VARIATIONS OF SPINAL ALIGNMENT IN EGRESS SYSTEMS AND THEIR EFFECT
Abstract
Fractures of the vertebral column constitute a serious and undesirably common medical complication of otherwise successful ejections from high performance aircraft. The reported incidence of spinal compression fractures attributable to the ejection forces exhibits a more than tenfold variation when the specific fracture rates associated with the several aircraft- ejection-seat systems currently used by the United States and Allied Armed Forces are compared. A variety of seat design factors have been suggested as having primary causal importance to explain the observed difference in injury rates. A study was therefore conducted to investigate quantitatively the influence of seat geometry and personal equipment design factors on the intrinsic spinal curvature and vector relationship with the catapult thrust axis. Fourteen male Air Force volunteers, encompassing the 5-95 percentile range of sitting heights, were x-rayed while seated with an ejection posture in the F/ RF-4C and F-105 ejection seat systems. Quantitative roentgenometric techniques were used to accurately determine individual vertebral body locations and measure absolute differences governed by seat design features. The sizable differences observed are discussed in terms of biodynamic injury mechanisms, and recommendations for improved seat design are derived.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 1969
- Accession Number
- AD0708123
Entities
People
- George C. Mohr
- James W. Brinkley
- Leon E. Kazarian
- Walter W. Millard
Organizations
- Air Force Research Laboratory