NASA to buy lightweight, semi-automatic rifles

[milktree]

The vacuum of space shouldn't make any difference in modern ammo. Rounds have oxidizers in them. Can fire in a vacuum, under water, etc.

I was thinking of the vacuum (lack of air) in the gas system that the gas from the burning power would normally push against, and the air in front of the gas rings that would provide some tiny resistance. There’s also a non-zero amount of resistance to the buffer movement in the buffer tube from pushing the air out of it.

Maybe the two effects cancel each other (enough)

What would be interesting though is the low G's of space and the moon. I wonder if there is an angle you could shoot while standing on the moon where it would be possible to shoot around the entire moon and hit yourself with it (ie. not enough angle to escape gravitational pull, but high enough to account for minimal bullet drop and little atmosphere to reduce velocity).

Commit suicide by shooting yourself on the back from 6,800 miles away!

 

[PappyM3]

What difference would the vacuum of space make? Maybe you might need to adjust the gas system a tiny amount because it’s empty of atmosphere, but maybe not, because the buffer and bolt wouldn’t have any air resistance.

The 50,000+ psi in the chamber is pretty huge and dwarfs the 15psi of atmospheric pressure.

Yes, the chamber pressure does dwarf the difference from atmospheric pressure. And the rifle would probably work fine. My point is that the vacuum would be the thing that would need testing when wondering about a gas impingement system in space, not gravity.

Regarding gravity though, ARs work right side up, sideways, upside down, every which way. All the springs make it ambivelant to earths gravity or a lack of gravity. It would require testing on bodies with a mass greater than the Earth though.

 

[Freddy B]

It's an RFP. Presumably some bidders will come in with bids that aren't strictly conforming because they have something better to offer.

Nah. Other bidders will realize the procurement is "wired" and not bother. That's the way it works in government contracting.

 

[not new guy]

Are most of the "competitively bid" .gov RFPs just going through the motions before handing the award to the predetermined winner? My experience is mostly in IDIQ contracts, where we don't have to deal with that shit.

 

[one-eyed Jack]

Maybe first they should think about what the guns could be used to shoot at? Jack.

 

[308rifleman]

Good for them. If only more agencies had a budget of $15k for rifles.

They used the HK MP5 for many years. Most agencies have long since retired their SMGs. Looks like NASA is doing the same.

 

[Glockster30]

The vacuum of space shouldn't make any difference in modern ammo. Rounds have oxidizers in them. Can fire in a vacuum, under water, etc. What would be interesting though is the low G's of space and the moon. I wonder if there is an angle you could shoot while standing on the moon where it would be possible to shoot around the entire moon and hit yourself with it (ie. not enough angle to escape gravitational pull, but high enough to account for minimal bullet drop and little atmosphere to reduce velocity).

No, not possible. The moon bullet will travel 6 times farther on the moon than on the earth, so if the bullet travels 3 miles on earth, it will travel about 18 miles on the moon.

 

[fshalor]

Does DI work in vacuum? I'd imagine piston may cycle.

 

[fshalor]

Does DI work in vacuum? I'd imagine piston may cycle.

Don't start with the physics or the mechanism. I know it will fire. But will it cycle due to the cold. Or due to the hot if it is in day side. Or the cold/hot cycle if it is external to a shield.

 

[ReluctantDecoy]

No, not possible. The moon bullet will travel 6 times farther on the moon than on the earth, so if the bullet travels 3 miles on earth, it will travel about 18 miles on the moon.

I've seen that figure before. It doesn't necessarily apply to my initial question though, as it doesn't account for atmosphere on earth and assumes a 0 degree shot angle. You'd get greater than 6x with the right adjustments. Still though, now that I'm actually looking at the moon's circumference, my initial question seems dumb. I've forgotten how large the moon actually is. You're right in that's just not possible without achieving low orbit with an escape velocity of 7,808 feet per second.

 

[E.Stoner]

SPAAAAACE FORCE!!!
I have a NASA M-1 survival knife (machete) which was made for the Gemini/Apollo mission. Good for space pirates and hacking through alien jungles.

