Thursday, August 27, 2009

Space Warfare VII: Kinetics, Part 2 - The Killer Bus

If we are dealing with deep space warfare, interplanetary or interstellar, we are probably in a setting with regular, extensive space travel, passengers and freight. These people throw a lot of luggage around, and they throw it fast. The whole interplanetary economy is based on their ability to do so, and do it (relatively) cheaply. Which makes kinetics, unlike lasers or other weapons, a 'natural' outgrowth of civil space travel.

So, why build a costly 10,000 ton space battlecruiser just to deliver a few dozen kinetic missiles of a few tons each? Cut out the middleman. Build a 10,000 ton killer bus - or buy an obsolescent cargo hauler at scrap price. It won't be cheap, but it will be a great deal cheaper than a reusable warcraft, and it allows you to use its full delta v to build up impact speed, and its entire mass (less expended fuel) as punch. A few thousand tons of that mass can go into an armor faceplate, making it harder to zap.

Now let's throw some luggage. Suppose a closing rate of 30 km/s, and assume that defensive laser fire will burn through the armor and wreck the bus at 3000 km = 100 seconds from the target. At that point the bursting charges go off and break up the bus into a cloud of fragments. Big ones and little ones, but say they average 10 kg - a million of them, delivering an average punch equal to rather more than a ton of TNT.

Let the wreckage fly apart at up to 25 meters per second. When the fragment cloud passes the target it will be 5 km across, with a cross section of about 20 million square meters - meaning a chunk of nasty for every 20 square meters of target cross section. Now, just how big is your laser battlestar? If it is 20 meters in diameter across the aspect facing the attack, it is in line for about 15 whacks, giving you 6 or 7 seconds of zapping time per frag on collision course.

The total mass you need to zap is about 150 kg, requiring up to 8 gigajoules to fully vaporize - thus average beam power of 80 MW. (And you'll generate up to a couple of dozen GJ of waste heat you'll have to get rid of, if you survive.) You can probably get away with less beam power by slapping frags aside instead of fully vaporizing them, but this is fairly unpredictable. And in orbital space you'll have a complex computational problem determining which four out of those million or so frags you need to zap. Plus, I'll let my killer bus carry a few dozen kinetic target seekers, released just before the bus frags, so the target seekers are mixed into the clutter of fragments till they light up their deflect motors to make intercept in the last few seconds.

Or you can sidestep the entire fragment cloud with a fairly modest lateral burn - a minimum 25 meters per second, though you had better add some safety margin, and unless you have very powerful deflect thrusters you must allow for acceleration time. Minimum acceleration is 50 milligees, pushing you to 50 meters per second, but again some safety margin is wise. This is a basic limitation of (unguided) kinetics - they can be sidestepped, which beams cannot be at less than light-second ranges.

You also have the option of turning the killer bus's closing rate against it by attacking it with kinetics - which can be launched along its track well in advance, at no great speed relative to you, since you see the killer bus coming and know you're at the end of the line. This is a Kirklin mine, named for Kirk Spencer, who proposed them on SFConsim-l. The countermeasure is another, smaller Kirklin mine, leading to a theoretically infinite regress of counter-counter-countermines. In practice it granulates at the minimim size/cost of effective guidance or buckshot-aiming.

Bear in mind that I am discussing a fairly modest midfuture tech. If you have uber-fast drive engines you can have much faster kinetics - with destructive effect going up as the square of velocity, while the evasion/countermeasures time window goes down inverse linear to velocity.

A killer bus is not an elegant weapon - but we are discussing battles, not costume balls. It is a brute force weapon, prose in motion, but it relies on standard transport technology that every spacefaring society will have. For this reason I tend to think of kinetics as particularly appropriate in less intensely militarized settings, such as rival trade federations that can raise semi-scratch forces in a crisis. (Of course, other industrial applications might also make high power laser tech readily available.)

And there is another curious property of kinetics that I only thought of while writing this. If your primary weapon is kinetics, most of your military procurement is expendables. A laser-armed enemy finds that their lasers are all 'defensive,' because you really have few if any targets to use offensive lasers against. There is not really much reason for kinetic-missile battlecruisers. Against the most heavily defended targets you expend a killer bus; against lesser targets you can deploy kinetics from modified transport types, with the only 'warships' being rear echelon sensor and command platforms.

In short, kinetics and lasers are not just alternate weapon options, they are highly 'assymetrical.' In the current era this has the connotation of insurgency, but in past era main forces of major powers have sometimes been similarly assymetrical - think Roman legions versus Parthian horse archers. If the tech is such that the weapons are in approximate balance, they may be deployed by different types of polities (or other power-exercising entities). Or, lasers may be the characteristic weapon of operational defense, deployed aboard orbital battle stations, while kinetics, which like to be thrown fast, are a characteristic weapon of attack.



Related links: Another kinetic weapon, the 'Lancer,' was discussed in my post on space fighters. And previously in this series:

I - The Gravity Well
II - Stealth Reconsidered
III - 'Warships' in Space?
IV - Mobility
V - Laser Weapons
VI - Kinetics, Part 1

42 comments:

pspinler said...

You mention orbital space being a considerably more complicated environment to project kinetics' paths through. However, closing velocities in orbital space are also notably lower, aren't they? So orbital space also give you more prediction time, and less damage for those impactors that do get through.

On the gripping hand - it seems like you'd need something utterly computationally amazing and require radar power sufficient to cook whales to track and predict several thousand 10kg fragments in that little time.

-- Pat

pspinler said...

And one other thought that occurred after my first comment -- so if you need a Bluegene computer and super Aegis radar to track and predict the frags, how much power and heat do you have from these?

