Memorandum on Water Tunnel Tests of a 2.37" Rocket Projectile with Collapsible Type Tails

This report covers water tunnel tests of a full scale 2.37" rocket projectile (designated in the laboratory as projectile number ND-11 Impervium) with four different collapsible tails. The purpose of the tests was to compare the drag coefficients for this projectile using each of the collapsible tails with the drag coefficient for the projectile using its original fixed-fin tail, and to determine the effect of the collapsible type tail on the center-of-pressure location