CREW SEAT DESIGN CRITERIA FOR ARMY AIRCRAFT AvCIR 62-20

摘要

Strength requirements set forth in military specifications governing the design and fabri cation of nonejection-type crew seats currently utilized in Army aircraft were analyzed in light of accident experience with this seat and human tolerance as presently known. The analysis revealed that the strength requirements quoted in current military specifications are con siderably lower than (1) those which would be dictated by the upper limit of accelerations which can be tolerated by the occupants of the seats and (2) the accelerations and forces that are associated with Army aircraft accidents. This substantiates the observation that these seats fail under relatively moderate accident conditions, thus subjecting the occupant to further hazards, especially in increased contact injuries. On the basis of the detailed ex amination of current specifications, human tolerance, and impact acceleration data, it is recommended that the crew seat specifications be revised and that dynamic load f of 25G for 0.20 second plus 45G for 0.10 second, measured in the pelvic region of a suitable anthropo morphic dummy, be adopted for crew seat design in the longitudinal and lateral directions, and 25G for 0.20 second for the vertical direction. In addition, an energy absorption capability must be incorporated into the seat system to reduce the vertical accelerations, which will frequently ex ceed 25G, to a tolerable level. (Author)