scoot capability, it probably comes from a chemfuel OMS, unrelated to the main reactor.

(A 1-minute chemfuel burn at 0.1 g uses about 2 percent of ship mass in propellant, and sidesteps the ship about 1.8 km, with a velocity change of 60 m/s.)

Anonymous said...

The Laser Star probably doesn't even need a chemfuel rocket for high thrust burns.

It can just vent some of its high temp coolant out a nozzle.

(SA Phil)

Rick said...

Coffin Nails / Cigarettes of Harm:

The minimum size for target seekers is partly set by miniaturization tech, partly by three other factors:

1) How much propellant a cigarette-lighter size tank can hold. The square-cube rule means this will go down faster than total mass.

2) Cost of guidance logic. This is more or less fixed, since the problem of making an intercept is the same for big or small weapons. As target seekers get smaller, guidance accounts for most of the total cost, to the point that a smaller one will cost just as much.

3) For typical encounter speeds, packing enough energy to do damage, even after punching through a Whipple shield.

My *guess* is that SCODs are a good balance, while coffin nails may be taking miniaturization too far, depending on target characteristics.

Anonymous said...

The CNOH is an adaptation to the "dominant" Laser-Star scenario.

It probably would only be useful where the Laser-Star's have higher capabilities.

If you can force the Laser-Star to fire and target more and more projectiles the better off you are.

Maybe the guidance can be simplified to just a receiver and directional actuators (vectored thrust and some jets maybe)

The actual course and control logic could be decided and transmitted by a Larger missile that followed behind them.

It might be that just having enough guided projectiles will overwhelm the tracking capabilities of the Laser-Star.

-------------
Although there might be other ways to get a similar result.

Maybe some of the Soda Can of Deaths are Blunderbuss Soda Cans of Death and they fire hundreds of Ball bearings from a close enough distance that the Laser-Star is forced to either do a quick burn or activate other defenses.

(SA Phil)

Locki said...

Rick said...
In that case I can (probably) keep them all under 'rotating' fire without physically pivoting the laser star.

They are all in my field of view, and I only need fine adjustments in the optical train to shift the beam from one closely grouped target to the next, (probably) on a time scale shorter than it takes to open your shutters.


Thanks Rick. That just gave me the most amusing mind-picture of a trillion dollar disco ball of doom, hyped up on amphetamines, gyrating in a random pattern trying to keep a flotilla of 3-5 frigates illuminated faster than they can snap open their shutters.
Aside from the fact that I’m likely to be able to snap open a 5m shutter faster than you can precision aim a 30m mirror, you could always just open two shutters simultaneously.

Besides I thought the only reason a Laserstar can achieve such stupendous feats of marksmanship is because the targeting is done by the same, near magitech, optics that focus the beam. This makes it very hard to quickly switch targets. In actual fact the Laserstar can only shoot what it happens to be looking at. Which makes deflection shooting a bitch. Now wait a second …

Isn’t the greatest weakness of a Laserstar the fact it uses the same optics for targeting that it does for shooting. That means it can only shoot what it is looking at. That makes deflection shooting impossible (you can’t shoot ahead of where you are looking). Which makes shots with significant light-speed delays totally impossible.

For example. At one light seconds range my optics bring you into focus and my computers calculate where you will be in 2.05 seconds time (1 second for the light to reach the Laserstar, 1 second for the laser to reach the target, 0.05 seconds to iniate the laser burst). To hit the target I actually have to point my optics in front of the target. Which means I’ve just taken my targeting optics off the target and I’m shooting blind. At the sorts of speeds we’re all talking about here 2 seconds is an eternity.

Unless my math is horribly wrong we’ve had it wrong for years. The effective range on a laserstar is not limited by power, wavelength and aperture. A Laserstar using the same optics for both targeting and shooting cannot take a deflection shot so its the range is limited by the relative speed of the target and the range (light speed delay). With the sort of velocities casually tossed around on rocketpunk even a 0.001 second light delay will cause you to miss big time. Which brings the effective range of a Laserstar down to 300km.

I guess you could have a second Laserstar providing targetting information but this is really expensive and frankly I do not accept you could align the optics and the laser so precisely.

For all you people who have born with me and are suffering from “armored shutter fatigue” thank you. But, surely, SURELY this finally sounds the death knell of Laserstars in a hard SF settting.

Anonymous said...

RE: Locki and "Light Second lag"

At 30 kps relative velocity and one light second range (300,000 km) the difference between the light speed Lag image and the actual ship position is 0.01%.

Therefore if for some reason you were shooting off angle 90 degrees you would need to lead the target by 0.01%. For a 1000 meter long spacecraft that would be 0.1 meters.

Since there is no stealth in space - we already know the target ship's relative vector. Not that 10 centimeters should matter all that much.

If instead as we described The two fleets are on vectors that are almost directly opposed to each other, the target additionally will be barely moving "up/down or side to side" So even that tiny lag wouldn't make a difference.

I think perhaps .. you are confusing the Light Second Targeting Lag problem with a ship that is changing position at a appreciable amount to the speed of light.

If you were trying to hit a ship with a velocity of .1 C for example it would matter a lot more. You would need to lead that ship by 100 Meters.

A light speed weapon is really really fast... Even at a range of 1 light second.

By way of comparison speed wise the 1st 30 kps example it is equal to a rifle shooting a target 1000 meters away, with the target able to step sideways at a maximum speed of 0.36 kph.

(SA Phil)

Anonymous said...

ahh Of course there is the return trip - good point.

it would be 20 centimeters lead for 30 kps

and 200 meters for 0.1C

Shooting at it broadside as it streaked across

(SA Phil)

TOM said...

Sorry i clearly lost the track, work, friends etc...

But i think it is good : http://gizmodo.com/5426453/the-physics-of-space-battles

Ultimate laser range is limited by targeting accuracy.
Mothership fires giant laserstar just a few times at beginning : half of the laserstars, sensor arrays of charging enemy fleet is gone.
Then giant laserstar shuttered for protection.
Middle lasers of mothership and frigates keep firing, suppress fire, jamming. Narrow band filtering on sensors also mean, if i employ a different filtering around my ships, you filter out their signs as well.
Missiles or barrages to small recon probes.
Accuracy drops to 1 arcsec.
Small ships are perfectly safe from a distance of 10.000 km with shuttered lasers.
/50m inaccuracy/
Finally, middle range lasers are also shuttered, and shooting from few thousand kilometres, short range lasers and missiles, coilgun fired minimal delta-V missiles, shrapnels and shells.
Kinetics are effectively ignoring armor, even if they dont ruin the ship, they will ruin the outer defence system, also it less expensive to equip the short range ships with heavy frontal shields against tiny shrapnels.

So lets see : enemy battlecruisers charging mothership are stripped from superior range, armor, superior firepower also countered by swarm tactics, they will be eaten by brown water ships.

You can make a trick like unshutter laser, fire shutter back... then i will see the unshuttering, and i will dodge, while mothership fires back, or if it is too far away, an escort frigate fires back with middle laser.
The smaller accuracy of small ships are countered by the networked accuracy, big targets dont make so big acc to counter this. /Big acc would make obsolate the coordinates you get from far away./

That makes the combo of MOTHERSHIP, middle and small ships combo very good IMHO, battlecruisers are still needed because they can operate independently, and counter anything but mothership and its swarms, or counter it if they are plenty enough.
But the queen will be the mothership, most times there wont be big naval battles, just pacifying jobs, brown water ships are just fine, they just need transport, and some frigates and cruisers can provide bigger area control.

Anonymous said...

Targeting IS the big issue. A laserstar may have a laser with a light second range, but could you really hit anything in a combat situation at that distance? With all the vibrations and thermal stress I doubt you could hit a target with every shot, let alone choose what to hit on the target. No matter how magitech your weapon system, it has to be mounted to a ship and slewed on target. That is a mechanical engineering problem. A very difficult mechanical engineering problem.

To compensate you would have to lay down a pattern, a barrage in artillery terms, to get a hit at stupendous range. Of course, then you have the problem of all that waste heat from firing your massive laser basically at full auto.

Why would anyone use their 30 meter laser as their targeting system? You would have separate sensor systems for that. It wouldn't take a very large telescope. If your RBOD is an x-ray laser, then you can't use it for targeting. It would have grazing mirrors for focusing while your IR sensors would need conventional mirrors or lenses.

To reduce the chance of a mission kill due to sensor loss, ships would have multiple IR sensor telescopes in armored and shuttered mounts. You only need to use one at a time. Targeting issues also mean that hitting the sensor is a lucky shot. You could use your laser as a searchlight in a wide beam to cover the entire enemy ship, but that would greatly shorten your dazzle range. Depending on the math, that might bring you down to actual effective combat range.

Ron

Locki said...

SA Phil said:
If instead as we described The two fleets are on vectors that are almost directly opposed to each other, the target additionally will be barely moving "up/down or side to side" So even that tiny lag wouldn't make a difference.

=======

Ah. Of course. My apologies. It is angular velocity that is important. If you are approaching dead on its a much easier shot.

However, I think my math is only half wrong instead of horribly wrong, so I don't yet have to change my username. I think you have over-analysed how much lead you have to give a target moving 90 degrees to yourself. To take your sniper analogy if I were taking a shot at a person running at 8m/sec (30km/h) at right angles to me and the flight time of my bullet were 2 seconds I would have to lead the target by 16m. To work out how much to "lead" the target you merely need to know the targets angular velocity and the "flight time" of your weapon. At 1 second it is effectively 2 seconds flight time.

So fo a Laserstar shooting at a target moving at 30km/sec at 90 degrees to you at 1 second light range the scenario is as follows. (Assuming the same optics are used for targetting and shooting)

a. Your 30m Optics/Mirror resolves the target and determines its exact location in time and space at 300,000km range. The Information is 1 second old

b. The computers initiate a laser pulse at this exact determined location. Lets call it a generous 0.001 seconds to initiate a multi-megawatt pulse

c. The laser pulse takes a further 1 second to reach the target. Total time elapsed 2.001 seconds

d. The target is now 60.03km away from where you first resolved the iamge and obtained the exact targetting location.

e. Alternately you could take your eyes off the target and repoint the laser at an expected location but you will have a 2 second time period during which anything can have happened.

But of course approaching dead on is all different since the angular velocity could be zero. eg Its much easier for a sniper to hit Usain Bolt if he is runnning straight at you. Which probably means my frigates should appraoch the laser star in a random zig-zag pattern that gradually increases in amplitude as I get closer to the laserstar. Kind of like the WWII merchant convoys zig zagged in submarine waters .... hey did I just bring back a trope from militarty history?

Locki said...

Rick said...

Lasers are 'durable' weapons. (Except for bomb pumped.) Set aside all the debate about laserstars. If you have laser-armed spacecraft, the implied expectation is that they can zap, and zap again. If your lasers use solar or nuke power, you won't run out of ammo.

======

I think this is where so many of us are running into trouble with this purple-green lasers vs kinetics argument. I presume lasers are very, very fragile weapons. If its even possible to build a Laserstar capable of hitting targets at stupendous lights seconds range it will literally be man's greatest feat of precision engineering. The thing will need to have tolerances down to the nanometer in order to hit anything at that sort of range. The optical path will require near 100% efficiencies to not be destroyed by the megawatts of energy its harnessing.

This same precision makes it awfully fragile as unlike other precision components (eg computers)it must be placed in athe most exposed position with its entire optical path out in the open in order to to fire. If Ensign Clumsypants bumps the thing the wrong way you are in trouble. I suspect a fly burping would knock it out of alignment. A hand grenades worth of energy from a counter-firing laser will devastate it. I'm obviously a bit biased as I've got a laser that requires 4 weeks of repairs and $10k everytime a staff member bumps it the wrong way.

With regards to "ammunition" for a laser. I've always assumed the lasers firing time would be limited by your ability to dissipate heat. Atomic rockets refers to lasers as blast furnaces that produce a bit of laser energy as a by-product. Assuming very generous 50% efficiencies here a 500 megawatt laserstar that needs to fire continuously would need enough radiators to radiate 250 megawatts of waste heat from the laser. In addition assuming the reactor is 33% efficient it will have to radiate an additional 1500 megwatts of heat for a total of 1750 megawatts of heat needing to be radiated away as IR. I can't do them math but i'm sure its several football fields of radiators with all the mass penalty this implies.

Handwaving it away by saying I've got that energy and radiator ability already for my electric drive is ignoring the fact you've only got that much generating power in the first place because you are lugging around such a giant laser cannon.

In comparison a laser mounted for point defence and blinding purposes probably only need 5-10 shots and could get away with just enough capacitors heat sinks for a a few shots. So the counter-battery lasers will again be that much smaller and cost efficient.

Anonymous said...

Locki said

Alternately you could take your eyes off the target and repoint the laser at an expected location but you will have a 2 second time period during which anything can have happened.

If the target is not maneuvering orbital mechanics will tell you exactly where the target will be, even if it is moving a 30 kps.

The question is can the target apply enough delta V during that 2 seconds to not be hit. Then again, if it's dodging, how can it keep its long range laser stable enough to hit a target?

Laserstars at 1 light second can sit there for as long as they want to prepare to hit a space station, but they would have to get in close for combat versus warships.

Ron

Rick said...

I don't need to move the mirror, so long as the target is within the telescope's field of view. To shift targets within my field of view, I only need make a fine adjustment to the 'camera holder.'

But only beams coming from targets within my field of view are magnified and concentrated onto the laser elements.


Having said that ... two provisos. One, that all this can end up being determined by the devils in the details, such as how long it takes to open shutters, etc.

The other is that I don't claim to be sure how the game-theoretical logic of blinding and shuttering plays out.

But on balance, if laser weapons are very useful at all, I suspect there will be advantages to having the most powerful practical laser zapping through the largest practical mirror. Which would probably be keel-mounted on the spacecraft that carries it.

I certainly don't think that is the only weapon a constellation would have, or even the only one mounted on the laserstar vehicle.


Really, what started me thinking about the laserstar concept was wanting to explore alternatives to the 'laser battleship' image of ships with half a dozen or so laser turrets. It may work out that day, but I wouldn't assume it will go that way just naval guns, a very different weapon, went that way.

And, the fact that large electric-drive ships have *lots* of electric power available, and a drive that doesn't provide decent tactical maneuver in the first place, so that diverting power from drive to guns doesn't really cost you much.

Rick said...

Welcome to a new commenter!

Targeting is indeed a huge issue. The reason to use the big main mirror for aiming (if possible) is because it has higher resolution than any smaller mirror, and thus provides more precise targeting information.

Remember that we already can aim large optics with uber-precision. Observatories do it all the time. Hubble does it in space.

Whether we can do so while handling dozens of megawatts of beam power, in close proximity to even more waste heat removal, is a very good but unanswered question.

But if laser weapons are worth having at all, I suspect it will be worth mounting some very powerful ones on electric-drive platforms.

Thucydides said...

Coffin nails are quite feasible from a technical or mechanical POV, but the main issue I can see is will they be able to make an effective course correction at the high closing velocities of a KKV attack? I suspect most coffin nails will run out of propellant before they can make the course correction to intercept the target. IF the argument is to unleash the coffin nails when the bus is very close so the dispersion cone covers the anticipated position of the target, then why spend the extra time/energy to make coffin nails when you can do the same thing much cheaper with ball bearings.

If your busses have to come in that close, then the obvious problem is the RBOD will burn the busses long before they come into range (until you have launched enough busses to reach overmatch).

The laserstar does not have to sight down the optical train to aim and fire; most of the sensor information will be coming from off board sensors in a cloud of drones surrounding the ship and constellation. Like Rick said, the ship will be using much of the power output to energize the beam since there is no way to make large course corrections in the time allocated with PMF drives. Tony is correct in pointing out the limitation due to heat rejection, so the fire may be broken up among multiple platforms according to the fire control computers calculations of number of targets that need to be engaged, recharging rates and heat rejection rates of the weapons. For tactical advantage there might be heat sinks or tanks of extra coolant that can be vented for short term relief.

From some of the comments, I think many people are still thinking of space combat as depicted in the movies, when Star Captain Errol Flynn fires a broadside, then throws the grappling hooks over before swinging from the rigging to the deck of the enemy Kineticstar. The one second kill range of the Luke Campbell RBOD is one light second, which is almost the distance from the Earth to the Moon. The scorch distance is some multiple of that. (A Luke Campbell laserstar in LEO can scorch a target on the surface of the Moon). Using Apollo era technology, the KKV cloud will take up to three days to reach the target area (Chemfuel missile busses), Torpedoes may be able to get there sooner, perhaps in 24 hr...The only way KKVs can engage faster is if they are being launched from a ship on a flypast trajectory at interplanetary speeds

Anonymous said...

RE: Targeting and SA Phil failing velocity math forever.

I realized as I had left the computer I had completely botched my math earlier --- Very sorry about that.

Locki was right if the Laser-Star is trying to shoot at a ship streaking across its field of view as it were - it is going to have a really hard time.

The only thing I made any sense about was the ship coming right at the Laser-Star.

My only defense - if you can call it that - was that I had watched Indiana Jones and the Crystal Skull earlier and I may have been suffering some sort of Post Traumatic effect.

(SA Phil)

Anonymous said...

Locki,


However, I think my math is only half wrong instead of horribly wrong,

----------

Your math was actually a lot closer than mine.

In that a ship moving 30kps across your field of view at 1 Light Second Distance would be 30 KM from it was when you first saw it, and around~60 km from where it was from the beginning of the sequence.

This lag would have to be compensated for -- and it really would compound any targeting related errors you had built into the system (such as an actuator having a 0.01 mm rounding error due to a/d to d/a)

As we mentioned the most likely scenario is the fleet coming right at the Laser-Star so it isn't as bad as all that ---> but you probably did a lot of damage to my idea of mounting big Laser-Stars on the moon instead, since it would be far more likely to be off angle.

(SA Phil)

Rick said...

I presume lasers are very, very fragile weapons.

I expect no less. They are precision optical devices, after all.

By durable I don't mean 'rugged'. I mean that you can zap something with it and still have your laser to use for another zap. A missile may be more rugged, but once you fire it, it's gone.


Handwaving it away by saying I've got that energy and radiator ability already for my electric drive is ignoring the fact you've only got that much generating power in the first place because you are lugging around such a giant laser cannon.

