During ejection from a military airplane, the pilot's acceleration must not exceed 16 g if injury is to be avoided (see Ref. [5]). Assuming the ejection pulse to be triangular, what is the maximum peak acceleration of the ejection pulse applied to the pilot?

Assurne as in Example that the seated pilot of 160 Ib can be modeled with a spinal spring stiffness of k = 450 Ib /in.

Example

For a man in a seated position, as when driving an automobile, the single-DOF model of Figure is often assumed for forensic studies.

From extensive biomechanical tests, the spinal stiffness of [81,000 N/m =458 lb/in] is assumed for the spring k supporting the body mass W/g. By assuming mg = 160 Ib, this results in a static deflection of [ δ_st=160/458=0.35] in  in.

Let us assume that in hitting an obstac1e, the driver not restrained by a seat belt is thrown upward and drops 3.0 in. in free fall onto an unpadded stationary sea to Determine the g acceleration transmitted by his spinal cord.