Stability of penetrators in dense fluids

Abstract The differential equation of yawing motion of a gyroscopically unstable, gigid body penetrator in a dense fluid is examined for application to flash radiographie measurements of a bullet penetrating gelatin. A functional form for the relationship of overturning moment to instantaneous yaw is derived. Using this expression for the overturning moment, a greatly simplified equation of gyroscopically unstable yawing motion is fitted to the bullet's yaw history. By pooling the data for the eight firings, a very good estimation of the overturning moment, valid for yaws up to 140°, is obtained.