No - really it is the other way around. Large electric-drive ships have enormous generating power because that is how they get around. So the question is, why not use all that power for a long range laser installation?

Anonymous said...

Thucydides said...

Coffin nails are quite feasible from a technical or mechanical POV, but the main issue I can see is will they be able to make an effective course correction at the high closing velocities of a KKV attack? I suspect most coffin nails will run out of propellant before they can make the course correction to intercept the target.
============

Hard to know that without knowing the Delta V of the CNOH's mission. Its peak accel needed, and the limits of propulsion scalability.

Same could be said for the Soda Can of Death.

Or a missile of any size.

----------------

Actually it is the mass not the volume of the coffin nail that is really important.

What if the CNOH is instead a Playing Card of Harm- basically A thin film solar panel mounted to a tiny Ion Engine.

(SA Phil)

Tony said...

Rick:

"And these drive units are capable of radiating off the waste heat during sustained full power operation."

Yes -- capable of radiating their own waste heat. The laser introduces more waste heat into the system.

"Remember that we already can aim large optics with uber-precision. Observatories do it all the time. Hubble does it in space."

We sure do. If they're on the ground, they have an entire planet as a stable base. If they're in space, even if they're rotated very slowly by reaction wheels and they still have to be allowed time to settle down before observations can be made. Rotating a precision optical instrument in space at combat slewing rates would induce jitters that we would find totally unacceptable in any astronomical telescope.

Anonymous said...

Tony,

Yes -- capable of radiating their own waste heat. The laser introduces more waste heat into the system.

-------------

The ship doesn't use its nuke electric drive and the Laser at the same time - therefore it takes advantage of the cooling system built for the Nuke Electric Drive to cool the Laser.

The sustained power /heat output of the nuke electric drive is near to that of the Laser.

The cooling system for the reactor it uses all the time.

(SA Phil)

Anonymous said...

Tony,

Rotating a precision optical instrument in space at combat slewing rates would induce jitters that we would find totally unacceptable in any astronomical telescope.

=============
Again with the sweeping slewing rates and the angles.

I think you envision space combat as being far more swoopy than it would actually be at Light Second Fractional ranges.

Instead the Laser is going to spend the entire combat facing in almost exactly the same direction making very small adjustments.

At 100,000 km a battle fleet roomily spaced out in a 100 km sphere has all of its units within 0.057 degrees of each other from the perspective of the Laser.

(SA Phil)

Tony said...

SA Phil:

"The ship doesn't use its nuke electric drive and the Laser at the same time - therefore it takes advantage of the cooling system built for the Nuke Electric Drive to cool the Laser.

The sustained power /heat output of the nuke electric drive is near to that of the Laser.

The cooling system for the reactor it uses all the time."


I was waiting for that. A Hall thruster, right now, is about 45-55% energy efficient. I've heard that 70% is considered an achievable goal. The laser is 20% efficient. Even with an electric thruster that is only 50% efficient, the ship needs 1.6 times the radiative capcity for its laser than it does for its thruster. However much that is in addition to the standard cooling for the power generation system is above my paygrade, but I doubt its insignificant.

Also, the 20 megajoule output equates to 5 kg of TNT in energy terms. That's presuming you can keep the spot focussed for a whole second, and on target for all of that time. That's why higher energy pulses make much more sense at space ranges. But high energy pulses require the inclusion of massive capacitors -- which also have to be cooled if we're rapid charging and discharging them.

WRT laser durability, I have to go with the people that think lasers are pretty fragile instruments -- or have to be made so massive that they would be ridiculously hard to aim with any kind of precission. I think "reusable, but of questionable durability" would be more accurate than "durable" to describe such a system.

IOW, all of this lasers-are-virtually-unlimited-instant-offense thinking just doesn't pass engineering muster.

Anonymous said...

Tony,

I was waiting for that. A Hall thruster, right now, is about 45-55% energy efficient. I've heard that 70% is considered an achievable goal. The laser is 20% efficient. Even with an electric thruster that is only 50% efficient, the ship needs 1.6 times the radiative capcity for its laser than it does for its thruster. However much that is in addition to the standard cooling for the power generation system is above my paygrade, but I doubt its insignificant.

Also, the 20 megajoule output equates to 5 kg of TNT in energy terms. That's presuming you can keep the spot focussed for a whole second, and on target for all of that time. That's why higher energy pulses make much more sense at space ranges. But high energy pulses require the inclusion of massive capacitors -- which also have to be cooled if we're rapid charging and discharging them.

WRT laser durability, I have to go with the people that think lasers are pretty fragile instruments -- or have to be made so massive that they would be ridiculously hard to aim with any kind of precission. I think "reusable, but of questionable durability" would be more accurate than "durable" to describe such a system.

IOW, all of this lasers-are-virtually-unlimited-instant-offense thinking just doesn't pass engineering muster.

==================

I think the numbers for efficiencies of both Lasers and Electric Drives vary. But a 1 to 2 ratio sounds plausible to me.

That wouldn't mean the system cant work. It just means the Laser's average power consumption will have to approximate the Electric Drive's average power consumption. The Laser will have to fire less often.

It can have a buffer built in to handle the peak demands.

-----------------

No different than the brakes on your car. Its relatively easy to exceed the maximum heat removal of the system. However under normal use you never get to that point.

(SA Phil)

Tony said...

SA Phil:

"Again with the sweeping slewing rates and the angles.

I think you envision space combat as being far more swoopy than it would actually be at Light Second Fractional ranges.

Instead the Laser is going to spend the entire combat facing in almost exactly the same direction making very small adjustments.

At 100,000 km a battle fleet roomily spaced out in a 100 km sphere has all of its units within 0.057 degrees of each other from the perspective of the Laser."


Don't assume things I haven't said, please. I'm talking about real world application issues, not operatic fantasies.

Hubble, for example, slews about 6 degrees a second. That's actually probably adequate. But even in the Hubble that only gets one close to the target -- the fast rate slewing just isn't that precise. Then the controllers have to make incremental adjustments on a guide star, and then let the induced vibrations from that settle out before observing can begin.

Now, removing ourselves from a relatively light structure like the Hubble that can be turned at 6 deg/sec with reaction wheels, we look at weapon systems and associated power/radiators/etc. These are heavy and have to be controlled by even less precise reaction control systems. Imagine slewing a tenth of a mil (about a tenth of the angular width of our 100km target dispersion at 100,000km) using RCS. At 6 deg/sec, the whole slew would take less than a millisecond. It would require RCS -- a mechanical system -- with sub-millisecond precision in operation. Or a mirror turret with similar mechanical precision. Or reaction wheels big enough to slew hundreds or thousands of tons at 6 deg/sec over such small angular distances, again with sub-millisecond mechanical precision.

I honestly don't think it's physically possible with the masses in question. It would be hard to be that precise on a lab bench with moving masses in only the kilograms.

jollyreaper said...

If we useaser-boosting for the kinetics then the laserstar and kinetkstar are the same vessel. Primary laser boosts bus for long range attack, then directly targets incoming ships and weapons at mid to close range.

Rick said...

I was waiting for that. A Hall thruster, right now, is about 45-55% energy efficient. I've heard that 70% is considered an achievable goal. The laser is 20% efficient.

That simply means that the reactor will have to throttle down somewhat when in zapping mode.

Let's try some rough numbers. Say that drive thrust power is 100 MW. Waste heat from the drive itself is 50 MW. Total drive power consumption is thus 150 MW, and it is 67 percent efficient.

The reactor, let's be conservative, is 25 percent efficient, so it generates 600 MW total energy production, 450 MW waste heat plus 150 usable power. The radiators must therefore shed 500 MW of waste heat, 450 MW from the reactor and 50 from the drive itself.

In laser mode we are limited by our main radiators to 500 MW of total waste heat, from the laser installation and the reactor combined.

Suppose I cut back reactor power by 20 percent, so that it is producing 125 MW usable power plus 375 MW waste heat. The laser installation draws the available 125 MW, emits a 25 MW beam, and dumps 100 MW in waste heat.

Total waste heat production is thus 475 MW, a bit less than the radiators handle in drive mode. So 20 MW sustained beam power turns out a bit conservative, as it should be.


Look, Tony, I am not trying to downplay the technical challenges involved in all of this. I am on record describing big weapon lasers as observatory-grade telescopes with a jet engine in place of the eyepiece.

It may well turn out to be non-doable, in which case laser weapons will not be in use, or only some minor special-case uses.

On the other hand, we are pretty good at making precision machinery that runs well even in tough operating environments. So having useful laser weapons strikes me as broadly on a par with having regular interplanetary traffic. That is to say, no more operatic than 'realistic' space battle settings are to begin with.

None of which means you have to have them. Laser weapons may not work, but if they do, the question then is what ways you can usefully deploy them, and to do what.

Tony said...

Re: Rick

Please understand that I'm not hostile to lasers per se. I'm just highly skeptical of mega/giga-watt lasers effective at more than a few thousand kilometers. And even then I'm skeptical of their economic and military practicality.

The issue I see is that people get so sucked into the bigger-laser-is-better ideal that they totally miss that in the real physical world, lasers probably can't get very big or precise.

BTW, has anyone considered how big a thermal control system would have to be to reject 500Mw of heat continuously? To put it in contemporary terms, that's the full power output of three Iowa class battleships (rated at 158Mw). Imagine stopping three 57,000 ton battleships, each steaming at 33 knots, dead in their tracks in one second. Obviously it can be done, because we have gigawatt nuclear power plants -- that turn thousands of tons of water into steam every day. Or, to put it another way, according to The Wiki article on cooling towers, a 700Mw coal-fired plant requires a coolant throughput of 100,000 cubic meters (or 100,000 tons, using water) per hour. Try that in a closed loop with just radiators.

Anonymous said...

Tony,

Please understand that I'm not hostile to lasers per se. I'm just highly skeptical of mega/giga-watt lasers effective at more than a few thousand kilometers. And even then I'm skeptical of their economic and military practicality.
===================

I would suggest you absolutely come across as hostile to lasers per se.


(SA Phil)

Anonymous said...

Tony,

Try that in a closed loop with just radiators

--------
It would suggest the radiators are going to be several square kilometers.

I think calling a Laser-Star a "ship" is going to be difficult - it is more like a slightly mobile piece of space artillery.

(SA Phil)

Anonymous said...

Tony,

I honestly don't think it's physically possible with the masses in question. It would be hard to be that precise on a lab bench with moving masses in only the kilograms.

=============

If you had a system which only had to deal with angles of <1 degree, you probably wouldn't design it to slew at 6 degrees a second.

You would also probably move the smallest piece of hardware in the system - since the mirror is postulated as having a variable geometry - that might be the better place for the actuator adjustment.

(SA Phil)

Tony said...

SA Phil:

"I would suggest you absolutely come across as hostile to lasers per se."

Ummm...sorry, but you're not reading me very carefully. I'm against laserstars and super long-range lasers, because I think they're impractical. Otherwise, I think lasers have their uses, and also their limitations.

It would suggest the radiators are going to be several square kilometers.

"I think calling a Laser-Star a 'ship' is going to be difficult - it is more like a slightly mobile piece of space artillery.

Making it a totally defensive laser battle station. I think I've said that before.

And I still don't think it's very practical, precisely because it would only work as a space equivalent of a fortification gun, without the benefit of a fortification.

"If you had a system which only had to deal with angles of <1 degree, you probably wouldn't design it to slew at 6 degrees a second."

Well, only <1 deg if you can be absolutely sure of the enemy approach vector. It may be possible, given the uncovered avenues of approach, but still an important caveat.

"You would also probably move the smallest piece of hardware in the system - since the mirror is postulated as having a variable geometry - that might be the better place for the actuator adjustment."

That's certainly what I would do. I still think one would establish a primary track by putting an appropriate rotation on the laserstar, just like the Hubble does. Also, you have the same problems of managing 1/10,000 mil pointing precision (to hit inside a 10m radius circle at 100,000km). Remember, no matter how precise the mirror pointer is, one has to have the rest of the ship not vibrate any more than 0.5mm per 10 meters of its cross section in order to maintain this level of pointing precision. Kind of hard to do with tons per second of cooling fluid running through your power reactor and hundreds of tons of coolant moving through your radiators.

Anonymous said...

Tony,

Well, only <1 deg if you can be absolutely sure of the enemy approach vector. It may be possible, given the uncovered avenues of approach, but still an important caveat.

===============

I think perhaps you rotate the ship to get it pointed at the approaching fleet, then use the <1 degree adjustments from there.

If they have 2 fleets coming from 2 widely spaced vectors presumably you have another defense force, or Laser-Star as well.

(SA Phil)

Anonymous said...

Tony,

And I still don't think it's very practical, precisely because it would only work as a space equivalent of a fortification gun, without the benefit of a fortification.

=========
A Fractional Light Second range, at Light Speed in a 30-50kps world is a fortification of its own in a sense.

I imagine the first "Laser-Stars" will likely be pointed at the planet they orbit - rather than into space though.

(SA Phil)

Anonymous said...

Tony,

Remember, no matter how precise the mirror pointer is, one has to have the rest of the ship not vibrate any more than 0.5mm per 10 meters of its cross section in order to maintain this level of pointing precision. Kind of hard to do with tons per second of cooling fluid running through your power reactor and hundreds of tons of coolant moving through your radiators
======

Unless you could somehow compensate for the cooling vibration. Possibly introduce a mechanical counter vibration at an opposing frequency.

Sort of the mechanical version of a white noise generator.

that could shake itself apart though--- competing harmonic frequencies are bad.

That is generally how brackets break and things go flying in engine development.

================

Another possibility is you shut off the cooling pumps to make the shot and then turn them on again after.

That would require bigger coolant buffers, Including using liquid coolant for the Nuke Reactor and again slow down how fast you could shoot.

(SA Phil)

Anonymous said...

Maybe move the Mirror onto another ship ... one that has a passive cooling system. (and no super laser/Nuclear heat source)

(SA Phil)

Rick said...

BTW, has anyone considered how big a thermal control system would have to be to reject 500Mw of heat continuously?

Yes. :)

But that is the standard you have to meet to push a few hundred tons along at a steady milligee or so. At quick and dirty estimate I get 3000 square meters of radiator, radiating at 1000 K.

And honestly, I really think the big main mirror is one of the less problematic elements of a laser weapon. The laser itself, running very hot and with a 'cooling' system going full blast, poses beaucoup challenges, all the things you have mentioned.

The main mirror is away from the direct heat and heat pumps, and the beam is spread out, thus less intense. That doesn't make it easy, but if the laser is doable at all, running it through a large mirror is not the worst additional complication.

Anonymous said...

Rick,


And honestly, I really think the big main mirror is one of the less problematic elements of a laser weapon. The laser itself, running very hot and with a 'cooling' system going full blast, poses beaucoup challenges, all the things you have mentioned.

The main mirror is away from the direct heat and heat pumps, and the beam is spread out, thus less intense. That doesn't make it easy, but if the laser is doable at all, running it through a large mirror is not the worst additional complication.
==================

Still if the mirror is attached to the same frame as all the rest the vibrations will be transferred along the frame. Unfortunately unlike a vehicle on earth it cant transfer the vibrational energy into the ground or water.

Unless it is somehow dampened - either floating in space, or some other medium. Liquid filed mounts, etc.

If the mirror actuators were really impressive, maybe they could compensate for the vibrations- since presumably they would be completely predictable. (Again because none are transferred elsewhere at variable rates)

(SA Phil)

Rick said...

Maybe move the Mirror onto another ship ... one that has a passive cooling system. (and no super laser/Nuclear heat source)

It doesn't need to be 'another ship' in the usual sense. Just separate the mirror module when in zapping mode. You aren't maneuvering while firing anyway. The separation distance can be a few centimeters - so long as there's no physical connection, there's no vibration.

You still have to correct for beam jitter, but that is something we can do pretty well with adaptive optics now, so it shouldn't be a deal breaker.


And I still don't think it's very practical, precisely because it would only work as a space equivalent of a fortification gun, without the benefit of a fortification.

What SA Phil said - range offers protection. At 10,000 km, it will take 1000 seconds for 10 km/s kinetics to close the gap.

At 100 km/s, kinetics will cross the engagement zone in just 100 seconds. But deploying kinetics at 100 km/s requires an electric bus, building up speed for weeks or months. That is a cumbersome and costly strike, and not one you can launch on a tactical time scale.

Anonymous said...

I kind of think to be truthful to the march of progress, if you have 100 kms as a typical closing speed the Laser-Star should be comparatively advanced.

While if its 10kms the laser should be shorter ranged.

I wonder if you could use a rule of thumb saying "typical time crossing the Laser's threat window is 500 or 1000 seconds"

In the 10kms world I think that kinetic stars will launch their missile busses with a space gun of some sort - an extra 5 kps would be huge.

(SA Phil)

Locki said...

I've been enjoying this discussion a little too much and my 3yo boy voted to restrict my access to Rocketpunk to just one post a day. It's nice to see someone else taking up the "lasers are specialty weapons for specialty purposes" only camp.

=======

Rick said...

Really, what started me thinking about the laserstar concept was wanting to explore alternatives to the 'laser battleship' image of ships with half a dozen or so laser turrets. It may work out that day, but I wouldn't assume it will go that way just naval guns, a very different weapon, went that way.

======

I understand your pain. I'd spent the last decade polishing up my stealth in space concept (everyone blinds everyone!). Fell in love with the idea. Planned a whole sci-fi trilogy around the concept. Then I tested it publically here. Realistically the idea was shot down in about 8 posts. I graciously conceded, of course, 30 "vigorous" posts later. I think I've managed to salvage my trilogy but my sleep has been haunted by Einstein's ghost ever since.

Really the writing is on the wall for any ship planning to use a Laser as its primary weapon. Going back to first principles the lasers are In reality are a horribly energy inefficient weapon and they deliver that energy in a pretty micky mouse sort of way. In an environment where mass is at a premium and radiating away waste heat is such a pain something like a laser with 20% efficiency just doesn't make sense. You might as well use all that energy you hauled into space to throw a ball bearing at them at some crazy velocity.

I'd suggest to find the correct role for lasers in a space sci-fi setting we should summarise the advantages and disadvantages of lasers in a space environment.