 

[Andy in NH]

Must work on talking apes.

 

[drgrant]

Say you needed a gun in space. Would a direct-impingement system work reliably in zero gravity, or would it change the behavior of the gases? I honestly don’t know.

NES Rocket Scientists! Out yourselves!

Interesting question. I'd be more concerned about the physics of the mechanicals than the gases, since the gun itself would have no problem firing and so
on, and propellant has its own oxidizers, if it didn't, it wouldn't work correctly. So not having oxygen isn't the biggest problem. I would think the effects of
zero-g on the parts (say the bolt carrier?) would be a bigger problem but that's just a guess. Scientifically it's probably less complicated than firing a gun underwater.

-Mike

 

[drgrant]

The vacuum of space shouldn't make any difference in modern ammo. Rounds have oxidizers in them. Can fire in a vacuum, under water, etc. What would be interesting though is the low G's of space and the moon. I wonder if there is an angle you could shoot while standing on the moon where it would be possible to shoot around the entire moon and hit yourself with it (ie. not enough angle to escape gravitational pull, but high enough to account for minimal bullet drop and little atmosphere to reduce velocity).

Yes, at least one thing I just read stated that if you could fire a gun on the moon that had a bullet that traveled fast enough, and you stood on a mountain on said moon, you could conceivably shoot yourself, but it'd be incredibly difficult to actually pull that off.

-Mike

 

[Picton]

...but it'd be incredibly difficult to actually pull that off.

-Mike

Not if you’ve pissed off the Clintons.

 

[ReluctantDecoy]

Yes, at least one thing I just read stated that if you could fire a gun on the moon that had a bullet that traveled fast enough, and you stood on a mountain on said moon, you could conceivably shoot yourself, but it'd be incredibly difficult to actually pull that off.

-Mike

Is it crazy that hearing that makes me want to try it just to see what would happen? I mean, I don't want to die, but I'd also die of curiosity. I suppose its a good thing NASA doesn't accept my astronaut applications.

At 6,786 miles circumference, or about 35,830,080 ft, a 556 round going, say 3,200 fps would take just over 3 hours to travel that distance. I'll have to have a copy of the Godfather on hand to pass the time.

 

[MisterHappy]

You think that this was an accident?

View: https://www.youtube.com/watch?v=hWZgrCcMbyg

 

[Mesatchornug]

Is it crazy that hearing that makes me want to try it just to see what would happen? I mean, I don't want to die, but I'd also die of curiosity. I suppose its a good thing NASA doesn't accept my astronaut applications.

At 6,786 miles circumference, or about 35,830,080 ft, a 556 round going, say 3,200 fps would take just over 3 hours to travel that distance. I'll have to have a copy of the Godfather on hand to pass the time.

Also, your head is like 5e-7 MOA (assumes 6" at 1.2e7 yards, please check my math) at that distance. - literally 1 in 2 Million. Even if we assumed you could make the range, and hold onto any meaningful energy, I'm going to put any amount of money on that shot not happening.*

assumes shoulder-fired. the Norden bomb-sight or some similar mystical whatever might be able to make it; that's different

 

[Glockster30]

I've seen that figure before. It doesn't necessarily apply to my initial question though, as it doesn't account for atmosphere on earth and assumes a 0 degree shot angle. You'd get greater than 6x with the right adjustments. Still though, now that I'm actually looking at the moon's circumference, my initial question seems dumb. I've forgotten how large the moon actually is. You're right in that's just not possible without achieving low orbit with an escape velocity of 7,808 feet per second.

If you use escape velocity, the projectile will leave the moon and keep going forever (unless it hits something). So, escape velocity is different than orbital velocity. For example, to reach escape velocity from the earth, an object would need to be going about 25,000 mph, but the orbital velocity for the space shuttle was a little over 17,000 mph. Therefore, for your example, the orbital velocity would be less than the escape velocity for your bullet on the moon.

 

[Sprocket]

Sealed system. All that is needed for the reaction contained within.

What if they are on a treadmill?

