A Novel Soft Recovery System for the 155-mm Projectile and Its Numerical Simulation

Report No. ARL-TR-2462
Authors: Avi Birk and Douglas E. Kooker
Date/Pages: April 2001; 38 pages
Abstract: There is a requirement to soft catch, without exceeding a deceleration rate of 1,600 g, and within less than 300 m, an unmodified 102-lb SADARM (Sense and Destroy Armor) projectile fired at 840 m/s. This report presents a soft-recovery concept and its numerical simulation. The concept entails aerodynamic deceleration of the projectile in a long tube attached to the gun barrel. The midsection of the tube is bound between a diaphragm and a free piston and is prepressurized to about 2 MPa. As the projectile enters the tube, the shock wave preceding it ruptures the diaphragm and the projectile decelerates as high pressure builds between it and the free piston. The piston disengages and travels forward scooping water. The waterlog that forms in front of the piston effectively increases the piston's mass and also induces braking force because of the water friction with the tube wall. The projectile's deceleration is controlled, and eventually the projectile exits the tube with a velocity of 10 m/s. The numerical simulation, based on the method of characteristics, incorporates unsteady one-dimensional fluid dynamics that captures the extensive wave dynamics. This report details the effects on the projectile's deceleration of the midsection length, initial pressure, and the water mass. From the simulation, it is possible to soft capture the SADARM projectile within 120 m.
Distribution: Approved for public release
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Last Update / Reviewed: April 1, 2001