Locki said...

Cons:

1. Targetting
- A serious pain at the ranges been touted here (100,000+ km). Probably impossible. I dusted off my trig tables again and tried to work out what angle the laser array would have to tilt at to hit a 5m radius target at 300,000km. It was an unspeakably small percentage of a degree. I'm pretty sure no one can build a gear that can tilt that laser to that tiny fraction - the teeth would have to be about the width of single atom. You certainly couldn't do it whilst supporting a few tonnes of laser array. You most certainly can't do it whislt trying to radiate away the waste heat of several hundred steel furnaces.
Futhermore, if you want to "track" a target for some period of time that laser will have to make that many corrections per second with an equal degree of precision just to keep the target illuminated. All whilst hoping no vibrations are introduced into your system. Impossible.

2. Light Lag
- A few of us, including me, failed math here. But since we've all been disciplined and ruled out magitech torch drives the fleets aren't going to be closing dead on and will likely to be closing on intersecting Hohman orbits. There will be significant lead times for extreme ranges.

3. Lasers will have really poor accuracy because you cannot "strafe into the target"

- This is a new one I thought of whilst I was trying to work out if it was inverse tan or inverse cos to get my angles. Modern Phalanx CIWS systems (or machine guns firing tracers) work by firing at a target and then gradually correcting till they hit the target. The problem with a laser is you will not get the opportunity to correct your aim if you are a tiny bit off. The problem is no one can see the laser beam. If I take a shot and miss I have no idea on whether I have aimed high, low or to the left. If the gears on my laser are a tiny bit off there is no way to correct. Whereas a CIWS can keep correcting into the target

4. Inefficiency and waste heat. 20% energy efficiency is pathetic in an environment where mass is a premium and everything has to be radiated away as IR

5. Fragile. My pet pony since it relies on internal consistency rather than physics. If lasers of that performance are possible its far too easy to put damage on them and knock them out. Ironically, the best way of delivering that energy is with a smaller laser (with a lower cycling rate) designed to held behind shutters until blinding range is reached. So even if you solve the engineering problems for your setting to be internally consistent you have to explain why every laser within blinding range just doesn't knock out the big laserstar.

Tony said...

Rick:

"At 100 km/s, kinetics will cross the engagement zone in just 100 seconds. But deploying kinetics at 100 km/s requires an electric bus, building up speed for weeks or months. That is a cumbersome and costly strike, and not one you can launch on a tactical time scale."

No major offensive in modern warfare has been launched on a tactical time scale. Additionally, given the threat a laserstar poses as a defensive weapon, not planning your initial strike around neutralizing all laserstars as close to simultaneously as possible is abjectly stupid. If military planners could manage Pearl Harbor, Overlord, the complete unhinging of the Iraqi air defense network, etc, it's absolutely inconceivable to me that men who have to know enough "stuff" to navigate interplanetary distances wouldn't figure out what their target priorities were and plan around them.

In that respect, barring tactical or technical surprise, the neutralization of laserstars presents itself as nothing more than a defense suppression exercise. Modern air forces know how to do that and have become very good at it. Regardless of the planning lead time and the expense -- in terms of both resources and opportunity costs -- it's just a cost of doing business.

Locki said...

Pros:

1. It delivers the punches really, really fast

2. It can deliver its energy very specifically (eg to sensisitive optical sensors)

3. There is no recoil

Given these limitations I put it to you lasers will serve a useful though secondary role in the future. They are a terrible primary means of delivering damage to a target.

1. Sensors and range finders

2. Sensor blinding

3. Last minute point defence systems as they punch so fast - shortening engagment times.

Bearing in mind these advantages and disadvantages I put it to you the most useful space warship one armed with kinectics with a chemical laser or two to handle the few engagement scenarios where the lasers inherent advantages outweigh the disadvantages. The laser only needs to be large enough to be able to blind the opponents sensors at near the expected kinetic kill vehicles engagement ranges.

Anonymous said...

Hmm is 20% efficiency (if that is all it is) really that horrible compared to kinetics?

We are talking about basically 3 stage kinetics.

Stage 1 - the Kinetic-Star (Missile buss carrier)

Stage 2 - the Missile Buss

Stage 3 - the actual missiles

Stage 3 is subjected to active defenses - some portion are destroyed/deflected.

I wonder what fraction of mass that starts the battle (in the strategic and tactical sense) actually hits the target ship?

(SA Phil)

Locki said...

SA Phil said:

I wonder what fraction of mass that starts the battle (in the strategic and tactical sense) actually hits the target ship?

=====

Hmmmm ok. That point of mine is dodgy its a new one and I didn't think it through properly. It should have been restated as the 80% inefficiency of the laser has to be awkwardly radiated away by the mothership. A Chemical rocket doesn't have that problem. Nor Orion drive.

I apologise about the length of the above posts. But to summarise every weapon system has advantages and disadvantages in certain scenorios. But your primary weapon system should be the one that best suits the most number of situations.

There are plenty of situations where a knife is far more useful than a gun. It doesn't mean I shuold primarily equip my armies with big honking bayonets. Nor does it mean I should just keep toting creating a bigger and bigger knife until I can finally offset the inherent advantage of the gun.

TOM said...

How long time, since laser exists?
Half a century.

What it is really good for? Jamming and blindening, and take out a few missiles if it has a really great power source.
I just suppose, it rather remains the same, due to the targeting, fragility, waste heat treatment, reflective armor, etc arguments, they wont just explode ships, like Death Star.
Kinetics will be the real anti-ship weapons, long-range torpedos, short range chem fueled warheads, coilguns with various ammunitions, so analogies of aerial combat can be applied instead of just rely to naval analogies.

Eth said...

WRT using laser mirrors as sensors. The primary reason given for that is because a smaller mirror would have less resolution than the precision of the laser.

However, a swarm of smaller telescopes can use interferometry to have a better resolution.
The problems with interferometry vs large mirror are that you don't receive as much light, and apparently you can't have a perfectly neat image. But the ships are arguably bright enough to be detectable even by smaller telescopes, and even if the progress of imaging doesn't allow to have a clear image, you don't need it, only the ship's position.

Thus, no need to use the laser as a target sensor ; which would be impossible if you use a X-ray laser anyway, as pointed above.
If laserstars are impractical, it also means that you don't need giant mirrors to guide your kinestars as well, swarms of smaller drones will do the job and fare better against blinding/destruction.

---

WRT laser heat management : if you use a chemical (or like) laser, you can eject the product used to generate the beam, ejecting much of the heat with it. Even with a solid-state (or like) laser, you can use heat-sink, and possibly eject coolant.
The need for radiators would be greatly reduced.

It would mean that the laser is limited in the number of times it can fire. But it would still be a reusable weapon, compared to kinetics : a tank has only so much shells, but it is still reusable, contrary to a cruise missile.
The cost of refilling reactive chemicals and/or coolant will probably be less than the cost of kinetic buses and missiles.

On the other hand, ejecting stuff makes the vibration problem worse, potentially limiting further the range of said laser.

It is another argument in favour of equipping patrol crafts with lasers instead of kinetics, regardless of what the 'crafts of the line' will use.
Patrol crafts don't need extremely powerful weapons (they are not meant to go against military crafts). And lasers, apart from being faster (useful against, say, a deploying Q-ship), can be fired with less cost per shot ; for example as a warning shot.

jollyreaper said...

Still catching up with all the new comments.

In a pmf future, delta-v will be limited. I like the description of two trains fighting in a tunnel. Given the layout of a system, there's only so many paths to get from one point to another. Once a fleet has committed, the options at this point are constrained.

A civilian ship would burn as much fuel to get moving from point A as can be done while retaining enough fuel to stop at point B. Stopping might be a combination of an initial burn plus aerobraking. The tanks will be empty when they get there but more fuel should be available locally. If not, the return fuel has to be carried and lower speeds will be involved.

Military ships might keep a far greater amount of delta-v in reserve. They might, say, have enough for a direct return if the defenders present a stronger force than anticipated.

The strange thing to consider is that it's no big thing for a sailing ship to head across an ocean and then stop to help a distressed vessel or make an unscheduled stop at a nearby port. A proper rocket ship outbound from Luna might be able to rendezvous with a distressed rocket inbound from Mars if the trajectories allow for it. And likely they would be travelling different directions on the same course since its the most efficient path between those points. But the rescuer would have likely emptied his tanks in the rescue and has to return to Luna to tank up again.

So in a military sense, the delta budget can make for some interesting drama. A commander who uses the bulk of his fuel to make it to a target will be saying "I intend to win or die trying because retreat is an impossibility."

More options open up the further past pmf we get.

It does make one wonder how courses would look in something like the Niven setting where it's rockets and orbits inside a system and hand wave FTL at the periphery of the system. A military fleet trying to travel several systems would try to shape a course that uses the least fuel. For a setting with wormholes in a system that the ships pass through, you're talking a very complicated billiards shot so that velocity can be maintained without extraneous burns.

Personally, I like the idea of being able to tank up near planets. There is real tech on the table explaining how gas harvesting from orbit could work. If fuel had to be shipped from home, logistics would be nuts. In WWII i think the numbers were 9 gallons of fuel to move one gallon from the US to the front.

Establishing local fuel production would be the biggest objective in any campaign. Of course, what rockers use for fuel can make it complicated or easy. The easiest would be if a reactor runs the ship and reaction mass is just scooped up and superheated somehow to fire out the back of the ship. If specialized processing is needed to create fusion pellets or whatever, it gets more complicated.

Locki said...

Thucydides said...

For a nuclear pumped Xaser in this environment, the laseing rods would only have to be in a bundle and pointed at the last moment at the target; any vibration caused by the firing sequence would be overtaken by the wave of nuclear energy being converted to x-ray photons in the bundle.

===========

I fell in love with lasers as a kid. Bomb pumped X-ray lasers seemed like the best bet. Sadly, they are a no show. Unless you are aiming at Texas the explosive jiggle utterly kills any accuracy. Jiggle is bad for aiming at ranges. If a sniper breaks wind whilst taking a shot at a mere 1200m he'll definitely miss. The "jiggle" from a few kilograms of HE will wreck your chance of hitting anything and you are just better off relying on the blast radius of the nuke.

I’ve finally recalled the other limitation of bomb pumped lasers. The maximum theoretical percentage of x-rays from the explosion converted to lasers is pathetic. I’m pretty sure it was below 1%. The percentage was so low that even if you could aim the damn thing you would just be better off mounting a warhead 100 times as big and hitting it with the blast radius. Or if you want to be clever 100 nuke submunitions.



TOM said...

How long time, since laser exists?
Half a century.
What it is really good for? Jamming and blindening, and take out a few missiles if it has a really great power source.


========

In 60 years of research lasers have just proved to be a really inefficient way of destroying things. Many moons ago I asked on Usenet (RIP) why the airborne anti-ballistic laser wouldn’t make a perfect AWACS and satellite sniper. The answer was illuminating. Despite been almost the size of a 747 and only having enough fuel for 20 shots the red laser, was so weak it could only affect ballistic missiles in their vulnerable boost phase. It wouldn’t do anything against a plane. Apparently ballistic missiles are really thin skinned and rotate for stability. The theory was the laser would merely weaken a section of the skin and the missile would then tear itself apart. Note after $12 billion US the whole project was cancelled because they couldn’t solve the jiggle problems at 300km range.
Kinetics is just a much more efficient way of destroying things. If you are going to spend megajoules of energy you are better off using it to hurl a bullet. Also note in terms of efficiency kinetics effectively get to “double” their energy by using the targets own speed against them. It doubles the speed which should quadruple the KE. See the Navy’s proposed rail gun for shore bombardment which supposedly can hurl an inert 3.2kg ferrous rod with 160km with so much force it explodes with the force of tonnes of TNT. Awesome. If you want to destroy something hit it!


Eth said...

And lasers, apart from being faster (useful against, say, a deploying Q-ship), can be fired with less cost per shot ; for example as a warning shot.

For those people who love guns I actually think railguns will have a large place in space warfare. Assuming you have a huge reactor they will be the most mass efficient (read cheap) way of putting the maximum hurt on a target. I know if I would choose between the airforce’s ABL or the navy’s railgun.

Laserstar bombardment of planets

- At the efficiencies lasers generate you would just be better off dropping a few tonnes of tungsten rods on top of the target. Ignores pesky atmospheric considtions and clouds too. Of course with all the energy you just wasted hauling the rods up into space in the first place you could launch a 100 times that volume from earth directly at the target. In the absence of space elevators Space based bombardment just doesn’t make economic sense.

Samantha said...

Something that just struck me about fleet actions in space is that the exhaust plumes from ships in a fleet may have deleterious effects on their neighbors. For example, a nuclear rocket would normally have its own shadow shield but it would be prohibitively heavy to install sufficient shielding over the entire hull. That might cause a problem when the ship ten degrees off your bow lights its main engines!

Even if you line up all your ships in a flat plane so that they're not pointing their exhausts at each other you still have the problems of maneuvering. If you have to check to make sure that you're not pointing your engine at a friendly ship every time you execute a maneuver that could be a problem.

I suppose you could get around the problem by putting more space between your ships but isn't the whole point of military superiority on the battlefield to concentrate your force?

I dunno...

My vote isn't on battleships at all but instead on interplanetary powers duking it out with successive rounds of espionage and counterespionage. If you really want to paste something probably the most cost effective way to do it in the world of rocketry would be to take a freighter and pack a really big bomb into it. Send it towards its target and when it gets close or docks make it explode.

Perhaps your spies can help arrange to have it pass security checkpoints?

Tony said...

jollyreaper:

"In a pmf future, delta-v will be limited. I like the description of two trains fighting in a tunnel. Given the layout of a system, there's only so many paths to get from one point to another. Once a fleet has committed, the options at this point are constrained."

No fighting in tunnels. With PMF propulsion technology, one simply couldn't establish a retrograde trajectory. The best a defender could do is establish a slightly higher solar orbit than the planet to be defended, fall behind a bit, then speed up to make a close pass at the attacking force. But everybody would be going in the same direction on roughly parallel trajectories.

Of course, if you don't get enough of the the attackers, you've doomed your reserve in planetary orbit to fight outnumbered and at a velocity disadvantage.

"Military ships might keep a far greater amount of delta-v in reserve. They might, say, have enough for a direct return if the defenders present a stronger force than anticipated."

No about face and return in the pmf. They might carry a small delta-v margin to establish a free return trajectory, and hope the food, water, and air hold out for the couple of years it would take to get home.

"The strange thing to consider is that it's no big thing for a sailing ship to head across an ocean and then stop to help a distressed vessel or make an unscheduled stop at a nearby port. A proper rocket ship outbound from Luna might be able to rendezvous with a distressed rocket inbound from Mars if the trajectories allow for it. And likely they would be travelling different directions on the same course since its the most efficient path between those points. But the rescuer would have likely emptied his tanks in the rescue and has to return to Luna to tank up again."

Nobody is travelling in opposite directions. Everybody, even with delta-vs in the hundreds of kps, is going 'round the Sun in the same direciton. If a rocket departs the Moon for Mars, it's trajectory will corss that of the incoming vessel in distress. Even if one had enough delta-v to match orbits, it's doubtful that there would be enough delta-v left to stop, if any dleta-v was left at all.

"So in a military sense, the delta budget can make for some interesting drama. A commander who uses the bulk of his fuel to make it to a target will be saying 'I intend to win or die trying because retreat is an impossibility.'"

In the pmf, that's the only option you get, aside from calling off the attack en route and giving the shole thing a miss.

Tony said...

jollyreaper:

"It does make one wonder how courses would look in something like the Niven setting where it's rockets and orbits inside a system and hand wave FTL at the periphery of the system. A military fleet trying to travel several systems would try to shape a course that uses the least fuel. For a setting with wormholes in a system that the ships pass through, you're talking a very complicated billiards shot so that velocity can be maintained without extraneous burns."

Niven and Pournelle explicitly state in three different books (The Mote in God's Eye, King David's Spaceship, and The Gripping Hand that merchant ships accelerate, coast for up to five or six weeks, slow down, then make a jump, repeating the process in the destination system to arrive at a planet. (Which is still a lot of energy, when ships are hundreds of meters long and that weeks-long coast gets one to a jump point at something like Jupiter orbit radius.)

Military vessels tend to accelerate/decelerate all of the way, all of the time. It is implied in The Mote in God's Eye that Imperial battlecruisers have enough delta-v in integral tanks to accelerate to .06 c and slow back down to system velocities. As the drive is described as fusion-powered and photonic in nature, that's believable, if just barely. In any case, that would be enough delta-v to support other claims made for the operational practices of the Imperial fleet.

"Establishing local fuel production would be the biggest objective in any campaign. Of course, what rockers use for fuel can make it complicated or easy. The easiest would be if a reactor runs the ship and reaction mass is just scooped up and superheated somehow to fire out the back of the ship. If specialized processing is needed to create fusion pellets or whatever, it gets more complicated."

I would think that fuel facilities, of any description, would be strictly off limits. The practice would be to win the battle then hold a gun to the defender's head to get him to refuel your fleet for the return home (minus any security forces you leave behind).

Anonymous said...

Tony,

No fighting in tunnels. With PMF propulsion technology, one simply couldn't establish a retrograde trajectory. The best a defender could do is establish a slightly higher solar orbit than the planet to be defended, fall behind a bit, then speed up to make a close pass at the attacking force. But everybody would be going in the same direction on roughly parallel trajectories.

Of course, if you don't get enough of the the attackers, you've doomed your reserve in planetary orbit to fight outnumbered and at a velocity disadvantage.
========

This goes back to defining the DeltaV of the ships involved and of the mission.

Just 200 comments ago you were suggesting the attacking force was closing at 100 kps.

(SA Phil)

Tony said...

SA Phil:

"This goes back to defining the DeltaV of the ships involved and of the mission.

Just 200 comments ago you were suggesting the attacking force was closing at 100 kps. "


I guess I expect people to know exactly the same things I do and come to the same conclusions. Mea culpa. The first wave in an interplanetary attack would be strictly defense suppression. It's job would be to blow through the target planet orbitals at high relative velocity, destroy as many defenses as possible, and go home. Follow-on forces would decelerate and mop up in the orbitals.

