An investigation has been made to determine the effect of propeller location and flap deflection on the lift, drag, and pitching-moment characteristics of a wing-propeller combination over an angle-of-attack range from 0 to 80 degrees. The model had four propellers, the slipstream from which covered practically the entire span of the wing. The wing had a 30-percent-chord slotted flap and an 8.5-percent-chord slat. Data were obtained for flap deflections of 0, 20, 40, and 60 degrees with the slat off and on. For one propeller position the power input to the model was measured and tuft studies of the flow on the wing were made. The data are analyzed to assess the feasibility, from consideration of stability and control, of a tilting-wing vertical-take-off-and-landing airplane with the wing pivoted behind the primary wing structure to provide a desirable structural configuration. The main object of the investigation was to determine whether advantage might be taken of the forward shift of the center of gravity of the airplane, as the wing is tilted from an angle of attack of 90 to 0 degrees, to minimize the change in trim pitching moment throughout the transition speed range for such a configuration. The results indicate that with proper propeller position and programming of flap deflection, it is possible to design a configuration of this type in which essentially no change in trim is required throughout the transition from hovering to normal unstalled forward flight.

Summary: An analysis was made to determine the effect on propeller performance of extension flaps added to the trailing edge of a propeller blade. A method of calculating the changes in the ideal angle of attack, the angle of zero lift, and the design lift coefficient of a propeller blade section having a trailing-edge extension flap was utilized to calculate the performance of a six-blade dual-rotating propeller with extension flaps varying up to 40 percent chord. The method was used to determine the angle that the flap extension must make with the chord in order to obtain a particular load distribution. Although the analysis in this report was made for a wind-tunnel propeller designed to operate at low advance-diameter ration, the method is directly applicable to any propeller section under any operating condition.