Ultramarine Dreadnought vs M1A2 Abrams

[Sea Skimmer]

Something else I'd point out, as about all tanks and some IFVs use fuel cells as armor, with or without armor being in the physical core of thefuel tank

. If a notional recoilless light bolt penetrates it might cause a major explosion if the fuel tank is say, half filled. The tanks are proof against bursting from hydraulic ram from taking shell hits when filled, and vapor explosions to a high degree, but a big enough one will probably result would still be the tank being destroyed, if only by the fuel fire blown back out the entry hole. If the fuel tank is filled it might still burn but an internal vapor explosion has no actual volume to take place in so it won't happen.

This also applies to aircraft fuel tanks. Is major part of the A-10 design, but against much smaller caliber weapons.

However explosion proof fuel already exists that won't propagate a fire when hit by direct explosions and shaped charge warheads. Nobody uses it presently because its 10% water by weight + additive, you can imagine what that does to the efficiency of the fuel supply system even if you source the water locally. But proven in full scale demonstrations multiple times in the 1970s and again in the 2000s.

https://www.youtube.com/watch?v=BhLzonmYA3w
As much more recent idea, this long chain polymer idea from cal tech is only proven against open flames, not explosions, but effective with only .3% additive weight. The polymers physically lock together to impede flame fronts and limit the burn rate away from an external heat source.

Cannot find a DARPA video of the RPG proof jet fuel tank presently, should exist on youtube somewhere.

[Simon_Jester]

You'd almost have to do coolant or ammo/coolant packs, unless you've gotten the thing to actual 100% efficiency. Say we want a 1 GJ thermal beam weapon that fires in .1 seconds. That's only 1 TW of power, about the rating of the entire US electrical grid, through an apparently man portable barrel for the smallest 40K lasguns. What material are these guns made out of, and why can't they just use that as armor becomes relevant, as even a very small thickness would have to be able to withstand the bore heat. Otherwise you get massive bore or lens or whatever the hell erosion on each firing. This is not a minor issue, because it's what holds back gun bores and thus muzzle energies too.

Well, there are reasons to think lascannon don't produce gigajoule pulses, because they don't cause "ton of TNT equivalent" damage to terrain as I recall.

[Also, one gigajoule in 0.1 seconds is ten gigawatts. It's one terawatt if you want it in one one thousandth of a second.]

[Rogue 9]

There are very few visual representations of a lascannon firing; one of those few is the intro cutscene to the original Dawn of War.



It isn't seen to do much; mostly kick up dust. There aren't any establishing shots of what it does to the ground it hit after the dust clouds clear, though.

(Also, that sergeant was a goddamned idiot.)

[Sea Skimmer]

I wanted 1/1000th second now that I read that paragraph back. Said time chosen because you need timing like that if you want to aim and fire it as a highly accurate shoulder weapon, as is the case for the smallest lasguns.

Perhaps the Dreadnought maybe it could be .1 second though with as stabilizer which lessens the wattage problem, but still in the nuclear reactors range, nor does it help the terminal effects issue, though that's its owns story. Either way the total waste heat is the same and has to be dealt with, whatever the number of nuclear reactors worth of power passed through the bore for a moment. Expending coolant still sounds like a plan over closed loop!

Ton of TNT is something to think about too, because you very quickly actually need bombs like that if you want to kill tanks with untamped air blast in real life, short of nearly actually landing a bomb on the tank, where fragmentation is generally going to be the killer. But HE doesn't just have high heat, it physically liberates a bunch of gas expansion in the process at as much as 8-9km/s while it does it, or a somewhat slower but still hypersonic speed for thermobarics. End result is same energy, but the HE blast should be much more intensive until we get to extremely small timescales of pure heat energy release. It actually has added mass expansion to project.

This is after all why nuclear weapons aren't that great against really solid targets, in terms of actually destroying them for rated yield. They can only vaporize themselves and the air around so much, and then a huge amount of thermal energy radiates out from the fireball for a while doing little of any destructive value. That can go on for minutes. The more fusion power a nuclear bomb has too, the less relative blast energy it will produce compared to neutron flux, part of how you make a true neutron bomb. Neutrons are interesting since they have KE, but can penetrate solid material before delivering it. This is why they kill tanks too. Notionally certain types of particle beam weapons might be able to snipe tank crews out of tanks without damaging the vehicle as a whole.

The lasgun is basically asking to have a massless mass having heat particle to get the kind of results I know people probably want from it. Something to keep coupling energy into the hit and shear away debris as its penetrates is needed. Otherwise otherwise runs into the the same conceptual problem HEP/HESH shells did against spaced armor.

[Sky Captain]

Neutrons are interesting since they have KE, but can penetrate solid material before delivering it. This is why they kill tanks too. Notionally certain types of particle beam weapons might be able to snipe tank crews out of tanks without damaging the vehicle as a whole.

How well that would work in atmosphere? If you had a weapon that can somehow shoot a pulse of high energy neutrons what kind of effective range it may have against tanks in Earth atmosphere. At very high power levels wouldn't it be possible to have explosions too when neutron pulse hits the armor, dumps a lot of heat into it causing armor to flash into vapor? Neutrons penetrate well into solid materials so the armor mass would be heated as a whole not just the surface as would be in case of normal laser weapon. This may actually look much like sci fi energy blasters that cause effects similar to high explosives when hitting target. Likely would irradiate everything too.

[Sea Skimmer]

Would depend on what exactly you built, but fast neutrons from nuke bursts can strongly penetrate armor after 1.5km of free air so range should be that kind of class. A proton beam may work out better however, I forget how that goes. Either way though you will have lots of secondary radiation from the accelerator to the target in the form of a bonus gamma ray beam.

