THE OPTIMIZED THREE WEIGHT RANGE, FIVE FORCE LEVEL EA SYSTEM FOR ENERGY ABSORBING CREW SEATS

摘要

The addition of small females into the helicopter pilot population has increased appreciably the weight range for which energy absorbing crew seats must provide low probability of spinal injury performance in survivable crashes. The three weight range, five force level (3WR/5FL) energy absorber system is a simple approach to the solution of the problems associated with providing maximum aviator protection against spinal injury even in thirty-degree nose-down survivable crashes for the total pilot population. This paper presents the results of an optimization study performed on the 3WR/5FL energy absorber system. This study indicates that in a 42 feet per second crash the dynamic response index (DRI) can be kept at or below 18.2, the maximum lumbar acceleration will be at least 1.0G below the acceptable level of 20.4G, and the maximum energy absorber stroke can be kept at or below 13.8 inches for small pilots, who will have the seat adjusted up for correct eye position, and at or below 12 inches for average and large pilots. This system is light weight, comparatively low cost, small size, easily maintained, simple in operation, truly reliable and can meet the specification requirements for energy absorber systems.