Yawsonde Data for M687-Type Projectiles With Application to Rapid Spin Decay and Stewartson-Type Spin-up Instabilities
ARMY BALLISTIC RESEARCH LAB ABERDEEN PROVING GROUND MD
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Specially prepared M687 projectiles were tested at Wallops Island, Virginia, on 28 September 1977 and 3 May 1978. Yawsonde data were obtained for all flights. The payload canisters were one piece cylinders of M687-type except that several of the canisters had heights that were non-standard. In an attempt to reproduce previously observed anomalous despin effects for M687 shell at shot exit, several types of liquids with fill ratios of 90 or 100 were tested at yaw levels up to ten degrees. The raw data from the projectiles tested did not indicate anomalous effects at shot exit, and these effects have only been observed when simulant-loaded binary canisters with burst discs were employed. It is most probable that the burst discs precipitate the anomalous spin behavior. Yawsonde data were also obtained for 100 filled canister whose height was selected to produce a Stewartson-type instability during liquid spin-up. The flight data from one unstable round was consistent with computations of spin-up eigenfrequencies from recently developed methods.
- Ammunition and Explosives