Rick said...

Pat - Welcome to the comments threads!

Closing velocities in orbital space don't have to be slower - an incoming kinetic can enter orbital space at full interplanetary transfer speed, perhaps 30 km/s for midfuture electric drives, more if you have uber-drives. The curve of their trajectory will be shallower, but still enough to spoil the simple flat-space model, at least till the last few seconds - which doesn't leave the defender much time.

And a good question about tracking all that stuff, to which I don't have a good answer. We currently track several thousand pieces of orbital junk, but they have accumulated over many years. Tracking up to a million frags in a couple of minutes and determining which ones are a threat will require a Whole Lot of number crunching, with a variety of non-trivial complications.

Anonymous said...

These Killer Buses, as they are described, seems more like course (or vector?) denial weapon systems then offensive weaponry in a constellation-to-constellation combat zone, but that doesn't mean that they can't do the job just as well.

One can imagine an orbital defense station launching these low cost Killer Buses to prevent an interplanetary warcraft from approaching the home world, maybe even utilizing a mass driver to give the bus the initial boost and have the on board engine drive be ignited at a later time to give the fragmentation damage just that little extra "oomph" to cause just a little more damage to the incoming spacecraft. If that little bombardment doesn't cause destruction, it can make those spacecraft that much easier to be defeated or destroyed while the defenders are just sitting at their orbital defense station and accompanying space force constellation twittling their thumbs before the attacking force is within effective weapon range. That kind of environment would probably be ideal for Q-Ships, or in this case Q-Crafts, to slip in and do damage to allow the main force to finish the job.

As for the military expendable notation of kinetic rounds and buses, well the same could be said of Lasers and other such Beam Directed Energy Weaponry due to the thermal limits of heat sinks and how notoriously difficult it is to armor radiators, if at all. Granted, heat sinks and radiators could be used to cool down the high energy systems once the losing craft surrenders, however this is depended upon the leniency (or stupidity) of the victor craft's commander to allow such a cool down period to occur after the engagement.

However, the notation of beam weaponry being "defensive" is rather interesting. And fitting since kinetics take time to reach their targets even within planetary orbital distances. Lasers, on the other hand, have a speed that allows at worst a few seconds delay of striking incoming kinetic rounds and buses.

- Sabersonic

Jean Remy said...

I had an idea for a compromise between your killer bus, kinetic weapons and missiles.

Take a large missile body. Give it an initial push, say using a rail/coilgun. Let is coast until it is in point-defense range and light the engine, make some last second adjustments, give it one final push with something that has high thrust low Isp (like a solid booster,) then blow the casing open. inside are penetrator rods or shrapnel, all on the same vector. Because they'd be a tight bundle the point defense would almost be forced to work its way in and through. Have enough of the little buggers and you might overwhelm the PD. Throw several missiles programmed to come in at different angles and you're sure to overwhelm PD. Add some reflective low mass metal foil pieces for radar jamming and beam diffracting effects. Maybe you don't have the high terminal velocity and spread of a shotgun blast, but you have a lot more metal on the same vector.

Depending on how easy coil/railguns are to build (ie: if you can make cheap railrifles and coilpistols) you could instead place a dozen or more loaded tubes in the missile and fire them on final approach, to get an even higher relative velocity.

Rick said...

The killer bus, as I described it, is deliberately an extreme case, to explore what a Really Big shotgun blast can do, requiring several km of jink to evade. Against most targets you would use something smaller! (But perhaps on the same principle.)


Sabersonic - Vector denial is an interesting approach to defensive use of a killer bus. Essentially you're using it as a jumbo Kirklin mine, to force an attacker off his intended approach track.

And to extend from your point about laser expendability, at some broad strategic level all military forces are expendable. There's still a distinction, though, between weapons you hope will survive for reuse and those that are inherently expended when used. Roughly the difference between guns and bullets!


Jean - The tighter the grouping of fragments, the tougher to defend against with lasers or armor, but the easier to sidestep. So there is a fairly complex and subtle set of tradeoffs between intensity and spread, both related to the distance at which the approaching bus/missile is expected to be damaged to the point that it is no longer under control and changes from a 'smart' target seeker to a 'dumb' kinetic.

If single-shot coilguns are cheap, they are another interesting option. There's a historical precedent, by the way. At one point in the 1910-1930 era the USN explored torpedoes that would carry a short, nonrifled 8" gun as their warhead, firing its shell on impact with the target's torpedo bulge. But conventional warheads turned out to be more effective. (So long as they went off, which regrettably US torpedo warheads in WW II often did not.)

Anonymous said...

Rick- your 'Killer Bus' seems like a strategic weapon; how would a tactical version look? Like a large missile , but with either a bursing charge with thousands of ball-berings, or Jeans idea of bundled penitrator rods, or maybe have the 'warhead' be a cluster of unguided rockets (metal or plastic tubes, with the front half filled with a dense material and the rear half filled with a solid rocket motor); perhaps a large pod with a heavy frame, fired from a coilgun, that has a seeker head, manuvering thrusters, a very large fuel supply, and ablative armor. At moderate distances it would simply crash into the target ship; for long distances, you could attach a drive unit to the back, or even have solid rocket engines for terminal boost, or both.

Oh, and as far as using kinetic weapons to defend against other kinetic weapons, why not just use a real shotgun? Or a grenade? Design something like a Claymore mine, but stand it off the ship's hull (attach it with a wire) and detonate it when needed. The ball barings go shooting off toward the incoming threat and the fireball from the explosive charge disapates into space.

Again, just some thoughts...

Ferrell

Jean Remy said...

