Hyper velocity impacts, EDM, cavitation, impact fission?

It's been a while since I made a ridiculously large gun, and I thought I'd give it a try and see if I could get to a point where I exceed .01c with a 1g projectile. I succeeded. And the thing still "bounces" off of my heavy armor target at as close to 90° incident of impact as I can get. In fact, it doesn't penetrate beyond the third layer of armor.



Now, I have made a similar thread before, but here I want to go beyond stating that the armor mechanic is broken. It is fairly clear that the projectile should be destroyed, there should be a big hole, etc. Rather, I want to show how broken it is and some of the implications (as far as I'm aware) of such high velocity projectiles. To fully understand these ridiculous impacts, more precisly why they are so, heres some math:

Let us assume that the projectile is simply absorbed by the armor but stays reasonably intact (this is implicated by the game having it bounce). Further more let us assume uniform deceleration (this is easier and more forgiving as the highest deceleration is just after impact and is significantly higher than average). With the given armor scheme and the observed maximum penetration depth, this gives us a distance to decelerate of s=1.06m. With s=1/2*a*t² and t=v/a we get a=v²/2s. Given the absorption of the projectil this gives us a velocity change v of 4.12*10⁶m/s and thus an acceleration of just above 8*10¹²m/s², or quadruple that if you assume a ricochet. The projectile mass is 10^-3kg, giving us a force of 8*10⁹N or 8GN. The projectile has an area of about 3.421m^-7, meaning it expieriences an aproximate 2.34*10¹⁶Pa or 23.4PPa, 23.4 Peta Pascal! Again, quadrupel that in the case of the ricochet, as the change in velocity has doubled. As a point of reference: the only figure I have seen for electron degeneracy pressure (link) is 29.4TPa, an order of magnitude smaller.

Assuming the games penetration mechanics are correct (which they are not), here are some implications for projectiles aproaching 1%c given the above math:

• Impacts will generate degenerate matter, which would then decay. This lessens the effect of wipple shields significantly, as it increases the time the projectile (or some part of it) remains intact for some time (relative to the time it takes the object to cross the gap between wipple shield and armor
  
• Impacts should give off a flash of radiation as electrons are dissasosiated and reasosiated from their atoms and some fusion/fission (likely) uccors

This also has some rather profund implications for hyper velocity projectiles in general (projectiles in the hundreds of km/s).

   First of all, impact initiated fission (and possibly fussion) should be possible with these projectiles. Considering that you can get about 10T of explosive power out of about a gram of fissionable material in implosion style nukes, this would mean a significant increase in destructive power, if these materials can be used in these projectiles.

Far more significant in my opinion is the effect these projectiles would have on armor. Even at 100km/s on sub mm projectiles, the impact forces go far beyond the binding forces of the atoms of the strongest of our materials and the velocities involved are tens to hundreds of times beyond the speed of sound in our materials. This means that, on impact, armor would act like liquid. The resulting damage would thus mainly take the form of a massive cavitation bubble, similar to those seen in flesh with modern projectiles. These bubbles would not collapse back on themselves the same way, though, as the material would stop acting like a fluid below a certain speed. As the material slows, the material at the edge of the bubble would turn to plasma/gas/liquid as friction turns its kinetic energy into heat. As the edge slows below a critical velocity and becomes difuse, it will shatter the material there, fracturing the remaining armor and cause massive spalling. The plasma/gas expands rapidly as it forms causing a secondary explosion, causing even more direct damage and generating futher fractures and spalling in/from the already damaged armor. In fact it will do all this regardless of if it hits armor or a fuel tank or anything else, dumping all of its energy (2T of TnT equivalent in the case of my example) into whatever it hits.

I feel if this was more accurately moddeled, high velocity railguns would do significantly more damage.