Gust and Manoeuvre Loads Alleviation

During certain manoeuvres it is beneficial for civil transport aircraft to reduce or alleviate aerodynamic loads by
concentrating lift inboard to reduce the wing root bending moment. Such Manoeuvre Load Alleviation (MLA)
systems respond automatically to manoeuvres commanded from the pilot ordinate deflections of the outer
ailerons and spoilers. Minimising the wing root bending moment using the MLA allows structural weight to be
reduced or span to be increased for improved performance. Such devices can also be used to alleviate the
dynamic loads on the structure due to a gust encounter (GLA). It should be noted that reducing discrete gust
effects is highly desirable due to structural benefits as well as passengers safety and comfort. During the
activation the GLA system the lift of the outer section of the wing is reduced. In addition to reducing the wing
root bending moment, the implementation of MLA and GLA increase the fatigue life cycle by reducing the
amplitude of the wing cyclic loading.
Current aircraft load alleviation systems are limited to the use of the existing control surfaces. Given that the
gust and the manoeuvre loads help to size the aircraft, a more effective load alleviation apparatus can deliver a
further weight reduction and fuel saving.
The research aims to develop and investigate a novel active aerodynamic load alleviation system which can
enhance aerodynamically the use of the existing control surfaces. The research will also consider the effect of
the alteration of the aerodynamic loads on the wing. The wing twisting and bending response to the activation
of the load alleviation devices will be analysed. Furthermore, the study will consider aspects such as aero
modelling fidelity, aeroelastics, aircraft response, actuation requirements and system weight. It is believed that
such analysis approach will enable to determine the most effective mean to reduce the manoeuvre and gust
load. The developed method would be compared to the conventional control surface load alleviation
arrangement in order to detail the potential benefits. CFD coupled to a wing structural FE model will be used to
investigate the aerodynamic behaviour of the novel aerodynamic MLA and GLA device. Two and three
dimensional analysis will be conducted in order to understand the governing physics related the flow behaviour
and the aerodynamic forces during load alleviation process.