Light speed projectiles
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- Knight-Baron
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Light speed projectiles
So, this belated NaNo, I kind of stumbled into a really strong submission. By happenstance I started watching this live reading of an r/HFY submission. At the beginning of November the reader had been in the middle of a break to work on their thesis and so I went to Reddit to finish the story and happened upon an open invitation to also write stories in the universe. He's a real nice guy, retired commissioned officer, and he's been providing me with details about the world.
One thing he mentioned in a document he sent me, was that standard military issue is a coil gun that fires projectiles at relativistic speeds. I think he's under the impression that because the projectile is propelled via electromagnetic impulse there wouldn't be any recoil. Of course that's not how physics works.
I have a pretty good idea what would happen to anyone actually firing such a weapon, but I was wondering if any of the big brains here at the den could give me the numbers on that. I'm really interested to know how hard that gun is pushing back as the projectile leaves the barrel.
One thing he mentioned in a document he sent me, was that standard military issue is a coil gun that fires projectiles at relativistic speeds. I think he's under the impression that because the projectile is propelled via electromagnetic impulse there wouldn't be any recoil. Of course that's not how physics works.
I have a pretty good idea what would happen to anyone actually firing such a weapon, but I was wondering if any of the big brains here at the den could give me the numbers on that. I'm really interested to know how hard that gun is pushing back as the projectile leaves the barrel.
Kaelik wrote:Fuck you Haruhi is clearly the best moe anime, and we will argue about how Haruhi and Nagato are OP and um... that girl with blond hair? is for shitters.darkmaster wrote:Tgdmb.moe, like the gaming den, but we all yell at eachother about wich lucky star character is the cutest.
If you like Lucky Star then I will explain in great detail why Lucky Star is the a shitty shitty anime for shitty shitty people, and how the characters have no interesting abilities at all, and everything is poorly designed especially the skill challenges.
Well, this is conservation of momentum. Now, relativistic speeds mean that the mass of the projectile will increase as it accelerates in some nasty bit of calculus. Without that, the gun would have the same momentum in recoil as the projectile, and would travel at (speed of the projectile) * (mass of projectile/mass of gun). Energy can then be derived from that (E=.5mv^2). With a gunpowder weapon, the acceleration would be highest at first and trail off, but I'm not sure if the same would be true of a coil gun.
virgil wrote:Lovecraft didn't later add a love triangle between Dagon, Chtulhu, & the Colour-Out-of-Space; only to have it broken up through cyber-bullying by the King in Yellow.
FrankTrollman wrote:If your enemy is fucking Gravity, are you helping or hindering it by putting things on high shelves? I don't fucking know! That's not even a thing. Your enemy can't be Gravity, because that's stupid.
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- Knight-Baron
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- Joined: Fri Apr 29, 2011 5:24 am
A coil gun is a projectile weapon system that accelerates a projectile via magnetism inside the barrel rather than a chemical reaction. So similar to the function of a firearm.
Alright correct me if I'm mathing wrong. But.
299,792,458*(4.02/4127.69)=291951.877921
E=.5(4127.69)(85235899021.6)
E=175,913,680,000,000 joule which makes 129,747,271,908,073 foot pounds of energy imparted upon the weapons user.
I just got visions of marine battalions exploding upon firing their weapons.
Alright correct me if I'm mathing wrong. But.
299,792,458*(4.02/4127.69)=291951.877921
E=.5(4127.69)(85235899021.6)
E=175,913,680,000,000 joule which makes 129,747,271,908,073 foot pounds of energy imparted upon the weapons user.
I just got visions of marine battalions exploding upon firing their weapons.
Kaelik wrote:Fuck you Haruhi is clearly the best moe anime, and we will argue about how Haruhi and Nagato are OP and um... that girl with blond hair? is for shitters.darkmaster wrote:Tgdmb.moe, like the gaming den, but we all yell at eachother about wich lucky star character is the cutest.
If you like Lucky Star then I will explain in great detail why Lucky Star is the a shitty shitty anime for shitty shitty people, and how the characters have no interesting abilities at all, and everything is poorly designed especially the skill challenges.
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- Knight-Baron
- Posts: 913
- Joined: Fri Apr 29, 2011 5:24 am
Neat, thanks XKCD.Hicks wrote:https://what-if.xkcd.com/1/
Kaelik wrote:Fuck you Haruhi is clearly the best moe anime, and we will argue about how Haruhi and Nagato are OP and um... that girl with blond hair? is for shitters.darkmaster wrote:Tgdmb.moe, like the gaming den, but we all yell at eachother about wich lucky star character is the cutest.
If you like Lucky Star then I will explain in great detail why Lucky Star is the a shitty shitty anime for shitty shitty people, and how the characters have no interesting abilities at all, and everything is poorly designed especially the skill challenges.
Your math is completely wrong, as you are using newtonian physics at relativistic speeds. If you were to accelerate a projectile to c, it would have infinite mass and therefore you would need infinite energy.darkmaster wrote:A coil gun is a projectile weapon system that accelerates a projectile via magnetism inside the barrel rather than a chemical reaction. So similar to the function of a firearm.
Alright correct me if I'm mathing wrong. But.