And 100kps is not all that fast. Accelerating at .01G, one could achieve that velocity in only 11.5 days, an proceed 50M km. That's quite within the parameters of a fast Mars-Earth or Earth-Mars transit.

Anonymous said...

Tony,

I guess I expect people to know exactly the same things I do and come to the same conclusions. Mea culpa.

-----------

I am going to assume you dont mean this to come off as condecending as it does.

If you have several hundred kps DeltaV and you are closing at 100 kps you aren't doing a strict Hohmann transfer. You are instead coming right at the denfenders.

If you are refering to the second wave slowing down and stopping at the target planet.. great .. so what? .. you defined that scanario on your own from the hip in order to claim the "coming right at them" wasn't ever going to exist.

In order to do lancing you need to come right at the defenders are some speed. Otherwise the deltaV and acceleration requirements of your missiles become unamanageble.

Suddenly Laser-Stars make sense again.

Even if you are coming in the same direction as your target, if you are "closing" All they need to do is turn around and in a relative sense you are coming right at them again.

(SA Phil)

Anonymous said...

RE: Tony and the orbital mechanics point--

I would like to point out that me saying this --

"If you have several hundred kps DeltaV and you are closing at 100 kps you aren't doing a strict Hohmann transfer. You are instead coming right at the denfenders."

Is a is a pretty near quote of something you yourself said a few months ago.

(SA Phil)

Tony said...

SA Phil:

"I am going to assume you dont mean this to come off as condecending as it does."

I said precisely what I meant to say. To put it in other words:

I form mental models which seem to me, from my knowledge and experience, to be perfectly obvious. Of course they aren't. My apologies.

"If you have several hundred kps DeltaV and you are closing at 100 kps you aren't doing a strict Hohmann transfer. You are instead coming right at the denfenders."

In any interplanetary transfer orbit, if you don't decelerate you're coming right at the defenders. In fact, at 100kps you're moving faster than Halley's comet by about 1/3. But you're still following an orbit about the sun, and somebody trying to come up your "tunnel" would have to accelerate into a retrograde solar orbit.

"If you are refering to the second wave slowing down and stopping at the target planet.. great .. so what? .. you defined that scanario on your own from the hip in order to claim the 'coming right at them' wasn't ever going to exist."

Sorry, but that's incorrect. I always had that operational approach in mind. I just assumed, incorrectly, that people would naturally see it as emerging from the orbital mechanics and the tactical situation, without me having to expalin it. But I'll stick to it, because I still think it emerges from the orbital mechanics and proper practice.

"In order to do lancing you need to come right at the defenders are some speed. Otherwise the deltaV and acceleration requirements of your missiles become unamanageble."

Once again, an interplanetary transfer trajectory of any plausible shape comes "right at the defenders" in terms of relative velocity, even if not in terms of orbital crossing angle. The orbital mechanics dictate that.

"Suddenly Laser-Stars make sense again."

No they don't. 100, or 50, or even 25 kps is still 100, or 50, or 25 kps, even if it comes from "behind" you in terms of your orbital motion.

"Even if you are coming in the same direction as your target, if you are 'closing' All they need to do is turn around and in a relative sense you are coming right at them again."

I never said they weren't. I'm just pointing out that taking off in a retrograde orbit to establish opposite closing vectors doesn't make much sense. Even trying to match vectors in the same orbital direction is probably more energy than you have, for the first, defense suppression, wave. That's in fact one of the reasons you mount your attack that way -- the first wave has all of the energy of its interplanetary trajectory and probably has to be engaged by "staic" forces in planetary orbit only.

For follow-on forces, decelerating into orbit, it would be a different story. But one would also presumably have much less to defend with, except for the "intercept" (actually almost trajectory matching, as described earlier) forces previoously deployed out of orbit.

Thucydides said...

The vibration problem is probably the easist to solve; the optical train will be mounted on a series of vibration damping "rafts" similar to the way nuclear submarines mount the rotating machinery to prevent acoustic vibration (sound waves) from exiting the ship.

Assuming bomb pumped x ray lasers work at all (evidently the various tests in the 1980's never came up with a clear answer), jitter from the conventional explosives is really the least of your problems; nuclear reactions take place tens of thousands of times faster than chemical ones, and photons burning down the lasing rod are moving at close to the speed of light (thousands of times faster than the nuclear reaction). The rod has been consumed and the beam is away long before the shockwave (moving at the speed of sound) travels the length of the rod. With all the rods bundled together you have a beam of x rays maybe 2m wide to start and 4m wide at the target.

Current lasers are highly inefficient in converting energy to laser light; FEL's have the promise of converting electrical energy at higher rates of efficiency, plus they have the added bonus of being tunable so you can adjust the wavelength of the beam (in a practical system you would not have a "full spectrum" laser, but probably be able to adjust the output enough to bypass narrow band filters for "scorch" missions.

Long range laser strikes may accept greater divergence in order to hit, or perhaps "rastering" the target area (the bright reflection of IR when the laser hits provides the confirmation that you have hit the target).

Tony said...

Thucydides:

"The vibration problem is probably the easist to solve; the optical train will be mounted on a series of vibration damping 'rafts' similar to the way nuclear submarines mount the rotating machinery to prevent acoustic vibration (sound waves) from exiting the ship."

Sorry, won't work. Submarine machinery mounts do damp out vibration, but only because they distribute the vibrationevenly through the hull, which is eventually transfered to the surrounding sea. (And they only damp down the sound to that of a passing bus, rather than that of a passing train.) That won't happen in space, where all of the vibrational energy will stay in the system.

jollyreaper said...

@Locki

I understand your pain. I'd spent the last decade polishing up my stealth in space concept (everyone blinds everyone!). Fell in love with the idea. Planned a whole sci-fi trilogy around the concept. Then I tested it publically here. Realistically the idea was shot down in about 8 posts.

---

I share your pain. To harsh facts that ruin my fun, I say dinofeathers!

The Into the Void setting is a way of trying to have my WWII in space setting without suspending my disbelief by the neck until dead. It's completely a special case but pretty much the only way I can think of where we can get battles across multiple planets with gnarly big warships and fighters, pew-pew and 'splosions.

I'm going to adapt my Hypersail material to the new blog format later. It's another special case of trying to keep space travel and combat interesting without chucking realism out the airlock.

Tony said...

jollyreaper:

"I'm going to adapt my Hypersail material to the new blog format later. It's another special case of trying to keep space travel and combat interesting without chucking realism out the airlock."

Aside from the fact that it's been sooo done, "Hypersail" absolutely does chuck realism out the airlock.

jollyreaper said...

Everything's been done before. All that remains is making your take on it interesting.

As for chucking realism out the airlock, it's about selective suspension of disbelief. It's certainly not strict, hard SF but it's self-consistent speculative science fiction. You are under no obligation to enjoy it.

Tony said...

jollyreaper:

"Everything's been done before. All that remains is making your take on it interesting."

Or totally avoiding nonsense plot devices as too bad to redeem.

"As for chucking realism out the airlock, it's about selective suspension of disbelief. It's certainly not strict, hard SF but it's self-consistent speculative science fiction. You are under no obligation to enjoy it."

Self-consistency isn't good enough. It has to pass the plausibility smell test. Hyperspace sailing is just too implausible. Even good writing can't redeem it, as David Drake has proven.

Anonymous said...

Tony,

Once again, an interplanetary transfer trajectory of any plausible shape comes "right at the defenders" in terms of relative velocity, even if not in terms of orbital crossing angle. The orbital mechanics dictate that.
--------

So in a relative sense - two trains coming down a (curved) railway tunnel

(SA Phil)

Tony said...

SA Phil:

"So in a relative sense - two trains coming down a (curved) railway tunnel"

On different tracks, moving in the same direction -- yes. But only for forces that are in solar orbits. And the trains have to start in the same place, or one has to be almost all engine and fuel. (In order to move back down the tunnel on its track, then restart in the opposite direction.)

If you're talking about forces on an interplanetary transfer trajectory interfacing with forces in planetary orbit, you're talking about the tunnel passing through a chamber where trains go around on a circular track, passing behind a structural column periodically. The incoming train can either just go through and do what it can while in the planetary chamber, or it can slow down and try to merge onto the planetary chamber track.

Anonymous said...

If you are going to throw realism out the airlock, I figure you may as well and try to go bigger than Trek and Star Wars.

If they have Terrawatt weapons, yours should be 100's of terrawatts

If they have 1000 G's of acceleration you should have 10,000 G's

If they can go 1000 Light Years in a day - you should be able to go 1000 Light Years in an hour.

That way when they do Star Wars vs Star Trek vs Setting X, at least Setting X will have bigger numbers.

===============
That said - you could probably pull off "Demi-hard Demi-opera + FTL+ stealth" and a lot of poeple would buy it as long as it resembled "modern" air/sea stealth.

Remember many Sci Fi fans feel Mass Effect is a Hard Setting and it had Stealth in space, Casual FTL Travel/Communication, Rubber Forhead Aliens, complete suspension of relativity, etc.

(SA Phil)

Anonymous said...

Tony,

On different tracks, moving in the same direction -- yes.

=============
But in a realtive sense Train A moving 100 kps and Train B moving 10 kps in the same direction

Is the same thing as Train A and Train B each moving 45 kps in opposite directions.

(SA Phil)

Tony said...

SA Phil:

"But in a realtive sense Train A moving 100 kps and Train B moving 10 kps in the same direction

Is the same thing as Train A and Train B each moving 45 kps in opposite directions."


Same relative velocity, completely different dynamic environment. The guy going 10 kps is in effect standing still, because he gets that veolcity just by being in orbit about a planet. Or, if he's on the opposite node of his orbit, the combined velocities are 110 kps. Gravity wells are such fun.

Tony said...

SA Phil:

"That said - you could probably pull off 'Demi-hard Demi-opera + FTL+ stealth' and a lot of poeple would buy it as long as it resembled 'modern' air/sea stealth."

Except for the stealth, that's the SF I grew up with. See Heinlein, Dickson, Anderson, Piper, Pournelle, etc. They invoked just enough magitech to move between planets or stars. Past that, they tried to stick with real world physics, biology, wtc.

"Remember many Sci Fi fans feel Mass Effect is a Hard Setting and it had Stealth in space, Casual FTL Travel/Communication, Rubber Forhead Aliens, complete suspension of relativity, etc."

Knowing that doesn't mean one has to take them seriously, or the works that cater to them.

jollyreaper said...


Or totally avoiding nonsense plot devices as too bad to redeem.


In your opinion.

Self-consistency isn't good enough. It has to pass the plausibility smell test. Hyperspace sailing is just too implausible. Even good writing can't redeem it, as David Drake has proven.

In your opinion.

Contrary to what you may believe, you aren't the tastemaker of science fiction.

Your opinions are yours to have and you may treasure them but they're not universal truths.

De gustibus non est disputandum.

Thucydides said...

Gentlemen, you will take ten paces, turn and exercise your suspension of disbelief.

Everyone is entitled to like or dislike what they want, I can go for magitech like the Honour Harrington series because there is enough "truth in advertizing" that I know to leave my suspension of dibeleif at the door. If a self advertized "hard" SF writer pulls out technobabble in chapter/scene 3, then I will take a walk since that is not hard SF as advertized.

So long as the author isn't trying to hoodwink the reader, and the reader knows and accepts what is being offered, then there is nothing to dispute. If Tony or Jollyreaper have different tasts than I do in our reading, then we might have a friendly dispute over "why" author x is/is not a good writer, but it is probably more interesting to see where our interests converge.

Byron said...

Note:
The following was written as I was reading through back posts, so some of it was addressed by others.
Rick.

Locki:
There are a number of technical factors in your blinding scenario which could greatly affect the entire thing.
1. How long does it take a shutter to open?
2. Can the enemy detect the shutter opening?
3. How fast can the enemy train the laser?
4. What is the relative scorch vs burn efficiency?
5. Why does the enemy only mount one laser, anyway?

For example, if the shutter takes a long time to open, and the enemy can train quickly, a countermeasure is to fire a burst at each enemy ship every few seconds (below shutter time) so that as they open, they get killed. If they can see the shutter opening, it's even worse. Given that adaptive optics allow some degree of off-axis firing, and work quickly, a few kilometers of separation will put you well within range of the enemy's laser. It's probably a case of "if you can effectively scorch, they can kill you". Phased arrays (and I've seen numbers for diffraction efficiency between 80 and 95% of a conventional laser) complicate this as they can probably go 20 degrees off-axis, and I'm not sure how vulnerable they'd be to any form of scorch.
Lastly, the optics involved in a conventional mirror only reflect one frequency with high efficiency. Unless you happen to know that frequency ahead of time, you'll see significantly reduced power on the target element (the rest will go as heat into the mirror, but it's designed to deal with similar heat loads from firing). While you will learn what the frequency is when it gets fired at you, your mirrors will already be built. I'm uncertain of the frequency spread possible from dielectric mirrors.

Phil:
I'm skeptical of cigarette-sized projectiles. They wouldn't be that much cheaper then SCODs, and transport costs start to fade at that scale.
But why are SCODs viable? To be honest, they are of a scale with modern missiles. The AIM-9 is only 5 inches in diameter. And the requirements are broadly similar. Shrinking the volume another couple orders of magnitude is likely to lead to more problems then it's worth.
Also, the ability of CNOHs to damage a target is dubious at best. There is going to be some size of projectile that will be armorable against. While later projectiles will go faster, I'd expect improvements in armor (composition and/or thickness) to make it a wash. You did make brief mention of this point, and claimed that they were intended for surface damage. That can be done much more easily with sand or gravel.

The problem with bomb-pumped warheads is that they are likely to be bigger then a conventional kinetic, and have to approach to within a few seconds of the target to be able to hit. Is denying the target the last five seconds of defense really worth that much, given that the thing weighs at least 100 kg, and that buys a lot of SCODs, even ignoring the inherent costs of nukes. The same applies to almost any nuclear-powered weapon. The standoff is not that great, and the cost and reduction in the number of weapons probably outweighs it. Not to mention the people who faint on hearing the word "nuclear".

Byron said...

Locki:
Nobody is going to deploy a weapon that is so fragile that it can't be used. Therefore, if we have laserstars, they are at least moderately durable.
Leading the target isn't the big problem. The issue is acceleration. If you can tell exactly where he is and where he's going, compensating isn't a huge issue. But if he starts to accelerate...
On the other hand, this is another reason why "shoot the gun out of his hand" doesn't work. You can't use the main optics as the telescope when you're actually firing.
On the gripping hand, I have no clue what the field of view on one of these things is. It's entirely possible that a closing target (side velocity quite low) the laser can still see the target.
All of the above assumes light-second ranges. I find maybe half that to be achievable, which reduces the problem significantly.

Tony:
BTW, has anyone considered how big a thermal control system would have to be to reject 500Mw of heat continuously? To put it in contemporary terms, that's the full power output of three Iowa class battleships (rated at 158Mw). Imagine stopping three 57,000 ton battleships, each steaming at 33 knots, dead in their tracks in one second. Obviously it can be done, because we have gigawatt nuclear power plants -- that turn thousands of tons of water into steam every day. Or, to put it another way, according to The Wiki article on cooling towers, a 700Mw coal-fired plant requires a coolant throughput of 100,000 cubic meters (or 100,000 tons, using water) per hour. Try that in a closed loop with just radiators.
You really need to check the math here. An Iowa at 33 knots has a kinetic energy of 7.5 GJ. So at best, it would take it 47 seconds to bring it to a stop using its engines. (This neglects the drag involved, which is considerable.) For more, see this.
And is the 700 Mw output power? Because vaporizing 27.7778 tons of water a second will take 62 GW of power. Even heating it up to just below boiling (75 degrees of temperature rise) will take 10 GW. So the situation is nowhere near as dire as you claim.

Tony said...

jollyreaper:

"In your opinion."

It may come across as crumudgeonly to you, but my opinion is based on deep and broad experience with the SF genre over almost 40 personal years, reading works from 60+ years ago to those published this year. Pile on top of that all of my military, work, and educational experiences. I've got a lot of context upon which to inform my judgments.

So while I'm not insisting that people agree with my opinions, they just aren't tossed off at random, based on nothing. You don't have to keep that in mind, but maybe you should -- it would certainly be refreshing if for once you asked "why" I thought something, rather than assumed I had no good reason...

"De gustibus non est disputandum."

Funny you should bring that topic up. In it I pointed out:

"...laser-like focus on technology and physical science strikes me as unadulterated wank. It misses the point that Romance is about people. Avoiding any obvious howlers in the science and tech are good enough for me."

The problem is that a lot of things that people want to insist on using really are howlers.

Byron said...

Locki:
For those people who love guns I actually think railguns will have a large place in space warfare. Assuming you have a huge reactor they will be the most mass efficient (read cheap) way of putting the maximum hurt on a target. I know if I would choose between the airforce’s ABL or the navy’s railgun.
You mean coilgun, right? Much better efficiency, no need to deal with the giant electrical explosion on the ship?

Samantha:
There is a world of difference between having to shield against a nuclear reactor 50m away and one 5 km away. The intensity of the radiation will drop by a factor of 10,000. Standard space radiation shielding should be sufficient. The exhaust itself might be more of a problem, but in the PMF, ion drives are useless in combat, and chemical exhaust is not that dangerous.

Tony:
I guess I expect people to know exactly the same things I do and come to the same conclusions. Mea culpa.
I've tried to tell you this about your view of debating for at least a year. And I fully intend to quote this to you the next time you do so.

Self-consistency isn't good enough. It has to pass the plausibility smell test. Hyperspace sailing is just too implausible. Even good writing can't redeem it, as David Drake has proven.
That wasn't the problem that I had with those books, which I generally enjoyed. The lack of math on space combat, on the other hand...

It may come across as crumudgeonly to you, but my opinion is based on deep and broad experience with the SF genre over almost 40 personal years, reading works from 60+ years ago to those published this year. Pile on top of that all of my military, work, and educational experiences. I've got a lot of context upon which to inform my judgments.
The problem is that you assume that your opinion is superior to those of everyone else around you. I don't mean that you have to view all opinions as equally right, as that is obviously silly. I mean that you view your opinions as being inherently superior. An example (though justified) would be me arguing with someone who believed in the four classical elements. I would consider my view (there are 92 naturally occurring ones and so on) as inherently better, and virtually ignore everything he has to say. You often (not all the time, and I applaud your concession on the drone issue) argue the same way, but on a subject that is inherently far more subjective.
I'm not trying to be mean, but this is really how your usual view of the debate strikes me.

