Aircraft taxi loads in unpaved surfaces

Abstract

Taxi is the intermediate phase found prior to takeoff or after landing. The aircraft normal modes are excited given a determined runway roughness profile. As a matter of fact, the coupling between the aircraft modes and the runway roughness profile contributes to the amplification of the aircraft response and the appearance of dynamic loads. The latter is intensified when taxiing on unpaved surfaces. Characteristic aircraft elements and magnitudes sized during taxi include the wing down bending moment and the loads acting on the landing gear, paying particular attention to the loads exerted on the nose landing gear. The experimental aircraft response is attempted to be reproduced by performing numerical simulations. So far, numerical taxi loads were computed by following the requirements established in Airworthiness Regulations specific to taxi: Constant taxi speed Symmetric cases Constant external loads Far from that, the experimental response gathered through a selection of taxi cases found at different Airbus taxi campaigns is reproduced in this Bachelor Thesis by introducing a series of modifications which represent what is indeed occurring during tests: Variable taxi speed Asymmetric cases Variable external loads The effect the braking coefficients have on the taxi problem, along with the nose landing gear load relief phenomenon encountered in poor cohesive surfaces is also analysed.