Prediction of Spin-Decay of Liquid-Filled Projectiles.
BALLISTIC RESEARCH LABS ABERDEEN PROVING GROUND MD
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An accurate method for predicting the spin-decay of liquid-filled projectiles throughout their flight is described. The method is based on Wedemeyers model for the spin-up of the liquid payload. The in-bore spin-up process is predicted using numerical solutions of the Navier-Stokes equations and Wedemeyers equation. Spin-decay calculations are compared to spin histories obtained from test firings of 155mm liquid-filled projectiles equipped with yawsondes. The 100-filled cases show excellent agreement between the theory and the measurement throughout the entire flight the errors being less than 0.8 of the measured spin rate. The errors are no larger than about 1 for 90-filled cases. The theory is used to calculate the spin-up time of the liquid defined as the time when 99 of the instantaneous rigid-body angular momentum is achieved. Author
- Ammunition and Explosives