High Velocity Guns for Free-Flight Ranges

Free-flight ranges have been modified for research in high velocity flight. Tests can be carried out under the conditions of re-entry of missiles and spacecraft. Instruments have been devised for recording the optical radiation, the ionization, and other features of re-entry flight. Guns have been developed which will fire aerodynamic models at the velocities of full-scale flight. A study of gun performance suggests that the highest velocities in firing aerodynamic models will be produced by a gun which accelerates the model with a constant force throughout the firing run. The accelerated-reservoir light-gas (AR-LG) gun appears to fire models with this constant acceleration performance. An analysis of the gun's operation is being carried out, and a systematic series of firings is being carried out to evaluate the gun's performance. Comparison of theory and experiment indicates that in fact the AR-LG gun accelerates projectiles with a nearly constant force. Experience in firing “difficult” projectiles substantiates this contention. An AR-LG gun at the Flight Physics Laboratory has fired a saboted glass sphere at a velocity of 26,800 ft/sec and a solid plastic cylinder at a velocity of 32,800 ft/sec. In both of these categories, it is believed that these velocities are the highest reached with guns up to the present time.