"A continuous 50-hour test was conducted to determine the effect of maximum cruise-power operation at ultra-lean fuel-air mixture and increased spark advance on the mechanical conditions of cylinder components. The test was conducted on a nine-cylinder air-cooled radial engine at the following conditions:brake horsepower, 750; engine speed, 1900 rpm; brake mean effective pressure, 172 pounds per square inch; fuel-air ratio, 0.052; spark advance, 30 deg B.T.C.; and maximum rear-spark-plug-bushing temperature, 400 F. In addition to the data on corrosion and wear, data are presented and briefly discussed on the effect of engine operation at the conditions of this test on economy, knock, preignition, and mixture distribution" (p. 1).

"As a part of a general investigation of control boosters, preliminary calculations were made to indicate the sizes of control boosters necessary to move the controls of airplanes of various sizes. The analysis was based on the assumption that the controls were moved with a rapidity and amplitude equal to that measured with a fighter airplane in simulated combat. A corollary purpose consisted in determining the effect on reducing booster-power unit size of incorporating an energy accumulator in the booster system" (p. 1).

Report presenting a bibliography and review of information related to the hydrodynamics of seaplanes. Characteristics of conventional hulls and floats are discussed to show the effects upon performance of changes in design parameters like dead rise, depth of step, and angle of afterbody keel. Other topics include floats, lateral stabilizers, aerodynamic and propulsive considerations, unconventional configurations, hydrofoils, and piloting and handling.

"Aileron and elevator stick forces and rudder pedal forces for the Bell XP-83 airplane in spins have been calculated. The results indicate that the aileron and elevator stick forces may be excessive unless some suitable booster or more highly balanced control surfaces are used. The pilot will be able to move the surfaces only slightly from their normal floating locations" (p. 1).

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.

Report discussing testing to determine the effects that using high-resistance ignition cable has on erosion of spark-plug electrodes. Erosion was found to be reduce about 70 percent when high-resistance ignition cable was used in place of standard cable.

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 an investigation of the power-off longitudinal stability characteristics of a tailless all-wing airplane model with various wing modifications in the free-flight tunnel. The results indicated that changes in the tip plan form or rotation of the wing tips did not appreciably reduce the instability at high lift coefficients.

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.

Report presenting wind-tunnel tests of a 0.175-scale model of a midwing airplane in order to determine the high-speed longitudinal characteristics, to test devices for improving longitudinal control at high Mach numbers, and to determine the aileron effectiveness at high Mach numbers. Force and moment coefficients are computed from test data. Control forces, elevator angle, and aileron angle for several flight conditions are predicted.

"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).

Report presenting two low-drag airfoils, the NACA 747A315 and the NACA 747A415, which are designed to have reduced pitching moments about the quarter-chord point and moderately high values of the design lift coefficient and are tested in the tow-dimensional low-turbulence pressure tunnel.