Experimental Aerodynamic Characteristics of a Joined-wing Research Aircraft Configuration

A wind-tunnel test was conducted at Ames Research Center to measure the aerodynamic characteristics of a joined-wing research aircraft (JWRA). This aircraft was designed to utilize the fuselage and engines of the existing NASA AD-1 aircraft. The JWRA was designed to have removable outer wing panels to represent three different configurations with the interwing joint at different fractions of the wing span. A one-sixth-scale wind-tunnel model of all three configurations of the JWRA was tested in the Ames 12-Foot Pressure Wind Tunnel to measure aerodynamic performance, stability, and control characteristics. The results of these tests are presented. Longitudinal and lateral-directional characteristics were measured over an angle of attack range of -7 to 14 deg and over an angle of sideslip range of -5 to +2.5 deg at a Mach number of 0.35 and a Reynolds number of 2.2x10(6)/ft. Various combinations of deflected control surfaces were tested to measure the effectiveness and impact on stability of several control surface arrangements. In addition, the effects on stall and post-stall aerodynamic characteristics from small leading-edge devices called vortilons were measured. The results of these tests indicate that the JWRA had very good aerodynamic performance and acceptable stability and control throughout its flight envelope. The vortilons produced a profound improvement in the stall and post-stall characteristics with no measurable effects on cruise performance

Wave Drag and High-speed Performance of Supersonic STOVL Fighter Configuration

A supersonic STOVL fighter aircraft aerodynamic research program is under way at NASA Ames Research Center. The research focuses on technology development for this type of aircraft and includes generating an extensive aerodynamic database and resolving particular aerodynamic uncertainties for various twin- and single-engine aircraft concepts. Highlights of the results from this program are presented. The highlights include propulsion-induced effects on the aircraft drag, prediction capabilities, volume integration for minimizing drag, and wave drag and aerodynamic efficiency comparisons. Results indicate that estimated STOVL fighter performance is roughly comparable to the performance of modern conventional fighters in terms of wave drag and aerodynamic efficiency