Fun With: Powered Armor & Tanks

[Admiral Valdemar]

WTF? The ablation issues with railguns are enormous, and the main reason they haven't been fielded yet, and Rhoenix is proposing higher muzzle velocities for his infantry weapon than current naval/artillery-scale prototypes can achieve.

Relatively. I didn't say they were non-existent, just low enough to be at the stage where larger calibre weapons can be considered and are. Newer materials on the horizon will make this less an issue more so, hopefully.

Why do you believe railguns produce higher muzzle velocities? If anything it should be the reverse.

Because the people I talked to on the subject said so? There's only so fast a magnetic field can be switched. Railguns suffer not this issue and are far simpler. There's also a reason the militaries of the world are looking at railguns today for the near future and not coilguns.

[Starglider]

Because the people I talked to on the subject said so?

With current technology this is true for practical barrel lengths. However the basic physical limits on coilguns are less restrictive than those on railguns.

There's also a reason the militaries of the world are looking at railguns today for the near future and not coilguns.

The basic reason railguns are much closer to being fielded is that we don't have room temperature superconductors. Most soft sci-fi settings (and some hard sci-fi settings) do.

[Admiral Valdemar]

Okay, assuming those technologies come by, then the would be a good bet. I thought we were discounting superconductors of that nature here though, my bad.

[rhoenix]

Based on the three links Starglider kindly linked to earlier as well as the input from those who replied, I'm revising further:

- No Repulsors. They have too many restrictions anyway. I'll quote from the site to describe "shrouded fans:"

There is an alternative, something much better for this use than either jets or rockets. Shrouded fans, driven by electric motors designed to provide high output for short durations, would be nearly ideal. There is almost no heat signature from such a system, much less noise than from either alternative mentioned above, and even the dust raised is less, since the downblast is spread over a larger area. This system would require a sizeable amount of power in brief pulses, but that could be supplied by one or more superconducting loops, as described above. The blades could windmill during descent, not only partially recovering the energy spent but slowing the suit, in much the same way as a maple seed pod or an autogyro makes a gentle landing. In the last part of the descent the motors power up again, cushioning the landing.

This would be much better for my uses than even the repulsors considered earlier. However, they have the disadvantage of only working where there's air to use.

A solution arises, though - having a more modular design so that different means of mobility can be attached pre-mission, allowing for rapid movement in a more specialized fashion depending on the environment expected.

- I'll stick with the graser and coilgun for the standard weapon, but discussions regarding those two guns, as well as the ramshell launcher Starglider pointed out have made it clear that having only one weapon choice for users of this armor will not work, and should have more varied weaponry for different uses.

The dual-barrel coilgun & graser could be the standard heavy sniper rifle, whereas a larger ramshell launcher would be the equivalent of a rocket launcher, much more so than the coilgun. The coilgun is more accurate, but the ramshell launcher would have a larger area of effect, and possibly a more powerful impact.

As for the caliber of shells, as I'm not very familiar with calibers, I wouldn't be able to say with certainty. I'd imagine it'd be roughly twice as large as a standard shotgun shell of today.

In addition to this, I think the coilgun would be the better choice to fire the jamming shell or the sensor shell Sea Skimmer described. The ramshell launcher, from what I can gather, doesn't look capable of varying the speed at which a shell is fired, other than with less or more propellant in the shell.

[Starglider]

I'll quote from the site to describe "shrouded fans:"

Note that current designs along these lines look like this;



You might get the fan diameter down a bit (to say 30cm), but they're still going to be huge bulky things. Presumably you're going to have them fold up against the back somehow.

A solution arises, though - having a more modular design so that different means of mobility can be attached pre-mission, allowing for rapid movement in a more specialized fashion depending on the environment expected.

Well at least you won't have to lug a flight system around for missions where it isn't useful (e.g. clearing enemy bunkers).

The dual-barrel coilgun & graser could be the standard heavy sniper rifle,

Dual barrel? That's going to be very heavy. Do users really need to switch between one weapon type and the other that quickly? If the suit is strong enough, you could have one weapon slung under each forearm and have the servos do the fine aiming. If it's being fired from the shoulder like a normal rifle you'd be better off having two seperate guns, one of which can stay in a back holster when not in use. Or more sensibly, you could have some of your squad carry one weapon and some of them carry the other weapon. Remember that a combined coilgun/laser weapon will be at best half as powerful in each role as a dedicated weapon of the same mass.

