COMBINING SENSORS WITH AIRBORNE TELEMETRY INSTRUMENTATION TO MAKE RANGE MEASUREMENTS AND OBTAIN AERODYNAMICS

Abstract

Obtaining a projectile’s free-flight motion profile and its aerodynamic coefficients is typically accomplished at indoor test ranges using photographic techniques synchronized to timing stations. Since these ranges are relatively short, many discrete tests are necessary to compile a complete understanding of the projectile’s behavior. When Time Space Position Information (TSPI) is requested over long-range flights, it has been gathered with expensive video, laser, and radar trackers. These can be inaccurate at times and are limited to locations where the range equipment is able to track the projectile’s entire flight. With the ever-increasing sophistication of ordnance, such as smart and competent munitions that have multi-stage thrusting and maneuvering capability, it is becoming increasingly difficult to make the necessary measurements using current measurement techniques. Microelectromechanical Systems (MEMS) sensors and other electro-optical and magnetic sensors referenced to the sun and earth allow the projectile’s angular rates (spin, pitch, and yaw) and accelerations (axial and radial) to be measured throughout the flight. These sensors have been packaged into miniaturized telemetry instrumentation systems and placed within empty voids of the munition or in place of the fuze or warhead section. By combining this sensor data with a 6-DOF trajectory code, many of the projectiles aerodynamic coefficients including drag, static moment, and damping moment over a large Mach Number range and over multiple flight paths have been obtained. These techniques decrease the number of test shots required, reduce the complexity of the test setup, and reduce the test costs. Test data from instrumented tank, artillery, and rocket flight tests are presented in this report to show the current capability of making inflight measurements using telemetry-based techniques.