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.

Summary: Some of the effects of pusher-propeller operation on the aerodynamic characteristics of a flapped wing were measured in the Langley propeller-research tunnel. The effects of propeller operation on the lift and profile drag of the wing, on pressure distribution, and on the position of boundary-layer transition were obtained. The results indicated that, at fixed angles of attack and with flaps deflected, the wing lift increased appreciably with increasing thrust coefficient. With flaps retracted, no appreciable increase in lift with increases in thrust coefficient was measured. Chordwise pressure distributions at several spanwise stations indicated that the effect of propeller operation was greatest in the region immediately ahead of the propeller and that the effect extended out-board from the propeller axis for about 2.5 propeller radii. Measurements of boundary-layer velocity on the forward part of the upper surface of the wing showed no appreciable shift of transition in the range of thrust coefficients investigated.

A previous report, NACA TN 3007, gave force and moment data for the NACA 64A010 airfoil section equipped alternately with a flap and a slat at the leading edge, and with a split flap and a double-slotted flap at the trailing edge. The present report presents the chordwise distributions of pressure measured concurrently with the force and moment data of NACA 3007. The pressure data for the leading-edge flap and slat have been converted into coefficients of normal force, chord force, and moment based on the geometry of the leading-edge device.

The model was tested at two different elevations with the wing pivot at 1.008 and 2.425 propeller diameters above the ground. The slipstream of the propellers was deflected by tilting the wing and propellers, by deflections of large-chord trailing-edge flaps, and by combinations of flap deflection and wing tilt. Tests were conducted over a range of propeller disk loadings from 7.41 to 29.70 pounds per square foot. Force data for the complete model and pressure distributions for the wing and flaps behind one propeller were recorded and are presented in tabular form without analysis.

The static-thrust characteristics of the NACA 8.75-(5)(05)-037 dual-rotation propeller having six and eight blades were obtained on the Langley static test stand in the course of an investigation set up primarily for studying blade vibratory stresses. Force data were obtained for a blade-angle range of 4 to 20 degrees, measured at the 0.75 radial station of the front propeller. The blade angle of the rear propeller, measured at the 0.75 radial station, was set 1 degrees less than the front propeller for most of the tests. The maximum propeller tip Mach number for the tests was 0.89.