I like the claymore strapped to the hull idea. It seems similar in concept to "reactive armor" which are basically just that and meant to counteract the incoming explosive jet created upon impact by a prenetrator to rob it of momentum. I don't know how effective it will be as a purely point-defense weapon because of the low probability of randomly scattered shrapnel to actually intercept the incoming ones at range, but perhaps as a last ditch resort when the normal CIWS's no longer have the time to intercept them or are already overwhelmed.

Rick said...

I intended the killer bus as a 'tactical' weapon, since even though grotesquely big its intended target is major combat spacecraft. In the 17th century, fireships were a regular part of fleets and even sometimes purpose built, so that's at least one precedent for very large expendable weapons!

Smaller versions could be any variation on what you describe, but note that in principle you need no 'warhead' other than the bursting charge - the structure, engines, fuel tankage, guidance computer, etc., all become part of the fragment cloud. Nothing is wasted, so to speak.

I suspect that a Claymore mine would be too late in the game to be very useful, but ordinary bullets fired toward an incoming kinetic might shatter it several km away, far enough that most of the sub-fragments will miss you.

Jean Remy said...

I don't really see the bus, even the big one, as a strategic weapon either. The explosion will spread the debris out far too fast to have any lasting effect beyond the day's battle. At worst they'll present a small hazard to navigation, but it would be a decidedly unlucky ship to randomly hit a one centimeter object in the whole lot of nothingness of space. It doesn't sound like the kind of weapon you want to use in orbit either, unless you know you're losing, and as part of a scorched-earth gambit.

Anonymous said...

The ship that is the target of your 'Killer Bus' seems to be a strategic asset, so to take it out would seem to be a strategic response. The weapon itself doesn't have to be a strategic one, just the purpose behind its use. And if you use one in the orbit of an enemy planet (Mars or Titan, for example), then it also becomes a strategic weapon. One 'Killer Bus' is a tactical weapon; use a hundred and it becomes a strategic one...

Ferrell

Jean Remy said...

Um... any weapon deployed on a battlefield would by definition be a tactical weapon no matter how important it is to the fleet. A strategic asset is one that matters over the course of a campaign, such as the shipyard that built it.

If you deploy a nuclear weapon on a battlefield it's a tactical weapon. If you use one to bomb a city behind enemy lines it's a strategic weapon.

The bus could be used in a strategic manner if it is targeted at a planet or a station, or even to interdict a shipping line by seeding it with navigational hazards. If it is used in battle against an attacking ship, it's definitely a tactical use.

Anonymous said...

Jean, a fine point of distinction! Thank-you, it's late and my thinking is starting to get fuzzy (my wife would say that was my normal state...); well, I'm off to bed so I'll talk to you later...I enjoy your comments and ideas; you've obviously have thought them through with great care!

Ferrell

Jean Remy said...

I only start getting fuzzy at about 1 am... oops look at the time.

Rick said...

What Jean said. I conceived the killer bus as a weapon primarily against big laser-armed 'battle stars,' thus in a tactical role. If you use it against, say, a spacecraft construction cageworks (i.e. 'shipyard'), then you're using it in a strategic role. But against undefended targets you don't need anything as even as semi-sophisticated as a killer bus - just release a cargo pod filled with scrap on a collision course.

In orbital combat, large scale use of kinetics could render orbits unusable - not necessarily from the kinetics themselves, if they are traveling above escape velocity, but from the wreckage of smashed targets.

Anonymous said...

Your scenario in which this bypasses laser defenses assumes that the laser destroys the bus, but that the bus then explodes as it was meant to. It is essentially based on the prediction that a defensive system designed to make the charges explode off target fails to make the charges explode of target. Well yes, if I have a system that does nothing to protect me it isn't going to protect me. But give the iron mongers their due, they are smarter than that. We've had HELRAM since 2004, and that is the exact kind of system needed here.

Your system is essentially moving artillery guns into space (yes, missile buses have an analogue in rocket artillery). Problem is that we've been working against that kind of design for quite some time. While cluster munitions may not pack as much of a punch as your 10 kg fragments, humans are much less resilient than a space cruiser. Once you adjust for scale, I see no reason to assume that the counters we are developing to protect soft and squishy infantry will be insufficient to protect an armed and armored space cruiser.

Anonymous said...

Really, for a rocket artillery to bypass an active defense system, you'd need a design so that the default was for it to explode. Tamper with it in any way, and boom goes the dynamite, the exact opposite of what you wanted to happen. Setting aside the orifice puckering that idea generates in me as one who would be working with such a munition (it could make the Forrestal look like a relaxing drill), it is rather hard to come up with such a design. The only thing that springs to mind is antimatter, and if I have a readily available supply of it I can think of many things far more useful to do with it then shoot people.

Rick said...

Anon - All I know about HELRAM is a very abbreviated Wikipedia piece, but the situations are not quite parallel, in a couple of respects.

In atmosphere, if you zap a shell and it breaks up, its aerodynamics are drastically altered, and the fragments will end up nowhere near the target the intact shell was aimed at. In space you just get a fragment cloud spreading out along its previous track - which is exactly what I want for a fragmentation kinetic.

And I picture most fragmentation kinetics as being (when intact) considerably bigger than artillery shells, and likewise much bigger than the spot size of the lasers zapping them. The defender's zaps are aimed to cripple it by knocking out key components, especially the main guidance logic and deflect motors.

The destruct circuits only need to be armed well after launch, and once armed they detect such crippling damage and send the destruct signal. (The destruct system can be networked so that no one zap knocks it out.)

