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 upcoming 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.

Experimental aerodynamic assessment and evaluation of an agile highly swept aircraft configuration

“…The suffix "E" (for "intake", in German "Einlauf") was added to indicate that the model contains a modular center body section that can be exchanged with a flow-through inlet section. The effect of the inlet as well as various leading edge shapes have been studied in previous high-speed tests of the DLR F17E [11]- [13].…”

A Polymorphing Wing Capable of Span Extension and Variable Pitch

“…Morphing aircraft is a promising technology that can help in mitigating the adverse effects of flight and meet the FlightPath 2050 goals. In addition, morphing wings can increase maximum lift, reduce drag [2,3] and vibrations, improve flight performance within a certain airspeed range [4], and enhance aeroelastic performance [5,6] and aircraft maneuverability [7,8]. By definition, a morphing aircraft continuously adjusts its geometry to enhance flight performance, control authority, and multi-mission capability.…”

A morphing wing with cellular structure of non-uniform density

“…The concept of morphing has attracted widespread attention from present aircraft designers [1]. It is found that morphing wings can improve the overall flight efficiency by adapting to different flight conditions by adjusting their shapes [2], and can improve their performance within a certain airspeed range, reduce vibration [3], increase maximum lift, reduce drag [4,5], or enhance aircraft maneuverability [4,6,7] and aeroelastic performance [8,9]. In addition, due to the reduction of discontinuous rudder surfaces, morphing wings can further improve the stealth performance [2].…”