The coilgun is more accurate, but the ramshell launcher would have a larger area of effect, and possibly a more powerful impact.

A combined coilgun/ramshell weapon is somewhat more practical. At least it could in principle be built with a single shared barrel.

I'd imagine it'd be roughly twice as large as a standard shotgun shell of today.

You cannot simultaneously have high calibre, high velocity and high rate of fire without running into insurmountable recoil and stabilisation issues. A 12 gauge shotgun has an inner diameter of 18mm; 36mm is the kind of calibre you would find on IFV cannon. There is no way you can fire a shell like that at mach 12 without flung backwards by the recoil.

The ramshell launcher, from what I can gather, doesn't look capable of varying the speed at which a shell is fired, other than with less or more propellant in the shell.

The propellant is pre-injected into the barrel, not in the projectile, but I'm not sure if you could practically vary the velocity without screwing up the ramjet combustion.

[Beowulf]

Couple notes:

You want your guns to be lightweight. Heavy guns are harder for troops to schelp around and fire.

A 10kg power suit is much too lightweight. You might as well not even have exoskeletons and such at that weight.

A laser of sufficient power to damage a target is going to ionize the air in it's path regardless of what wavelength it's running at.

A canister type round isn't strictly necessary if you also have shrapnel. You could just set the fuse on the canister to go off immediately upon leaving the barrel. Might be a bit less effective, but simplifies the logistics enormously.

A shell that's twice the size of a 12 gauge shotshell would be enormous. A 12 gauge shot shell is already almost 3/4 in. in diameter. Also, 12 gauge slugs aren't close to being the right form factor. Better off with a 6.5mm to 12.7mm round. Maybe up to 20mm at the limit.

Something to note is that at these high powers of weaponry, you will have guns capable of knocking people off their feet. You'll need to figure out some way to stop that.

[rhoenix]

You might get the fan diameter down a bit (to say 30cm), but they're still going to be huge bulky things. Presumably you're going to have them fold up against the back somehow.

Actually, that's just fine, and was my first solution for it. However, not to get into mech territory here, but would this sort of flight system need wings for better flight, or could one direct the flight just fine with only small directional changes of the fans?

Remember that a combined coilgun/laser weapon will be at best half as powerful in each role as a dedicated weapon of the same mass.

You have a good point there.

The way this is developing, it actually looks better for this rifle design to have the ramshell launcher as an undersling for the graser rifle, and leave the coilgun as a dedicated heavy weapon.

As the coilgun approaches bazooka size though, it looks more and more likely that one would need some sort of powerful artificial stablizing mechanism as well, or the user would get an involuntary flying lesson backward.

I'd imagine it'd be roughly twice as large as a standard shotgun shell of today.

You cannot simultaneously have high calibre, high velocity and high rate of fire without running into insurmountable recoil and stabilisation issues. A 12 gauge shotgun has an inner diameter of 18mm; 36mm is the kind of calibre you would find on IFV cannon. There is no way you can fire a shell like that at mach 12 without flung backwards by the recoil.

This is the other reason for the possibility of the change above - having the coilgun be a bazooka-type heavy weapon that you need to brace for.

[Starglider]

Getting back to the original topic, if you can armour the surface of this suit with material that has about 40 times the protection/weight ratio of current state of the art body armour, then it seems reasonable that your tanks would have armour roughly 40 times as effective as well.

So what weapon would we use to kill M1s if they had the equivalent of 24 metres of RHA on their front facings?

[rhoenix]

You want your guns to be lightweight. Heavy guns are harder for troops to schelp around and fire.

A 10kg power suit is much too lightweight. You might as well not even have exoskeletons and such at that weight.

These two points together seem to suggest either single guns, or a heavier suit to account for the enhanced exoskeleton and such.

A laser of sufficient power to damage a target is going to ionize the air in it's path regardless of what wavelength it's running at.

That's fine. It won't affect the beam unduly at closer ranges, anyway.

A canister type round isn't strictly necessary if you also have shrapnel. You could just set the fuse on the canister to go off immediately upon leaving the barrel. Might be a bit less effective, but simplifies the logistics enormously.

