A rational method for predicting alighting gear loads during landing impact is discussed. The equations describing the motions of a vehicle dur¬ing landing impact are developed for an arbitrary vehicle configuration. The method is of sufficient generality and accuracy to allow the formulation of alighting gear dynamics problems in flight vehicles including V/STOL air¬craft, high gross weight logistic vehicles, recoverable booster vehicles, advanced tactical and defense vehicles operating out of remote areas, and lunar vehicles. It allows for the effects of varying coefficients of friction and damping, combinations of initial conditions of pitch, roll, yaw angles and rates, vertical, longitudinal and lateral motion, slippage of the gear relative to the alighting surface, flexible alighting gear and vehicle struc¬ture, simultaneously applied triaxial ground loads, and various types and number of alighting elements. The formulation is intended for the cantilevered type of gear, although the articulated type may be handled through some extensions of the formulation. A survey of the various types of forces which occur during landing impact is made, and the manner in which these forces en¬ter the equations of motion is described.
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