Pneumatic Morphing Aspect Ratio Wing

Abstract

This paper discusses the design, development and testing of a pneumatic telescopic wing that permits a change in the aspect ratio while simultaneously supporting structural wing loads. The key element of the wing consists of a pressurized telescopic spar that can undergo large-scale span wise changes while supporting wing loadings in excess of 15 lbs/ft. The wing cross-section is maintained by NACA0013 rib sections fixed at the end of each mobile element of the telescopic spar. Hollow fiberglass shells are used to preserve the span wise airfoil geometry and ensure compact storage and deployment of the telescopic wing. A fullscale telescopic wing assembly was built and tested in the Glenn L. Martin Wind Tunnel at the University of Maryland. These tests included measurements of Lift, Drag, and Lift to Drag ratio at a variety of Reynolds numbers. The telescopic wing was tested in four different configurations and experimental results were compared to finite wing theory results. Preliminary aerodynamic results are promising for the variable aspect ratio telescopic wing. It was expected that the telescopic wing at maximum deployment should incur a slightly larger drag penalty and a reduced lift to drag ratio. Thus, it may be possible to develop UAVs with variable aspect ratio wings using pneumatic telescopic spars and skin sections. This paper presents and discusses parts of the aspect ratio morphing concept, using pneumatic telescopic spars to actuate the wing and sustain aerodynamic wing loads, while being fully controlled in a timely manner.