SBIR-STTR Award

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 actuality, extreme high altitude/airspeed conditions still exist. A simple means for reliably determining supersonic airspeed conditions 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 decelerated 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 outer escape systems.

This program plan outlines the efforts that are needed to modify the Optimized Mach Number Immune (OMNI) Sequencer based on Phase I test results, to define all its components, to fabricate and assemble a prototype test unit, to run preliminary bench tests as required, to run simulation tests using actual test input pressure data, and to run simulation tests using a low speed, low altitude test stand. After an evaluation of the test data, changes as indicated by the test results would be incorporated into the OMNI sequencer. The input data for the first series of simulation tests will be the actual digitally recorded data in track and flight tests of NACES and other seats. The input data for the later series of tests will be absolute pressures that will represent the Pitot and Base/Beam pressures in low speed, low altitude ejection conditions. Improvements to the OMNI sequencer can result from these simulation tests and will be incorporated if such is the case. The OMNI Sequencer at the end of Phase II should be ready for full system ejection seat tests.