I call BULLSHIT

[unixronin]

A centrifuge-based gun with no sound, no heat, no mechanical wear, no recoil even when firing .50-caliber projectiles at up to 8000fps at up to 120,000rpm cyclic, that cannot jam ...

Um, excuse me.  But.  This article was supposed to be published on April 1, right....?

Update:

phanatic, a poster on the guns thread, calculated the power requirements of this weapon from the specs claimed by the crank inventor and assuming perfect 100% efficiency.  Using those assumptions, he came up with a sustained power consumption of 100MW -- approximately 134,000 horsepower.

Noiseless?  Heatless?  Portable?  .... Yeah, RIGHT.

Comments

[unixronin.livejournal.com]

recoil? I'm going to refer to newton rather than TANSTAAFL, sorry- object in motion tend to stay in motion. Alrighty, all your "notfree lunch" is on the front end in the energy of accelerating the projectiles..... all of the acceleration occurs BEFORE "firing". Think terbuchet, not onager.

No, it doesn't work that way. OK, assume it's all spun up and foll of balls... everything is in dynamic balance. Now you open the firing gate, and balls start blying out. The moment the first ball leaves the wheel, there is an out-of-balance moment due to its opposite number.

Think of it this way: all the spinning balls are exerting force on the inner wall, all around. Open that wall at one point, and a "jet" of balls escapes. At that point, there is no force being exerted on that part of the wall. What else works this way? A rocket engine. You can call it recoil or you can call it thrust, but you can't evade conservation of momentum -- there WILL BE an equal and opposite reaction.

[koyote.livejournal.com]

okay, yes. releasing the kinetic energy pressed against the side of your centrifuge at one point is going to create a small imbalance opposite that point- but to maintain a rate of fire, you have to be adding another ball into the mix, which would alleviate that.

The force being removed isn't going to be enough to matter to a 28 pound weapon, for sure. certainly not pintle or roof mounted. Depending on how the mechanism works, the imbalance could be *before* release and thus accounted for in the design, static in point, or precessing. It's even possible (though I can't figure out how) to use the imbalance to feed the machine.

[unixronin.livejournal.com]

okay, yes. releasing the kinetic energy pressed against the side of your centrifuge at one point is going to create a small imbalance opposite that point- but to maintain a rate of fire, you have to be adding another ball into the mix, which would alleviate that.

No it won't, because the new ball you're adding isn't up to speed yet. So in addition to the reaction from the ball you've just released, there's the rotational drag of getting the new ball spun up.

The force being removed isn't going to be enough to matter to a 28 pound weapon, for sure.

From a single ball, you might not notice it. But it's still there. With a weapon firing as many as 2,000 balls per second, you most definitely will. Trust me on this, there WILL be a recoil force, and it won't be small. You can't just "account for" conservation of momentum through a clever design. The inventor is a crank, and his claims for this weapon are every bit as bogus, if perhaps slightly less obviously so, than those for every "perpetual motion machine" ever invented. There's ways to cheat recoil and not pass it on to the firer or mount point by ejecting a countermass (be it gas, as in a recoilless rifle (http://en.wikipedia.org/wiki/Recoilless_rifle), or plastic strips as in the Armbrust 300 (http://en.wikipedia.org/wiki/Armbrust)), but there's no way to construct a projectile weapon that does not produce any recoil forces in the first place that doesn't require obtaining an exemption from compliance with the physical laws of this Universe. Even the sling you mentioned earlier has recoil.