AERODYNAMIC CHARACTERISTICS OF THE HL-20

Wind-tunnel tests were made from subsonic to hypersonic speeds to defi ne the aerodynamic characteristics of the HL-20 lifting-body configura tion. The data have been assembled into an aerodynamic database for fl ight analysis of this proposed vehicle. The wind-tunnel data indicated that the model was longitudinally and laterally stable (about a cente r-of-gravity location of 0.54 body length) over the test range from Ma ch 20 to 0.3. At hypersonic speeds, the HL-20 model trimmed at a lift/ drag (L/D) ratio of 1.4. This value gives the vehicle a crossrange cap ability similar to that of the Space Shuttle. At subsonic speeds, the HL-20 has a trimmed L/D ratio of about 3.6. Replacing the flat-plate o utboard fins with fins having an airfoil shape increased the maximum s ubsonic trimmed L/D to 4.2.