Measurements of Angular Momentum Transfer in Liquid-Filled Projectiles
ARMY BALLISTIC RESEARCH LAB ABERDEEN PROVING GROUND MD
Pagination or Media Count:
In-flight spin-decay measurements were performed on M687 liquid- filled projectiles by means of yawsondes. The shell spin-decay is used to infer the instantaneous liquid angular momentum and its rate of change by applying the moment of momentum equation. Through this inference one can deduce the time required for the liquid to acquire rigid-body-like rotation. This is called the spin-up time. This time becomes important when studying other aspects of the liquid-filled projectile problem namely, that of projectile instability induced by liquid eigenfrequency resonance with the projectile nutational frequency. The results indicate that for liquid Reynolds numbers below 1,000,000 the liquid spins up in less than 5 seconds. Above this Reynolds number the spin-up time is a strong function of Reynolds number reaching about 17 seconds at Re 1.7 x 1, 000,000.
- Ammunition and Explosives