C-14 Ammunition

[Biffer]

Almost all modern weapons break the sound barrier, but the muzzle flash isn't caused by that - it's from the explosion of the propellant/powder mixture.

I understand that we are dealing with newtonian physics, but I am under the impression that the force exerted is in a different direction. For one, my understanding is that the force is exerted sideways against the rails, not backwards into the user.

I suppose it's also the definition of terms - I think I was mixing up a coil gun with a rail gun. Rail guns use a Lorentz force to "whip" a projectile out via oppositely charged rails. Again, what I've researched on this is that recoil is much less than a standard cartridge-based projectile. Because the recoil is caused by momentum and not kinetic energy, a small (8 mm is very small) projectile would in fact be devastating when fired at such high speeds but still wouldn't (in my opinion) yield a higher recoil than any modern weapon. No need for some CMC based recoil compensation.

Good discussion! I enjoy this site immensely!

[AdmiralMengsk]

Wow. I actually learned a lot with that article and this thread. Who would of thought SC lore forum would have been educational?

OP: One thing I preach to 40k, SC, and Sci Fi fans in general is that its all made up to an extent. Anything you see in SciFi and fantasy is subject to the rule of cool. While it's been explained here(very well actually)scifi doesn't always conform to real life. I see people get frustrated with 40k a bunch because they believe certain things are simply impossible and that just isn't the case. It's fiction.

[Kimera757]

Pretty sure the shuttle exceeds the speed of "sound" in space after it reaches escape velocity. Of course, given the paucity of air molecules, the concept of "sound" doesn't have much meaning there.

(The speed of sound varies depending on air pressure. It's around 1200 km/hr at sea level and 2000 km/hr at 40,000 feet, IIRC, and I could be horribly wrong.)

[Quirel]

Almost all modern weapons break the sound barrier, but the muzzle flash isn't caused by that - it's from the explosion of the propellant/powder mixture.

True, but this isn't just supersonic. It's hypersonic. Five times the speed of sound, at least three times the speed of regular bullets.

I understand that we are dealing with newtonian physics, but I am under the impression that the force exerted is in a different direction. For one, my understanding is that the force is exerted sideways against the rails, not backwards into the user.

I suppose it's also the definition of terms - I think I was mixing up a coil gun with a rail gun. Rail guns use a Lorentz force to "whip" a projectile out via oppositely charged rails.

Actually, there is a force exerted sideways on the rails, as they push against each other. That's one of the problems in development, as it severely limits what you can do with them and how often you can fire them with today's technology. You just hear about it more because all the plans for the rail guns involve mounting them on destroyers, where recoil and power supply aren't an issue, but gun wear is.

Does anybody REALLY believe recoil is a problem with that thing?

Again, what I've researched on this is that recoil is much less than a standard cartridge-based projectile. Because the recoil is caused by momentum and not kinetic energy, a small (8 mm is very small) projectile would in fact be devastating when fired at such high speeds but still wouldn't (in my opinion) yield a higher recoil than any modern weapon. No need for some CMC based recoil compensation.

I seem to recall that the bullets are referred to as "Spikes", so I'm going to bet that the bullets are somewhat longer than conventional rifle rounds. In addition, these things fire in burst mode, and the bullets are commonly depleted uranium (almost 70% denser than lead) fired in burst mode. If that's not enough to kick like a mule, (And not the mineral-harvesting ones!) then recoil compensation would be desirable to keep the gun on target after each shot, like the Kriss Super V.

[l33telboi]

I've been thinking about the muzzle flash and how the weapon looks so very much like modern weaponry (despite being called a gauss rifle) ever since I wrote that article, and I've decided to jettison my earlier coolant idea for another one.

The weapon ejects casings, specifically called casings (in Heaven's Devils). It has a muzzle flash, as well as a bang that's more like ignited propellant then a thundercrack (which you'd get if it was a simple matter of something breaking the sound barrier). We’ve also seen some of the ammo for these rifles up-close now, and they look like modern ammo, not jacketless spikes. On the other hand the weapon also has capacitors, is called a gauss rifle, and needs power to work.

The simplest solution would be to assume it's both a gauss rifle and a normal rifle. A hybrid weapon, of sorts. It uses the chemical propellant in a bullet to get the bullet moving, just like a normal rifle, but then it has electromagnetic coils in the barrel to further increase the velocity beyond what the propellant is capable of.

This would neatly explain why it looks like a modern weapon, but is called a gauss rifle. So that’s the idea I’m rolling with these days.

Because the recoil is caused by momentum and not kinetic energy, a small (8 mm is very small) projectile would in fact be devastating when fired at such high speeds but still wouldn't (in my opinion) yield a higher recoil than any modern weapon.

The recoil would still be high, but not as high as a modern weapon with similar kinetic energy. This is an intriguing concept though, and if you're familiar with the firearms in Mass Effect, then you've seen this concept taken to extremes. In Mass Effect you have weapons firing grain-sized projectiles, and yet they have about as much recoil as a normal weapon does. I once ran the numbers on what exactly that would mean, and, well, the results were fairly amusing:

This was discussed some time ago in another thread. There were a lot of differing opinions and a lot of things to consider. Having mulled over it for some time, I'll get started simply by pointing out the different possibilities involved.

My initial reaction to this weapon was that it was ingenious due to the fact that the bullets will have a lot of kinetic energy when compared to momentum. This is good because a low momentum would mean that the weapon will have less of a kickback when fired, yet the bullets will carry a tremendous amount of kinetic energy when compared to modern weapons. And indeed, it's stated in the codex that the biggest limiting factor on Mass Effect weaponry is the recoil it produces.

