A 1/20-scale model of the F-106 aircraft with simulated underwing engine nacelles was tested in the Lewis Research Center 8- by 6-Foot Supersonic Wind Tunnel. Boattail pressure drag, wing pressures, and nacelle pressures were obtained on a series of con¬figurations including changes in nacelle and inlet geometry and location under the wing. Boattail pressure drag was obtained with jet boundary simulators on 15°, 20°, and 25° conical boattail afterbodies each with a boattail-to-nacelle area ratio of 0. 551. Data were obtained with and without inlet airflow through the nacelles at angles of attack from 0 to 15°. Installed-boattail pressure-drag coefficient was lower than isolated-nacelle values at all Mach numbers, and transonic boattail drag rise was delayed to Mach 0. 98. The effects of changes in nacelle and inlet geometry and location were generally small. Conical bottail angles greater than 15° tended to increase local regions of flow separa¬tion.
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