The development and design integration of a variable camber wing for long/medium range aircraft

Abstract

AbstractA deliberate product strategy is usually aimed at creating a transport aircraft family on the basis of a common wing by stretching the fuselage. Due to this policy of high fleet commonality the costs for development, manufacture and maintenance can be reduced. On the other hand the wing designer has to choose an appropriate wing area for the maximum stretched version and try to find the best trade-off between design and off-design conditions.A transonic wing however shows optimum performance at high loadings which are not achieved at entry into service with such a conventional fixed geometry wing. Variable Camber (VC) is offering an opportunity to achieve considerable improvements in operational flexibility, buffet boundaries and performance which allow a reduction in optimum wing size.Significant drag reductions and increases of the buffet boundary were found from research work. This work led to the current concept where the trailing edge flaps and ailerons are used to modify the wing camber in cruise according to the lift demand.An efficient VC system requires a change in design philosophy and several new constraints in the design problem were found to effect the extent of the supersonic region, the acceptable pressure gradients in the recompression zone and the required surface curvature. Theoretical and wind tunnel results are given as well as a discussion of the effects on the system design, loads, weight, handling qualities, propulsion integration and mission performance.Variable camber will contribute an average reduction of 3 to 6% in fuel burn and enable the use of one wing for medium range and long range missions respectively. The introduction of VC will launch a new generation of intelligent airliners which will optimise their camber schedule throughout the entire mission. A further improvement potential due to leading edge camber devices and spanwise differential camber is emphasised.