Torso Experienced Aerodynamic Forces Experienced during Ejection

摘要

The aerodynamic forces which are experienced by an ejecting aircrewmember are momentarily unique in direction and can be of severe magnitude. One difficulty of analyzing extremity injury during emergency escape is the diversity and intensity of the aerodynamic environment the human torso experiences entering free-stream flow. Aerodynamically, an appreciation of these forces, which can be resolved into positive and negative pressure locally, can be achieved from correlation of the relative likeness of anatomical segments to investigated geometric shapes (i.e., spheres, cylinders, etc.). Since aerodynamic forces are related to aircraft proximity, a more anatomically localized understanding must necessarily be available to support biomechanical analysis of the ejection event. To gain insight into operational injury, the McDonnell-Douglas F-4E aircraft was chosen, because of the available accident data base. A 1/32 scale model was constructed. The modelled crewmembers were machined to allow static porting at torso extremity locations of elbows, knees, top of the head and others. In addition, the model crewmembers were designed to be movable along an ejection path to four man-seat heights relative to the canopy-off fuselage rim: below, shoulder high, knee high and toe high. The aerodynamic data were obtained from tests in a five-foot wind tunnel and coefficients-of-pressure calculated from manometer readings. These coefficients are determined for crewmember location and pitch and yaw trim of the aircraft from -10 to +10 degrees each and graphically analyzed using three-dimensional computer plots. Severity, gross kinetic changes, and points of force application are described. (Author)