Optimized Mach Number Immune Parachute Deployment Sequencer

Shock waves which form forward of an occupied ejection seat in a supersonic airstream can produce static and total pressure values which indicate safe altitude/airspeed conditions suitable for recovery parachute operation when in acutality, extreme high altitude/airspeed conditions still exist. A simple means for reliably determining supersonic airspeed condisitons and an optimum means for deploying the recovery parachute are described. The technique used to determine whether a supersonic airspeed exists depends only on measuring the rapidly decreasing static pressure which occurs as the ejected seat and occupant mass is declerated by the airstream. The technique used to set the recovery parachute deployment time is to continuously measure the airspeed and altitude, and after deceleration to subsonic airspeed conditions, deploy the parachute immediately upon reaching a preset airspeed for the measured altitude. The improved reliability of post-ejection sequencing as well as the increased performance capability of the escape system that will be provided by this optimized Mach number immune sequencer is discussed. A program is proposed to demonstrate the feasibility of such an optimized Mach number immune sequencer which is suitable for use in futer escape systems.