That would be an excellent short-range shell.

A shell that's twice the size of a 12 gauge shotshell would be enormous. A 12 gauge shot shell is already almost 3/4 in. in diameter. Also, 12 gauge slugs aren't close to being the right form factor. Better off with a 6.5mm to 12.7mm round. Maybe up to 20mm at the limit.

Something to note is that at these high powers of weaponry, you will have guns capable of knocking people off their feet. You'll need to figure out some way to stop that.

Yes - I hadn't seen your post when I thought the coilgun might be better as a bazooka-like weapon that needs to have something to stabilize it.

===

Getting back to the original topic, if you can armour the surface of this suit with material that has about 40 times the protection/weight ratio of current state of the art body armour, then it seems reasonable that your tanks would have armour roughly 40 times as effective as well.

So what weapon would we use to kill M1s if they had the equivalent of 24 metres of RHA on their front facings?

As you mentioned on IM - "nuclear shaped landmines."

[rhoenix]

Further revisions, based on discussions with Starglider in the chat:

- Graser rifles and coilgun rifles are now separate. The coilgun rifle also is an effective launcher for bombs, particularly the fusion type.

- Size of the suit has been increased to adding 20cm to the wearer's height, and about 80kg total in weight.

- Possible weapons right now are three - the coilgun/launcher, the graser rifle, and the heavier ramshell launcher.

[Admiral Valdemar]

Have you not factored in smart munitions and nuclear weaponry as a standard load out? If you're able to get grunts suits of this calibre, then expense and technical know how are not major burdens, which means having mini-guided missiles or tactical nukes as standard can't be too big a stretch. If armour cannot keep up with firepower and stealth is a no go, then having an active defence system helps. You could even just use the graser or coilgun system slaved to your suit's sensor suite so that should you find an ATGM popping over the horizon, you don't waste milliseconds thinking about it and you just have the suit target and dispose of the threat like a compact point defence system. It won't work perfectly all the time for all threats, but it should enable greater survivability without excess armour.

And for a suit like this, I'm thinking over 100 kilos at least. I weigh 65 kg and I'm a lanky bastard. I can't see an all environment exoskeleton weighing less than my work backpack. You'll need extra mass even if you did have such lightweight materials, just to help counter recoil issues.

Additionally, what damage controls does it have? If you lose an arm in hard vacuum, you may notice it even before the shock wears off. Does it constrict the limb and supply analgesics? Would this seriously hamper the control systems and are they neural linkages via the cranium, or are they electro-muscular control based?

[Connor MacLeod]

If these suits are becoming so powerful, wouldn't it just make more sense to take the human out of the suit and make them remotely piloted/controlled drones/robots?

[rhoenix]

Have you not factored in smart munitions and nuclear weaponry as a standard load out?

Quite honestly, I hadn't before, and am starting to now. I had assumed the coilgun shells would be "smart" bullets, having their own thrusters for course-corrections even possibly, but hadn't given nuclear armament thought until brought up.

If you're able to get grunts suits of this calibre, then expense and technical know how are not major burdens, which means having mini-guided missiles or tactical nukes as standard can't be too big a stretch.

That does make sense.

If armour cannot keep up with firepower and stealth is a no go, then having an active defence system helps. You could even just use the graser or coilgun system slaved to your suit's sensor suite so that should you find an ATGM popping over the horizon, you don't waste milliseconds thinking about it and you just have the suit target and dispose of the threat like a compact point defence system. It won't work perfectly all the time for all threats, but it should enable greater survivability without excess armour.

Well, I was considering "stealth" capabilities, but they would be tapdancing into handwavium territory again somewhat. From my earlier notes - thermal matching (handwavium), and chameleon-skin.

As for auto-tracking and firing, I do like the idea, but I don't see of a feasible way to do so, since the weapon carried would be a gun, and not a turret on the suit - would you mind elaborating?

And for a suit like this, I'm thinking over 100 kilos at least. I weigh 65 kg and I'm a lanky bastard. I can't see an all environment exoskeleton weighing less than my work backpack. You'll need extra mass even if you did have such lightweight materials, just to help counter recoil issues.

