Propulsive wing

Lore & Background

The propulsive wing concept relies on a cross-flow fan partially embedded within the airfoil section. The fan draws flow in from the suction surface and exhausts it at the trailing edge. In cruise, distributed boundary-layer ingestion and wake filling increase propulsive efficiency, while distributed vectored thrust improves pressure drag. At high angle of attack with the fan off, the airfoil fully stalls and produces a large wake; when the fan is turned on, the suction effect eliminates the wake, significantly increasing lift. Lift and drag forces can be managed through circulation control, particularly by deflecting the exhaust downward. Even at low angle of attack, high lift coefficients have been shown with CFD and validated with wind tunnel experiments. Pitch and roll controls are achieved through vectored thrust: multiple thrust deflection flaps along the span allow collective changes for pitch and spanwise differential changes for roll. The circulation control effect of vectored thrust produces substantial rolling moment with little control input.

Reader's Guide

The propulsive wing technology represents a shift in UAV design by integrating propulsion and lift generation into a single thick wing. Its ability to maintain flight at very high angles of attack and manage lift and drag through circulation control offers potential for new aircraft classes. The concept won first prize in the graduate category at the American Institute of Aeronautics and Astronautics International Student Conference in 2007, indicating early academic recognition. International groups have investigated the technology: a group from Bauhaus Luftfahrt in Munich, Germany presented computational work for regional aircraft applications, and a research group from Nanjing, China built and tested a wind tunnel model demonstrating high lift and low drag. The technology is patented and has been covered in several publications, including Scientific Computing World, Dynamics, Develop3D, and US Airways Magazine. Its legacy lies in demonstrating a novel approach to distributed propulsion and vectored thrust that could influence future UAV and aircraft designs.

Did You Know?

• The propulsive wing uses a cross-flow fan partially embedded within the airfoil to draw air from the suction surface and exhaust at the trailing edge.
• At high angle of attack, turning on the fan eliminates the wake and significantly increases lift.
• Pitch and roll control are achieved through vectored thrust using multiple deflection flaps along the span.
• The technology won first prize in the graduate category at the 2007 AIAA International Student Conference.