Thucydides:
The speed of sound in the various components of the bomb is much higher then it is in air. It is entirely possible that shockwaves from the bomb could reach the rods well before the bomb detonates.
In the Honorverse books, I believe the lasing rods are explicitly described as being ejected from the missile and independently targeted to avoid this sort of problem. Of course, some form of grav lens is used to focus the blast, so that may not work today.

Tony said...

Byron:

"You really need to check the math here. An Iowa at 33 knots has a kinetic energy of 7.5 GJ. So at best, it would take it 47 seconds to bring it to a stop using its engines. (This neglects the drag involved, which is considerable.) For more, see this."

It was a "feel for the scale" type of comparison. The point is that it takes the power plants of three Iowa class battleships to generate close to 500 Mw, and that this power could drive them at 33 knots. That's the kind of constant energy output that has to be managed in a system that has to radiate 500 Mw of power every second.

"And is the 700 Mw output power? Because vaporizing 27.7778 tons of water a second will take 62 GW of power. Even heating it up to just below boiling (75 degrees of temperature rise) will take 10 GW. So the situation is nowhere near as dire as you claim."

Output power.

And I said "coolant throughput", not "coolant vaporized". For a fossil fuel steam plant, this would obviously be coolant through steam condensers. (For a nuclear plant, pretty much the same.) The point is that it takes a lot of coolant flow to keep things down to a safe operating temperature when you're talking megawatts of power.

If you want to translate things into the environment of Rick's particular example, fossil fuel power plants are generally stated to be about 33% thermally efficient. So, presumably, that 700 Mw output comes from a total of 2,100 Mw of generated heat. Therefore, the coolant throughput (totally ignoring how much heat goes out the stack, BTW) for a 500 Mw cooling requirement, would be something like 25,000 tons/hr. Okay...that's a hair off 7 tons/sec of coolant through steam condensers. How many hundreds of tons of coolant do you actually need to be running constantly through your radiators to keep this up indefinitely? And just how much vibrational energy is that going to create, not to mention the vibrational energy of even the most efficient coolant pumps?

BTW, the "thousands of tons of water into steam" comment comes from the fraction of the water that is boiled off (some is evaporated off too) in cooling tower operations. From the same Wiki article, the 700 Mw coal plant needs 3,600 tons an hour of makeup water. And I think we've all seen the large clouse of steam that come out of nuclear plant cooling towers.

Eth said...

Everyone is entitled to like or dislike what they want, I can go for magitech like the Honour Harrington series because there is enough "truth in advertizing" that I know to leave my suspension of dibeleif at the door. If a self advertized "hard" SF writer pulls out technobabble in chapter/scene 3, then I will take a walk since that is not hard SF as advertized.

So long as the author isn't trying to hoodwink the reader, and the reader knows and accepts what is being offered, then there is nothing to dispute. If Tony or Jollyreaper have different tasts than I do in our reading, then we might have a friendly dispute over "why" author x is/is not a good writer, but it is probably more interesting to see where our interests converge.


Thucydides hit the nail on the head here. The important thing is that the 'contract' passed between the author and the spectator/reader at the beginning of the work is respected.
Which includes, of course, how the work is advertised.

It can be trickier than one think, though.
First, it works both way. Star Wars is about magic, swordfight and WWII in space. Try to suddenly put 'real' SF there, and it may break.
Also, you may give the wrong message by mistake, for example by trying to be too realistic on some points despite having plot holes in others. For example, the film Avatar is trying very hard to have astronomy, biology and space engineering right despite having rubber forehead aliens with neural USB plugs right next door.

And that's where internal consistency is important. Here, it is about being consistent with the promise you made at the beginning of the work.
I promised laser blades and space Immelmann turns in space? I won't suddenly put RKVs on play.
I promised PMF pure diamond-hard SF? I won't put magical powers and causal interplanetary travel in it.

JR promises 'following reality unless noted' + the Rifts + tech limit slightly above today? He suddenly won't put StarTrek-like warp drives on his fighters (you won't do that, would you?)

Of course, a work can respect it and still be bad, and one is free to like or disline works or entire genra based on taste.
Tony points out one particular trap, which is the 'techno-wank'. Due to the efforts to do hard enough SF, it's easy to forget that you are telling a story, not writing a brochure about the Future.

(Though I'm not sure if Honor Harrignton is a good example here. Apart from the fact that I had a slight personal dislike for the heroin and that the antagonists' story is far more interesting yet under-narrated, there are some problems of internal consistency.
One example amongst others, their missiles have limited range because after they burn all their fuel, they go ballistic and are easily intercepted. The immediate question is, then why not put several stages on them? Surprisingly, it's just that they didn't think about it in 200 years of warfare, as someone finally do it later and triple their effective range.
But those inconsistencies are not that glaring, and while I personally found the series to be the very disappointing use of good and sometimes brilliant ideas, there is nothing wrong to like it for its qualities, if its defaults don't bother you too much.)

Sean said...

Tony said..."Even good writing can't redeem it, as David Drake has proven."

I've never believed that I would see the name David Drake invoked in a sentence containing the phrase 'good writing'.

jollyreaper said...

@thuc

What you said is right -- I can enjoy comfort food and high cuisine and if I don't like Vietnamese food I don't have to eat it. If I like it and the restaurant can't make a good bowl of pho, I can tell them. Someone who doesn't even like the food telling them it's not to their taste isn't really useful feedback.

Regardless of the details of genre, plot and characterization remains pretty universal. You have to get that right otherwise I don't care if your bounty hunter is riding a horse, driving a car or flying a spaceship, it's not going to be a good read.

Personally, that's why I stopped reading Honor. It was bad writing even for glorious space opera. Had a decent enough start though.

Byron said...

It was a "feel for the scale" type of comparison. The point is that it takes the power plants of three Iowa class battleships to generate close to 500 Mw, and that this power could drive them at 33 knots. That's the kind of constant energy output that has to be managed in a system that has to radiate 500 Mw of power every second.
Really? Direct quote, from you: Imagine stopping three 57,000 ton battleships, each steaming at 33 knots, dead in their tracks in one second.
This implied that the magnitude involved was similar to that of the kinetic energy from those battleships. Which it wasn't. Also, what kind of power? Boiler power? Shaft horsepower? Because this is a far cry from shaft horsepower.

And I said "coolant throughput", not "coolant vaporized". For a fossil fuel steam plant, this would obviously be coolant through steam condensers. (For a nuclear plant, pretty much the same.) The point is that it takes a lot of coolant flow to keep things down to a safe operating temperature when you're talking megawatts of power.
You countered an example about 500 MW total power with an example involving 700 MW output power. I was trying to avoid saying this, but you're treading very close to being intentionally deceptive. The numbers on how much radiator area would be required exist. It's large, but not impossibly so.

And can we please skip the so far inevitable debate over realism in sci-fi? It's happened in just about every long thread, and no progress has ever been made.

Eth:
One example amongst others, their missiles have limited range because after they burn all their fuel, they go ballistic and are easily intercepted. The immediate question is, then why not put several stages on them? Surprisingly, it's just that they didn't think about it in 200 years of warfare, as someone finally do it later and triple their effective range.
They finally developed the technology to miniaturize fusion drives to fit on missiles. Your question is like criticizing reality for not creating HMS Dreadnought ten years earlier.

Jollyreaper:
Personally, that's why I stopped reading Honor. It was bad writing even for glorious space opera. Had a decent enough start though.
Where did you stop? I've found the latest books to be hit and miss. At All Costs and A Rising Thunder were really good, but Ashes of Victory, War of Honor, and Mission of Honor were not great.

Tony said...

Byron:

"I'm not trying to be mean, but this is really how your usual view of the debate strikes me."

Actually, I think it's perfectly valid to think that. I don't think it's mean at all.

I also think that my opinions are not spur-of-the-moment, that they're based on sound knowledge, and that sometimes things just aren't as subjective as others would like to think. IOW, I'm not hostile, I'm just dogged.

jollyreaper said...

@eth

No warp drives on the fighters. :) The tech plateau is baked into the setting to explain why roughly similar tech is in use for hundreds of years. Civilizations more advanced than th plateau end up dead and they can't explain why. There's a reason for this and it's one of the key mysteries of the setting.

Byron said...

Tony:

Actually, I think it's perfectly valid to think that. I don't think it's mean at all.

I also think that my opinions are not spur-of-the-moment, that they're based on sound knowledge, and that sometimes things just aren't as subjective as others would like to think. IOW, I'm not hostile, I'm just dogged.

If you accept my statement as correct, it's either unmitigated arrogance, or you didn't understand what I said.
Your opinion is not inherently more objective then mine is. I would say the same thing about my opinion as you would about yours. And I would also credit you with the same level of objectivity. You refuse to do the same to anyone who disagrees with you.
You might find that perfectly reasonable, but it strikes me as incredibly arrogant.
And I do know you don't do it all the time. But it happens often enough to make debating you no fun. I'm not sure what the fact that I keep doing it says about me.

jollyreaper said...

The last Honor book I read was the one where the French Revolution happened offstage and Monsieur Himmler came to power. An entire doorstop of padding and the biggest ever gets closed over?! I don't think so.

Eth said...

Byron:
The problem with bomb-pumped warheads is that they are likely to be bigger then a conventional kinetic, and have to approach to within a few seconds of the target to be able to hit. Is denying the target the last five seconds of defense really worth that much, given that the thing weighs at least 100 kg, and that buys a lot of SCODs, even ignoring the inherent costs of nukes. The same applies to almost any nuclear-powered weapon. The standoff is not that great, and the cost and reduction in the number of weapons probably outweighs it.

I would hide them in the (sub-)missile buses. Some of the buses would contain one warhead and its shielding, others some SCoD. If possible, I'd release the SCoD of a targeted bus before it is destroyed.
Again, for it to be interesting depends on the mass, speed and power of the varied elements, but I can see it work in some cases. For example, if you have 5000km range for a bomb-pumped laser, you gain 50s even at 100kps, which is not negligible.
And even if you have 1% of effectiveness, even a 1kt warhead gives you a 40 000 MJ laser...

Not to mention the people who faint on hearing the word "nuclear".

That's a good point.
Maybe explaining to them that there is no uranium in your pure fusion bombs and thus no fallout (and let aside that even fusion produce some hard radiations and radioactive material) may help. People see fusion energy as 'clean', after all.
On the other hand, pure fusion bombs would probably be triggered by micrograms of antimatter, and people may go 'OMG planet-busting antimatter!!' at this mention.
(And yes, military would use it despite being inherently unstable : we already build traps stable for months, albeit with tiny payload and quite unwieldy, and there may be possibilities for passive traps as well. But go explaining that to people.)

About shockwave disrupting the aim : even if the speed of sound is immensely accelerated in the superheated plasma of the explosion, it is still vastly inferior to the speed of light, and photons should still outrun it.

(Also, Vorkosigan saga is a better example than Honor Harrignton, IMHO. It does have plasma weapons, but it's a fine example of SF good enough to make you forget its softness. And it's also free to read like HH.)

Tony said...

Byron:

"This implied that the magnitude involved was similar to that of the kinetic energy from those battleships. Which it wasn't. Also, what kind of power? Boiler power? Shaft horsepower? Because this is a far cry from shaft horsepower."

Shaft horsepower. Straight from the Wiki:

212,000 shp = 158,000 kw = 158 Mw

Not the kinetic energy, B. The constant power output. IOW, how mcuh power would it take to resist three such ships steaming at full speed.

You know, you're right, I described it wrong. It's not stopping the ships that's the issue, it's resisting their forward motion that I'm trying to invoke. Still, given that correction, it still illustrates the scale of the problem.

"You countered an example about 500 MW total power with an example involving 700 MW output power. I was trying to avoid saying this, but you're treading very close to being intentionally deceptive."

You know -- and feel free to turn my own words on me now if you want to -- but I really didn't think I needed to explain how the cooling system in a fossil fuel power plant worked.

As for the rest, absolutely no deception was intended. Once again, I was giveing an example of problem scale, not trying to make a specific comparison. Do I really have to pedantically go through the thermal efficiencies of fossil fuel power plants and do simple multiplication and division?

How about from now on, let's just assume that I'm either not being clear or I'm skipping steps that I think others can take for themselves.

"The numbers on how much radiator area would be required exist. It's large, but not impossibly so."

Certainly it's doable. I just don't think people are thinking through the implementation issues.

"And can we please skip the so far inevitable debate over realism in sci-fi? It's happened in just about every long thread, and no progress has ever been made."

Sure. Especially as my side in the debate is do whatever you want but avoid nonsense. I have some strong opinions about what "nonsense" consists of, but otherwise I'm about as liberal as they come.

Tony said...

Byron:

"If you accept my statement as correct, it's either unmitigated arrogance, or you didn't understand what I said."

Neither. I understand what you are saying. And I'll be the first to tell you that I'm not the smartest person I know. But I'm not the dumbest either. And I'm from a long line of Missourians on my mother's side. You've gotta show me, not just tell me.

Byron said...

Eth:
I would hide them in the (sub-)missile buses. Some of the buses would contain one warhead and its shielding, others some SCoD. If possible, I'd release the SCoD of a targeted bus before it is destroyed.
The point is that it would be easy to tell which held SCODs and which didn't, unless the SCODs were held back until the bus was disabled. And that would raise the very real possibility the bus would be disabled without releasing them.

Again, for it to be interesting depends on the mass, speed and power of the varied elements, but I can see it work in some cases. For example, if you have 5000km range for a bomb-pumped laser, you gain 50s even at 100kps, which is not negligible.
And even if you have 1% of effectiveness, even a 1kt warhead gives you a 40 000 MJ laser...

Somewhat. However, if you have 100 km/s capability, I'd imagine that 5000 km is fairly close range. Also, nukes are a lot more expensive then kinetics, and at that tech level, throwing a bunch of stuff isn't terribly difficult.

About shockwave disrupting the aim : even if the speed of sound is immensely accelerated in the superheated plasma of the explosion, it is still vastly inferior to the speed of light, and photons should still outrun it.
This assumes they happen at the same time. The chemical explosives will go off before the nuclear reaction starts. The best source I can lay hold of right now (Stuart Slade's The Big One) says 20 microseconds. A basic search suggests that in steel, the distance covered will be 12 cm or so. This is an incredibly simplistic analysis. I'm not sure if a shockwave will form in the structure of the bomb, which would move faster then the speed of sound, and at long ranges, the pointing accuracy requirements would be quite large.

Byron said...

Tony:
Not the kinetic energy, B. The constant power output. IOW, how mcuh power would it take to resist three such ships steaming at full speed.
Again, directly from you: To put it in contemporary terms, that's the full power output of three Iowa class battleships (rated at 158Mw). Imagine stopping three 57,000 ton battleships, each steaming at 33 knots, dead in their tracks in one second. The implication there was that the amount of power we are talking about is the kinetic energy of those three battleships. Not the amount of power that it takes to keep them at 33 knots. And given that the number is shaft HP, the actual power output of the boilers is significantly higher.

You know -- and feel free to turn my own words on me now if you want to -- but I really didn't think I needed to explain how the cooling system in a fossil fuel power plant worked.

As for the rest, absolutely no deception was intended. Once again, I was giveing an example of problem scale, not trying to make a specific comparison. Do I really have to pedantically go through the thermal efficiencies of fossil fuel power plants and do simple multiplication and division?

How about from now on, let's just assume that I'm either not being clear or I'm skipping steps that I think others can take for themselves.

My problem is that you, who have a vested interest in making cooling seem difficult, (and don't try to deny it, that is where this started) are using poor analogies that give a grossly misleading "feel" for where the numbers are. The 700 MW power plant you describe has a total power output that is at least four times that of the reactor that Rick described. By the same numbers, it's only 125 MW.
I'm trying very hard not to accuse you of being intentionally dishonest, but posts like this make it difficult. The objective is to figure out what the magnitude of the problem is by the use of relevant examples. The question is how large a heat rejection system would have to be. Sadly, I'm not at school right now, so I don't have access to the library. However, looking at actual space-based reactors would seem to be the way to go. Which is what I'm doing now.

Neither. I understand what you are saying. And I'll be the first to tell you that I'm not the smartest person I know. But I'm not the dumbest either. And I'm from a long line of Missourians on my mother's side. You've gotta show me, not just tell me.
Funny, I grew up there, and I go to school there. And you generally show using poor analogies. See above.

Eth said...

Byron:
They finally developed the technology to miniaturize fusion drives to fit on missiles. Your question is like criticizing reality for not creating HMS Dreadnought ten years earlier.

In centuries of warfare, they only did manage multistage missiles now? This strikes me as odd.
Another example (this one did made me cringe) is when they discuss about new weapons, and they evoke spinal-mounted dreadnought RBoD. Which is rejected because it would make them vulnerable (they have impenetrable barriers above and below their ships, and 'side-wall' force fields on each side, but nothing in front and rear.)
But you have front-walls already (instead of side-walls) for your fighters, you idiot!
(Also, how did they manage to make fission powerplants lasting 17 years to replace fusion powerplants lasting 3 weeks for said fighters? They fission uranium to pure energy?)

That said, those were relatively minor points for me. The main problem I had was with the story.
Basically, I find that the heroin is a textbook Mary Sue. And the story of Manticore is not that compelling. Ok, so they are attacked by bad guys who are more numerous, but less well armed and quite disorganised. Ok, so you have your own utterly corrupt politicians here and there.
What do extraordinary people in extraordinary situations? Sometimes it works, sometimes it doesnt. But nothing outstanding on average.

