Experimental Investigation of Semispan Model Testing Techniques

Abstract

An investigation has been conducted in the NASA Langley Research Center’ s 14 by 22 ft Subsonic Tunnel to further the development of semispan testing capabilities. A twin-engine, energy efe cient transport model with a four-element wing in a takeoff cone guration was used for this investigation. Initially, a full-span cone guration was tested, and force and moment data and wing and fuselage surface pressure data were obtained as a baseline data set. The semispan cone gurations were then mounted on the windtunnel e oor, and the effects of fuselage standoff height and shape were investigated. Results indicate that the semispan cone guration was sensitive to variations in standoff height, and that a standoff height equivalent to 30% of the fuselage radius resulted in better correlation with full-span data than no standoff or the larger standoff cone gurations investigated. Undercut standoff leading edges improved the correlation of semispan data with full span data in the region of maximum lift coefe cient.