Morphing UCAV Wings Incorporating In-plane & Folding Tips - aerodynamic Design Studies

A drag breakdown is presented for a typical UCAV configuration. From this, L/D estimates are deduced. The flight envelope of current aircraft (airframe and powerplant) is limited by materials available, design methods employed and the status of flight control systems. To accommodate the wide range of flight speeds encountered various options have been employed such as flaps for high lift at low speed, variable sweep and variable geometry for high speed. The requirement for stealth also limits the capability and performance. Unmanned aircraft are able to extend the flight envelopes in terms of manoeuvrability. Developing “smart” materials will allow a single aircraft to morph into shapes that are suitable for the extremes of current flight envelopes and beyond. “Smart” materials will allow wings to stretch to increase span and Aspect Ratio, shear to alter sweep, fold to reduce span and volume, twist and warp to alter camber and lift distribution. The ever increasing demands of the end-user and the greater scope afforded by developing technologies, materials, communications, sensing and flight control systems, can now be integrated into future designs. A new wing design method is presented. By using selected solvers at its core, it is capable of designing throughout the expanding flight envelope. The method has the capability of dealing with complex configurations and may be further enhanced by the inclusion of inverse design techniques. We take a simple UCAV planform based on USAF recommendations and generate a further three morphed configurations. The morphing includes folding, stretching and shearing thus altering Sweep, Area and Aspect Ratio. Currently we are interested in low speed performance, up to Mach 0.8. The designs and results presented here employ a panel method solver. The results will eventually need to be validated with Euler and Navier Stokes approaches, if required. Performance, in terms of Range and Endurance, can then be assessed with regard to power-plant and structural limitations.