On the other hand, Haven's story completely caught me. You have this (surprisingly believable) dystopian space-France, caught in a spiral of increasing conquests to delay the inevitable self-destruction of the system, where billions of people will die in the resulting nuclear-powered anarchy.
Then, you have a guy brilliant, ambitious, hate-fuelled and really trying to save what can be (while knowing that it's probably futile) who manage to do the impossible and decapitate the government, taking power.
And then, things go downhill. They are caught in a war of anihilation against an opponent they can't beat. They can't surrender because it's the only thing preventing the population to revolt with nukes. That and a bloody reign of terror. Even if he is horrified by what he created, he has no choice but continue.
On the front, things are not better : the army was decapitated as well, letting general staff without experience commanding poorly trained and poorly equipped fleets whose political officers are as deadly as the enemy. All that to defend a monstrous regime killing millions of people, which is the only thing preventing a far worse chaos to be unleashed on their homeworlds. And they can't win.
What do extraordinary people in a desperate situation? Now that's for a good story.

Which is funny, because despite a clear attempt to make it look like the revolutionary France, the author got many things completely wrong. (For example, the historical Robespierre was a well-intentioned extremist, and the almost exact opposite of the magnificent bastard he is in the book. Saint-Just in the book is indeed closer to Himmler than the historical Saint-Just.) But hey, no-one forced him to repeat history in the first place.

And yet, all this far more interesting story makes it for a tenth of the book.
What made Jollyreaper quit, IIRC, apparently, was that Pierre is killed of screen. Which was indeed unforgivable.
What made me quit was that after the under-narrated but brilliant way the war finally ends without the anihilation of Haven, Theisman manages to pull a military coup d'état in 2 pages, and where he realises the extraordinary feat of ending the reign of terror, stabilizing the population, convincing it to not riot and bring back a legitimate democratic government in six friggin' months, it happens off-screen between two books!
The author ended the story I was by far the most interested in off-screen. That's when I stopped reading. Though I couldn't tell you the title of the offending book.

Rick said...

Never mind arguing about the details of laserstars. If I have commenters talking about the enormous constraints that demi-realistic technology imposes on spacecraft movements, my work here is done.

I could make some quibbles. It wasn't clear whether 'retrograde' was suppose to be about solar orbits or planetary orbits - apparently the former. If you are coming from deep space, choosing a retrograde orbit of a planet is easy. Just make your approach pass on the other side of it.


No major offensive in modern warfare has been launched on a tactical time scale ... Regardless of the planning lead time and the expense -- in terms of both resources and opportunity costs -- it's just a cost of doing business.

Absolutely no disagreement. But while I may have used informal expressions like 'take on all comers,' I have never conceived of laserstars as an invincible superweapon.

I see a laserstar as essentially a 'defensive' weapon for controlling some region of local space. (This can be defending a planet or blockading one.) If you must launch a 'major offensive' to dislodge me, then I own that region of space until and unless you actually do so, and win.

In the meanwhile it can brush off weaker attacks without expending costly munitions. And arguably exercise coercion in a more selective way, burning targets rather than smashing them.


On the laser pro and con points, note that I am mainly thinking of ranges well under a light second.

And I am not really a laser fan. I merely grew uncomfortable with assuming that lasers would be crippled by the devils in the details, not just constrained by them. Plus electric drives being a natural fit for lasers (plenty of power and waste-heat dumping capacity).


But as this discussion is starting to bring out, delta v constraints have a bigger impact than the purple-green stuff. Amateurs study tactics, professionals study logistics, and all that.

Eth said...

Byron:
The point is that it would be easy to tell which held SCODs and which didn't, unless the SCODs were held back until the bus was disabled. And that would raise the very real possibility the bus would be disabled without releasing them.
That's what I would do, releasing them at the last moment. The first role of the SCoD buses would be to act as decoys, the SCoD would be there because just sending lump of metal wouldn't cost much less, and SCoD add some bonus chances to do damage.

Somewhat. However, if you have 100 km/s capability, I'd imagine that 5000 km is fairly close range. Also, nukes are a lot more expensive then kinetics, and at that tech level, throwing a bunch of stuff isn't terribly difficult.
At this tech level, I imagine nukes to not be terribly difficult either.
Inversely, I imagine 100 km/s to be an impressive speed. I'd expect far less, meaning that those 50s could be 5 min or longer. Meaning that the nuke may be more expensive, but gives a far greater advantage.
And, again, the price of the nuke may or may not be minor compared to the price of getting mass up there.

This assumes they happen at the same time. The chemical explosives will go off before the nuclear reaction starts. The best source I can lay hold of right now (Stuart Slade's The Big One) says 20 microseconds. A basic search suggests that in steel, the distance covered will be 12 cm or so. This is an incredibly simplistic analysis. I'm not sure if a shockwave will form in the structure of the bomb, which would move faster then the speed of sound, and at long ranges, the pointing accuracy requirements would be quite large.

This assumes fission-fusion bombs, which I read somewhere would be very bad at producing bomb-pumped lasers. Which may be precisely for this reason, for what I know.
I assume pure fusion bombs, maybe antimatter-triggered bombs, since we may see the first of those in the next decades. Those don't require conventional explosives. They just require that the trap to stop working. Which is easy if it is a powered trap.
Fusion bombs also give the advantage of smaller bombs, as you don't need a fissile critical mass. So if you need only 1000 Mj lasers to destroy your target, build 0.025 kt (eq.tnt) bombs.

Again, not saying that bomb-pumped lasers will be the main weapon used. Only that they may one of the weapons used, and possibly the main one.
And they could also be used as orbital mines along many dumb debris, if you have some years to prepare your defences. Any hostile fleet arriving would have to stay clear of or destroy any debris big enough to be a bomb passing in the X km (the exact X may even be unknown to the attackers). This could seriously fortify a planet, depending on the factors.

jollyreaper said...

Wow. That's dreadful. Glad I stopped reading it.

When I find a story I like and the author has gotten his characters into a fix, I'll sometimes stop and try to figure out how I'd resolve the conflict. I'm rarely satisfied with my own answers and also rarely satisfied with theirs. The times in blown away not just by how well it's done but how right it feels, that's when I want to raise a libation in salute.

I think that only rarely does an off-screen action work well. Most of the time it's just a bloody cheat.

Byron said...

Eth:
I'm not going to debate the plot with you. I enjoyed it. You didn't. Actually, that one was probably the worst of the series.

What made Jollyreaper quit, IIRC, apparently, was that Pierre is killed of screen. Which was indeed unforgivable.
Actually, it was written and appeared in one of the anthologies. I think they cut it for length.

Tony:
The best source I could find on space cooling systems was on atomic rockets. The author suggests that heat pipe systems would require virtually no moving parts and would be quite light. While this is obviously not a 500 MW system, it's a better start then you gave. Apparently, the heat pump and such are generally included in the mass per unit area numbers that occasionally get thrown around. If you'd like to do more research, and need a paper that you can't get to, I'd be happy to get it for you. (This applies to everyone here, within reason).

Anonymous said...

Tony,

And just how much vibrational energy is that going to create, not to mention the vibrational energy of even the most efficient coolant pumps?

----------------

Sounds like on any spacecraft with those kind of cooling loads - it is going to want to use something other than a 20th century conventional electric water pump.

Bit like that Dyson fan spiel complaining about air buffeting with conventional fans.

There are more ways than one to skin even a 700 MW cat.

(SA Phil)

Anonymous said...

heh - sounds like Byron has already suggested the idea already is out there.

(SA Phil)

Anonymous said...

Byron,

. Of course, some form of grav lens is used to focus the blast, so that may not work today.

----------

Or ever -gravity may never turn out to be what the string theorists and others want it to be.

Not that bomb pumped lasers are impossible - they probably are feasible to some extent.

grav lenses though .. heh

(SA Phil)

Tony said...

Byron:

"Again, directly from you: The implication there was that the amount of power we are talking about is the kinetic energy of those three battleships."

Did you miss the part where I said:

"You know, you're right, I described it wrong. It's not stopping the ships that's the issue, it's resisting their forward motion that I'm trying to invoke. Still, given that correction, it still illustrates the scale of the problem."

???

To play in your ballpark for a moment, I wouldn't want to accuse you of being disingenuous...

"And given that the number is shaft HP, the actual power output of the boilers is significantly higher."

Okay. Two battleships. Still a lot of energy do radiate away.

"My problem is that you, who have a vested interest in making cooling seem difficult, (and don't try to deny it, that is where this started) are using poor analogies that give a grossly misleading 'feel' for where the numbers are. The 700 MW power plant you describe has a total power output that is at least four times that of the reactor that Rick described. By the same numbers, it's only 125 MW.
I'm trying very hard not to accuse you of being intentionally dishonest, but posts like this make it difficult. The objective is to figure out what the magnitude of the problem is by the use of relevant examples. The question is how large a heat rejection system would have to be. Sadly, I'm not at school right now, so I don't have access to the library. However, looking at actual space-based reactors would seem to be the way to go. Which is what I'm doing now."


I know this is going to frustrate you, but it's 100% the absolute truth. I seriously considered going through all of the numbers to show that a 700 Mw output fossil fuel plant had the cooling requiremnts for 2,100 Mw of thermal energy. Then I would have pointed out that we're talking about only 500 Mw total cooling for our theoretical laserstar, which means that you only need to run 25,000 gallons of coolant through the condensers per hour, or just about 7 tons per second. I thought about going through all of that, but you know what? I didn't want to be accused of being pedantic or arrogant for telling people stuff they could figure out for themselves.

Now, where do you think I got the impression that that might happen? Food for thought.

"Funny, I grew up there, and I go to school there. And you generally show using poor analogies. See above."

I do use poorly thought out analogies from time to time. I'm also stuck at times figuring out what is and isn't too much detail.

If you ask me, I'll tell you a little anecdote that will illustrate how the Missouri in my background affects my attitude about discourse. You don't have to ask. I'm not expecting you to ask. I won't force it on you if you don't want to hear it.

Anonymous said...

RE: Honor Harrington and "Bad Writing"

I am always amazed at how people will site bad writing as if there is some sort of objective scale.

Weber writes in a particular way - I personally don't really like the style - but is it "bad"?

His grammar seems reasonable. His dialog isn't horrible. Sentence structure seems ok. The vocabulary isn't hard to follow .. etc, etc.

Jollyreaper points out some plot points as to why it is bad - and that particular criticism of the coup is a reasonable complaint - but you see far worse plot turns in many TV shows, movies, etc on a daily basis.

Weber basically took the Horatio Hornblower in Spaaace Opera! trope and ran with it to the hilt.

On that end he was pretty successful.

(SA Phil)

Locki said...

I actually enjoyed the discussion on the morality of remote-drone combat more so I'll take a quick break from my armored shutters and trig tables.

Samantha said...

My vote isn't on battleships at all but instead on interplanetary powers duking it out with successive rounds of espionage and counterespionage. If you really want to paste something probably the most cost effective way to do it in the world of rocketry would be to take a freighter and pack a really big bomb into it. Send it towards its target and when it gets close or docks make it explode.
Perhaps your spies can help arrange to have it pass security checkpoints?


=======

I think Samantha has hit the nail on the head with this. Given even semi-realistic future tech with accelerations of 0.001G, Transit times of year, no stealth, limited Delta-V *YAWN* errrr and the need to radiate away waste heat the most interesting stories, the most human stories are going to be the ones told back on earth. The events that triggered you to send these trillion dollar robotic weapons of doom in the first place. Most of the “human” combat would be in the human espionage, politics and I guess computer hacking. Writing about the starships would be like writing about the sex life of a cruise missile. The interesting story is about what triggered Captain Ahab to fire the cruise missile at the warp-whale in the first place. But since the title of this blog is rocketpunk and not cyber-punk I guess we are left to quibbly over delta-Vs, radiators, power efficiencies ……

Its part of the reason I'm trying so hard for stealth in space and so anti-Laserstar. I just can't imagine an interesting space combat story talking about Giant Death Rays of Doom, shooting over a featureless desert, and able to zap you months before you reach engagement range Its just so boring.

SA Phil said …

Remember many Sci Fi fans feel Mass Effect is a Hard Setting and it had Stealth in space, Casual FTL Travel/Communication, Rubber Forhead Aliens, complete suspension of relativity, etc.

=====

Mass Effect is the best damn thing that has happened to SF in any media form, movie/comic/novel/computer game/whatever in the last 20 years. Its almost as entertainging as rocketpunk-manifesto.com. But its unashamedly space opera rather than hard SF. It has FTL, psychic powers, dark energy and yes a stealth ship. But they didn’t cross the line into great honking Laserstars.

The genius of the Mass Effect universe is they set out to create a space opera universe informed by more modern concerns of science rather than looking backwards and being informed by the genres of yesteryear. Whereas Starwars is basically just a western/samarai adventure in space the whole Mass Effect Storyline incorporates much more modern ideas into its universe.

At the core the Mass Effect story is an answer to the Fermi Paradox. The solution involves the implications of an AI singularity explosion. The alien races are mostly humanoid with bumpy foreheads but at least they are physiologically vastly different rather than just being a largish human with a perpetual bad hair day (Klingon). These physiological differences (fast metabolism, quick thinking, short life span) believably inform the culture of the race.

Mass Effect is brilliant space opera stuff and the jolt of fresh air the mass market SF genre has needed since Neuromancer hit the scene.

To ward of the inevitable criticism its not an original idea but it’s the first one to make these more modern SF ideas so accessible to the non-hardcore public (kind like the Matrix vs Neuromancer).

Speaking of Laserstars. I’ve always assumed they were space opera anyway. And considering the difficulties in heat management in space they probably only work with magitech heat sinks or radiators. Which gives me … drum roll … stealth in space!

Anonymous said...

I am still going to agree with Tony the cooling demands of these big Nuke Electric and Laser-Star space craft would be monstrous engineering problems.

And clamping down on the vibrations would be really difficult.

What would happen is they would get a rally good design on paper - something far quieter than a conventional pump.

Then they would build some small mockups and eventually get them to work.

Then they would build the full sized system and spend *years* tracing down inconsistencies between the design and the actual implementation.

Not that it would be impossible to make a vastly improved system from "worst case" but it would be a heck of a project.

Of course the Managers of the project would completely underestimate the complexities, cost and time, like they always do.

(SA Phil)

Anonymous said...

Locki,

Mass Effect is the best damn thing that has happened to SF in any media form, movie/comic/novel/computer game/whatever in the last 20 years. Its almost as entertainging as rocketpunk-manifesto.com. But its unashamedly space opera rather than hard SF. It has FTL, psychic powers, dark energy and yes a stealth ship. But they didn’t cross the line into great honking Laserstars.

=================

sure they did ... they used relativity(mass) alteration to enable relativistic coil guns.

same difference.

(SA Phil)

Byron said...

Tony:
To play in your ballpark for a moment, I wouldn't want to accuse you of being disingenuous...
Sorry, I did miss that part. My apologies.

I know this is going to frustrate you, but it's 100% the absolute truth. I seriously considered going through all of the numbers to show that a 700 Mw output fossil fuel plant had the cooling requiremnts for 2,100 Mw of thermal energy. Then I would have pointed out that we're talking about only 500 Mw total cooling for our theoretical laserstar, which means that you only need to run 25,000 gallons of coolant through the condensers per hour, or just about 7 tons per second. I thought about going through all of that, but you know what? I didn't want to be accused of being pedantic or arrogant for telling people stuff they could figure out for themselves.
OK. Then explain why it was relevant. Just because a power plant (which can be considered to have unlimited amounts of water available for these purposes) requires that much doesn't mean that a spacecraft would need that much. Implying that it would is like using that same power plant to get specific power numbers. Both are obviously red herrings.

Now, where do you think I got the impression that that might happen? Food for thought.
No, I would criticize you for the same reasons I did. It's a really bad analogy.

Anonymous said...

RE: Mass effect "Laser-Stars"


Actually I should elaborate - the setting's battleships are 1km coil-guns that use mass effect fields to lighten 20kg projectiles to mass almost nothing (temporarily) and then shoot them at ~3% C IIRC. The accelerated mass somewhere in transit regains its mass and slams into the target with kiloton force.

The entire ship is built around the gun. In Mass effect 3 you even have a fire fight inside of one.

But it gets worse(tm); they do the molten ferros thing ... the collectors and the reapers can accelerate molten steel somehow so becomes a giant death ray.

Now they don't fight at light second ranges - because everyone nicely does the "Space is a World War 2 dogfight" trope and fights at hundreds of meters.

Its fun, the setting is cool, too bad they ruined it forever. But still - amazingly in the Star Wars/Trek influenced world of Sci Fi fans that stuff passes for Hard SF.

So does Honoverse btw.

(SA Phil)

jollyreaper said...

The funny thing about writing is that sometimes it's good for a genre without broader appeal and sometimes it's bad even for the genre. Sometimes it's an acquired taste and sometimes there's just really no way to justify it.

Some writing is technically proficient but promoting terrible ideas. Sometimes the terrible ideas are paired with terrible writing and yet it's still a success.

I think most people on this blog might agree the new Star Wars trilogy is terrible but more than a few would have no love for the original, either.

Sometimes a story is dire and full of gloom and important stuff. Sometimes it's lightness and fun. Is the writer doing what he set out to accomplish?

I'm sure there are people who enjoyed Battlefield Earth, both the book and the movie. There are people on this blog who liked the way Battlestar Galactica turned out.

What I look for in a story is something that feels real. Even if the writer or writers are making or up as they go, don't let me see the seams. I want characters defined, motivations established, and the consequences playing out. Things that come out of left field should make sense when you get your brain wrapped around it.

My problem with Honor is she did become a Mary Sue and the whole thing took on the feel of being phoned in for the money. I felt the same thing with Dune starting at book 4. Some people thought that one was the best. Go figure.

Fittingly enough, we've got a kind of purple/green argument when it comes to writing. Few can agree on what's good and what's bad!

Anonymous said...

Jollyreaper


My problem with Honor is she did become a Mary Sue and the whole thing took on the feel of being phoned in for the money. I felt the same thing with Dune starting at book 4. Some people thought that one was the best. Go figure.

================

Might be an inherent problem with Space Opera - you have an idea for some "special ability" and then you add it to the main character .. then things quickly spiral out of hand.

Kirk was the youngest, best Captain of his Era.

Spock was the only human vulcan hybrid.

Scotty wrote the book on Engineering.

Anakin cant just be a Jedi who went bad, he has to be "the most powerful ever"

Bobba Fett can't just be a bounty hunter he has to be the clone of the greatest bounty hunter ever.

And so on.

(SA Phil)

Sean said...