 

[Picton]

Is it crazy that hearing that makes me want to try it just to see what would happen? I mean, I don't want to die, but I'd also die of curiosity. I suppose its a good thing NASA doesn't accept my astronaut applications.

At 6,786 miles circumference, or about 35,830,080 ft, a 556 round going, say 3,200 fps would take just over 3 hours to travel that distance. I'll have to have a copy of the Godfather on hand to pass the time.

But wait. You couldn't fire the round parallel to the moon's surface, because the moon's got gravity. It would act only 1/6th as effectively on the flying bullet as the Earth's gravity, but it would act, and ultimately the bullet would augur in. So, if you wanted to circumnavigate the moon with a single 5.56 round, you'd need to fire it on some ballistic trajectory that would put it into lunar orbit: an ellipse.

So your range is actually greater than 6,786 miles. And that's all I can productively add. But I'd still vastly rather have a piston design than DI on the moon.

 

[Glockster30]

But wait. You couldn't fire the round parallel to the moon's surface, because the moon's got gravity. It would act only 1/6th as effectively on the flying bullet as the Earth's gravity, but it would act, and ultimately the bullet would augur in. So, if you wanted to circumnavigate the moon with a single 5.56 round, you'd need to fire it on some ballistic trajectory that would put it into lunar orbit: an ellipse.

So your range is actually greater than 6,786 miles. And that's all I can productively add. But I'd still vastly rather have a piston design than DI on the moon.

That's true. In the case of the space shuttle that I used, if it orbited the earth at 200 km, 200,000 meters would be required to be added to the earth's radius to reach orbital velocity.

 

[AHM]

The National Aeronautics and Space Administration, or NASA, will acquire lightweight, semi-automatic rifles, ... The rifle shall be easy to accessorize and deploy the following characteristics:
...
3. Weight: Less than 107 oz

On what planet?

9. Stock: 6 position collapsible

Better not crash land in Massachusetts.

NASA has its own Emergency Response Team (ERT)

It's about freaking time.

I wonder if gravity is low enough that you could fire a round and the bullet would come back around the other side of the moon and hit you...

Need a wildcat cartridge, but sure.

Shoot the Moon​

Paging @EddieCoyle...

Regarding gravity though, ARs work right side up, sideways, upside down, every which way.

It would require testing on bodies with a mass greater than the Earth though.

The solar system has no bodies with surface gravity greater than 1g
where you can run gun tests.

Maybe first they should think about what the guns could be used to shoot at?

Well, that's a no-brainer.
The visitor parking lot at KSC is ringed with these signs:

 

[exo]

So, couple questions.

Which gun is better for space, AR-15 or AK-47?

What caliber for space-bear? Is 9mm still good enough?

 

[DW357]

What caliber for space-bear? Is 9mm still good enough?

.40.....always .40

 

[beaker]

They have their own cops/security. Meh.

NASA actually has their own SWAT team...

 

[beaker]

Yes. Ill show you my scar.

The vacuum of space shouldn't make any difference in modern ammo. Rounds have oxidizers in them. Can fire in a vacuum, under water, etc. What would be interesting though is the low G's of space and the moon. I wonder if there is an angle you could shoot while standing on the moon where it would be possible to shoot around the entire moon and hit yourself with it (ie. not enough angle to escape gravitational pull, but high enough to account for minimal bullet drop and little atmosphere to reduce velocity).

 

[meh]

The art of orbiting is falling and missing the ground.

But wait. You couldn't fire the round parallel to the moon's surface, because the moon's got gravity.

Yes, 5.56 rounds aren't nearly fast enough to orbit the moon. I like to think of orbiting in Hitchhiker's Guide terms: orbiting is falling and missing the ground. That takes some serious speed, even on the moon.

 

[M1911]

The visitor parking lot at KSC is ringed with these signs:

They need to post those signs wherever NASA bureaucrats gather.

 

[Sauer Grapes]

I wonder if gravity is low enough that you could fire a round and the bullet would come back around the other side of the moon and hit you...

If your accuracy is spot on, yes, theoretically it could. I read something once about a similar theory involving Jupiter instead, because of it's massive gravity