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Level Flight Bullet

 Counter spinning cylinders on either side impart stability without spinning entire bullet
 
(+1, -1) 		  [vote for,
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To eliminate the spinning of a rifling stabilized projectile so that electronic devices such as cameras may have a more effective platform to operate from.

The bullet is slightly ovoid shooting out of a barrel of the same shape. The rifling is cut into the left and right side of the barrel in a contra-rotating configuration. The bullet has two rotating cylindrical portions on either side along the bullet's long axis that spin in the directions that their respective rifling turns them therefore spinning them in opposite directions to each other. Thus the bullet flies flat and stable with the two spinning masses counteracting each other while imparting stability to the unit as a whole.

So basically you use specialized rifling and projectile/muzzle shape to create two contra-rotating gyroscopes to keep your projectile stable rather than spinning the whole thing in one direction.

—doctorremulac3, Jun 04 2016

Brunswick rifle https://en.wikipedi...iki/Brunswick_rifle
Lovely little thing ... actually, a carbine. [8th of 7, Jun 04 2016]

or get smarter bullets Bulls_20Eye_20Bullets
[theircompetitor, Jun 04 2016]

[link]






       This is just a twist (ha, ha) on the idea behind the Brunswick rifle.   

       <link>
—8th of 7, Jun 04 2016
   

       I don't think I described this well. The new design is for a 3 part bullet, a body that holds two articulated rotating cylinders, each rotating in opposite directions to each other.   

       A picture will really clarify this but maybe tomorrow. Busy as heck today.
—doctorremulac3, Jun 04 2016
   

       We thought about Glock polygonal rifling. A trilobal design with twists in opposite directions for each portion of the projectile would spin each section in opposite directions.   

       The problems would be (1) getting the two segments to separately engage "their" bit of the rifling, and (2) projectile obturation (gas seal).   

       Something like a plaswad base on each section might do it.   

       It's still going to be very, very hard to make a couple of bearings that are effectively frictionless at high RPM and temperatures, and that withstand the shock.
—8th of 7, Jun 04 2016
   

       No need for the bearings to be frictionless, they just need to not significantly retard the turning of the gyroscopic elements for the duration of the flight.   

       //The problems would be (1) getting the two segments to separately engage "their" bit of the rifling,//   

       Which is solved by having them on two separate axes nestling them side by side. The rifling also is located in two different positions on the barrel, the left and the right.   

       This really needs a drawing. Tomorrow maybe.
—doctorremulac3, Jun 04 2016
   

       So, if I understand this idea, you want a bullet with two rollers, one on each side, whose spin stabilises the bullet while the body of the bullet does not spin?   

       I think the first problem is that, even if the rollers and their bearings survive the firing, they will not be friction-free. Given the high speed of their rotation, any friction will be a problem.   

       Moreover, if the friction of one bearing is even slightly different from that on the other, there will be a net torque on the bullet. This torque will be about an axis which is not coaxial with the bullet itself, and hence the bullet will tend to corkscrew.
—MaxwellBuchanan, Jun 05 2016
   

       //a bullet with two rollers, one on each side, whose spin stabilises the bullet while the body of the bullet does not spin//   

       Yes.   

       //if the friction of one bearing is even slightly different from that on the other, This torque will be about an axis which is not coaxial with the bullet itself, and hence the bullet will tend to corkscrew.//   

       Hmm Good point, you're absolutely right. Any variance in rotation between the two cylinders is going to cause the projectile to roll.   

       Have them contact each other via a gear so they're both rolling at the same speed.   

       I"m just curious, how many RPMs to you really need to stabilize a bullet? The little toy gyroscopes I had as a kid kept upright just fine and I know it was spinning a heck of a lot slower than the 180,000 RPM of a bullet. So if it were necessary to impart a slower spin to the cylinders due to issues of friction it seems like you'd have some leeway there.   

       I also just though of another way to do this, you could have...   

       let me put up another idea.
—doctorremulac3, Jun 05 2016
   

       I guarantee this will not work even a little bit, and the bullet will be just as unstable as it would be without the two cylinders spinning (barring some unexpected stabilization from the Magnus effect or something). Any two equal-in-magnitude-(the site tells me I need to put a space here)-moment-of-inertia counter-rotating rotors will cancel out each other's momenta of inertia, leaving you with no stabilization. (I know because I have looked into this before, for CMGs.)
—notexactly, Jul 03 2016
   
      
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