Numerical Flow Investigation of Morphing Leading Edges for the Enhancement of Maneuverability of Unmanned Combat Air Vehicles

Abstract

Observing the progress in the technology of unmanned combat aerial vehicles (UCAVs) than it can be foreseen that in future the role of manned combat aircraft will be taken over more and more by unmanned systems. The abandonment of pilots allows for more freedom in the aerodynamic and structural design of vehicles in regard to weight or acceleration. However, new stealth constraints will have a severe impact on the freedom of scope. The design of UCAV configurations is driven by the special requirements of up-coming missions, as for instance the capabilities of long endurance flights joined with low observability. The new military demands have a crucial impact on the aerodynamic shape, and, hence, require new solutions for maneuver control in respect to integration of engine in- and outlets, ailerons and rudders, actuators and other devices. In particular UCAVs are suited to the exploitation of non-conventional control technologies, such as aerodynamic morphing, flow control, or thrust vectoring. This paper presents a numerical investigation of innovative leading edge morphing for aircraft applications and explores the feasibility of such technologies to enhance the manoeuverability of unmanned combat aerial vehicles. It is in particular concerned with the investigation of effectiveness of morphing devices for the aerodynamic control of UCAVs under the special constraints of needed low radar signature. One focal point of this work is the possibility to generate additional lift or role moments for UCAVs flying at different angles of attack without using classical flaps which would increase the risk of detection by higher radar signatures. Therefore, the objective of the numerical investigations is the evaluation of the potential and limitations of morphing leading edges especially for the enhancement of the maneuverability of Delta- and Lambda-wing configurations with their vortex-dominated flow field. Of special interest is flow control at high angles of attack (AoA) by targeting a minimized shape adaptation in order to generate needed additional lift, to induce rolling moments or to reduce the risk of the potential deleterious effects of vortex breakdown.