Comparison Study between a Microwave Interferometer and an Electrical Contact System for Following the Motion of High-Speed Projectile

A comparison study has been made between two different methods of tracking a high-speed missile in a barrel. This comparison between a microwave interferometer and an electrical contact system indicates that there are no systematic errors in either system in the velocity range from 250 m/sec to 425 m/sec. It is pointed out, however, that the microwave system must be used if reliable isentropic pressure vs density curves are to be obtained for the expanding gas behind the missile.