09:40
Gust 1
Chair: Wolf Krüger
09:40
30 mins
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Active flutter suppression and gust load alleviation of wings incorporating floating wingtips
William Mansey, Fintan Healy, Huaiyuan Gu, Djamel Rezgui, Jonathan Cooper
Abstract: In this paper, a two degree of freedom mathematical model was used to analyse active flutter suppression on wings featuring flared folding wingtips, via an additional control surface on the wingtip. The active control system took the wingtip fold angle as the input parameter. Using a proportional controller gain, the flutter onset speed could be increased by 25%, and a proportional controller can also be used to recreate the effect of a flare angle. Using a derivative controller, it was found that flutter could be prevented across all reasonable airspeeds. Both benefits could be realised without a significant change in the gust load alleviation provided by the flared folding wingtip. However, the control surface angular rates required to achieve flutter suppression were very high under certain conditions. If these control surface velocities are limited to realistic values, then the controller can no longer suppress the growth of instabilities for larger gust amplitudes.
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10:10
30 mins
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Nonlinear Gust Effects On Flexible Aircraft With Flared Hinged Wings
Kelvin Chi-Wing Cheng, Alvaro Cea, Rafael Palacios, Andrea Castrichini, Thomas Wilson
Abstract: This paper presents a study on the modelling and coupled dynamic analysis of a flexible aircraft with flared hinged wings. A geometrically-exact composite beam model in a non-stationary reference frame, complemented with Lagrange multipliers to enforce multibody constraints, is coupled with unsteady vortex lattice aerodynamics to perform time domain simulations. A full-vehicle configuration featuring flared hinged wing tips is introduced, based on a high-altitude long-endurance T-tail aircraft. Aeroelastic trim and equilibrium states are computed for both the original vehicle and the modified aircraft with hinged wing tips, for the analysis of 1g plus gust responses in the vertical and lateral directions. Results shed light on the coupled nonlinear aeroelastics and flight dynamics exhibited by various HALE configurations in gust encounters of various intensities. It is found that the response of the aircraft with flared hinged wings considering geometrical nonlinearities is predominantly bounded by that of the stretched and upturned wing tips cases, with nonlinear trends uncovered and weighed in their contributions to the overall coupled system dynamics of aircraft configured as such.
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