Objectives
The purpose of this research is to develop a preliminary analysis method that is fast, accurate and reconfigurable to determine the aerodynamic properties of a morphing aircraft as it changes its shape in three dimensions. A computational fluid dynamics (CFD) package is not efficient since a new mesh is needed for every shape and flow field configuration, requiring high computational cost. Instead we use a modern adaptation of Prandtl’s lifting-line method, which is based on a fully three-dimensional vortex lifting law. This method can be used for systems with arbitrary camber, sweep, and dihedral.
Adaptation of Lifting-Line Method
For the numerical lifting-line method, a wing is analyzed with a number of discrete, finite composite horseshoe-shaped vortices.
Figure 1: Horseshoe vortices distributed along the quarter chord
This lifting-line method decouples a 3-D finite wing into a series of 2-D airfoils.
Figure 2: Decoupling of a 3-D wing in to series of 2-D airfoils
Using the decoupled series of 2-D airfoils, the lifting-line method computes the vortex strength at each control point, and the lift and drag are calculated by integrating the contribution of each horseshoe vortex at each airfoil section.
Out-of-Plane Wings
Using this modified lifting-line method approach, we want to be able to calculate the aerodynamic forces and moments of wing configurations with arbitrary camber, sweep and dihedral.
Figure 3: Out-of-plane wing with arbitrary sweep and dihedral
Figure 4: 2-D decoupling of the wing with arbitrary sweep and dihedral
Aircraft Dynamics and Control
The aerodynamic forces and moments calculated by the above method will be applied to analyze the dynamics of different out-of-plane wing configurations of interest for morphing aircraft applications. Using the aerodynamic properties calculated, we want to study the effects on the aircraft dynamics of a morphing wing configuration. We want to investigate the effects that specific configurations will have on stability and control of the aircraft. We can take advantage of these properties by utilizing shape change in the wing to perform maneuvers that conventional aircraft cannot perform.
One particular wing configuration of interest is a wing configuration that has two sections, an out-of-plane dihedral section and a horizontal section, like a V-shaped wing configuration. An investigation as to how the partial dihedral will affect the dynamics and control of the vehicle will be performed. For this wing, since some of the lift force at the dihedral portion will have a horizontal component, this could provide roll control. An analysis of symmetric and asymmetric wing shapes will be performed. The effect of having flaps on the dihedral part of the wing and seeing how this effect can be applied to perform different maneuvers will also be examined.
Publications
- Cuji, E. A. and Garcia, E. "Prediction of Aircraft Dynamics and Control with Shape Changing Wings", Smart Structures and Materials 2008: Active and Passive Smart Structures and Integrated Systems II, March 10-13, San Diego, CA. published in: Proc. SPIE Vol. 6928, 2008. (PDF)
- Cuji, E. and Garcia, E. "Analytic Modeling of the Aerodynamics of Shape Changing Wings", 18th International Conference on Adaptive Structures and Technologies, October 3-5, Ottawa, ON, 2007. (PDF)
- Wickenheiser, A. and Garcia, E. "Aerodynamic Modeling of Morphing Wings Using an Extended Lifting-Line Analysis", Journal of Aircraft, Vol. 44, No. 1, 2007, pp. 10-16. (PDF)