Performance Comparison between Optimised Camber and Span for a Morphing Wing
CS Beaverstock, BKS Woods, JHS Fincham & MI Friswell (Swansea University)
Aerospace, Vol. 2, No. 3, 2015, pp. 524-554
Morphing technology offers a strategy to modify the wing geometry, such as the wing planform and cross-sectional parameters can be optimised to the flight conditions. This paper presents an investigation into the effect of span and camber morphing on the mission performance of a 25 kg UAV, with straight, rectangular, unswept wing. The wing is optimised over two velocities for various fixed wing and morphing wing strategies, where the objective is to maximise a aerodynamic efficiency or range parameter. The investigation analyses the effect of: the low and high speed velocity selected, the weighting on the low and high velocity for computation of the mission parameter, the maximum allowable span retraction and weight penalty on the mission performance. Models that represent the Adaptive Aspect Ratio (AdAR) span morphing concept, and Fish Bone Active Camber (FishBAC) camber morphing concept are used in the investigation for the respective effect on the wing parameters. The results indicate that generally morphing for both span and camber, is maximised for a 30-70 to 40-60% weighting in the flight conditions. The span morphing strategy with optimised fixed camber at the root, can deliver up to 25% improvement in the aerodynamic efficiency over a fixed camber and span, for an allowable 50% retraction with a velocity range of 50-115 kph. Reducing the allowable retraction to 25% reduces the improvement to 8-10% for a 50-50% mission weighting. Camber morphing offers approximately a maximum of 4.5% improvement for a velocity range of 50-90 kph. Improvements in the efficiency achieved through camber morphing are more sensitive to the velocity range in the mission, generally decreasing rapidly by reducing or increasing the velocity range, where span morphing appears more robust for an increase in velocity range beyond the optimum. However, where span morphing desires considerable modification to the planform, the camber change required for optimum performance is only 5% tip deflection to chord length. Span morphing, at the optimal mission velocity range, with 25% allowable retraction, can allow up to 12% increase in mass, where the camber morphing allows up to 3%. This provides the designer with a mass budget that must be achieved for morphing to be a viable for increasing the mission performance.
This material has been published in Aerospace which is an open access journal.
Link to paper using doi: 10.3390/aerospace2030524
Link to paper on journal website