299,792,458*(4.02/4127.69)=291951.877921
E=.5(4127.69)(85235899021.6)
E=175,913,680,000,000 joule which makes 129,747,271,908,073 foot pounds of energy imparted upon the weapons user.
I just got visions of marine battalions exploding upon firing their weapons.
If we assume low relativistic speeds it seems that it starts to matter at around .15c (source).
virgil wrote:Lovecraft didn't later add a love triangle between Dagon, Chtulhu, & the Colour-Out-of-Space; only to have it broken up through cyber-bullying by the King in Yellow.
FrankTrollman wrote:If your enemy is fucking Gravity, are you helping or hindering it by putting things on high shelves? I don't fucking know! That's not even a thing. Your enemy can't be Gravity, because that's stupid.
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- Knight-Baron
- Posts: 913
- Joined: Fri Apr 29, 2011 5:24 am
Never mind, I forgot a decimal point.
Last edited by darkmaster on Wed Nov 14, 2018 7:26 am, edited 2 times in total.
Kaelik wrote:Fuck you Haruhi is clearly the best moe anime, and we will argue about how Haruhi and Nagato are OP and um... that girl with blond hair? is for shitters.darkmaster wrote:Tgdmb.moe, like the gaming den, but we all yell at eachother about wich lucky star character is the cutest.
If you like Lucky Star then I will explain in great detail why Lucky Star is the a shitty shitty anime for shitty shitty people, and how the characters have no interesting abilities at all, and everything is poorly designed especially the skill challenges.
Probably, but I'm not a physicist so I can't say for sure.
The concerns raised in the xkcd are still an issue, as you are so far past the speed of sound that unless you are in a hard vacuum, your projectile will be destroyed by the stress and its energy will start to diffuse.
Lasers will probably work better. If you are really doing hard sci-fi, then infantry wouldn't exist, humans are just too slow and fragile to keep up with drones.
The concerns raised in the xkcd are still an issue, as you are so far past the speed of sound that unless you are in a hard vacuum, your projectile will be destroyed by the stress and its energy will start to diffuse.
Lasers will probably work better. If you are really doing hard sci-fi, then infantry wouldn't exist, humans are just too slow and fragile to keep up with drones.
virgil wrote:Lovecraft didn't later add a love triangle between Dagon, Chtulhu, & the Colour-Out-of-Space; only to have it broken up through cyber-bullying by the King in Yellow.
FrankTrollman wrote:If your enemy is fucking Gravity, are you helping or hindering it by putting things on high shelves? I don't fucking know! That's not even a thing. Your enemy can't be Gravity, because that's stupid.
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- Knight-Baron
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- Joined: Fri Apr 29, 2011 5:24 am
I mean, how hard are we talking? But no, not hard sifi, FTL exists in form of gravitationaly induced space-time contraction. So, you know, magic might as well just exist.
Drones are an interesting idea though, because they would probably be cheaper than human lives too.
Drones are an interesting idea though, because they would probably be cheaper than human lives too.
Kaelik wrote:Fuck you Haruhi is clearly the best moe anime, and we will argue about how Haruhi and Nagato are OP and um... that girl with blond hair? is for shitters.darkmaster wrote:Tgdmb.moe, like the gaming den, but we all yell at eachother about wich lucky star character is the cutest.
If you like Lucky Star then I will explain in great detail why Lucky Star is the a shitty shitty anime for shitty shitty people, and how the characters have no interesting abilities at all, and everything is poorly designed especially the skill challenges.
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- Knight-Baron
- Posts: 913
- Joined: Fri Apr 29, 2011 5:24 am
Okay, I redid my math at actual .01c, instead of 01c.
3,000,000m/s(4.02g/4127.69g)=2,554.17m/s
2,554.17m/s^2=6,523,784.39m/s
E=.5(4127.69g)(6,523,784.39m/s)
E=13,464,079,794.4J
Which comes to a mere 7,324,431,457.35 foot-pound
3,000,000m/s(4.02g/4127.69g)=2,554.17m/s
2,554.17m/s^2=6,523,784.39m/s
E=.5(4127.69g)(6,523,784.39m/s)
E=13,464,079,794.4J
Which comes to a mere 7,324,431,457.35 foot-pound
Kaelik wrote:Fuck you Haruhi is clearly the best moe anime, and we will argue about how Haruhi and Nagato are OP and um... that girl with blond hair? is for shitters.darkmaster wrote:Tgdmb.moe, like the gaming den, but we all yell at eachother about wich lucky star character is the cutest.
If you like Lucky Star then I will explain in great detail why Lucky Star is the a shitty shitty anime for shitty shitty people, and how the characters have no interesting abilities at all, and everything is poorly designed especially the skill challenges.
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- King
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XKCD misses a bit here:Hicks wrote:https://what-if.xkcd.com/1/
"Suppose you’re watching from a hilltop outside the city. The first thing you see is a blinding light, far outshining the sun. This gradually fades over the course of a few seconds, and a growing fireball rises into a mushroom cloud. Then, with a great roar, the blast wave arrives, tearing up trees and shredding houses."
Between the light and the blast, you also get the heat flash. And there can be quite a while between that and the blast, maybe long enough for people to think things are over. Duck and cover and stay covered.