Report presenting calculations of numerical values of the jet-boundary corrections to the angle of attack and the induced-drag, rolling-moment, and yawing-moment coefficients for complete airplane or wing models in 7- by 10-foot closed rectangular wind tunnels. The results showed that the wing area was the most important variable, as has usually been assumed in previous calculations. When the corrections were based on wing area, the effect of most of the other variables was negligible.

Report presenting an investigation that was conducted to determine the effect of carburetor dry-air temperature on the cooling characteristics of a typical full-scale air-cooled engine cylinder mounted on a single-cylinder crankcase.

Report presenting a study to determine the effect of a carburetor and an inlet elbow on the flow at the supercharger impeller inlet. Tests were conducted on a commercial vaned supercharger inlet-elbow assembly to determine the effect on the velocity distribution at the elbow outlet. Results indicated that the velocity profile obtained at the outlet of the vaneless elbow was better than that with the vaned elbow at all throttle settings.

From Summary: "Efficiency tests have been conducted on a single-stage impulse turbine having a 13.2-inch pitch-line diameter wheel and a cast nozzle diaphragm over a range of turbine speeds from 3000 to 17,000 rpm, pressure ratios from 1.5 to 5.0, inlet total temperatures from 1200 deg to 2000 deg R, and inlet total pressures from 18 to 59 inches of mercury absolute. The effect of inlet temperature and pressure on turbine efficiency for constant pressure ration and blade-to-jet speed ration is correlated against a factor derived from the equation for Reynolds number. The degree of correlation indicates that the change in turbine efficiency with inlet temperature and pressure for constant pressure ration and blade-to-jet speed ration is principally a Reynolds number effect."

Report presenting the results of an investigation to determine the impact properties of flush-riveted joints manufactured by different riveting methods. Testing occurred on a pendulum impact machine at temperatures of 70, -50, and -70 degrees Fahrenheit using rivets made of aluminum alloy A17S-T and plates of aluminum alloy 24S-T.

Report presenting an investigation of a thermal ice-prevention system for a Curtiss-Wright C-46 airplane, which included a determination of the change in stress at various locations in the wing outer panel caused by operation of the thermal system. Curves are presented showing the chordwise variation of stress and temperature for two wing stations.

Report presenting a method for calculating the temperature of a surface wetted either by a pure liquid, such as water, or by a mixture, such as alcohol and water. The method is applied to the problem of protecting, by alcohol, propellers and the induction system of the engine against ice. The psychrometric equation, used in wet-bulb hygrometry, is deduced in its general form.

Report presenting an equation by which the overall performance of any number of oil coolers when operating in series can be related to their performance when operating singly. A comparison was made of the experimental overall performance of two conventional type 15-inch-diameter oil coolers, selected according to the analysis and equipped first with spring-loaded valves and then with rotary valves, with the desired overall performance.

Finite trigonometric series is fitted by harmonic analysis as an approximation function to the psi function of the Theodorsen arbitrary-airfoil potential theory. By harmonic synthesis, the corresponding conjugate trigonometric series is used as an approximation to the epsilon function. A set of coefficients of particularly simple form is obtained algebraically for direct calculation of the epsilon values from the corresponding set of psi values.

Report presenting efficiency tests on a single-stage gas turbine with an 11.0-inch pitch-line diameter wheel and a nozzle diaphragm with cast airfoil-shaped nozzle blades using atmospheric air as the driving fluid. A comparison is made with the same turbine but with different nozzle blades. Results regarding the efficiency curves and further information about velocity effects are provided.

Report presenting testing of models of three flying-boat hulls with a length-beam ratio of 10.5. Testing occurred at two depths of step and two angles of dead rise. Results regarding resistance, trimming-moment, and wetted-length data for general fixed-trim and free-to-trim tests at load coefficients up to 4.0 are provided.

