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Measurements of the drag and of the nacelle internal pressures on a wing and nacelle that housed a horizontally opposed piston engine were made in the 40- by 80-Foot Wind Tunnel at Ames Research Center. These tests are follow-ons to earlier tests made with the same wing and nacelle but in which the engine was replaced with an electric motor and an adjustable orifice plate. In the initial tests the orifice plate was used to control the rate of cooling-air flow through the nacelle and thereby to simulate a range of gasoline engine types. Good agreement was found between the results of those tests and of the test reported here. Also, the upper and lower plenum pressure and cooling-air flow rate were found to be related by conventional equations used to represent the flow through orifices. Tests were run with three cooling air inlet sizes over a free-stream velocity range from 50 to 150 knots, an angle of attack range from 0° to 10°, and a cowl-flap deflection range from 0° to 30°.

An initial wind-tunnel test was conducted to investigate the aerodynamic interactions between a propeller slipstream and a supercritical wing at transonic Mach numbers. The primary independent variables examined included Mach number, wing lift coefficient, and slipstream Mach number and swirl. The interference effects were found to be weak functions of free-stream Mach number, wing lift coefficient, and slipstream Mach number; swirl was found to have a significant effect. At a free-stream Mach number of 0.8 and a lift coefficient of 0.5, incremental drag results for 7° of swirl (upwash inboard) and a slipstream Mach number of 0.87 indicate a penalty equivalent to a 0.024 loss in propeller efficiency. However, at 11° the drag increment was favorable and was equivalent to a 0.032 increase in propeller efficiency. Wing pressure data indicated the effects of the slipstream were essentially restricted to that section washed by the slipstream.