Flight test of a 6 inch diameter 2400 lbs thrust solid rocket motor. Rocket weight at takeoff = 145 lbs. Motor was designed for a two stage 220 lbs rocket, but rocket was not ready in time and a lighter weight single stage airframe was substituted. As a result, the thrust to weight ratio was 16 to 1 (too high) instead of a more sane 10 to 1. Recovered flight data indicated acceleration exceeded 40 g's. Propellant grains collapsed under the high acceleration causing the chamber pressure to exceed the max design pressure of the motor case. The forward closure failed, ejecting the forward bulkhead and separating the airframe. The rocket tumbled end over end at ~Mach 2, and the resulting aerodynamic loads shredded it into pieces which fall and impact the desert. Balls Experimental Rocket Launch Black Rock Desert Nevada Sept. 19, 2005