You do make a good point about the recoil issues - to have a much better chance dealing with the coilgun, a heavier suit would be able to withstand the unholy kick of that thing.

Additionally, what damage controls does it have? If you lose an arm in hard vacuum, you may notice it even before the shock wears off. Does it constrict the limb and supply analgesics?

This is an excellent point, I hadn't thought much about this one yet. Within the confines of the tech so far, I would say it constricts the limb and supplies a limited supply of certain drugs, yes.

In the case of a limb getting wholly blown off, the edges around the hole would have to be sealed quickly - do you have any suggestions on this count?

Would this seriously hamper the control systems and are they neural linkages via the cranium, or are they electro-muscular control based?

They have brainwave-reading sensors that respond without need of a true cybernetic linkup once they "learn" the user's thought patterns, and a two manual systems as a backup that the suit uses until the brainwave-reading sensors acclimate to the wearer, and also in case of emergency.

[rhoenix]

If these suits are becoming so powerful, wouldn't it just make more sense to take the human out of the suit and make them remotely piloted/controlled drones/robots?

Actually, this power armor started rather wanky, admittedly; but as it's refined, it's losing the wanky baby fat and taking shape into something very interesting.

It also gives good suggestions on what the drones will have and be capable of, since they usually go in en masse in front of the humans wearing this power armor.

[Ford Prefect]

If these suits are becoming so powerful, wouldn't it just make more sense to take the human out of the suit and make them remotely piloted/controlled drones/robots?

That would be dependant on the state of computer technology, and how well it can make decisions should communication with its control centre become jammed. It shouldn't be too hard to come up with a reasonable set of autonomous functions that could protect the armour in case remote control is lost. Unless of ocurse they're managed by fully fledged AI, or 'uploaded' personalities.

[kinnison]

Mind if I throw in my 2¢ worth here?

Your projected technology has grav generators and extremely advanced computer tech, with brain-computer links as standard.

The forcefields and grav repulsors imply control and understanding of gravity, which (this is a bit more of a stretch) implies that the physics and engineering of your setting includes control of "Theory of Everything" level phenomena. (You are turning, presumably, electricity into gravity, and what I mean is the stage beyond Grand Unification Theory - which only joins strong, weak and EM forces - this setup throws in gravity as well).

The recoil problems can be solved rather neatly by having the coilgun weapon include a focused gravity generator - in other words the recoil is spread over an entire planet instead of into the user's shoulder. In fact, as an extension of this, the launch mechanism could be gravity-based as well. Which allows non-metallic projectiles as a bonus.

With the degree of miniaturisation your setting has, possibly the projectiles could be something exotic as well - perhaps the warhead is based on GUT-scale energy release (call it a vacuum energy warhead if you like!)

In addition, it may be possible, also, to make the suit not a remote-controlled drone - but one controlled by a personality upload inside the suit's CPU. And, by the way, with good control of gravity why do there have to be any problems with accelerating as fast as you like?

So what do we end up with? A fleet of human-shaped, roughly human-sized, sentient AI battle droids with weapons firing projectiles capable of vapourising mountains at the very least. (I remember reading that there is enough latent vacuum energy in a space the size of a teacup to evaporate Earth).

And they'd be cheap, too - all the above implies nanotech is routine.

All I can add to all that is that I'm sorry for the planet these things are fighting over.

[Starglider]

Quite honestly, I hadn't before, and am starting to now. I had assumed the coilgun shells would be "smart" bullets, having their own thrusters for course-corrections even possibly, but hadn't given nuclear armament thought until brought up.

At the velocities these things are going fins will outperform any plausible thruster system, in terms of maneuverability-for-mass. They probably already have fins for stabilisation anyway, since spinning them up with EM is complicated, wastes power and doesn't work well with really narrow projectile diameters.

From my earlier notes - thermal matching (handwavium), and chameleon-skin.

Thermal matching, as in refrigerating the surface of the suit, is quite practical if you already have neutrino radiators.

As for auto-tracking and firing, I do like the idea, but I don't see of a feasible way to do so, since the weapon carried would be a gun, and not a turret on the suit - would you mind elaborating?

