Report presenting a description of a short method of estimating propeller efficiency for a given operating condition. The efficiency is determined for any design condition by evaluating separately from charts the induced losses and the profile-drag losses. The report covers single-rotating propellers of two, three, four, six, and eight blades and includes charts showing the rotational-energy loss for the given operating condition.

Report presenting flight data, which shows that the absolute minimum or limit pressure coefficient on an airfoil is a function mainly of the Mach number for Mach numbers above about 0.3 and for usual flight values of the Reynolds number. The curve of limit pressure coefficient as a function of Mach number is established.

Report presenting a convenient technical method to evaluate changes in the airfoil characteristics resulting from an extension of the chord at the trailing edge of a propeller blade section. The method determines the change in the angle of zero lift, the ideal angle of attack, and the difference in these angles as a function of the angle and length of the trailing-edge extension.

Report presenting tests of a low-drag wing-inlet section at high speeds in the 8-foot high-speed tunnel. Satisfactory section characteristics could be obtained only for a small range of angle of attack and inlet-velocity ratio, as a result of internal separation and external pressure peaks. Results regarding external-flow conditions, internal-flow conditions, section characteristics, modifications, and design considerations are provided.

Report presenting testing of 0.15-wing-chord, internally balanced ailerons on a low-drag tapered wing at Mach numbers up to 0.75. Both a normal-profile and beveled trailing-edge aileron were tested without a seal and with a partial seal. Results regarding variation of lift, static characteristics of the ailerons, aileron control characteristics, pitching moment induced by ailerons, balance pressures, and pressure distributions are provided.

Report presenting an investigation in the 19-foot pressure tunnel to determine the nacelle drag, the cowling-air flow, and the propeller characteristics of a model of a high-performance military airplane. The model is fitted with NACA D(sub S)-type engine cowlings and with propellers embodying NACA 16-series airfoil sections. Results regarding the propeller characteristics, drag and cowling-air flow with the propeller removed, the effect of propeller on flow through cowling, and the influence of cooling requirements on airplane performance are provided.

Report presenting the effect of Reynolds number on the aerodynamic characteristics of a low-drag airfoil section tested under conditions of relatively high stream turbulence. The data are presented as curves of section angle of attack, section profile-drag coefficient, and section pitching-moment coefficient against section lift coefficient for various flap deflections.

Report presenting simple curves by which the basic pressure-drop characteristics of unheated tubular radiators can be corrected to operating conditions in which the radiator is heated and in which the Mach number of the tube flow is of appreciable magnitude. The only data required for the use of the curves are the radiator dimensions, the rate of heat input, the pressure and temperature ahead of the radiator, and the rate of mass flow of air through the radiator.

"A technical method is given for calculating the axial interference velocity of a propeller. The method involves the use of certain weight functions P, Q, and F. Numerical values for the weight functions are given for two-blade, three-blade, and six-blade propellers" (p. 53).