Locki said..."Mass Effect is the best damn thing that has happened to SF in any media form, movie/comic/novel/computer game/whatever in the last 20 years."

Agreeing with you is the all more painful when I remember that bloody awful ending in Mass Effect 3.

Rick said...

My vote isn't on battleships at all but instead on interplanetary powers duking it out with successive rounds of espionage and counterespionage.

This points toward something I've mentioned here before: The possibility that, in the post-industrial era, war 'as we know it' is obsolescent, just in practical terms.

If building and deploying 'battleships' ceases to be an effective form of coercion, because the weapons would just destroy each other - and possibly everything else - power players will look for more usable ways to try and impose their will on rivals.

jollyreaper said...

Might be an inherent problem with Space Opera - you have an idea for some "special ability" and then you add it to the main character .. then things quickly spiral out of hand.
---

I think it's a danger in any fiction but especially one with teams of writers. The first stories were told about extraordinary people doing extraordinary things or ordinary people caught up in great events. Myth-making has always seen a power creep and more than one historian has suggested that traditional gods were likely folk heroes based on forgotten real people. Lacking primary sources and writing, George Washington could well have been remembered as a god-king and son of heaven, virgin birth and all.

As I seem to recall with Honor, she was supposed to be remarkably homely and later grew in beauty as the story went on. Kills Havenites by the hundreds. She consumes them with fireballs from her eyes, and bolts of lightning from her arse.

I don't think scifi is worse than any other genre for this kind of failure, though we as an audience are likely more familiar with the genre's failings than, say, the failings of erotic horror or Christian rapture porn like Left Behind.

Locki said...

Aurgghh! Please be careful of Spoilers!!! I'm only halfway through Mass Effect 3! I already know its got a crappy ending but my Sheperd has been with me for 5 years. Please, please don't spoil it. My Sheperd and I have been sneaking past the wife and kids for 5 years now to slowly complete our journey together and I'd rather see how it all ends for myself.

SA Phil said ...

sure they did ... they used relativity(mass) alteration to enable relativistic coil guns.

same difference.


========

Well I did preface it by saying its unashamedly space opera. I give good Sci-Fi 1-2 free passes when it comes to magitech. Mass Effect's FTL tech neatly ties into their artificial gravity which informs there coilguns of doom. Its space combat is at least internally consistent with the original magitech free pass.

Also there is a huge difference between a Dreadnaught and a Laserstar. The dreadnaught cannot dominate the spacescape because the chance of hitting you is dependent on how much thrust the target has. Eg it can be dodged by a ship which mounts a smaller gun which is inherently quicker. The Dreadnaught just doesn't zap anything that moves withing a light seconds range before you can close.

I'd be happy to give Laserstars one of my patented Magitech free passes (TM) too if they made for interesting stories. My main opposition to them is there's a subsection on this forum who are touting the Laserstar as a Lighthouse of Doom able to lay waste to anything within a few lightseconds of range and utterly dominate the spacecape. Surely this makes for horrifically boring rocketpunk. So my opposition is rooted in the boredom of the concept.

I've been going looking for good technical reasons to exclude them ever since. Which is why I have a preference for ruling them out with an internally consistent counter-laser blinding shot rather than crunching the technical math (which appears to make them impossible anyway).


So enough of an aside. I'm going back to my trig tables and range tables to do battle with the Laserstars with a good honest bullet.

Anonymous said...

I guess the question is --

Why do the Laser-Star Battleships need to fade away?

For the sake of a story? Just wave a wand .. make the Fractional Light Second targeting impossible. Set the max range to whatever you want. Set some specific restrictions based on things that come up during these purple vs green dramas.


For the sake of the PMF? Why? Just let the exercise play out.

(SA Phil)

Anonymous said...

Just a thought, but I'd think that you'd release the manuvering kenitics first, at a goodly distance from the enemy (outside the effective range of the longest laser weapon); once you got close, (a few seconds of flight time), you'd release the ballistic kenitics. And a ton of metal slamming into you at 100kps will vaporize your ship- whether it is a smart impactor or a 'dud' nuke.


Ferrell

Locki said...

SA Phil said re:laserstar:

For the sake of the PMF? Why? Just let the exercise play out.

Oh I'm enjoying that one too I'm happy to sit in with Tony on the anti-Laserstar camp and argue all day long. All day.

Re: light second lag. There is no handwaving in explaining the difficulty of targetting something where the information is old. I will point out even in modern warfare, at puny terrestial speeds, 0.01 of a second is an absolute eternity. There isn't a modern guided weapon system in use where the engineers would tolerate an uncertainty of +/- 0.01 seconds. If you went and asked a General Dynamics AMRAAM engineer if they could please swap out the radar seeker for a slightly cheaper one that introduced a mere extra 0.01 second of lag into the system - but the lag was compensated for with special predictive software - he would punch you in the head.

There's no way you can hit anything with the energy and speed we are talking about here if your targetting data is 0.01 second old. Which brings the range down to 3000km or less.

In the modern day even if you can predict where the target will be in 0.01 seconds there just too much uncertainty introduced into your targetting equations to guarantee a hit.

Anonymous said...

Thinking about the limited orbital mechanics and then the "Laser-Stars are only good for putting holes in things" It occurs to me --


That is actually false -- there would be a lot of utility to a Laser capable of repeatable fire with superior targeting.

A Laser Thermal Craft has a much better mass budget than a Nuke Thermal craft, assuming there is a Laser available ... The Laser Star could easily be used to boost outbound space craft or to slow down inbound ones.

In fact the primary job of the Laser-Star might be for supporting the PMF space industry, the secondary job is in defense from attack.

(SA Phil)

Locki said...

Sorry. 1500km or less for a 0.01 second lag. Got to allow for the return trip of the laser beam of doom.


A question for potential Bioware employees on this blog.

Do any Bioware employees reading this blog want to own up?

I've noticed the "pixellation" around the Normandy on my trips and was stunned to read in the Mass Effect Wiki the pixels were an honest to goodness droplet radiator. The only type of radiator that may work in space combat. Surely you guys got the idea from rocketpunk or atomic rockets?

The Normandy stealth ship is ok too since they've thought through the difficulty of hiding a hot object. Its a giant zero-point energy heat sink or something. At least they thought about it.

Come on Bioware employees reading this blog own up!

Anonymous said...

Locki

There isn't a modern guided weapon system in use where the engineers would tolerate an uncertainty of +/- 0.01 seconds

==============
No modern weapon is capable of destroying things at 300,000 kms.

At that speed you might be able to tolerate more uncertainty.

(SA Phil)

Byron said...

Locki:
I'm not sure where you got your information on the AMRAAM. First off, it's made by Raytheon, not General Dynamics. Secondly, there is quite a bit more delay then that in the entire guidance system. They already compensate for it. The missile travels about 13.6 meters in .01 seconds. Thirdly, you are confusing velocity with acceleration. No matter how fast it's going, if it's not accelerating, I can hit it with a laser. The acceleration that can be applied is fairly minor, probably enough to prevent precision targeting, probably not enough to avoid a hit. I did the math in my paper. One interesting effect is that the more operatic the drive, the shorter the laser range is, though the ship would still have to pivot.
My understanding is that the people in the "Isaac Newton is the Deadliest SOB in Space" bit are Winchell Chung and Ken Burnside. So yes, that is where they got it from.

Byron said...

The discussion of what makes good sci-fi is totally purple vs. green. The only thing that can be treated as an objective fact is the Star Wars Holiday Special.

The definition of hard sci-fi varies depending on the audience. For the general populace, anything with orbits and newtonian movement is hard. And to some degree, I can't fault them. For us, however...

Locki said...

No modern weapon is capable of destroying things at 300,000 kms.

At that speed you might be able to tolerate more uncertainty.

(SA Phil)


=======

This is exactly the thing. Lasers may travel really fast but they destroy a target really really slow. If I hit you with a kinetic it kills you dead, instantly. But even the biggest baddest laser needs some dwell time.

At any sort of reasonable angular velocity at huge range you are going to have to do some significant tracking even if the dwell time is a few tiny hundredths of a second.

Now that we have finally woken up to the fact we will close on intersecting Hohman orbits rather than approach dead on we know there will be significant angular velocities. Note counter-battery laser fire from supporting ships still shoots straight down the barrel of the opposing ship as you are effectively looking at each other whilst passing on different train tracks.

Feel free to correct my math again SA Phil this could be dodgy ...

At 1 light seconds range if your aim is off by 1 degree you will merely miss your target by 5,237km.
To hit a target with a 5m diameter you would have to be accurate down to 9.549 x 10(-7) of a degree. And then for arguments sake your dwell time was 1 second and our relative angular velocity was a leisurely 100m/sec. You’ld have to adjust your aim ? 10 times in that second just to stay on a 10m target.

To give you an idea of how small these numbers are you would need 376,991,118 teeth on your supporting gear cog to be able to adjust to hit a 10m target. If you have a 20m gear cog you will need a tooth every 1.67 x 10(-7) meters. To give you an idea of how small that is its about the same size as the transistor gate on a Pentium 3 chip or the smallest bacteria known. Now this tooth has to stabilise a couple of tonnes of laser array and readjust 10 times in ten seconds. Whilst pumping away the waste heat of a couple of power stations. Every second.

- Please also note my point about the inability for a laser to calibrate whilst shooting. If you miss the target in a vacuum there is no way to know if you went high, low or to the left. So if your calibration is knocked out by one bacteria width you’ll never hit the target and you’ll never know which way the alignment got bumped in the first place. This fact alone makes lasers an inherently inaccurate weapon.

Come on guys.

Its IMPOSSIBLE.

Locki said...

Sorry.

That cog is 70% the size of the world's smallest bacteria.

Just in case someone finds a bacteria that can lift a couple of tonnes, 10 times per second.

Byron said...

Locki:
Not impossible, just very difficult. There are several ways to deal with the problem. Phased arrays can adjust to levels smaller then the spot size. I'm not kidding. Adaptive optics should allow more precise pointing then gears do. Also, the gear system does not have to be capable of 360 degree turns, so the effective radius could be quite a bit larger. Or electromagnetic systems could be used. Figuring out where the laser is pointing is not that difficult. Defocus the laser to get a bigger spot, which will hit the target, then focus down.
Also, pulse the laser, and engage considerably closer than 1 light-second. It might be possible at half that range.

Eth said...

When I talk about bad writing in Honor Harrington, it may not be the best term. The style is good. It's fluid, immersive and quite enjoyable.
The problem I have is with what is - and is not narrated. In particular, the Mary Suish heroin and the narration from the least interesting side (both are probably linked). Which is too bad, because she could have made for a great anti-villain. A terrifying figure, crushing any opposition, becoming a dark legend, until the characters meet her and discover that she's just someone trying to defend her home, albeit very skilled, and who sometimes screws things up like everyone.
But this series still have its qualities (the writing style being one, IMO). Again, my dislikes of it are personal, there is nothing wrong in enjoying it.
I did enjoy the old Star Wars and the new Battlestar Galactica despite their many flaws that drove other people away, after all. There is nothing wrong with liking something for its qualities, nor disliking it for its flaws.

About Mass Effect, I'm one of the few who didn't like it. Don't get me wrong, it really looks like a great game. But the first few hours of gameplay didn't impress me, neither the story's beginning.
The first villain was such a caricature that it pulled me off the game, even though I heard that he's in fact a fairly minor character.
And I had just read the Inhibitors books ('Revelation Space' and sequels), who answer the Fermi paradox the same way, but with far harder SF and no rubberhead aliens (despite other flaws, but still). So it was like seeing the children's cartoon version of a dark film.

And yes, for a video-game, Mass Effect is close to hard-SF. Scales are relative, after all.
The only game with harder SF I can think about is Shattered Horizon, and it did have half the Moon blowing up in a He3 mining accident. (Though the developers did imply that yes, it would be impossible and there was something else behind it.)
Unless you also count Orbiter as a game, though.

Eth said...

WRT Mary Sue, it is indeed a problem in Romance, not just Space Opera. Harry Potter is the wizard with the greatest talent of his generation. I won't even talk about Twilight...
And in some cases, flawless characters can be justified. In some stories, you need a paragon. Children stories, for example, can have those. Some mythical tales, also. After all, the listeners will (hopefully) try to emulate those. And in simple stories, having a paragon is a better way for the listener to identify to the character. Tragedies can also have a paragon, as the dilemma is still unsolvable. And sometimes, the point of the story is precisely to talk about a flawless character.

The problem is the 'wish fulfilment' side of the Mary Sue. It has to not be completely blatant and/or exaggerated.
To come back to this poor Honor Harrington, that's where she fails as a character. She is beautiful but don't know it. She is taller and stronger than almost anyone, and black belt in martial arts. She becomes near-instant champion in space katana fencing. She is a tactical genius like there is one per generation. She has an alien pet, who grant her the extraordinarily rare gift of telepathy/empathy.
People around her fall in two categories : those who are (or will eventually be) recognising her extraordinary abilities and fall in admiration/adoration ; and those who hate her with guts, are utterly corrupt and have not even one redeeming quality.
What are her flaws? She is not that good in n-space maths, that people can do for her anyway. She lost an eye and an arm, who is replaced by a better mechanical versions (telescopic sight/hidden weapon included). She has reconstructed nerves on half her face, which is near-invisible anyway. She has inherited improved genetics who make people stronger and prevent her to gain fat, meaning that she has to eat twice more ; there is an inferred prejudice against those 'genies', but people don't know she is one anyway. She punches in the face people utterly corrupt, incompetent and stupid enough to do their damn best to anger her.
She becomes personal friend with the Queen, she becomes (the local equivalent of) Duchess on another planet (with lands/wealth/fanatically devoted bodyguards included), has a state burial on two systems simultaneously (she gets better), she gets a class of the best dreadnought ever named after her...
Piles of incredible qualities including outright supernatural and/or unique ones, inferred flaws who aren't important, when they aren't downright bonuses, people dividing in two categories, good-guys adorers and bad-guys haters, the world tending to revolve around her, you have the complete Mary Sue syndrome (apart from ridiculous clothing and misplaced/exagerated angst, fortunately).

Compare the hero of Vorkosigan Saga : he is the son of the Regent/Prime minister of his world, but he is hunchbacked, short, with brittle bones in a militarised society with harsh prejudices against 'mutants'. He is very intelligent and quick-thinker, but insecure and sometimes borderline psychotic. And despite his damn best efforts, the world doesn't revolve around him.
The point is that the character has real, visible flaws who will regularly bite him in the back. And he will sometimes do incredibly stupid things, with dramatic consequences he won't always get away with.
(This is one of the reasons I liked this series so much. On the other hand, others will probably be driven away by the plasma beams, force-fields and other magitech, causal interplanetary travel/FTL and space infantry.)

Again, you can still have a good story with a Mary Sue, or a story who avoids having one but is still bad. Still, it is generally a flaw, and one which is sometimes difficult to avoid.

Locki said...

Eth:

Honor Harrington sounds ... ghastly.

How many novels featuring this great Grandmummy of Mary Sues did you actually suffer through?

And you couldn't make it through a few hours of Mass Effect???

Locki said...

Byron said...

'm not sure where you got your information on the AMRAAM. First off, it's made by Raytheon

Hi Byron. Nice to see you back after a couple of days away. I see I haven't frightened you off with my armored shutters and blinding lasers so I've dusted off my 20yo scientific calculator and go into battle with math (god help us all)

My statement on Raytheon (lousy wikipedia!) engineers still stands. If you introduced an extra 0.01 second delay (range 1500km) into his hardware he would punch you on the nose. If you introduced an extra 0.1 second delay (range 15,000km) he'd rip your arm off. If you dared mention a 1 second delay (range 150,000km) he'd probably just spontaenously combust.

Targetting at speed with a high angular velocities is hard.The USAAF is like 0 from 6 in intercepting ballistic missiles in the terminal phase. The USN on the other hand has an almost perfect record in killing Ballistic missiles in the boost phase (much slower closing velocity - not accelleration!) Predicting future location will only get you so far.

When the russians swapped over to mach 3 Sunburn missile the USN swapped out their Phalanx CIWS for missiles. 1 they just couldn't hit it with a bullet despite its "predicted location" and 2 the missile was going so damn fast even if you hit it at 1.5km the fuselage would still slam into your ship and mission kill you.

Phased arrays utterly change everything so I'll deal with them a touch later.

Locki said...

Byron:

There's quite a few unknowns about scorch vs burn laser,

1. How long does it take a shutter to open?


- surely you can slam open a 1-5m shutter really really fast - a few fractions of a second. Whatever the time is you bet you can unshutter a smaller laser a lot faster than a bigger laser.

2. Can the enemy detect the shutter opening?

- even if they could with the light second round trip delay I can probably open the shutter and send a shot back just before your shot arrives. Eg my shot arrives 0.8 seconds after yours at 1 light second range.

3. How fast can the enemy train the laser?

- Accurately at the types of ranges touted? Slowly. You also have to wait for the vibrations to settle. I thought about an electromagnetic aiming system too but that would just make the vibrations after retraining even worse. Note vibrations make rapidly suppressing multiple targets (in a time period before they can open shutters and aim) impossible.

4. What is the relative scorch vs burn efficiency?

- Someone please look up how much energy it takes to blow up a diode vs an inch of ceramic armor. I know my laser diodes at work blow up at 60C within seconds. I'm sure the space shuttles tiles can taKe 1500+C for minutes.

- Note phased arrays are still unspeakably fragile compared to armor but have the slight advantage in not suffering from your own optics concentrating my laser for me.

5. Why does the enemy only mount one laser, anyway?

Laserstar scenario. You have decided to bet the house on one giant 30m wide laser with enough power generation and radiators to allow virtually continous firing time.

I've chose to go with the smallest possible laser whose scorch range exceeds your burn range. In addition I don't need continuous fire so I can just get away with enough capacitors for a few shots, much lower energy generating capacity and can probably just dump the waste heat to the heat sinks. I'm going to be able to afford a LOT of lasers which can effectively blind before you can burn.

6. Lastly, the optics involved in a conventional mirror only reflect one frequency with high efficiency. Unless you happen to know that frequency ahead of time

This always bugged me. The laws of phyics dictates that in a vacuum the shorter wavelength laser has an inherent advantage (less diffration far greater range and more likely to hit with shockwave than just heat). Assuming similar tech levels everyone's gonna use the shortest wavelength technically possible.

