EXPERIMENTAL INVESTIGATION OF SEMISPAN MODEL TESTING TECHNIQUES

An investigation has been conducted in the NASA Langley Research Cente r's 14 by 22 ft Subsonic Tunnel to further the development of semispan testing capabilities, A twin-engine, energy efficient transport model with a four-element wing in a takeoff configuration was used for this investigation. Initially, a full-span configuration was tested, and f orce and moment data and wing and fuselage surface pressure data were obtained as a baseline data set, The semispan configurations were then mounted on the wind-tunnel door, and the effects of fuselage standoff height and shape were investigated. Results indicate that the semispa n configuration was sensitive to variations in standoff height, and th at a standoff height equivalent to 30% of the fuselage radius resulted in better correlation with full-span data than no standoff or the lar ger standoff configurations investigated, Undercut standoff leading ed ges improved the correlation of semispan data with full span data in t he region of maximum lift coefficient.