Citation

Perry CE. SAFE J. 2003; 31(1): 1-12.

Affiliation

Biodynamics and Acceleration Branch, Human Effectiveness Directorate, Air Force Research Laboratory, Wright-Patterson AFB, OH 45433-7947, United States

Copyright

(Copyright © 2003, SAFE Association)

DOI

unavailable

PMID

unavailable

Abstract

Ejection seat headrest position is important for pilot visibility of cockpit controls and displays. Pilot head mobility in the cockpit with a helmet-mounted visually coupled system is important for both offensive and defensive maneuvers, and can also be influenced by the location of the ejection seat headrest relative to the seatback. However, the location of the headrest may also increase the risk of neck injury during the catapult phase of ejection. An experimental effort was conducted to evaluate the effect of a 1-inch aft headrest position on human biodynamic response during vertical impact while wearing a heavy helmet that simulated the mass properties of a generic helmet-mounted visually coupled system. Vertical impact tests representative of the ACES II ejection seat catapult acceleration were completed on the Air Force Research Laboratory's Vertical Deceleration Tower (VDT) with human volunteer subjects wearing a 4.5 lb helmet. Tests were also conducted with a baseline HGU-55/P helmet weighing approximately 3.0 lb. The headrest position was varied between the current ACES II headrest position relative to the seat back, and 1 inch aft of that position. Measured head accelerations and head displacement data were analyzed to evaluate the effects of the headrest position with each helmet configuration. Overall, the data indicated that there were no significant detrimental changes in the human response to +Gz impact acceleration as the headrest was shifted aft with either the baseline HGU-55/P helmet or the heavy helmet. In terms of head dynamics for both helmets, the aft headrest position improved the human head impact response compared to the standard position as was indicated by a significant decrease in negative x-axis head acceleration and forward head displacement. These results suggest the aft headrest position may improve pilot neck safety during ejection with a helmet-mounted visually coupled system.

Language: en