Explosives are dangerous stuff, but there's no reason the destruct system would be so sensitive that it goes off if a maintenance tech looks at it funny. In fact the safety factors should be not unlike the destruct explosives used in present day space boosters if they stray off course during launch.

Luke said...

Anonymous: High explosives work because they decompose when a sufficiently strong shock wave passes through them. This adds the energy of the decomposition to the shock, and is what gives the explosive its explosion. Since any hypervelocity impact generates a pretty serious shock wave, a kinetic round with an explosive bursting charge will naturally tend to explode when struck by a kinetic missile defense round. Pulsed lasers could also detonate an explosive charge if the beam goes through (or perhaps near enough to) the explosive, for the same reason. To have the bursting charge detonate when the missile is merely being cooked by a laser heat ray, you would need to specifically fuse it to go off once it reached medium rare.

Anonymous said...

Put damage sensors on strategic places and assembles (nose, guidance, engines, ect)of your 'Killer Bus' and a negative signal detonator for your bursting charge. For all of you who don't know, a negative signal detonator causes the explosive to go off if it loses the signal to inhibit the detonator, once you've activated it.

Jam the control signal and it goes off; damage its vital components and it goes off; its timer reaches zero and it goes off; trip its proximity fuse and it goes off; its nav package says its in the right place and it goes off; if any one of a dozen or more sensors or circuts trips, it goes off...if none of them are triped, it will (probably) hit the target and make a rapidly expanding cloud of shrapnel. In the age of sail , fire ships were feared, and rightly so, but in the age of space warfare, 'Killer Buses' may well become the new fire ships.

Ferrell

Jean Remy said...

Minor quibble: if your switch is a dead man's switch linked to your guidance system, what stops me from frying your electronics with a high-power laser/maser or an EMP bomb well before it's in range, thereby forcing it to detonate prematurely? You're going to need hardened electronics and a dumb-fire option in case your sensors go black. I'd probably use a dead-reckoning navigation package.

During WWII the V1 missiles had a very simple "guidance" systems. Basically you just pointed them at a target and launched them. There was a tiny impeller in the nose and inside the missile a system to count the number of rotations. The speed of the missile being known, it was just a question of maths: at the proper rotation count the missile would angle down. Not the most precise way of hitting something, but it worked well enough.

I would equip a missile with a gyroscope and accelerometer deep in the missile body. In case the guidance package gets fried, the missile would continue on its final real-time figures, accounting for range and vector, and detonate at the predicted distance. Only if severe damage is registered, risking the total loss of the bus, then blow it up, but only as a last resort, not at the point where it becomes blind.

Citizen Joe said...

In the case of a laser ship vs. exploding killer bus, you don't need to destroy all the fragments, you only need to destroy the fragments on an intercept course. If it is a tight cloud, you just jink out of the way. If it spreads wide, you can just punch through the middle.

Of course, if you're a ship defending other things, then you do kinda need to destroy all the fragments.

Rick said...

Citizen Joe - True, you only have to punch through the cloud, not zap the whole thing. In flat space, identifying the threats is theoretically easy. But in orbital space at moderate mid-future speeds - up to dozens of km/s - trajectories are significantly curved, and picking the threats out of the clutter is tough till the last few seconds. And the last few seconds doesn't leave you much time.

A key metric in evaluating the blue/green tradeoff is seconds of unguided flight time from when laser defense cripples an incoming bus till the wreckage or fragment cloud passes the target. The unguided flight time is the interval in which you can jink, or else zap the dangerous handful of incoming frags.

If a kinetic target seeker gets within 10 seconds of you before you cripple it and force it to fragment, you'll have trouble either sidestepping or blasting through the frag crowd. If you can cripple it more than a minute out, only a jumbo kinetic, like a killer bus, poses much threat.

So, take 30 km/s as a reference speed that midfuture electric drives should be able to reach. Even small target seekers will be deadly if they can get within a few hundred km of a target before being crippled. Kinetics must be jumbo sized if defending fire cripples them at several thousand km out.

Anthony Jackson on SFConsim-l suggested a figure of merit, that the steady beam power you can put out might be on the order of 1 percent of drive engine output. Supposing gigawatt range electric drive, that give average beam power of 10 megawatts, or 600 MJ per minute, enough to burn through 12 kg of graphite.

That's not a lot of armor, so I'd say that a modest sized target seeker with an armored faceplate will be hard to stop.

With terawatt torch drives you'd expect 10 GW of zapping power, enough to burn through 12 tons of armor in a minute. But a torch missile could be coming at you at hundreds of km/s, maybe 20,000 plus km in a minute. You pretty much need X-ray lasers to stop airplane-sized torch missiles.

Luke said...

Rick: As I recall, Anthony Jackson's figure of 1% drive output for beam weapons was the minimum available beam power for torch drives using inertial confinement fusion (because otherwise, you couldn't light the torch). It would not necessarily apply to, for example, antimatter initiated microfission/fusion or Z-pinch fusion, which might have much feebler beam zappers. Also, a nuclear-electric spacecraft with a 10 MW reactor could mount a laser that took its entire electrical output at maximum firepower (giving it something like a 3 MW zapper with modern laser efficiencies, perhaps somewhat better farther in the future).

Anonymous said...

The discussion suggests an evolution of space warfare. In the early days of the first conflict, both sides have light defences (Probably against terrorists and hijackers) and the weapons are barges set on crash courses. Someone upgrades their defences to a laser/kinetic combo that can break up and deflect an incoming barge, so the other side rigs the barge into a killer bus - Essentially a mulitstage warhead on top of a barge loaded with Rick/Ferrell's bursting charge. The best defence against that is EM warfare, setting off the bursting charge before the killer bus is in range. This forces both sides to upgrade their electronic warfare systems, and we've gone from fire barges to autonomous attack craft in a series of relatively inexpensive steps. A similar evolution could turn other fire barges into Rick's lancers, and with all that lethal hardware around you need a command craft to carry the minds (Human, AI, or GMed brain in a bucket) that make the strategic decisions.

