Variable Camber Aerodynamic Control Surfaces and Active Wing Shaping Control
- Saturday, 01 March 2014
Concepts are examined to reduce aerodynamic drag and decrease fuel consumption.
A new concept of aircraft aerodynamic control surfaces has been developed in connection with another new concept of active wing shaping control for reducing aircraft drag that will result in less fuel burn. The first concept is referred to as a variable camber continuous trailing edge flap or, alternatively, a variable camber continuous leading edge slat. The variable camber trailing edge flap (or leading edge slat) comprises multiple chord-wise segments (three or more) to form a cambered flap surface, and multiple span-wise segments to form a continuous trailing edge (or leading edge) curve with no gaps that could be prescribed by a mathematical function or the equivalent with boundary conditions enforced at the end points to minimize tip vorticities. Aerodynamic simulations have shown that this type of flap can reduce aerodynamic drag substantially as compared to a conventional flap. A new active wing-shaping control concept is proposed in connection with the presently disclosed variable camber continuous trailing edge flap (or leading edge slat). The active wing-shaping control is designed to change a wing shape in-flight in order to achieve a desired optimal wing shape for optimal drag reduction.
Currently, as fuel is burned, wing loading is reduced and causes the wing shape to change in bending and twist. This wing shape change causes the wings to be less aerodynamically efficient. This problem can be further exacerbated by modern high aspect flexible wing design. Aircraft designers typically address the fuel efficiency goal by usually reducing aircraft weights, improving propulsion efficiency, and/or improving the aerodynamics of aircraft wings passively. In so doing, the potential drag penalty due to changes in the wing shapes would still exist at off-design conditions.
The unique or novel features of the new concepts are:
1. Variable camber flap provides the same lift capability for lower drag as compared to a conventional flap.
2. Continuous trailing edge flap (or leading edge slat) provides a continuously curved trailing edge (or leading edge) with no gaps to minimize vorticities that can lead to an increase in drag.
3. The active wing-shaping control method utilizes the novel flap (or slat) concept described herein to change a wing shape to improve aerodynamic efficiency by optimizing span-wise aerodynamics.
4. An aeroelastic method for analyzing wing deflection shape under aerodynamic loading is used in a wing-control algorithm to compute a desired command for the flap-actuation system to drive the present flap (or slat) system to the correct position for wing shaping.
This work was done by Nhan Nguyen of Ames Research Center.