[Bergeron]

Has anyone checked out the latest American Rifleman? Really interesting article about one of NASA's hypervelocity 2 stage guns. I'm fortunate enough to be instrumenting a back plate for a smaller gun of similar design for my senior research starting in the fall, and was fascinated to read about the one that they featured.



Talk about a game of one-upmanship to those .600 Nitro revolvers. :cool:

[Mike Irwin]

Rifleman has run a couple of articles on hypervelocity guns over the years. One VERY interesting one back from the late 1980s showed a very interesting either X-ray or spark photograph of a 1-lb. projectile in flight at something like 30Kfps. The air resistance deformation was pretty dramatic.

[Delmar]

Interesting.....
Roy Weatherby was approached back in the 1950/1960's to experiment on just how fast they could get a conventional projectile to go. IIRC, the max speed he could get was about 6,000 fps or so. A bigger charge would not raise the velocity and it appeared that this was the max velocity which could be obtained with the gun powders of the day on a cupro nickel jacketed bullet.
Makes me wonder how much faster they could get stuff to go on conventional propellents and incorporate a sabot or plastic driving bands.

[Mike Irwin]

I believe that about 6,200 fps is considered to be the theoretical maximum with any type of nitrocellulose based gunpowder. That's about as fast as the gasses from the burning powder can move.

[Orthonym]

I used to help load/shoot one of these when I was a co-op at MSFC in the early 70's. As I recall, we used a sawed-off 20mm cartridge case behind a polyethylene slug behind the actual projectile, usually an itty bitty Lexan cylinder. The thing was called, officially, the 1/8" Boeing Light Gas Gun. To this day I have trouble bending my left thumb as a result of my boss insisting on my using stamp dies and a hammer to mark the high-pressure sections of the gun. They were, of course, made of the very best steel, so I had to swing the hammer VERY hard to make a faint mark. Well, of course I missed from time to time and got my thumb. I still hate that man, almost as much as I hate NASA for what they've done to kill space exploration.:fire:

[Triad]

I read about one of these in Discover magazine some time ago. IIRC it used a plastic ball in some kind of sabot and they had a mechanism to strip the sabot rather than let air resistance do it. They showed a piece of aluminum they shot with the gun, it was described as being the size of a NYC phone book, that little plastic projectile blew a five inch hole through it.

[Bergeron]

Yeah, the gun uses the smokeless powder to drive a piston that compress hydrogen or helium, hence the term "Light Gas" Gun. Once the gas reaches a certain pressure, it ruptures a disk that then propells the projectile, giving those awesome velocities.

The gun whose back plate I am instrumenting starts the process with a Sako IIA action, and gets projectile speeds of 3-7 km/s. Smokin!

[Orthonym]

Same principle as a spring-piston air rifle, but the powder gases replace the spring. I always wondered if one could put ,oh, a tire valve on an air rifle, squirt it full of He, and get more velocity that way.

[Keith]

If you hang around any gun store long enough, you can hear about selected 30.06 handloads that will easily top 6000 fps with certain rare powders that they don't make any more. Those loads were frequently used to take world record bucks, but since the shooter "ain't no trophy hunter" he just threw the antlers away...

Keith

[Bergeron]

Orthonym, that gun is still there, and I understand that there might be some intrest in getting it work again.

[goon]

If you hang around any gun store long enough, you can hear about selected 30.06 handloads that will easily top 6000 fps with certain rare powders that they don't make any more. Those loads were frequently used to take world record bucks, but since the shooter "ain't no trophy hunter" he just threw the antlers away...

Keith

It is then that I point out that if that really were the case, peices of the rifle would also be doing about 6000 fps in every direction.:D