Takeoff dynamics of flexible aircraft with multiple underwing pod-mounted landing gears

Resumo

© Universal Technology Corporation, 2018.Formulations for the flight dynamics of flexible aircraft have been commonly applied to aircraft having all six rigid-body degrees of freedom unconstrained. However, during takeoff and landing, the aircraft motion becomes constrained by the ground. An intricate dynamical problem arises when the flexible aircraft has multiple underwing pod-mounted landing gears. During liftoff, the most outboard landing gears become airborne earlier than the most inboard ones. The equations of motion used in a simulation model must then include time-varying ground constraint forces. Aerodynamically, the ground effect becomes relevant and can be modeled using the method of images. Wheel-to-ground rolling resistance also needs to be considered. This paper aims at the derivation of equations of motion that allow simulating the takeoff of such complex aircraft configurations. The developed formulation is important because it is readily applicable also to the landing phase, allowing the calculation of landing loads and the design of takeoff and landing control systems with less uncertainties. As spinoffs, the stability analysis of flexible aircraft in ground effect and evaluation of takeoff performance are also made possible.

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