Speed of Sound at High Pressures

[rsterne]

Info posted here.... http://www.gatewaytoairguns.org/GTA/index.php?topic=66866.0

Bob

[Booger]

Info posted here.... http://www.gatewaytoairguns.org/GTA/index.php?topic=66866.0

Bob

Oh mighty sage, this leaves a question that has been in my mind for months.

Does breaking the speed of sound (pellet going into and out of the speed of sound) cause inaccuracy in pellets or is it in the harmonics of the barrel? Could it be a combination of both?

[rsterne]

Pellets/bullets are the least stable right at the speed of sound (OK, 1 fps under, not over).... It is possible for a projectile to be stable over Mach 1 and under, but tumble at just under Mach 1.... The stability curve would be like this....



Note the Stability Factor is below 1.0 at just under Mach 1, so the bullet would be unstable.... However, if it was a fraction shorter, or the barrel had a fraction higher twist rate, it would be OK all the time.... Pellets, because of the narrowing immediately behind the head band, have a very tight curvature right at the back of the head, and can develop local shockwaves that can destabilize the pellet as it slows through Mach 1.... It doesn't always happen, but it can.... Barrel harmonics is a separate issue.... This post really had nothing to do with either, it was more of a general interest thing.... There is a related thread in the GEEK Gate about Sonic Choking of Ports, and that is where this information is really useful....

Bob

[bnowlin]

Dang Bob you keep giving me headaches.
Bob

[Booger]

Dang Bob you keep giving me headaches.
Bob

I heard that. Much too intelligent for a slow mind like mine.