Report presenting a study of the effect of aftercooling on the brake horsepower, weight, and weight-power ratio of a power plant consisting of a 2000-horsepower air-cooled engine, an intercooler, and two stages of supercharging. Three cases are considered: inadequate supercharging, supercharging to constant manifold pressure, and supercharging to detonation-limited manifold pressure.

"A relatively simple equation has been found to express with fair accuracy, variation in manifold-charge temperature with charge in engine operating conditions. This equation and associated curves have been checked by multi cylinder-engine data, both test stand and flight, over a wide range of operating conditions. Average mixture temperatures, predicted by the equations of this report, agree reasonably well with results within the same range of carburetor-air temperatures from laboratories and test stands other than the NACA" (p. 1).

Report discussing an investigation to determine whether the crank angle for maximum rate of pressure rise can be used to indicate maximum-economy spark advance. Information about spark-advance tests at constant inlet-air pressure and fuel-air-ratio test results are provided.

"Air-consumption data from calibrations of two radial aircraft engines were analyzed to show the relation of engine air consumption to its primary influencing factors: intake-manifold pressure, exhaust back pressure, intake-manifold temperature, and engine speed. The analysis of the test data from these two engines led to the establishment of a relation of variables upon which the design of automatic metering controls can be based. The data obtained from one engine indicate that the air-consumption correlation obtained for this engine is accurate within 2 percent except under certain conditions that are well outside current engine-operation limits" (p. 1).

Report discussing basic performance data obtained on the PV-2 helicopter rotor. Blade motion, rotor forces, and power were measured for static-thrust condition and a limited range of forward-flight conditions. Recommendations are provided for further testing to obtain blade-motion data and force-test data in order to develop a more detailed analysis.

Report discussing the effects of various inlet pressures, inlet temperatures, wheel speeds, pressure ratios, and cooling-air flows on the performance of a radial-flow exhaust-gas turbosupercharger turbine with a 12.75-inch tip diameter. Information about efficiency is provided for a given blade-to-jet speed ratio.

Report discussing testing of an HNS-1 (Army YR-4B) helicopter to determine the hovering data in the ground-effect region and at altitude with an original set of rotor blades and an alternate set with different aerodynamic design and surface condition.

Report presenting an investigation of the cooling of a Franklin 6-AC-29S horizontally opposed cylinder air-cooled engine installed in a Fleetwings model 33 trainer. The cowling on the airplane did not provide satisfactory cooling, but several alterations were tested, including with cylinder baffles. Results regarding engine cooling, aerodynamics of the cowling installation, and predicted versus actual cowling performance are provided.

Report presenting testing to determine methods for reducing the temperatures of the hot cylinders on air-cooled aircraft engines. A Pratt & Whitney R-1830-43, 14-cylinder engine used for the tests. Results regarding the cooling-air ducts, mixture-enriching tests, additional cooling area, baffle modifications, and an application of the information are provided.

Report presenting an investigation conducted with the propeller cuffs and spinner removed to determine their effect in flight on the pressure recovery of the cooling-air flow. Curves are presented to compare the pressure and temperature distribution over the front row of cylinders for flights with and without cuffs and spinner.

Report presenting testing of a Pratt & Whitney R-1830-43 engine mounted in a B-24D nacelle in the full-scale wind tunnel in order to investigation the potential improvements of fuel economy. Suggestions for improving the cruising power and cruising range by operating at specified fuel-air ratios are provided.

Report presenting tests of representative models of flying boat hulls to determine the resistance at low speeds. Results regarding the effect of load coefficients, resistance coefficients, and towing and drifting calculations are provided.

Report discussing the effects of internal coolants injected with fuel on the icing characteristics of a twin-barrel injection carburetor mounted on an engine-stage supercharger assembly. The tests were made at conditions that simulated war emergency power and at a variety of water-fuel ratios, carburetor-air temperatures, and carburetor-air relative humidities.

Report presenting an investigation of the flying qualities of a Curtiss SB2C-1 airplane. Tests were made to determine the effect of a bobweight in the elevator system and the effect of seals in the aileron gaps. Results regarding longitudinal stability and control, requirements for lateral stability and control, and stalling characteristics are provided.

Report discussing the changes in static longitudinal stability due to tilting the propeller axis of an SB2C-3 airplane downward. Tilting the propeller was found to be beneficial for stability, but only if the pilot was in a forward center-of-gravity position with a tilted engine. Installing a tilted engine reduced trim forces due to the changes in power up to 25 percent.

Report discussing testing to determine the longitudinal stability and control and stalling characteristics of a DeHavilland Mosquito F-8. Special focus is given to the control forces, elevator control, trim changes, and stick fixed and stick free characteristics of the aircraft.

Report discussing testing of the Douglas A-26B to determine the longitudinal stability and control characteristics. Information about the elevator, stick-fixed and stick-free stability, center of gravity, and flap effects are described.

Report discussing testing of the Douglas A-26B to determine the lateral and directional stability and control characteristics. Information about the control-free lateral and directional oscillations, sideslip due to full aileron deflection, control-fixed and control-free directional stability, effective dihedral, side force due to sideslip, rudder control characteristics, variation of rudder and aileron force with speed, and response to abrupt aileron deflection are described.

Report discussing testing on the Douglas A-26B airplane to determine the stalling characteristics, variation of maximum normal-force coefficient with flap position, and a calibration of the service airspeed installation.

Report presents a comparison of predicted qualities of the A-26B airplane with actual flying qualities determined in testing. From Summary: "The results indicate that the control-fixed, power-off stability and control characteristics of a conventional airplane can be predicted from the dimensions of the airplane and from general wind-tunnel data now available with sufficient accuracy for design purposes. No estimate of control forces, of effects of power on stability, or of adverse aileron yaw has been made."

Report discussing the flying qualities of a high-speed bomber with a dual pusher propeller aft of the empennage. The airplane was found to have satisfactory flying qualities except for stability issues with aft center of gravity, high elevator control forces in landing, insufficient elevator control in take-off, and low rudder-free directional stability.

Report presenting power-off wind tunnel tests of a scale model of a twin-engine cargo airplane equipped with amphibious floats. Longitudinal and lateral stability and control characteristics were investigated for three flap positions.

From Summary: "Compression tests were made of two groups of panel specimens with hat-section stiffeners. The groups were identical except that the flat sheet of one group was Alclad 24S-T81 and of the other Alclad 24S-T86. Results of the tests are given in tables or charts which show the average stress at which the sheet buckles and the average stress at the maximum load."

"The longitudinal-stability and -control characteristics of a twin-engine patrol airplane as predicted from the results of wind-tunnel tests of a powered model and as measured in flight are compared in this report. The accuracy of the wind-tunnel predictions and the reasons for discrepancies are analyzed and discussed" (p. 1).