All this probably wouldn't happen in a short conflict. The designs might be in place, but if the shooting ends by Christmas then it's hard to justify building new weapons systems. Particularly when there's all that ruined infrastructure to rebuild and treaties to work around.

Ian_M

Jean Remy said...

Ian said: "All this probably wouldn't happen in a short conflict."

In fact I would say that very little weapon development is done during any war. World War II's uniqueness was that then end of the war saw a seeming technological leap, with the introduction of jet fighters and nuclear bombs. However, both these avenues of research had been initiated well before the beginning of the war. From theory to prototyping to pre-series to field testing to full-blown production, the life cycle of new weapon development is far longer than any war. The fact that those weapons (jet fighters and nuclear bombs) even saw action was an act of utter desperation from the sides that fielded them.

The Me 262 design was held back several times, notably when Hitler asked it be modified as a bomber, and it was finally crash-released as a fighter, mostly untested, and in the hands of pilots that were never fully trained on the new aircraft. It was only because it was released in a hurry and in too few numbers that it did not affect the war, because its superiority was apparent almost immediately. The allies, GB and the US, had jet fighters in the pipeline, but they were unwilling to throw such an untested weapon into battle. Because unlike Hitler they were not desperate, those jets only went past prototyping after the end of the war. Only the British Comet saw limited pre-series production, and never saw significant action.

The nuclear weapons released by the US were born in the same philosophy of desperation. The two bombs released on Hiroshima and the Nagasaki were completely different in theory and development, and were in no way production weapons. They were barely suitable for testing, but they were rushed to the Pacific front anyways. Hastily built, they were jury-rigged into their bombers, with the crew having a crash course in dropping methods, which mostly consisted of getting the hell out of dodge and not looking back once they dropped it.

All other "new" weapons, tanks, aircraft carriers and submarines, were merely advances on existing technologies from WW I, and had had the inter-war period to undergo rigorous testing before they were fielded.

Most weapon development is done between wars, not in the middle of the fighting, and only desperation forces the arrival of poorly developed weapons, and they are rarely miraculous: while the atom bomb shortened the war, it did not win it, and the Me 262 did not do Germany much good either. Although the development of space weaponry might follow the progress you lay out, most of those developments will happen between conflicts, as both winners and losers will assess the effectiveness of the weapons they did field.

Anonymous said...

"Most weapon development is done between wars, not in the middle of the fighting, and only desperation forces the arrival of poorly developed weapons, and they are rarely miraculous: while the atom bomb shortened the war, it did not win it, and the Me 262 did not do Germany much good either. Although the development of space weaponry might follow the progress you lay out, most of those developments will happen between conflicts, as both winners and losers will assess the effectiveness of the weapons they did field."

Most innovations developed during one war show up in the next...many times changing the way that next war is fought; take jets and missiles for example. Wars in the 50s and 60s were fought the way they were due to developements during WWII. I don't see the way space-warfare developing as any different.

Ferrell

Jean Remy said...

As I said, those weapons (jet fighter and nuclear bombs) were under development from before the second war and actually the research started in the inter war period. Yes once a weapon is fielded in a war the deigns will change again. That's the part called field-testing.

For example after the Koran war--where missiles saw tentative first uses--the USAF thought guided missiles would be the end-all of aerial warfare. In Viet-Nam they discovered that they were a lot less accurate than predicted. The F-4 Phantoms, which were a missile-exclusive weapon, were retrofitted with *guns* to dogfight the MiG-15 because the slippery buggers could ditch guided missiles too easily and the had to be shot down. After Viet-Nam they went back to the drawing boards and redesigned the missile guidance systems, culminating with the likes of the AMRAAM and even the Phoenix which could shoot a fighter down at 300 miles. Yet the F-14, which mounted said Phoenix, was still armed with a 20mm cannon. Lesson: learned.

My point was exactly this: each war shows us how weapons behave under real conditions. In the pause between wars, the weapons are redesigned for the next war. The development process is long, as in decades long: new weapons need to be theorized, researched, prototyped, tested, modified, re-tested, pre-serialized, field-tested (that's where the wars usually come in) re-modified, re-tested and finally actively produced. Never has a conflict seen one entire cycle, never mind several cycles of development.

The cynic would say wars are declared really just to test the shiny new weapons that were built during peace-time.

Anonymous said...

That's the modern pattern of constant tech R&D, but there's no guarantee that future politics or military procurement will support it. Right through the First World War military development worked on (Roughly) the pattern I described: Making it up as you go along. This is probably the typical pattern for technological plateaus - Eras of incremental technology change rather than our divergent era of rapid development and deployment. Singularitans aside, there's no real reason to believe our current pattern will continue into the future. All of the weapons systems we're talking about could be built with current technologies if we really needed to.

Our current rapid R&D/deployment cycles are also political, a continuation of the 20th Century's post-First World War arms escalation. Political regimes that valued stability over brute-force statecraft could put military development behind terraforming, developing the outer system's resources, or make-work projects on Earth.

This takes us to the point that we need to know what the political system is, what resources they have, and what they consider worth fighting over before we can really argue over the 'best' weapon systems. Otherwise we're just redeveloping current doctrine (Aircraft carriers, smart missiles, and drones) for space.

Ian_M

qwert said...

