Analysis Of Four Landing Gears Aircraft Ground Dynamic

With the development of modern aircraft design technology, the new lay-out of landing gear must be researched to match new aircraft coping with new mission requirements, which becomes more refining and more professional in the future. The research object in this paper is an aircraft with four landing gears. Ground dynamic model is established and dynamic characteristics of ground taxiing and turning are researched.Firstly, the ground dynamic model of four landing gears aircraft is established to analysis taxiing stability of aircraft under the influence of small disturbance. The critical damping is calculated and the structure parameters of landing gear are investigated to indicate the influence of critical damping. Based on the stress and geometry relationship of aircraft, turning radius of aircraft center of gravity and each wheel is calculated. The influence of aircraft center of gravity and each wheel is investigated with different taxiing speed or nose wheel steering angle. Then, based on the ADAMS/Aircraft simulation platform, four landing gears aircraft virtual prototype is established. Running the simulation of ground taxiing to investigate how the taxiing speed, nose wheel steering angle and main wheel differential brake influence aircraft turning radius. The result shows that under ideal circumstances, when nose wheel steering angles unchanged, the turning radius become larger with taxiing speed getting greater; when taxiing speed stays the same, turning radius become smaller with the nose wheels steering angles getting larger. Four landing gears aircraft turning radius is smaller than conventional tricycle landing gear aircraft under the same taxiing circumstances when nose wheel steering is applied. However, the turning radiuses are almost the same when main wheel differential brake is applied. When both nose wheels steering are applied, the four landing gears aircraft has minimum turning radius; when outside nose wheel steering, turning radius gets larger; and when inside nose wheel steering, turning radius is the largest.