So, this gives us a starting point for trying to figure them out. Let's assume a Mass Effect assault rifle will have as big a kickback as an M-16. Momentum is calculated by p = m * v, a very simple formula, so for the M-16, we get a bullet momentum of 3.9 kg*m/s, because the bullet is said to weigh around 4 grams and the muzzle velocity is 975 m/s.

However, we could also assume the bullet weighs less then normal bullets due to the decreased size and that thus the velocity would be higher, in order for the momentum to stay the same. Here comes the main problem with 'grain of sand' statement. Just how massive is a grain of sand? Is it one hundredth of a bullet, one thousandth? To give you a demonstration, let's assume one hundredth (this means the bullet now weighs 0.00004 kg). So, we know the momentum, we know the mass, and we need to get the velocity. Just mix up the momentum formula and try it again, this time we get v = p/m, or v = 3.9 / 0.00004, which results in a velocity of 97,500 m/s. You can already see that it's pretty high, no modern weapon even comes close to firing projectiles at those velocities.

But like I said, the interesting thing would be kinetic energy. Because if you fire a 1 gram projectile at 1,000 m/s, it's going to have more kinetic energy then a 1,000 gram projectile at 1 m/s. This because of the kinetic energy formula, which looks like this: ke = m * v^2 * 0.5. Very similar to the momentum formula which was p = m * v, but in the case of kinetic energy, velocity is raised to the power of 2.

So, how much kinetic energy would a Mass Effect assault rifle bullet carry? Just plug in the figures and check: ke = m * v^2 * 0.5 = 0.00004 * 97500^2 * 0.5 = 190,125 Joules, or 190 kilojoules. How does that compare to the kinetic energy of a M-16? Again, ke = m * v^2 * 0.5 = 0.004 * 975^2 * 0.5 = 1,901.25 joules, or 1.9 kilojoules. There's more then just a bit of a difference. If memory serves, modern weaponry that has muzzle energy as high as 190 kilojoules would be high-caliber stuff, like 30mm autocannons and the like. Weapons you mount on vehicles, not people. Weapons used to kill lightly armored vehicles, not people.

However, there are a few more things to point out, so don't stop reading. You might've noticed that the way which we obtained mass in the previous example is pretty arbitrary; we simply assumed it was a hundredth of the mass of a normal bullet. A better way could be to, as Connor suggested, assume the magazine weighs as much as a modern one, and then divide that by the number of bullets the rifles are said to be capable to fire, which would be thousands (so at least 2,000). So, assume the magazine weighs a simple 0.5 kg, which would mean that individual bullets would weigh 0.00025 kg. Of course, ‘thousands’ could be much more then just 2,000, so again, this is nothing final, just something to give you a sense of direction.

So let's redo the momentum figures in order to get a new velocity: v = p / m = 3.9 / 0.00025 = 15,600 m/s. And then get the new kinetic energy: ke = m * v^2 * 0.5 = 0.00025 * 15600^2 * 0.5 = 30,420 Joules, or roughly 30 kilojoules. So you see, these things do definitely seem much more powerful then normal rifles, or even .50 cals for that matter, at least when it comes to kinetic energy. Yet they retain the same kickback as that of a normal modern assault rifle. So on a purely theoretical basis, these things are dandy as hell.

However, having played the game, there are a few contradictions. In the game for instance, you do see a number of people getting shot by these things, unarmored and unshielded, and they don't explode, like they should. Though, naturally this could just be a game-engine limitation. Or it could be that the weapons used were less powerful then normal ones. Or that they can be set on variable velocities, thus making them less lethal in situations where such is preferred.

But, if we do go ahead and assume there is a definite contradiction between the theoretical and the displayed effects. Then there is one explanation I could offer that would reconcile the differences, namely that the slugs aren't less massive then normal bullets, just smaller. Mass Effect technology, according to the codex, can be used to create highly dense materials; maybe such is the case here? But then we'd be talking about someone lugging around an 8 kilogram magazine, which is rather heavy. But again, Mass Effect technology could be used to explain the problem, as it does give the user the option of lightening the mass of the magazine. Indeed mass accelerator weaponry is said to suspend the bullets in a mass-lightening field, though if this is when they’re in magazine form or already in the barrel is a question.

Those are my ten cents on the issue. Note that I'm a bit pressed for time here, so I didn't have time to double-check the numbers. Speak up if you notice something funky.

[Norfindel]

The simplest solution would be to assume it's both a gauss rifle and a normal rifle. A hybrid weapon, of sorts. It uses the chemical propellant in a bullet to get the bullet moving, just like a normal rifle, but then it has electromagnetic coils in the barrel to further increase the velocity beyond what the propellant is capable of.

This would neatly explain why it looks like a modern weapon, but is called a gauss rifle. So that’s the idea I’m rolling with these days.

Well, the problem with that, is that you have a very complicated rifle, and you don't have the advantage of caseless ammunition. Realistically, as they can power armor for extended periods of time, the supply to the rifle shouldn't be a problem, and you also have a lot of space to put big coils, so an hybrid design doesn't looks like something really necessary.

Ejected casings and muzzle flashes just look cool, and that's why they're into the game.

[Rake]

I like the idea that the muzzle flash comes from a lubricant powder that protects the surface of the barrel and allows firing for longer.