I would say concepts for new weapons are born only during wartimes, it is after the war when they are improved and set ready for the next war, where they will be decisive:
Tanks were entirely developed during WWI. And Allied forces fielded them in important numbers at the end of the war. Of course it was not an important weapon until the next big war.


About killer-buses: Interesting idea. It seems to be some equivalent to a modern day long range antiship-missile. Wheter it will be an important weapon will depend on multiple variabels.
I think pure warships will have at least some use: How do you hold your recently adquired "territory", after all you may want to be able to use space as safely as possible while at the same time negate acces to it to your enemy.

Rick said...

Luke - Good points about drive power and beam power. I forgot that an externally powered electric drive could indeed put its full reactor power into the laser, and get a fair fraction of it as zapping power.

Power density limitations - i.e. not wanting to melt your laser - mean that a laser installation like that would be pretty massive, and surely keel mounted.


On wartime tech developments, I can see an upcoming blog post here. A couple of points I'll add to the mix. In World War I new aircraft were sometimes developed and deployed in a matter of months. In the earliest stages of a military tech you are more or less throwing things together off the shelf, so crude weapons could proliferate quickly.

And taking up on what Ian said, in the 19th century military tech followed rather than leading industrial tech. So it is not just a matter of mature techs. I agree that military procurement won't necessarily follow the patterns we've seen in the last century. There's a wide zone between everyone singing 'Kumbiya' and intense 20th century style militarism.

Turbo10k said...

Previous comments-WOW! If kinetic warfare at long ranges leads to an escalating frag vs frag conflict, it could easily turn into two WWI biplanes trying to dodge clouds in a storm :/

Rick-Electric Ion drives being used as powerplants for a laser is another example of redundancy that Hard Sci-Fi likes.
However, in a midfuture setting, where torch drives are used, I'd see kinetic weapons as more of a 'military thing' than lasers. A cargo ship just hooks up its drive to a laser and presto it has a MW weapon. Kinetic missiles are HEAVY, cutting into Delta v budget and the merchant's pockets. Economically, a KKV bus is more akin to a Tomahawk strike today (if you get my drift), than an AMRAAM.

I see my KKVs not leading into larger and larger spreads of shrapnel, covering a larger and larger area, but into more and more precise impactors.
Example:
-THE BURN STAGE:The initial bus sent from the warship is a nuclear thermal rocket that increases its temperature until maximum acceleration/drive meltdown. This gives the whole bus say +10km/s relative to launch craft.
-THE EW STAGE:This divides into say 10 missiles each with a targeting system that does up to 10 course-correction burns before splitting into 100+ shotgun-rockets.
-TERMINAL STAGE: The resulting 1000 little rockets (1 meter each, 200kg) are all travelling at roughly the direction of the trarget. Those too far away explode and release their shrapnel anyway into a sphere. Those within the manoeuvre cone do a final correction burn and explode.

There!

Siloxr said...

I know it's an old post, but it got me thinking:

Seems like it would be more cost effective to just grab up asteroids, drill some optimum expansion pattern into it, pack it with explosives, then use some sort of space dumptruck to accelerate it to speed, rotate, drop it, and accelerate away. You get to keep your dumptruck and the presumably more expensive portions (and the ones that don't want to die) like practically all of the electronics, drive systems, and the hull, but still have a lot of KE hurtling at some target with a method for increasing the area of affect--which can easily be tailored via the locations and depth which you choose to drill, power and location of explosives, along with the detonation time and sequence.

A more elegant version could be instead of hauling in asteroids (or hunks of an asteroid), pull in modules that I figure would be shaped similarly to cone with a rounded bottom...or maybe a hemisphere on a stick. The rounded part points toward the target and is made out of some high density material in a frangible design (like pineapple grenades). This part is filled with explosives. The back portion is filled with electronics and attitude/yaw thrusters (mayhap just slap like a solid fuel drive on it so you can milk a little more acceleration out of it if maneuvering is not necessary and use thrust vectoring/displacement for yaw/attitude adjustments). With some relatively simple target tracking software, you can greatly expand the potential area of effect just by tracking any acceleration of the target before blowing it up to make your shrapnel death cloud.

Additionally, depending on how many of these are available, you can stagger launches to make the depth much greater, so instead of having a lot of shrapnel flying off in most all directions only putting a small fraction on target, you have a smaller, better directed area of effect, many times over. Additionally, think of the additional trouble for running point defense. Maybe you have the first one blow up at an earlier point than the rest are intended to: now point defense has to track all of that, plus the coming threat behind it, and when each one blows up, it further compounds the problem. But as you said, the killer bus is something that was envisioned as an inelegant, quick, fast, and dirty solution.

Hrm...you also could get a little of this effect with your killer bus too. I figure bulk carriers for many materials would be far more akin to a barge and tugboat arrangement than a modern container ship--especially for raw material transport and for items that being exposed to vacuum does not bother--why waste the energy and mass it takes to keep them pressurized? But if such is the case, depending on design(specifically, where are the engines), it might easily be possible to, while accelerating towards the target to release sections and allow momentum to take care of things. Additionally, as you're dropping off large hunks of the mass your engines are moving, you're going to be increasing your acceleration. If I'm not mistaken overall KE should remain about the same even though the earliest dropped off bits'll have a much lower KE than those that are under drive until the end, but with this, you've got the possibility of the higher speed section fragments doing enough damage to weaken point defense for the following, lower speed waves less defensive capability to deal with.

Rick said...

A rather belated reply - welcome to the comment threads!

The killer bus concept that I outlined here turned out to be less than optimal. In a nutshell, I was not considering the possibility of small guided target seekers.

