A THEORETICAL ANALYSIS OF UNDERCARRIAGE LOADS AND TAXYING VIBRATION ON A SUPERSONIC TRANSPORT AIRCRAFT WITH EXPERIMENTAL COMPARISONS AND AN ASSESSMENT OF MODIFICATIONS TO REDUCE GROUND LOADS

摘要

Development flying of an SST showed that the vibration during taxying was more severe than had been predicted and that the landing impact was harsh. Taxying vibration caused a significant reduction in the predicted fatigue life of the fuselage structure and would have restricted the use of the aircraft on poor runways because of crew discomfort. Flight records showed that friction was causing the main oleos to stick much of the time, and when this was included in the calculations good agreement with experiments was obtained. Studies showed that landing and taxying performance of the main undercarriage could be improved by reducing friction, reducing air spring stiffness at taxying deflection, reducing the preload with a two-stage oleo and increasing hydraulic damping. The effects of these changes on the undercarriage and air-frame loads and structural vibration are considered.