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Hypersonic bullet

 A bullet that can fly around the earth
  (+6, -11)(+6, -11)
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This is a bullet that can be fired from an ordinary high powered rifle. The bullet is shaped so as to compress the air flow around it (as in a scramjet), and the circumference of the bullet is coated with a material that ignites during firing, so that it burns for several seconds, accelerating the bullet to a much higher velocity. The material thickness and burning characteristic can be tailored—for instance, if you wanted to send the projectile into space, its geometry would change in a prearranged fashion as it burned down, so that that the scramjet surface is always optimized for altitude.
—ldischler, Nov 20 2004

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       Usually bullets are emnt for shooting things.   

       And a bullet with such a high velocity would have a similar effect as a bullet with massive calliber.Not to mention the fact that the fuel would cause a big explosion on impact.   

       Two problems: The recoil if it was put in a rifle it would probably tear your arm off. It would tend to vapourise and explode at lower altitutes where bullets are normally fired.   

       In affect, what's invented is a special rocket launcher thingy.
—Cats Whiskers, Nov 20 2004
   

       I think [ldisch] has left the building. so I'll withdraw some of my questions; and I think he has also a problem with the orbit claim.
—dentworth, Nov 20 2004
   

       Fly around the earth? Well, that may be a bit of Burt Rutan hype at this point, so I’ll settle for sub-orbital. As for recoil, Cat Whiskers, since the acceleration happens after the bullet leaves the gun, no problem.
—ldischler, Nov 20 2004
   

       Hypersonic flight requires huge amounts of energy, even for little tiny things, this energy is then dispersed in the sonic boom that follows. You would need a seriously powerful propellant.
—wagster, Nov 20 2004
   

       I think it would have problems. However, a small dollop of high explosives in the base of the bullet could help. It would have to be delayed a few 1/1000 ths of a second so it cleared the barrel, then the little bang would kick it up another 1000 or 2000 feet per second. Maybe not hyper velocity, but 5000-6000 FPS yields impressive energy in a 1000 grain bullet.
—bobad, Nov 20 2004
   

       Well...a few hundreds would be significantly safer, [bobad], a bullet that has on explosion on the end doesn't seem safe to have 12 feet from some-one.
—my-nep, Nov 20 2004
   

       What's a scramjet surface? Where's the nozzle? Nevermind. I think this would make a lovely signal flare.
—Shz, Nov 21 2004
   

       Bullets are fired to hit things.   

       How is this thing guided if you can't see what you're firing at? Or are you really aiming for the back of your own head, in a peculiarly Quixotic suicide attempt?   

       And what's wrong with a standard issue cruise missile?
—DrCurry, Nov 21 2004
   

       A bullet made of solid magnesium might do the trick. The bullet itself would burn and provide the impetus. It might be fairly small after it made it once around the earth, but that would make it safer for all involved.   

       As regards [Curry's] question about hitting a target you cannot see, the obvious answer is that many, many bullets must be fired.
—bungston, Nov 21 2004
   

       Good thinking, bung. Except magnesium oxide is not a gas, so, while a mag-bullet will make a lot of light, the burning magnesium won’t add much in the way of thrust.
—ldischler, Nov 22 2004
   

       It is if you're going to use this think in close combat.   

       Other problems - the air resistance may cause the bullet to explode before it even hits something. The prson firing the gun would be sprayed with hot gasses from the scramjet if the timing goes wrong.
—Cats Whiskers, Nov 22 2004
   

       /magnesium oxide is not a gas/ - this leads me to one of my questions about scramjet technology. There is no way to filter out oxygen, so the 70% nitrogen must come thru too. The nitrogen would be greatly heated by the magnesium/oxygen reaction, and this could serve to provide thrust.
—bungston, Nov 22 2004
   

       Good point. Scale it up—with a nuclear reactor as the propulsion surface you could tear around through the atmosphere at hypersonic speed for a good long time, just by heating the air. At least until you hit a bird or something.
—ldischler, Nov 22 2004
   

       [-]This is just a rocket, launched by gun. Rocket Powered Grenade (RPG) is baked. Oh, this is a "faster" RPG? How is that really different or if different, how is it better or doable?
—sophocles, Nov 22 2004
   

       This is not a new idea. I have seen it written before.
—Knife Knut, Jan 26 2005
   

       How about a tungsten bullet with a magnesium outer casing???   

       Tungsten has (if I remember correctly) the second highest melting point of any element (carbon is #1) and has significant mass so as to penetrate whatever it hits   

       The only problem I can see with it is that it will not deform on impact like your average lead bullet
—torch0, Sep 08 2006
   

       I'm reading this, thinking, not another stupid bullet idea. And then I see it's mine. Jeez.
—ldischler, Sep 08 2006
   

       I give this a bun because with some calculus and information about global windspeeds, one might shoot him or herself in the ass.
—bungston, Sep 08 2006
   

       So it's an aerospike SFIRR, or a tubeless ram accelerator?
—notexactly, Jan 13 2016
   


 

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