As far as exploding armor goes, how much power density you need depends on how strongly the armor stops the neutrons. If its got a low attenuation factor the energy disposition is spread out in depth, and thus an explosion harder to induce. Though when that explosion did take place it would be bigger. In practical terms you will need energy densities comparable to large explosions that would breach tank armor conventionally. The neutron gains an advantage from its speed in shock effect, but the fact that the shock is delivered in depth is a serious counteraction to effectiveness. You'll kill crew and even computer boards long before you can induce this effect.

To put it in perspective 10,000 rads will raise a human body to about 140F, causing megadeath by thermal eating even if nothing else mattered. That's your kind of goal with a weapon like this. Blowing things apart is kind of silly, a pure fusion bomb would really be the way to go if you want that effect.

Manpack in any universe connected to reality won't work because it will need non trivial bulk and emit too many gamma rays and needs, the same kind of power were talking about for the lasgun, but a vehicle mounted system should be possible, at least in that nothing says that can't happen. Once you had that it'd be nearly like a laser in principle, in that you could keep firing for long periods with high accuracy. You need some matter feedstock sure, but its trivial, the main limit might be the vehicles ability to withstand its own gamma rays. Job for robots. Killing infantry behind walls and such, also falls within sorta plausible missions.

Another option if you have unlimited tech-money and limited need for plausibility of materials would be to make a landmine fired by some high of supertech explosive generator, it'd need a battery to warm itself up. This would also not have the requirement to be extremely short. Sight it for stand off attacks and enfilading key routes. This would make sense against possible future tech tanks with extremely strong active protection, and stuff like anti grav warships and other very heavy vehicles that could resist conventional attacks or hover above you. Unless the enemy also has a magic tech neutron shield they'd have a very hard time having any protection against this kind of attack other then dispersion and large fuel tanks.

Anyway if you have super high density personal scale power packs, you can think about a number of different weapons and missile/shell warheads like MAHEM which might produce exceptional or at least, new, effects.

[The_Saint]

First time I saw information on MAHEM all I could think of was variations of WH40K melta weapons.

It seems like the effort to explosively defeat armour has moved from "place explosive material against armour and then cause an explosion" to "cause an explosion and move that to the armour"

HESH -> EFP/MAHEM -> WH40K Melta's

[Sea Skimmer]

Both HEAT and EFP weapons continue to evolve to defeat changing types of armor arrays. EFPs are functionally insensitive to stand off range as long as your talking about a difference of 30-100 meters. Finned ones, created by overlaying the fin shape on the liner (a shaped doubler plate pressed on, which becomes the mass of the fins) can actually fly over 1km without destabilizing though accuracy would only suffice against a zerg swarm. That was with 2000 era conventional explosive tech.

EFPs are very popular right now because we can finally computer model hydrodynamics in useful terms now, even if we can't fully explain why, and that lets all kinds of designs be tested without literally thousands of actual test explosions as used to be the way that was done. This has led to some fairly extreme stuff, like EFPs that produce long rods 12+ calibers long. More or less an exploding tank gun.

Also remember that in basic physical terms, the penetration mechanic of high velocity APDSFS type ammunition, HEAT and EFP charges is all the same. The only thing that is changing is the velocity range. That RADICALLY affects materials properties and your results, but it's not because we call the weapon an EFP or a cannon.

So nothing here vindicates the idea of a thermal based anti tank weapon as the melta seems to be. Notionally one might consider for sci fi say, a hypervelocity railgun launched shell with a liquid metal core superheated by whatever your pulse power supply is as it fires. Thus giving a powerful penetrating incendiary that's completely safe before firing, and breaks up from its own melting after a certain distance so you can spray it like mad in action.

Also guns that melt or fuse dirt into projectiles. A lot is possible in theory.


The value of MAHEM is on two fronts. The first is multiple warhead liners. In theory almost any concept of a shaped charge will work, but you may have no plausible way to carry out the design and create required explosive blast paths in an actual design you can build. At least not if its going to have more then one operating mode.

With MAHEM you can just setup whatever liners you want, and then solid state controls and wires link that to a distinct explosive driven pulse generator. Though this will take up more volumn. Also you can have variable delays in the firing order, somewhat dependent on the fact that the device is still exploding, and any firing order you want. A slight delay in liner firings could be very valuable against advanced armor, to a point that already exists in HE driven devices. It would make much less difference against notional semi infinite RHA targets. That's why RHA spec spam gets dumb fast.

The other thing MAHEM can do is give you much higher velocity with a slug like shape. This may not increase specific depthof penetration over a simpler purely explosive warhead of sufficient design, materials dependent. But what it certainly will do is begin to massively increase lateral damage to the target when hit. The 'destroy the tanks armor problem'

That's extremely valuable for certain roles, one of which is ABM defense. Its not enough to hit the enemy missile,you need to make sure your damage propagates through the warheads on board which you might have missed with your hit to kill weapon. MAHEM research for the US military appears to have gotten going in the 1980s for that role under the SDI program. A high explosive warhead won't work in this role because doesn't explode fast enough while with MAHEM the HE blast at ~10km/s just drives a generator, and then the liners can all launch at much higher velocities in principle, and in any directions we want. Say at 40km/s.

90km/s was actually done with high explosives as it is, but basically by building a long piston and projecting material as a aerosol. 140km/s was reported by not confirmed in the 1960s era.

This is also really valuable for say, destroying a bridge pier with a SOF attack, or breaching a strong but normal wall with a shoulder fired rocket where a normal EFP would only make a fist sized hole. Depth of penetration is key for attacking heavy tanks, but not so much other targets.

Downside is the MAHEM equipment weighs something, and you aren't actually increasing your energy doing this, so it's no magic with present materials. But at least for the moment nearly everything useful about it is also still classified. It's certainly an excellent place to employ lots of sci fi magic.