Equations of motion for a three-degree-of-freedom, two-body airdrop system were derived and numerical solutions obtained by use of a digital computer. It was assumed that, for given initial conditions, the parachute drag area was a function of time only. The results indicated that: (1) The derived equations of motion result in calculated trajectories which are good representations of actual airdrop trajectories. (2) The parameter which most affect altitude loss to equilibrium are parachute-cargo line length and parachute opening time. (3) There is an optimum parachute opening time which results in minimum altitude loss to equilibrium. Longer or shorter opening times will result in greater altitude losses to equilibrium. (4) Moderate variations of aircraft flight path inclination, initial cargo acceleration, and initial cargo velocity have only a small effect on altitude loss to equilibrium. (5) For a given equilibrium velocity, a cluster of small parachutes appears to be a better choice than a single large parachute for obtaining minimum altitude loss to equilibrium. (Author)
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