Results of the Missile Technology Demonstration Flight-2

The Ballistic Missile Technology Office of the Air Force Research Laboratory, Kirtland AFB, NM, in cooperation with the Theater Targets Product Office of the US Army Space and Missile Defense Command, Huntsville, Alabama, launched a sub-orbital missile flight from White Sands Missile Range on 29 January 1997. Designated Missile Technology Demonstration-2 (MTD-2), it was the second flight of its kind with the principle objective of demonstrating Global Positioning System (GPS) and Differential GPS (DGPS) technology in an application to range safety and tracking. The MTD-1, successfully flown on 16 August 1996, was the first. MTD-2 was composed of a SR-19 booster and the Maneuvering Tactical Target Vehicle (MTTV) which is based on the Pershing II maneuvering reentry vehicle. In addition to the GPS/Inertial Navigation System (INS) and DGPS/Inertial Measurement Unit (IMU) systems, both MTD-1 and MTD-2 flew an experiment package consisting of an earth penetrator instrumented with accelerometer packages. The MTD-2 went unstable when the first bending mode of the flight vehicle was excited at approximately six seconds into the flight. The instability resulted from the control system going into a limit cycle while trying to control the unstable mode. This resulted in the thrust vector control actuator hydraulic fluid being prematurely expended 26 seconds into the flight. The trajectory was nominal up until that time, afterwards the vehicle began to tumble and the vehicle was destroyed by Range Safety at 62 seconds. In this paper the MTD-2 vehicle configuration, the GPS/INS experiments and DGPS/IMU guidance systems, and the penetrator/accelerometer experiments are described. The contributing factors leading to flight termination of the MTD-2 vehicle are discussed with emphasis placed on lessons learned and applied. GPS data were transmitted from the MTD-2 vehicle throughout the entire flight resulting in a very accurate record of the trajectory up until the time of flight termination. This paper contains a summary of the GPS experiment results and their potential future application to range safety and tracking, which may ultimately reduce US dependence on costly range instrumentation while improving flight safety systems.