NACA TN-3250, NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS TECHNICAL NOTE 3250: AN EXPERIMENTAL INVESTIGATION OF THE EFFECT OF WHEEL PREROTATION ON LANDING-GEAR DRAG LOADS (OCT-1954) (POTTER, D.M.)

NACA TN-3250, NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS TECHNICAL NOTE 3250: AN EXPERIMENTAL INVESTIGATION OF THE EFFECT OF WHEEL PREROTATION ON LANDING-GEAR DRAG LOADS (OCT-1954) (POTTER, D.M.)., The effect of prerotation on the wheel spin-up drag loads on a small landing gear during landings has been investigated by means of tests in the Langley impact basin. A series of simulated landings with various amounts of prerotation was made with a dropping weight of 2,500 pounds and a forward speed of 85 fps at a strut angle of 150 • The results were compared with data from previous tests made with various forward speeds and no prerotation. The effect of prerotation on the maximum drag load was the same as the effect of reducing the horizontal velocity. At low horizontal velocities any amount of pre rotation reduced the drag load. The reduction became greater as the vertical velocit y was increased. Reductions in drag load result ing from prerotation were accompanied by reductions in vertical load. At high forward speeds somewhat beyond the range where prerotation was tested, however, consideration of existing data indicated that large amounts of prerotation would have to be used in order to assure a reduct ion in drag load. In this higher speed region, insufficient prerotation could actually increase the drag load. The wheel spin-up process appeared to be a small factor in tire wear and prerotation therefore should not materially increase tire life.