These are almost certainly more cost effective than throwing a mass of unguided rubble, because a substantial proportion will hit unless actively engaged. Whereas most of the rubble will miss.

The individual target seekers might well have something like the cone configuration you outline, for the reasons you give.

So I would expect a more effective killer bus to carry a payload of target seekers. You might be able to release the target seekers and recover the bus - though delta v considerations often will rule this out.

In that case you might as well put a small bursting charge in the bus as well. If you're expending it anyway, why not produce a clutter of fragments to complicate the defense's life? But the guided target seekers would be the primary threat.

Rick said...

I should have added that the errors in this post are covered in a subsequent post in the Space Warfare series.

One of these days I'll even update this post with a link!

Isaac said...

A thought I had with the killer bus scenario is the addition of a nuke.

The killer bus would be fired from a ship already going incredibly fast, and would be guided in towards the enemy. After an initial explosion bursts open its payload (hundreds of guided soda cans, possibly with additional rubble), spread across the general trajectory of their ship, a nuke, left near behind, would go off.

While presumably ships would be well protected against radiation, the blast may damage some of their sensors. What it would certainly do is up the background radiation behind the incoming payload, so as to make it essentially invisible.

The payload would then home in, immune to point defense; being small, erratic, incredibly fast and coming out of what is in essence a sun.

This, instead of camouflaging the missiles, camouflages the background to match them. Multiple killer buses, some with nukes, some without, compound the problems for defense - as you would have to destroy not only the stuff that will hit you, but also the stuff that will get near, as any of it could be a nuke about to blind you in a crucial moment.

Blinding nukes in combination with kinetics I think really alters the balance in favour of kinetic armament, especially as I can't think of a suitable countermeasure.

Also, maybe you could use a nuclear blast to hide your own ship behind? Pockets of radiation that mask your signature (or your shutter) could be really useful, and would liven up empty space.

Feel free to shoot me down (heh) on any of this, everyone here seems to know waayy more than I do.

- Isaac

Isaac said...

Also, a question about killer buses. If they are to carry guided munitions, why not just fire the guided munitions without the bus, and cut out the middle man?

I get how cool it is to have missiles that explode into missiles that explode into more missiles, but I don't see why its more efficient to spend fuel accelerating a group of missiles in the form of a bus, than accelerating them as a group of individuals. It's been mentioned that fuel only needs to be proportional to the total mass.

Maybe on a bus you could get a larger more efficient drive , but then you're carrying drives for the second or even third stage as well, rather than each missile only carrying what it needs. Maybe you could fit a better guidance system on a bus, but it seems to me that the bus only gets you near the enemy, which is the easy bit, making an advanced system a bit useless. I imagine a group of missiles having some sort of hive mind, with constant tight-beam information exchange and shared processing power.

Firing the missiles as a group of individuals makes them harder to track, and harder to hit. It also allows you to spread out your trajectories further, casting a wider net to kill them with.

As we've decided that shattering isn't that useful, with most fragments inevitably missing the target (making it a waste of fuel to get them there), a killer bus seems to me to be an easy target for a counter-kinetic. They hit a bus with a cloud of flak and all of its munitions will probably get hit too - its an 'all your eggs in one basket' scenario. Spread out your net and they have to track and defend a much larger area.

Nonetheless it does seem a shame to stick a pin in a really cool idea. But then again, isn't thousands of guided missiles arcing through space, dancing to avoid point defence, in an all out mass wave to totally overwhelm the enemy , cool enough?

Byron said...

Siloxr:
Trying to use an asteroid in that manner is harder then it sounds. For starters, it's not a controlled, engineering piece of material. You literally cannot know exactly how it will fragment. You can guess, but there's still a decent bit of uncertainty. It's also not balanced, which makes moving it hard, and rock is not a great material for penetrating things. And all of this assumes that there's a conveniently-placed asteroid available. Proper kinetics will be cheaper when all is said and done.
The problem with the killer bus, and all shrapnel methods, is that explosive charges will tend to scatter the shrapnel at hundreds of meters per second. That in turn means that the cloud will spread out too much in the course of a few seconds, and that detonation range will have to be much shorter then might be preferred.

Isacc:
The nuke is likely to do more damage to the projectiles then it is to the ships. Assuming that the enemy has some sensors left undamaged, you're not that much better off then you were when you started, because in space there is no fireball, and the flash is over in something like a tenth of a second. The nuke will have to be quite close to do any sensor damage at all, and when I say quite close, I mean probably no more then a few hundred kilometers, well within the range of the ship's defenses.

Also, a question about killer buses. If they are to carry guided munitions, why not just fire the guided munitions without the bus, and cut out the middle man?
The cost of propulsion systems. A killer bus as described here (which is, BTW, an obsolete concept) uses a nuke-electric drive to get delta-Vs impossible with chemical rockets. Even for tactical chemfuel missiles, the economies of scale are quite strong, so the SCODs would probably be bussed. Carrying the empty booster would be a major problem, so staging is required, and a single large engine weighs and costs less then a dozen or more small ones.

The kinetics themselves are not likely to be that maneuverable, dodging and weaving as you describe. That costs fuel, which drives up the mass of everything. Better to just use that mass (and the resulting costs) to throw more SCODs. And the missiles are likely to burst early enough to avoid the worst of the counter-missiles. On space scales, even low chemfuel accelerations are more then enough to get the missile up to speed before the CMs get it.

Kurt said...

