Personnel Protection Concepts for Advanced Escape System Design

Abstract : The severe emergency escape conditions associated with low-altitude and high-speed environments are often beyond the performance capabilities of contemporary ejection seats. A new escape system design approach is needed to extend the performance envelope without increasing the stresses imposed on the ejecting crewmembers. A new approach has been developed and specific ejection- seat subsystem design technologies are being explored by the United States Air Force. The central concept of the approach is the automatic selection of the performance characteristics of the escape system based on the conditions that exist at the time of ejection, and the adaptive control of the escape-system performance throughput the escape episode. Ejection-seat subsystem design concepts being developed to implement this approach are summarized. Several crew-protection concepts are reviewed, including a method to control the risk of injury to be proportional to the life threat of specific escape conditions and a windblast protection device called the flow-stagnation fence. A means to provide real-time assessment and control of the accelerations imposed on an ejection seat's occupant is vital to the new escape system design approach. This paper presents a six-degree-of-freedom acceleration exposure-limit method currently being developed to meet this requirement.