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Post by uberdude9001 on Oct 22, 2016 21:25:32 GMT
I'm making a spreadsheet to help design weapon modules. Does anyone have any additional information they would like the spreadsheet to calculate? For the sake of comparison it will contain real projectile weapons in addition to the default ones. So far it calculates:- Muzzle Energy
- Joules per square millimeter(should be useful for determining armor penetration at relatively lower velocities, less useful for rail and coilguns)
- cross sectional density
- The wattage the gun outputs in muzzle energy(should be useful for determining raw damage, especially against unarmored targets)
Planned calculations:
- I plan to treat each fragment from flak warheads as a projectile of its own on a separate table and include variables for the velocity of the warhead relative to the target and detonation range. I don't know all the math for this yet, I'll probably have to go back over one of my old calculus books.
Spreadsheet |
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Post by nerd1000 on Oct 23, 2016 1:57:17 GMT
The projectile's cross sectional density should give some idea of armour penetration by railguns or coilguns.
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Post by uberdude9001 on Oct 23, 2016 3:33:08 GMT
The projectile's cross sectional density should give some idea of armour penetration by railguns or coilguns. Added, please post any errors if you see them. |
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Post by zuthal on Oct 24, 2016 7:41:15 GMT
One thing this is also useful for is quickly checking whether your weapon breaks physics - if the input power is smaller than the output kinetic power, you should either not use that weapon or reduce its fire rate.
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Post by captinjoehenry on Oct 24, 2016 19:47:22 GMT
one thing to note about cross sectional density is the fact that when you are talking about many km/s of velocity all that really matters is the mass and velocity as after hitting something the projectile will just turn to plasma under more or less all situations. As such it cross sectional density doesn't really matter
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Post by cuddlefish on Oct 24, 2016 22:00:48 GMT
one thing to note about cross sectional density is the fact that when you are talking about many km/s of velocity all that really matters is the mass and velocity as after hitting something the projectile will just turn to plasma under more or less all situations. As such it cross sectional density doesn't really matter I thought it was more or less the opposite of that, at least so far as ability to penetrate barriers? Newtonian impact depth is all about density and length - do the plasma effects really flip the script that aggressively? |
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Post by captinjoehenry on Oct 25, 2016 1:09:40 GMT
one thing to note about cross sectional density is the fact that when you are talking about many km/s of velocity all that really matters is the mass and velocity as after hitting something the projectile will just turn to plasma under more or less all situations. As such it cross sectional density doesn't really matter I thought it was more or less the opposite of that, at least so far as ability to penetrate barriers? Newtonian impact depth is all about density and length - do the plasma effects really flip the script that aggressively? Yeah it really does here is a comparison of with a whipple shield and without:  The issue is that plasma is a gas and begins to rapidly expand out ward as soon as it exists so if you can make the projectile into plasma which isn't that hard at these velocities all you need is enough distance between the whipple shield and the hull to be able to shrug it off. So what matters is the amount of plasma you have and how fast it is going forward. As more plasma means more energy, mostly heat, delivered to target and the faster the plasma is going the shorter the amount of time it has to dissipate. As such behind a whipple shield what you mostly want is something that can soak up heat not kinetic projectiles. Not the same test but an example of what happens to a solid mass of armor without a whipple shield at these types of velocities:  |
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Post by cuddlefish on Oct 25, 2016 5:22:05 GMT
Huh. I took the 'warheads' out of my kinetic missiles... and the dang things still work. I guess a few kilos of plastic at 4+ km/s is still enough to ruthlessly through-and-through the Gunship, unless it's the remote control doing the business. I would never have guessed that.
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Post by zuthal on Oct 25, 2016 6:42:58 GMT
The remote control is one kilo, 10 cm in diameter and looks to be ~2.5 cm thick, so it has a volume of ~0.2 L, for a density of 5 kg/L (or 5000 kg/m^3). So it actually makes for a relatively decent kinetic impactor, plus it has the missile behind it.