If UV lasers are possible you'd be a moron to go with IR and everyone will use UV. If blue is the shortest wavelength our magitech mirrors and optics can handle then blue it is. Note this excludes lasers shooting in atmospheres where you are basically forced to use a red laser because of moisture etc. Even if we are using lasers of different wavelengths the energy is still going to play havoc with your laser calibrated to micron tolerances.

Mirrors, phased array elements, optics with 100% efficiencies whatever laser you choose - they are all way more fragile than a plate of armor.

My blinding scenario is sound. A laserstar dare not shoot if there are ANY lasers within blinding range. Its main gun is horrifically fragile whichever way you slice it, whatever type you choose to go with. It will be the most fragile piece of equipment on the warship and its sitting right out in the open just begging a belligerent person to punch it.

Scorch range is going to exceed burn range by a significant margin.

The only question is can the Laserstar keep all of the potential blinding lasers suppressed with its disco ball of death, rapid aiming trick.

Considering the large numbers of blinding lasers I can afford compared to the big laserstar - it is more plausible than not the laserstar can be suppressed too easily without handwavium.

Anonymous said...

Locki,

Now that we have finally woken up to the fact we will close on intersecting Hohman orbits rather than approach dead on

All that did was adjust us from dead on to almost exactly dead on. (minus the effect of gravity)

It did not change us to kps of relative lateral motion. (Except when ships are very near a planet and orbiting it)

(SA Phil)

Anonymous said...

Locki

You’ld have to adjust your aim ? 10 times in that second just to stay on a 10m target.
=========

Why do that?

Just aim ahead of the target and have the computer fire at the right time.

(SA Phil)

Samantha said...

Locki: You're making the assumption that the playing field is level, which it's not.

The faction with the laser star is likely on the defensive. That means the mass of their laser star isn't accountable to the same delta-v limitations. So while you're coming at me with, say, 100k tonnes of laser plus generator plus engines plus reaction mass plus radiators plus hull plus ect... I'm sitting back on my moon with 100k tonnes of laser and generator.

I'm pretty sure that as long as you're on the defensive you can build a laser star with a burn range far outside the scorch range of anything anyone could conceivably move into place.

Also, if you place your laser at the bottom of a long tube/behind an aperture some distance in front of the laser's "muzzle" you can prevent any scorching laser with the exception of the one actually getting SHOT at from being able to blind you. Of course, that makes aiming even slower so it's a trade-off.

I think this massive imbalance between defender and attacker in the plausible midfuture extends to kinetic weapons as well. I could see nations maintaining huge, massive laserstar installations on moons and asteroids in the same way that modern nations maintain nuclear arsenals. It's not that they're particularly useful for fighting battles it just creates a huge insurmountable obstacle that no foe could really, reasonably handle.

Thucydides said...

I'm not sure where this "My scorch range exceeds your burn range" is coming from; if my laser is more powerful my scorch range is also greater than yours as well. Regardless of how far the range is, it is in my best interest to open the engagement from the greatest practical range of my system in the PMF environment; you simply will be unable to move out of the way of a laser, but much more capable of evading a KKV cloud until it is reaching terminal manoeuvre range.

WRT bomb pumped xray lasers; they would be part of the mix in order to make point defense more difficult. If the standard bus can carry an xray laser or SCoDs; you pretty much have to target all of them at xray range since you don't know which ones are which until they dispense submunitions. For additional fun, the dispersal or xray laser firing can be done at any time once you pass the xray laser range...The reason bomb pumped xray lasers were dropped may have more to do with inefficient coupling of the bomb energy to the lasing rod than anything else. The physics seems to have been sound, or at least sound enough to convince decision makers to give it a try.

It takes a long time for technologies to become accepted in practice (althought the three stage missile example is a bit out there). The Dreadnought was anticipated by an article in Janes in 1903 (and informally there was some movement in this direction in the late 1890's). Carbon fiber composites were recognized as being superior to metal in the 1980's, but the first commercial airliner to use composites is the Boeing Dreamliner with rollout in 2007. So there will probably be a lag between the identification of certain technologies as being useful/viable and the actual rollout of the product.

Eth said...

Locki:
Honor Harrington sounds ... ghastly.

How many novels featuring this great Grandmummy of Mary Sues did you actually suffer through?

And you couldn't make it through a few hours of Mass Effect???


I wouldn't call it ghastly. At least, it is a sympathetic Mary Sue, someone who, in real life, you would indeed like. That's already better than most Mary Sues. She react as would do a real human. It's more how other people react to her who is the problem, as well as the the blatant accumulation of qualities and lack of real flaws.
(Did I mention that she is also very, very good with handguns?)
To her credit, she doesn't always save the day by herself. There is at least one moment where she is helpless and it's individual actions from her crew who save it.

Again, the style is neat. Some passages in the first books are weak on this point, but it does get better IMHO. The action sequences are mostly good and believable (once you accept the magitech of the setting, and the occasional minor mistake).
The plot is often quite enjoyable, and sometimes quite smart.
And the story of the antagonists is really interesting. Note that as being on the other side, they are out of range from the Mary Sue effect.
So there are definitely things to enjoy in those books.

So I wouldn't call it awful. More like frustrating. If you can go past those problems, it's a quite enjoyable space opera. But I was too often stuck with 'Why did you write this like that?' moments and gave up.
Some day, I'd like to write something inspired from Haven's story in those books (in a harder setting, though) and try to make it right(er).

About Mass Effect, it was more bad luck. I read a hard-SF and far darker series treating about the same thing (near god-like mechanical beings exterminating space-faring species, though their reasons are different). There was kind of a contrast.
Someone told me that this game had such a 'great gameplay', 'great story', with 'super-detailed background' and a quite hard-SF setting.
The gameplay didn't impress me, so I was kind of disappointed. The background world felt quite generic to me, so I was kind of disappointed as well. The SF setting was hard ... for a video game. After reading a space-opera without FTL, it was brutally soft. Particularly as 'incredibly ancient' seem to be for them 'at best a few millions years old'. In the book mentioned above, the antagonists use galactic rotations for years. Billions of years are almost short-term for their galactic plans.
And about the great story, well, the card-carrying villain and utterly stupid council also disappointed me.
The unfortunate combination of all of the above drove me out of the game.

I should have been wary, though, it was the same people who told me how KotOR was such a great game...


WRT laserstars :
So we are back to impenetrable orbit defences.
We may still have emergent powers/backwaters colonies fighting each-other, though, or great powers fighting each-other to control said colonies. The latter would give more symetrical battles.

Also, again, why not constitute your 30-m laserstar with small independent phased-array lasers? After all, the elements are already independent, so why not make them modular? Then, if they're too close for your one big laserstar to be effective, use the smaller lasers separately. If possible, separate them on different crafts, so they won't be a unique target.

Byron said...

Locki:
I just found the flaw in your plan. The shutter will introduce its own vibration, quite likely more then training would. You're certainly not firing instantly. And then it's a quick-draw contest, which the laserstar probably wins. It only has to deal with training vibration, and can accept a much larger spot size. Scorch the mirror of the opponent, and go on to the next one.
I'll deal with point-by-point later.

Anonymous said...

RE: Burn/scrotch ranges

I wonder -- targetting seems like it is the biggest problem.

It could easily happen that you can only effectively target well within your burn range.

Example: Laser-Star North California can burn at 200,000 km, but can only accurately target at 100,000 km.

This is actually the problem the actual battleships faced- their guns had longer reach than their targetting.

Before radar it was even worse.

(SA Phil)

Samantha said...

Byron: That's not a problem. The shutter doesn't need to be part of the focusing system which means that vibrations in the shutter don't matter. Since all the shutter has to do is sit between the two lasers it doesn't even need to be attached to the ship! It could just float out there and snap open with as much vibration as it's little shuttery heart desires!

Anonymous said...

Eth,

I should have been wary, though, it was the same people who told me how KotOR was such a great game...

----------------

I liked both games ... but I had no illusion that Mass Effect was anything other than pure Space Opera with larger than life mostly cardboard characters. Bioware always uses up most of their characterization points on your companions.

Mass effect 1 was literally a Knights of the Old Republic game anyway.

Saren was a Jedi secretly fallen to Sith Lord, the council was the same myopic Jedi Council from KOTOR 1, your character joins the Jedi/Spectere order ...

Sovereign was the dark side infused vessel of the forgotten dark side empire race that corrupted Sarren ...

The reapers were the true Sith hiding beyond the Outer Rim...

(SA Phil)

Anonymous said...

Eth,

WRT laserstars :
So we are back to impenetrable orbit defences.
=======================
I dont know - The defenses are still vulnerable even with 1 Light Second quick targetting Laser-Stars.

You just need to calculate how many missiles the Laser-Star can destroy/deflect within the engagement window .. and make sure you send more missiles than that.

If the Laser Star can destroy 1000 missles, send 1100.

(SA Phil)

Tony said...

Rick:

"I could make some quibbles. It wasn't clear whether 'retrograde' was suppose to be about solar orbits or planetary orbits - apparently the former. If you are coming from deep space, choosing a retrograde orbit of a planet is easy. Just make your approach pass on the other side of it."

Actually, on further consideration, the argument against meeting the enemy out in space on an opposing trajectory is pretty much the energy argument against space fighters. Until we're talking about operatic drive performance, everybody is moving between planets in the direction of planetary orbits, even using relatively high energy cometary orbits. If you want to go out an meet an attacking force, you have to establish a retrograde solar orbit, cancel it, establish a prograde solar orbit, then cancel that when you get back home. Your enemy just has to establish a prograde solar orbit to get to your planet, and cancel it when he arrives. That makes your warfleet much more fule and much less weapons than your enemy, all other things being equal.

Another problem, you give the enemy, who may be using kinetics, the gift of extra relative velocity that he couldn't generate for himself. You get the same relative velocity, but you can't carry as many kinetics as your enemy can.

Finally, if you go out to meet your enemy, you're inviting the enemy to concentrate all of his force against part of your force in space, then against part of your force in the orbitals. Or, if you take all of your force out to meet him, his survivors get to attack undefended orbitals when they get to your planet. And anyway, no matter how you cut it, your forces that go out to meet the enemy are relatively weak to begin with, for reasons already discussed.

Tony said...

Byron:

"The best source I could find on space cooling systems was on atomic rockets. The author suggests that heat pipe systems would require virtually no moving parts and would be quite light. While this is obviously not a 500 MW system, it's a better start then you gave. Apparently, the heat pump and such are generally included in the mass per unit area numbers that occasionally get thrown around. If you'd like to do more research, and need a paper that you can't get to, I'd be happy to get it for you. (This applies to everyone here, within reason)."

"OK. Then explain why it was relevant. Just because a power plant (which can be considered to have unlimited amounts of water available for these purposes) requires that much doesn't mean that a spacecraft would need that much. Implying that it would is like using that same power plant to get specific power numbers. Both are obviously red herrings."


I'll take these together because they're really two sides of the same coin.

First of all, I showed the numbers on the coal-fired plant because they represent the state of the art in electrical generation technology after more than a century of development. And we are, after all, talking about waste heat from electrical generation. The relevance comes from the fact that we're talking about a fluid (probably liquid) cooled fission power plant. Apart from the nature of the heat source, such plants work essentially the same way as fossil fuel plants:

Steam is generated by some highly concentrated heat source,

The steam it is run through a turbine or turbines to drive electrical generators,

Then exhaust steam from the turbines is condensed back into liquid by conduction cooling, using fluid running through a separate loop, and

The cooling fluid is in turn cooled by some kind of heat rejection system (cooling towers in the case of commercial power plants).

So the coal-fired plant and its requirements represents a very good point of comparison.

Ahhh, Byron says, but in space we can use direct conversion of heat to electricity and heat pipes for cooling. Yes, at 100 kw you can do that. You can do that on the Earth too -- at 100 kw. For hundreds of megawatts, I don't think those technologies would scale. There's just too much heat in too small a space, in too short a time. We use steam turbines, condensers, and outer coolant loops because they're what works at the scales we're discussing.

So, in realistically thinking about such power levels and their support requirements, we have to think about realistic systems already in use. And those systems are very highly developed. It's not like there are any realistic options that we haven't tried, or that those systems are somehow not as efficient as they could be. We're talking about simple heat engines that work a certain way for good physical and engineering reasons. If you want to replace them in your speculative spacecraft, you have to show good physics and engineering at the same power scales.

jollyreaper said...

I reread the spherical war cows threads. In all these years we're still spinning with regards to purple and green.

I'm wondering if we could put together a larger spreadsheet that could factor in the major necessary variables:

1. Reactors/Available Power
2. Beam Power
3. Mirror Size
4. Rocket tech (from mili-gee to opera torch)
5. Targeting accuracy
6. Armor performance
7. Dazzle/blind/scorch/burn ranges for lasers of various power
8. Radiator tech
9. Performance/weight ratios for the above hypothetical equipment

Definitions:
dazzle=interfere with a sensor but not damage it

blind=destroy sensor

scorch=damage to delicate exterior components of a ship -- likely the point at which radiators are pulled in which means the target will start heating up

burn=armor will ablate.

The thing I'm thinking is that the optimum solution given the tech will vary as the tech does. Let's look at the 20th century.

In the beginning, big guns were obviously king in naval battle. You have the pesky presence of torpedoes trying to ruin the grand show but the battleship admirals wouldn't have it. Of course, the biggest big gun battle of the war was inconclusive in the tactical sense but kept the Germans bottled up for the rest of the war.

The airplane meant the end of the primacy of battleships but that ascendancy lasted for only a little while. Even during the course of the war it became clear that guided missiles were the future, we only lacked the technology to put a mechanical guidance system in it.

Of course, there was a period at the end of the war where proximity-fused shells made it pretty much suicide for aircraft to attack surface ships. If two 1945-era American carrier battle-groups were to fight each other, they might well rely on battleships to break up the other formation before risking aircrews in the attack.

At this point carriers remain the queens of the ocean and we haven't had a large-scale naval battle since WWII. Those ships that have been attacked have been destroyed with missiles. (And possibly a few bombs in the smaller conflicts.) I personally have the suspicion that carriers are too vulnerable at this point and are obsolescent but I think it will take losing a few before we truly rethink the approach.

Now with railguns possibly being added to the arsenal, perhaps a big gun ship becomes viable once more.

The constant shift of technology keeps changing the calculus on most effective weapons.

In a PMF setting, if the tech is in a state of continuous improvement, we could see a tipping point between one technology and another. Rick's original analysis on laserstars showed how with one set of assumptions you might have to throw enough hardware to equal half the cost of a laserstar into the attack to neutralize one while the laserstar itself can affordably plink targets up to that point. But what if there's a breakthrough in drive tech that doubles drive speed and means it now takes half the number of kkv's to suppress a laserstar? What if improved radiators let a laserstar fire twice as frequently and double the amount of kkv's for suppression?

In these disruptive turning points the old calculus can change and thus introduce uncertainty.

Tony said...

Re: laserstar cooling

It occurs to me that Byron might still question the relevance of commerical power plant cooling requirements because a large portion of the cooling load is coming from weapon system cooling. Correct. However, how is the cooling going to work, if you want to use a closed-loop system? Fluid flow through the parts of the weapon that need to be cooled, and subsequent cooling of that fluid somehow. It's the same essential problem as a power plant cooling system, though maybe the coolant isn't allowed to turn to steam. Or maybe it's treated like the hot loop of a pressurized water reactor -- used to create steam which is then used to run a combined cycle steam generator for more elctrical power. But of course all that does is marginally increase the efficiency of the nuclear power plant, and only while the laser is shooting. And of course the exhaust steam from that part of the cycle has to be cooled too.

Tony said...

jollyreaper:

"I'm wondering if we could put together a larger spreadsheet..."

A spreadsheet is worthless, because:

"The thing I'm thinking is that the optimum solution given the tech will vary as the tech does."

Not quite. The optimum solution will vary as assumptions about the tech does. As one learns quite well in real world engineering, numbers are worthless when dealing with dueling assumptions.

"Let's look at the 20th century."

Lets...

"In the beginning, big guns were obviously king in naval battle...

The airplane meant the end of the primacy of battleships..."


Note that through the first half of the century, the dominant approach varied WRT the increasing efficiency of controllable heat engines.

"Of course, there was a period at the end of the war where proximity-fused shells made it pretty much suicide for aircraft to attack surface ships. If two 1945-era American carrier battle-groups were to fight each other, they might well rely on battleships to break up the other formation before risking aircrews in the attack."

Nope. The air groups would still dominate, but they'd have to accept higher casualties in accomplishing their missions.

Also, war is a process of adaptation. The Japanese probably never figured out that proximity fuzes existed. So they couldn't adapt. Two American carrier groups would know for sure that proximity fuzes existed, how they worked, and what their weaknesses were. The side which adapted better to that knowledge would have an edge.

"At this point carriers remain the queens of the ocean...I personally have the suspicion that carriers are too vulnerable at this point and are obsolescent but I think it will take losing a few before we truly rethink the approach."

You still have to get your guided weapons platforms within range of the carrier. The carrier has a wide variety of guided weapons defense platforms in its battle group. It also has a large number of offensive guided weapons platforms in its air group. The carrier battle group needs and has to rely on good tactical intelligence and apprpropriate response, but it's far from helpless just because an enemy has guided weapons.

"Now with railguns possibly being added to the arsenal, perhaps a big gun ship becomes viable once more."

I doubt it. The railgun ship still needs accurate tactical intelligence about where the target is, and the railgun projectile is not much of a weapon at long range -- the equivalent of a 5-6" HE projectile.

"The constant shift of technology keeps changing the calculus on most effective weapons."

Nope. Heat engine technology improved to the point where aircraft have dominated warfare for 70 years. Precision guidance have made aircraft more efficient, but aircraft are still the dominant weapon system.

"In a PMF setting, if the tech is in a state of continuous improvement, we could see a tipping point between one technology and another...

In these disruptive turning points the old calculus can change and thus introduce uncertainty."


Sorry, but again, nope. We've already gone over how various heat engine technologies can be made only so efficient. Digital computer technology will top out sometime as well. After that, what's next? I can't think of anything, and believe me, I've tried.

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