I'd got for some short range defensive mini-missiles rather than a gun system. Unlike a tank, an infantryman is probably only going to have to deal with one or two incomings in any given battle. Missile systems give superior performance for a given mass as long as you can handle a low number of reloads - current US ships are phasing out point defence gatling guns in favour of point defence missiles. The mini-missiles can stay in vertical launch cells on the back of the suit (which is getting pretty crowded) until needed.

[quoteIn the case of a limb getting wholly blown off, the edges around the hole would have to be sealed quickly - do you have any suggestions on this count?[/quote]

Flash-cauterisation. Via lasers or a ring of thermite. Hey, it's better than bleeding to death. Probably.

They have brainwave-reading sensors that respond without need of a true cybernetic linkup once they "learn" the user's thought patterns,

Note that your suit had better be a farraday cage (i.e. form a complete conductive shell) or this would be horribly vulnerable to EM pulse in particular and EM interference in general.

[Feil]

In the case of a limb getting wholly blown off, the edges around the hole would have to be sealed quickly - do you have any suggestions on this count?

A completely amputated limb will spurt a couple times, then quickly cut off bloodflow to a slow ooze as shock cuts in. Ideally, each artery would be tied off or fused. The amputated limb and the soldier should be immediately evacuated to a hospital capable of reuniting one with the other. Consider: a field dressing full of insect-sized robots (which should be far more efficient than any nanomachines), or some chemical or biological agent which induces semimagical clotting speeds a la 40k Space Marines.

[Admiral Valdemar]

The body's own damage control systems will stop blood flow, but you've still got a hostile environment to deal with, so a protective covering like a nanopaste that hardens around the area after being electrically cauterised would be best. I was also thinking a mini-VLS system as Star mentioned for defence. Missiles could be pen sized given the range and technology progress with MEMS and so on. They need only be small shrapnel charges or KE for taking out threats of a certain size.

If the gun was turreted, rather than being held by the manipulators, then it could be used automatically too without harming the user's limbs. Should mounted or hip mounted would be suitable given reasonable sizes. The larger coilgun and grasers would be the best part of a couple of metres long, so you'd need to carry those traditionally anyway.

For IR signatures, I always liked the reversible computing concept where cryo-arithmetic engines essentially "compute" heat down to a tolerable level. No idea how this can be applied any time soon, but the effect is real if you can make such things work and it doesn't rely on vulnerable heat exchanger fins on the suit etc. This is a wee bit magical for the more grounded in near-future tech suit here.

[Starglider]

If the gun was turreted, rather than being held by the manipulators, then it could be used automatically too without harming the user's limbs.

The problem is then you're got the mass of the powered mount /plus/ the mass of the manipulators, since you still need the later for clearing rubble, forcing doors, digging field fortifications, grabbing hostages etc (otherwise why would you need infantry at all). You've also got more structural/support mass.

However depending on the graser tech it may be practical to mount the graser beam generator vertically on the back and just have a little pop-up laser turret over the shoulder - there's no such thing as a gamma ray mirror in real life but it may exist in this setting.

For IR signatures, I always liked the reversible computing concept where cryo-arithmetic engines essentially "compute" heat down to a tolerable level

This does not work for waste heat from other systems. All it does is reduce the power draw of your computing system which is likely to be negligable compared to the other systems. AFAIK what you are suggesting would violate the laws of thermodynamics if it did somehow work. Reversible computing is mainly useful in the context of preventing extremely powerful and dense computers from melting.

[Admiral Valdemar]

The problem is then you're got the mass of the powered mount /plus/ the mass of the manipulators, since you still need the later for clearing rubble, forcing doors, digging field fortifications, grabbing hostages etc (otherwise why would you need infantry at all). You've also got more structural/support mass.

However depending on the graser tech it may be practical to mount the graser beam generator vertically on the back and just have a little pop-up laser turret over the shoulder - there's no such thing as a gamma ray mirror in real life but it may exist in this setting.

A graser being based in a dome turret like that would be preferable since you don't need a large barrel which would be suited best for the coilgun. I'd make all this modular anyway, so should you want just the coilgun and extra ammo, you can get rid of the graser and have a back mounted ammo feed of larger capacity.

This does not work for waste heat from other systems. All it does is reduce the power draw of your computing system which is likely to be negligable compared to the other systems. AFAIK what you are suggesting would violate the laws of thermodynamics if it did somehow work. Reversible computing is mainly useful in the context of preventing extremely powerful and dense computers from melting.

