DRAG REDUCTION ON AN EJECTION SEAT DURING HIGH SPEED EJECTION

THE PERFORMANCE CAPABILITY OF EMERGENCY ESCAPE SEATS IS LIMITED AT HIGH AIRPLANE SPEEDS AND LOW ALTITUDES BY THE OCCURRENCE OF WINDBLAST INJURIES. CURRENT STATE-OF-THE-ART SEATS, AT SPEEDS OF 600 KEAS EXPOSE THE OCCUPANT TO FORCES BEYOND PHYSICALLY TOLERABLE LIMITS, DUE TO LARGE DRAG FORCES ACTING ON THE ESCAPE SYSTEM. FUTURE AIRCRAFT MISSIONS WOULD REQUIRE OPEN SEAT EJECTION AT UP TO 725 KEAS. THEREFORE, NEW WINDBLAST PROTECTION AND STABILIZATION CONCEPTS WILL BE IDENTIFIED AND ANALYZED. IN THIS PROJECT, AN ADVANCED CFD CODE WILL BE DEVELOPED AND VALIDATED FOR STATIC AND DYNAMIC ANALYSIS OF EJECTION SEATS. IN PHASE I, AN EXISTING CFD CODE (REFLEQS-3D, WHICH ALREADY HAS WELL-TESTED BODY FITTED COORDINATES CAPABILITY) WILL BE MODIFIED TO ACCOUNT FOR ALL GEOMETRIC DETAILS OF THE SEAT, OCCUPANT, EQUIPMENT, AND PROTECTION/STABILIZATION DEVICES. A THOROUGH AERODYNAMIC ANALYSIS WILL BE PERFORMED FOR A SELECTED EJECTION SEAT, TO DEMONSTRATE THE FEASIBILITY OF THE APPROACH. IN PHASE II, THE CODE WILL BE FURTHER IMPROVED, VALIDATED, AND APPLIED TO EVALUATE SELECTED NOVEL CONCEPTS OF WINDBLAST PROTECTION, DRAG REDUCTION, AND STABILIZATION. THE CODE WILL BE WELL DOCUMENTED AND SUPPLIED TO NADC.