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winglet optimization: sweeplet Disclosure Number: IPCOM000240466D
Publication Date: 2015-Feb-02
Document File: 4 page(s) / 244K

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09876: IP.COM


Abstract winglet optimization: sweeplet

It is an idea to optimize a winglet design by a specific design process. The outcome is called a sweeplet.

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Abstract winglet optimization: sweeplet

It is an idea to optimize a winglet design by a specific design process. The outcome is called a sweeplet.

Sweeplet optimization

The sweeplet (optimized forward swept winglet) is a wing tip device that could be used for any commercial aircraft, intending to improve overall aircraft performance. It is a general kind of winglet, whose characteristics (planform/profiles mainly) would enable a different optimization between different design disciplines, through a given process.

Wing tip device for commercial aircrafts have been subject to many inventions: different devices where generated based either on a fixed design or on a system with actuation. In the field of fixed devices, different solutions were proposed, ranging from rake tip ("rearward swept wing tip" ), to blended winglet ("winglet extension with a smooth transition area between wing and winglet"), to sharklet ("kind of vertical fin used as wing extension"). On top of that, some other fixed devices were studied, based on complex 3D shapes like spiroids. The common aim of all these devices is to improve the aerodynamic performance of the aircraft, by decreasing the so called induced drag (generating some vortex at the wing tip), thanks to the generation of a more outboard loaded lift distribution. The counterpart of this is the associated increase of loads due to the increase of lift appearing on outboard wing. This increase of lift will for instance have a strong impact on the wing root bending moment through the lever arm effect. The existing devices are then aero performance oriented and are having a bad influence on the aircraft weight, through an increase of loads. They are finally designed by either looking for a desired aero gain or by accepting a maximal loss on loads side, but with no lever arm on a combined optimization of both.

The idea of this invention is to change the focus from an aero performance to overall aircraft performance and to really enable an optimization at global level. The penalizing increase of loads could be removed or strongly alleviated thanks to the sweeplet and the related proper optimization process. We need to distinguish two different behaviors of the sweeplet:

- Point of design of the aircraft: the design of the sweeplet could be slightly less interesting from a pure aerodynamic point of view than the one of a classical optimized device (the area of joint between wing and wing tip will be subject to high speed of flow and will require deep aero design knowledge, to avoid a significant drag increase in high speed and to avoid a flow separation in low speed). The difference should nevertheless remain small, thanks to a relevant design philosophy or by changing the outer wing constraints (thickness, local camber of leading edge, system allocation, ...)

- Off-design points: With a "classical" design, the winglet twist angle would decrease while the aircraft incidence increases, leading globally to a...