The way I understood the concept, for computing tasks you couldn't work the magic, but if you're just using it for controlling entropy, you can lower heat expenditure via the processing, so long as the computations aren't observed and worked on at the quantum computing level. That's assuming the system works and this trick in thermodynamics exists. It's really not modern physics anyway, so neutrino radiators and ordinary coolant are at least understood here. I'd focus on the other EM spectrums that could be exploited then, like UV or detecting any other emissions like using a MAD.

[Starglider]

The way I understood the concept, for computing tasks you couldn't work the magic, but if you're just using it for controlling entropy,

Controlling entropy? I have never seen this proposed. I can't see how you could possibly do this and not have a free energy device.

so long as the computations aren't observed and worked on at the quantum computing level.

Sounds like technobabble to me. AFAIK no plausible concept for quantum computing has these properties.

It's really not modern physics anyway, so neutrino radiators and ordinary coolant are at least understood here.

Neutrino radiators are an /extension/ to existing physics, like repulsors or hyperdrives. You seem to be suggesting something that directly violates existing physical laws.

[Admiral Valdemar]

Controlling entropy? I have never seen this proposed. I can't see how you could possibly do this and not have a free energy device.

Oh no, you still need power and specific quantum algorithms to work it, if you find the right one. It's like a refigerator, but using a quantum computer. I suppose a laser cooling unit would be similar as well, but far more capable.

Sounds like technobabble to me. AFAIK no plausible concept for quantum computing has these properties.

That we know of yet, anyway. I hear reversible computing being used in fMRI touched on the idea of future breakthroughs in the way we process information at such a level. I'm not ruling it out entirely, though it's certainly not ground in current physics understandings. This technology in the universe it was from was absolute bleeding edge and also dangerous even when it did work (however that is).

Neutrino radiators are an /extension/ to existing physics, like repulsors or hyperdrives. You seem to be suggesting something that directly violates existing physical laws.

I've heard of apparent violations in thermodynamics at micro scales before, just not anything that can be used at the macro-scale. In any case, I expect it'd take a lot more power to use even if plausible than the other ideas proposed, especially when in-universe the first such cyro-arithmetic engines were city sized.

[Starglider]

Oh no, you still need power and specific quantum algorithms to work it,

What are these 'quantum algorithms' and how do they have anything to do with cooling?

if you find the right one. It's like a refigerator, but using a quantum computer.

Then where is the heat going, if you are not making it vanish?

I hear reversible computing being used in fMRI touched on the idea of future breakthroughs in the way we process information at such a level.

Yes but that has nothing to do with how we deal with waste heat in non-computing systems.

This technology in the universe it was from was absolute bleeding edge

So it's something a sci-fi author pulled out of their ass, not a real research paper or experiment. Sounds like you've been technobabbled.

I've heard of loopholes in thermodynamics at micro scales before,

This comes up regularly in Singularity discussions. All the ones proposed so far have exactly the same issue as proposals for conventional perpetual motion machines; they have a fatal flaw that is non-obvious to non-specialists but which a qualified physicist will soon shoot down.

just not anything that can be used at the macro-scale.

The only plausible macro-scale dodges are creating negative matter and energy (not the same thing as antimatter and currently not proven to exist at all), accessing other universes and somehow 'hacking' the 'substrate' of this universe (should one be found to exist at all).

when in-universe the first such cyro-arithmetic engines were city sized.

It sounds to me like this author just ripped off the plot of 'Logopolis' (from Doctor Who) and gave the technobabble a superficial modernisation.

[Admiral Valdemar]

You're asking for details I can't give. If I had those details, don't you think that would help us in building it? As I said, this was basically god technology that is never fully explained (and the author is a Ph.D in astrophysics from ESA). The idea is that it's beyond our grasp to the extent that we simply can't fathom it. It's just a neat idea to think of for perfect space stealth, since we already mentioned repulsors which are just as likely.

And yes, this does come just before metric tampering, so when you can locally play with space-time, I expect the fun you can have is boundless.

Oh yeah, amended the "loopholes" comment before you posted. I meant to put "apparent" ones, since we've never seen a true violation on any scale, or at least not one that would be workable or lasting.