Vacuum Hoover on the moon & 1 million rounds per min gun

[grooble]

What would happen if you took a vacuum up to the moon and tried to suck up some lunar dirt? Would it work? Would it explode?<br /><br />Another question, can a gun be used as propulsion? There is a gun that can fire 1 million rounds a minute, would that generate good thrust?

 

[spacelifejunkie]

Physics doesn't suck.<br /><br />SLJ

 

[ve7rkt]

2) Sure, guns make thrust. But who needs a million rounds per minute? There have been plans for things like "massdriver asteroid tugs" that would move an asteroid back to Earth for mining by digging out small chunks of the asteroid, loading them into a gun (well, a magnetic linear accelerator, but that's just a really fancy gun), and firing twice a second or so.<br /><br />From Wikipedia article on the A-10 Thunderbolt II (Warthog) aircraft and its big honking gun that fires 4200 rounds/minute:<br />This gun is said to produce almost the same amount of force as one of the A-10's engines, leading to a persistent military legend that if enough bullets could be carried and fired in a long burst, the plane would stop flying (or move backwards, in some versions of the legend). Using the specs from the GAU-8/A product homepage, the recoil force of the GAU-8/A is measured to an average of 10,000 lbf (45 kN). This is a considerable amount: more than 50 percent of the thrust of both of the A-10 engines at full power. But the A-10 will certainly continue flying forward, assuming both engines are operating at full capacity. If one of the engines is damaged and unable to operate, the recoil force of the cannon would overpower the thrust of the remaining engine.

 

[chriscdc]

Ok what have you done with grooble? At the worst the motor would melt due to no resistance and lack of convection currents to remove heat.<br /><br />The gun that fires 1 million rounds per minute is abit of an urban legend. True the rate at which it fires is at 1million rounds per second but it is really a box with a bunch of barrels, all of which are packed with alternating projectiles and explosive charges. Designed to cover a large area with a hundred or so explosive rounds in a fraction of a second.

 

[mlorrey]

Actually, pulse detonation propulsion concepts are the 'hot' area of rocket research these days, with theoretical specific impulse in the thousands. Think Project Orion without the nukes, at a smaller scale.

 

[vogon13]

Project Orion with out the NUKES ? ! ? ! ? ! ? ! ?<br /><br />That's blasphemy.<br /><br /><br />Guess who's going to be duck taped to the pusher plate on the next demo flight . . . .<br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

 

[nyarlathotep]

>>"The gun that fires 1 million rounds per minute is abit of an urban legend. True the rate at which it fires is at 1million rounds per second but it is really a box with a bunch of barrels, all of which are packed with alternating projectiles and explosive charges."<br /><br />What, say, would you have if you took 5000 metal storm boxes, and hooked them up in parallel? Would that not be a gun that can fire 1M rounds per minute?

 

[mlorrey]

No, not unless each barrel has enough bullets so the total bullets equal 1 million. Then you would fire 1 million in a minute (or less if you wanted). The problem with such a system as a propulsion device is that almost all barrels are offset from the axis of the center of gravity, so it could not provide sufficiently balanced thrust without a lot of computer controls.

 

[grooble]

This is the prototype of the gun:<br /><br />http://www.uglyjackass.com/media/videos/?id=gun<br /><br />About 44 seconds in you will see it fire 180 bullets @ the 1 million rounds a minute rate. A million bullets would probably be too expensive to use all at once in a test.<br /><br />Anyway checkout the recoil, i was thinking maybe you could use it as an accelerator before kicking in an ION drive. Those ION drives have slow acceleration, so if you can get to a high initial speed fast then the overal mission times would be quicker.

 

[mlorrey]

a rate of 1 million rounds per minute is different from actually firing 1 million rounds per minute, which implies one can fire for at least a minute.<br />That sounds like picking nits.<br /><br />However, initial velocity really doesn't matter much, nor does firing rate. It would be more efficient and better performance overall if a probe booster fired a few dozen rounds right at perigee, waited till the next orbit, did it again, etc to maximize gravity boosting at the same time. However, it is more important that the Isp of the vehicle be maximized when travelling long distances in interplanetary space. This minimizes fuel needs and total probe mass, which is what really allows you to maximize your initial velocity.