Aircraft Landing Gear Dynamic Loads Induced by Soil Landing Fields. Volume I. Prediction Model and Wheel Loads

摘要

A mathematical model to predict sinkage and the resulting loads for aircraft wheels operating on bare soil surfaces is presented together with experimental results for a 29 x 11-10 8PR Type III tire. Four primary factors which determine soil rutting and drag consist of the tire spring rate, the soil load deflection relation, a drag inertia force, and a lift inertia force. Soil load deflections are based on the mobility number concept. Empirical constants were used to compute the inertia forces. Comparisons of predicted and measured rut depths and drag loads are made for a clay soil with CBR(California Bearing Ratio) ranging from 1.5 to 2.3 and speeds from 0 to 90 knots for tire inflation pressures of 30, 45, and 70 psi. Similar comparisons are made for sand having a surface strength of CBR 1.5. The experimental program included 173 tests with a single wheel and 39 tests with two wheels in tandem on buckshot clay and 24 single wheel tests on sand.