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Post by nivik on Oct 25, 2016 17:48:21 GMT
Huh. I took the 'warheads' out of my kinetic missiles... and the dang things still work. I guess a few kilos of plastic at 4+ km/s is still enough to ruthlessly through-and-through the Gunship, unless it's the remote control doing the business. I would never have guessed that. 1.0 kg (the mass of a remote control) at 4,000 m/s is 4,000 kg * m/s of momentum. Momentum is force divided by time, and stress is force over area. The area is the area of the 10cm circle (about 0.0785 m^2), and penetrating 10cm of armor at 4,000 m/s will take at most 0.00005 seconds (assuming 10cm of travel time, with an average velocity of 2,000 -- which assumes the armor brings the projectile to a dead stop). That makes the stress on the impact area in this example about 1.0 GPa, which is about 30% over what the RCC used by most ships can withstand. So I'd definitely expect a 1.0 kg 10cm diameter penetrator at 4.0km/s to penetrate two 5 cm layers of RCC, plus some squishy bits in the middle. Math seems to agree with your results! |
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Post by cuddlefish on Oct 25, 2016 18:16:54 GMT
Are there any mass+cost expedient armor plans which could actually necessitate something like a long rod, in your experience, or are those just overkill?
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Post by uberdude9001 on Oct 25, 2016 19:59:58 GMT
Are there any mass+cost expedient armor plans which could actually necessitate something like a long rod, in your experience, or are those just overkill? I just made that to see if it would work to be honest, it was almost useless in combat because the holes it poked were so tiny. LRP was invented to penetrate composites equivilant to several hundred mm of steel. Most of the ships in game have the equivilant of a few dozen mm at best. |
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Post by nerd1000 on Oct 26, 2016 2:15:27 GMT
I thought it was more or less the opposite of that, at least so far as ability to penetrate barriers? Newtonian impact depth is all about density and length - do the plasma effects really flip the script that aggressively? Yeah it really does here is a comparison of with a whipple shield and without: The issue is that plasma is a gas and begins to rapidly expand out ward as soon as it exists so if you can make the projectile into plasma which isn't that hard at these velocities all you need is enough distance between the whipple shield and the hull to be able to shrug it off. So what matters is the amount of plasma you have and how fast it is going forward. As more plasma means more energy, mostly heat, delivered to target and the faster the plasma is going the shorter the amount of time it has to dissipate. As such behind a whipple shield what you mostly want is something that can soak up heat not kinetic projectiles. Not the same test but an example of what happens to a solid mass of armor without a whipple shield at these types of velocities: The whipple shield works because it greatly reduces the cross-sectional density of the impactor. While heat is important, the plasma still has enough kinetic energy that I wouldn't use silica aerogel as my inner bulkhead (maybe basalt fiber composite would be a good compromise?). One thing I'd like to test is the differences in performance between short, flat 'coin' impactors and longer thinner ones (Coilguns typically fire the former, railguns the latter). It may be that, much like thinner flak bombs produce a wider spread (and smaller splinters) than short fat ones, thinner projectiles get spread out more if they hit a whipple shield while 'coin' type projectiles produce a tighter jet of plasma. |
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Post by captinjoehenry on Oct 26, 2016 3:45:59 GMT
Yeah it really does here is a comparison of with a whipple shield and without: The issue is that plasma is a gas and begins to rapidly expand out ward as soon as it exists so if you can make the projectile into plasma which isn't that hard at these velocities all you need is enough distance between the whipple shield and the hull to be able to shrug it off. So what matters is the amount of plasma you have and how fast it is going forward. As more plasma means more energy, mostly heat, delivered to target and the faster the plasma is going the shorter the amount of time it has to dissipate. As such behind a whipple shield what you mostly want is something that can soak up heat not kinetic projectiles. Not the same test but an example of what happens to a solid mass of armor without a whipple shield at these types of velocities: The whipple shield works because it greatly reduces the cross-sectional density of the impactor. While heat is important, the plasma still has enough kinetic energy that I wouldn't use silica aerogel as my inner bulkhead (maybe basalt fiber composite would be a good compromise?). One thing I'd like to test is the differences in performance between short, flat 'coin' impactors and longer thinner ones (Coilguns typically fire the former, railguns the latter). It may be that, much like thinner flak bombs produce a wider spread (and smaller splinters) than short fat ones, thinner projectiles get spread out more if they hit a whipple shield while 'coin' type projectiles produce a tighter jet of plasma. In my experience it has overwhelmingly been the case the heavier round does more damage almost no matter the speed. I have a physics breaking rail gun throwing 1 gram rounds down range at almost 50km/s at a rate of about 1000 a second. This weapon is great but unless it can hit the same spot for a good while it isn't going to do squat. Meanwhile the stock coil gun if it hits it is going to screw things over and a rail gun firing a heavier round will almost always do more damage than the same gun with a lighter round. |
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