Exploiting control surface reversal for active and passive manoeuvre load alleviation

Abstract

High-aspect-ratio wings offer significant aerodynamic efficiency gains but face substantial structural mass penalties because wing sizing is strongly driven by manoeuvre loads. Effective manoeuvre load alleviation is therefore a key enabler of such configurations. However, current manoeuvre load alleviation strategies still require trade-offs: active systems demand high torsional stiffness and therefore increase structural mass, whereas passive manoeuvre load alleviation through composite tailoring reduces roll control authority. This paper shows that intentionally operating control surfaces beyond their reversal point can combine key elements of both approaches within a single aeroelastic design framework, enabling simultaneous active and passive manoeuvre load alleviation while satisfying a prescribed steady-roll authority requirement. An aeroelastic optimisation framework incorporating analytical control-deflection sensitivities is developed and applied to a representative mid-range transport wing. Detailed aeroelastic analysis reveals that, in swept composite wings, control surface reversal is governed by wing-level spanwise load redistribution arising from bending-torsion coupling and misalignment between the elastic and flexural axes, rather than by a purely local sectional effect. Load redistribution extends far inboard of the control-surface region, providing an effective mechanism for shifting manoeuvre loads away from the outboard wing. The reversal-enabled design achieves 13.3 % structural mass reduction compared to a conventionally optimised baseline while meeting the prescribed steady-roll requirement in nominal operation and in a representative single-surface loss-of-function case with the midboard control surface disabled. These results indicate that, within the present modelling scope, control surface reversal can be purposefully exploited for manoeuvre load alleviation and structural-mass reduction in high-aspect-ratio wings.