Improving the safety-of-flight certification process: helmet/HMD dynamics during aircraft ejection

摘要

Abstract: In the event that all pilot efforts to recover a serverely disabled aircraft have failed, the pilot may be forced to eject from the aircraft. A pull of the ejection handles launches the pilot into the violent, complicated environment of an aircraft ejection. Aircraft altitude and velocity, pilot physiology and body posture, pilot personal equipment, and helmet/HMD characteristics are just a few broad categories comprising the vast list of variables potentially influencing the pilot's chances of surviving an ejection. The nearly infinite number of permutations of these variables describing any given ejection makes predicting, modeling, and simulating such an environment very difficult. Moreover, developing criteria and designing test and evaluation methodologies for certifying advanced helmet systems as 'safe-to-fly' is an increasingly frustrating process characterized by too many unknowns and too little data. In order to accurately simulate the aircraft ejection environment in performing test and evaluation of advanced helmet systems, especially helmet-mounted displays (HMDs), a better understanding of helmet/HMD dynamics is required. This study attempts to develop a model combining the two major force contributions during aircraft ejection: windblast forces due to canopy jettison and g-forces imparted by rapid acceleration out of the aircraft. By superimposing data collected from windblast tests and from ejection-tower tests, more accurate resultant headeck loads can be calculated in determining whether a given helmet/HMD design should receive the 'safe-to-fly' certification. !5