Lift and Drag Characteristics of a Blended-Wing Body Aircraft

Abstract

The aerodynamic characteristics of a blended-wing body aircraft were assessed in the Air Force Institute of Technology low-speed wind tunnel. The scaled-down model (Re ∼ 10 5 and M = 0.10 to 0.20) of a strike tanker consisted of a shaped fuselage and slender, sweptback wings. The model evaluation and analysis process included force and moment measurements acquired from a wind-tunnel balance along with complementary pressure sensitive paint measurements and computational fluid dynamics solutions for a few cases. The force and moment coefficient data suggested that the aircraft is affected by both vortex lift and potential flow lift mechanisms. This was manifested in an apparent stall mechanism with a significant dependence on airspeed. One of the most intriguing aspects of the results was the striking difference in the force and moment measurements before and after the paint was applied to the surface. Although the roughness for both models was below the threshold suggested by 2-D boundary layer theory for all data acquired, the application of the paint led to a clear and repeatable effect on the force coefficient data. The lift slope was steeper and the onset of stall, when it occurred, was sudden across the entire wing for sufficiently smooth models. By contrast, the lift slope was reduced and stall was indicated only through a mild change in lift slope for the measurements corresponding to the rougher surface.