In the book series centered around 'The Lost Fleet' (Jack Campbell) the concept of /BFRs/ use against orbital platforms is discussed, rendering the whole concept of these giant defensive satellites moot because they cannot readily change position to evade even Big Rocks thrown from half a system away (where closure to system primes was dictated by Lagrange Radials). Such would not be the case for ship to ship combat and even a 5km/sec dispersion pattern would be minimalistic because: A. The ship would only have to evade the pattern closest to it's chosen path and even nuclear armed warheads in the frag pattern would be meaniningless.
B. The ship can likely generate more DV than any 'brilliant pebbles' can impulse-muster.
C. The ship will likely hover behind a convenient moon or go GEO to ensure it is always got the planet between it and the majority of any aerospace defenses.

Finally, the reason you don't glass planets with orbital NGS is because you cannot economically afford to.

There are too few unistar systems with planetary life belt worlds that are M class and it costs -way- too much to ship hard goods to non-habitable systems just to make them happy. You have to conquer worlds intact for population expansion or whatever reasons. And that means you bring your war with the intent of occupation, not annihilation. Conventional visions of economics fall down on their thermodynamic faces at interstellar distances because the profit-from-waste motive inherent to transport of manufactured items as opposed to just plans and automan technology to make whatever consumer goods -on site- is just short of laughably obvious.

Люси Сорью said...

Necroposting again: seeing how the discussion in space fighter threads went, I can't possibly see how a nuclear electric drive-equipped killer bus could even be -considered- as a viable weapon, while nuke electric fighters were rejected outright? I'm not seeing too much difference between the two.

As to kinetic battlecruisers derisively mentioned in the post, modern naval warships practically ARE rear-echelon combat platforms. SOP for Russian missile cruisers in case of shit hitting the fan was to expend ALL of their missile loadout (20 Granit ASMs on Kirov-class battlecruisers, 12 on Slava-class CGs) in a single first salvo designed to break through an American carrier battle group's defenses. Of course, there would have been some bombers added to the mix to saturate the defenses.

My point is, what's the difference? A modern Aegis-equipped warship practically IS the rear echelon sensor and command platform. In a hypothetical all-out engagement it would probably expend all of its anti-ship armament in a single salvo. Of course, modern warships put a huge emphasis on air defense, which doesn't leave them nearly as useless, but can't space warships do the same?

Anonymous said...

Kind of necroposting here...personally I'm not so sure about the "killer bus" concept. You want to make sure that
Your craft survives until, say, a light-minute or less away from its target, or boom, they change
Inclination and your kinetics sail past them like a bunch of rocks. Literally, in most cases.
This goes for planetary installations as well as interplanetary space. It's crazy to try to launch enough material to blanket a whole planet, so you'll be aiming for a target orbit. If they change it, and your bus is disabled, your weapon simply burns up in the atmosphere.

So we want to keep the propulsion going for a long time. We could protect it by embedding it in the weapon mass and installing PD - we have to install PD at some point - over the craft. We'll also need a command craft within reasonable range for decision-making.

But wait! Now we have to throw away a point defence system and sensors as well as the kinetic mass! Maybe we could keep the PD and sensors on the command ship? And have the command ship closer by? Here lies the fact of reusability - if your survival : Losses ratio is greater than the ratio of the reusable ships cost : The one-use ship cost ratio, you're saving money. And that means as long as you keep survival rates up, you can spend a little on better systems. Look at the shuttle, for example. It could use fantastically good - and similarly expensive - main engines because they reused them. We could do the same in our spaceship, adding better PD and sensors. In fact, come to think of it, rocket engines are expensive. Why not put them on the command ship too and have the kinetics separate from it at the last- wait a second, we've just built a missile ship.

Of course, this isn't a classic missile ship- the kinetics will likely be lumps of matter, tens of centimetres in radius, that have to be completely burnt through to eliminate, compensating for the lack of guidance with sheer mass and number. The ship separates from them around ten light-seconds away after placing them on a collision course. Effectively, we've recreated your very own dive-bombing Lancer craft. They'll essentially be giant masses of kinetics with crew compartments, sensors, radiators, PD and engines stuck around them.

There are two ways to go about this - either better, reusable ships with a higher initial purchase price, or cheaper, crappier ships with low purchase prices. It comes down to strategy - if you're conducting large, one off attacks, you want cheaper, one-use ships because reusable ones won't earn back their cost. If you conduct more frequent, smaller attacks, you can operate a smaller fleet of reusables and they'll save you money eventually.

With the second option, you have to take into account new technology. Common mounts may be useful to filter old technology to less important ships to save money, while replacing them with newer tech on your important ships. It's a bit of a common ground between

As with many things in space, it depends entirely on your mission.

Rick said...

There's no such thing as necroposting! Though I apologize for very belated replies!

Lucy - To me the basic difference between a space fighter and a comparable size kinetic bus is that the fighter carries a pilot, who you expect or at least hope to recover (along with the rest of the fighter, usually).

But unless the pilot adds to effectiveness - and I don't think so, for this mission - why risk trained pilots? Use an expendable bus. If it can just launch submunitions and return to base, fine, but if you expend it, also fine!

Your point about missile battlecruisers is valid! There are reasons to put kinetic missiles aboard the same ships that serve as sensor/support platforms. But in the space context it may not be inevitable, especially perhaps in lower intensity political/military environments, such as sprawling trade empires, etc.

Anon - truth to be told, I ended up rejecting the killer bus concept not long after I posted this. (See comments above, and I think I discussed it in a later post of the Space Warfare series.)

I think that, to generalize on your point, there is some balancing point between the fancy, expensive stuff that you try to recover for reuse if possible and cheaper stuff that you expend as ammo. But specific tech factors will determine where that dividing line will be. At one extreme, your entire military procurement is 'ammo'. At the other extreme, you expend only slugs - or photons!