A comparison of human and ejection seat test manikin static centers of gravity and moments of inertia

Regardless of specific design differences, all manikins used for ejection seat testing were designed with the primary objective of mimicking humans in ejection seats. The purpose of this study was to compare one key characteristic between manikins and humans-static mass properties. To do this, a broad selection of ejection seat test manikins (from the 1960s through today) was measured for Centers of Gravity (CG), Mass Moments of Inertia (MOI), and weight. In the measurement: procedure, each manikin was seated and secured in an orthogonal, lightweight-aluminum chair. The CG and MOIs were measured about the three cardinal axes (X, Y, and Z), and MOIs were also measured about the three non-cardinal axes (XY, YZ, and XZ). The properties of the aluminum chair were subtracted to determine each manikin's mass properties alone in a seated position. These manikin data were then plotted against human data collected using identical methods. The human data were collected previously on 35 males and 34 females representing the anthropometric range of future Naval and Air Force pilots. Results indicated manikins are good approximations of their human counterparts, but manikin users are cautioned against altering manikin mass properties with ballasts without consideration of human segmental and whole-body mass properties data.