Effect of a wing-tip mounted pusher turboprop on the aerodynamic characteristics of a semi-span wing

An exploratory investigation has been conducted at the NASA Langley Research Center to determine the installed performance of a wing tip-mounted pusher turboprop. Tests were conducted using a semispan model having an unswept, untapered wing with a air-driven motor located on the tip of the wing, with an SR-2 design high speed propeller installed on the rear shaft of the motor. All tests were conducted at a Mach number of 0.70, at angles of attack of approximately -2 to +4 deg, and at a Reynolds number of 3.82 million based on the wing chord of 13 inches. The data indicate that, as a result of locating the propeller behind the wing trailing edge, at the wingtip, in the cross flow of the tip vortex, it is possible to recover part of the vortex energy as an increase in propeller thrust and, therefore, a reduction in the lift-induced drag as well.