Report discusses the results of testing of measurements of the static-thrust performance of six sets of rotor blades mounted on a helicopter fuselage. The blades differed in surface condition, pitch distribution, airfoil section, plan form, and solidarity. Results indicated that rotor-blade surface condition is important for performance and the optimum performance will only be obtained if the blades have a smooth, accurately contoured surface that will not deform during flight.

Report discusses the results of tests on single-cylinder engines to determine the worth of several changes in exhaust-valve and port design to extend the useful life of the valves used in air-cooled engines. Changes explored included the valve-head diameter, the valve-stem diameter, the valve coolant-flow area, the valve-head material, and the size of the exhaust-valve guide boss. In the normal range of temperatures encountered in engine operation, valve material was found to be the most important factor.

Report describes the lubrication characteristics of an aircraft-type piston as visually studied in a V-type engine with a glass cylinder. Information about the movement of the piston, the piston rings, and the oil-control rings and their effect on lubrication is included.

Report presenting wind-tunnel tests to determine the aerodynamic section characteristics of an NACA 0009 airfoil with a plain flap with a chord 25 percent of the airfoil chord and a balancing tab with a chord 50 percent of the airfoil chord or 200 percent of the flap chord so linked that the tab would deflect at a given rate with respect to the flap. Three linkage ratios were tested on the model. Results regarding theory and test results including lift and hinge moments are provided.

From Introduction: "The purpose of this analysis was to investigate the use of function of intake-manifold temperature and pressure, exhaust back pressure, and engine speed in place of a ventri as a means of measuring engine air consumption and to determine if this function is suitable for automatic mixture control."

From Introduction: "The lift increments of different flap arrangements were determined by the method of reference 1 with a simple chord correction factor being applied. This procedure is somewhat similar in basic principles to the method of reference 2. The accuracy of the present method was determined by calculating by means of this method the lift and moment increments of flaps on 10 different finite wing-flap combinations for which wind-tunnel data were available."

Report presenting some principles for designing the optimum hull for a large long-range flying boat in order to suit the requirements of minimum drag, seaworthiness, and ability to take off and land at all operational gross weights. The principles include the use of moderate gross-load coefficients, ample forebody lengths, and deep steps and the close adherence of the form to that of a streamline body of revolution with a moderate fineness ratio.

Report presenting an investigation to determine the effect of fuel volatility on engine power and economy as influenced by mixture distribution. Tests of four fuels of different volatility were conducted on a Wright R-2600-8 engine at desired cruising power, maximum cruising power, normal rated power, and takeoff power.

Report presenting a study to determine the effect of several methods of increasing the knock-limited power on critical cylinder temperatures. The knock-limited indicated horsepower and cylinder temperatures were determined for a Wright R-2600-8 cylinder under specified operating conditions. The most satisfactory method of increasing knock limited power was found to be internal cooling with water and the least satisfacotry was increasing the engine speed.

Report presenting the fatigue data obtained at the Aluminum Research Laboratories from tests of various types of 17S-T and 53S-T specimens. The specimens were large enough to represent actual service conditions, but the repetition of loading was more rapid than would occur in ordinary service.

Report presenting a flight investigation made on a wing section of a P-47D airplane to determine the effect of roughness on wing profile drag with transition fixed far forward. Surveys of the wake were made for two surface conditions with transition fixed by a thread at 5 percent chord back of the leading edge on the upper and lower surfaces. Below the Mach number at which shock occurred, variations in Mach number of as much as 0.16 appeared to have no appreciable effect on the section profile-drag coefficients of either the smooth or roughened surfaces with transition fixed.

Report presenting an investigation conducted on the foaming characteristics of representative aircraft-engine lubricants in order to arrive at an adequate theory of the foaming of such oils. Methods of measuring foaming are compared and analyzed for their significant factors.

Report presenting a paper in a series about the cooling of aircraft-engine installations with special reference to the difficulties of cooling at high altitudes. This particular paper discusses the properties of NACA standard air and Army summer air, with corresponding stagnation conditions for a range of flight speed, as summarized in tables and figures.