Report presenting a method for calculating the stick-fixed neutral point of an airplane with the propeller windmilling, the flaps neutral, and landing gear retracted. The methods used in this report should be useful in estimating the stick-fixed neutral points of new designs for all flight conditions.

Report presenting a procedure for determining the motions of an airplane resulting from the deflection of the lateral or directional controls for the case of non-linear derivatives. A simple computation table is presented to illustrate the application of the procedure.

Report discuss the results of force tests, yaw-trim tests, and power-off tests to compare the stability and control characteristics of a powered airplane model in the erect and inverted flight attitudes. Due to the violent and uncontrollable maneuvers that sometimes occur after flight in the inverted attitude, more information was requested about stability and control characteristics in this position. Testing found that with the power on, a serious reduction in longitudinal and directional stability occurred in inverted flight.

Report presenting design charts for 24S-T aluminum-alloy flat compression panels with longitudinal Z-section stiffeners. It was found that maximum possible structural efficiency with these panels requires closer stiffener spacings than those now in common use.

Report discusses data obtained from measuring sideslip characteristics via the continuous-record method and the steady-record method. The situations in which each recording method is preferred are presented.

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.

From Introduction: "The tests reported herein, conducted during the early part of 1945, were made to determine the inherent charge-air distribution characteristics of the engine-stage supercharger of the double-row radial engine."

From Summary: "Small high-speed single-cylinder compression-ignition engines were tested to determine their performance characteristics under high supercharging. Calculations were made on the energy available in the exhaust gas of the compression-ignition engines. The maximum power at any given maximum cylinder pressure was obtained when the compression pressure was equal to the maximum cylinder pressure. Constant-pressure combustion was found possible at an engine speed of 2200 rpm."

Report presenting an investigation to determine the effect of the amount of oil flow to the piston on the ring-sticking characteristics of a piston and ring assembly and on the engine oil consumption. Results regarding the blow-by, lubrication, oil consumption, and method of supplying oil are provided.

Report presenting a theoretical study of a diesel engine-compressor-turbine combination for aircraft application. The performance characteristics of the compressor and turbine chosen for analysis are believed to be attainable on present aircraft equipment.

Report presenting an investigation to determine the knock-limited performance of AN-F-28, Amendment-2, fuel in a DCFR engine when water solutions of the following aliphatic amines were added as internal coolants: monomethylamine, dimethylamine, ethylendiamine, diethylamine, triethylamine, and butylamine. Results regarding the mean effective pressure, indicated specific fuel competition, indicated specific liquid consumption, and knock-limited inlet-air pressure plotted against fuel-air ratio are presented for each fuel and amine combination.

Report presenting the results of tests to determine the extent to which the knocking tendency of an air-cooled engine cylinder is increased when the cylinder head is poorly cooled and when the cylinder temperature exceeds the maximum specified by the engine manufacturer. The tests showed that, when the cylinder-head temperature was increase from 400 to 600 degrees Fahrenheit, the knock-limited indicated mean effective pressure was reduced 3 percent at a fuel-air ratio of 0.097 and 39 percent at a fuel-air ratio of 0.065.

Report on the NACA test-rig installation, measurements, instrumentation, test procedure, methods of calculation, and presentation of data for rating and testing centrifugal superchargers. Special precautions for certain portions of testing are also provided.

Report discusses the results of bench testing on a German BMW 301D2 to determine the relation between the control parameters and any special methods by which the control principles are adapted to the control of the engine. Characteristics are presented for a variety of simulated manifold pressures, charge-air temperatures, engine speeds, and altitudes. Special attention is paid to the pressure characteristics of the servo-oil system and the potential effects of its failure on the operation of the automatic engine-control system.

Report discusses an investigation into the tensile strength of cast-iron piston rings, NACA microtensile specimens, and bar specimens. Photographs showing the relation between graphite-flake size and tensile strength and radiographs showing the shrinkage cavities in the piston rings are provided. Piston rings tend to be one of the first parts of an aircraft engine to fail, so discovering the ideal material composition and foundry treatment is very important.

Report presenting testing to determine the stresses and bending moments required to break pieces 1 inch or less in length from the ends of cast-iron, keystone, compression piston rings. Strain gages were used to determine the stress pattern for various modes of vibration. The maximum-stress points of vibrating piston rings were at the antinodes or points of maximum deflection.

Report presenting an electron-diffraction examination of cast-iron piston rings used in a single-cylinder test engine, which showed the presence of a layer of graphite covering the surface. The wear curves from the rings studied had shown variation from high rates to very low rates of wear.

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.

"An injection system that supplies water to each cylinder of a double-row radial engine was tested...as part of a general investigation of the power-plant installation of a four-engine heavy bomber. The tests were conducted to determine the effectiveness of water injection in cooling the engine during take-off. The injection of 500 pounds of water at the take-off power condition reduced the maximum measured exhaust-valve-seat temperature 64 degrees Fahrenheit and the maximum spark-plug-gasket temperature 55 degrees Fahrenheit" (p. 1).

Report discussing testing to determine the cooling effect of modified baffles and auxiliary-cooling ducts on the rear-row cylinders of a double-row radial engine. The modified baffles were found to reduce the temperatures of the exhaust-valve seats, but did not have an effect on the valve-guide temperatures. The auxiliary-cooling ducts reduced temperatures of the exhaust-valve seats and rear spark plug gaskets.

Report presenting an attempt to establish a correlation of the cooling characteristics of the Wright R-2600-8 engine with water as an internal coolant and to investigate methods of introducing the water. A cooling correlation, including the effect of water as an internal coolant, was established by use of the NACA cooling-correlation method. Results regarding the cooling-performance predictions and engine condition are provided.

Report presenting testing of a German superchrager from a Junkers Jumo 211F engine. The supercharger differed from conventional American superchargers in that it had a fully shrouded impeller, which discharged through a very short vaneless diffuser into a scroll-collector case. Tests were run at impeller tip speeds from 400 to 1200 feet per second at increments of 100 feet per second for a wide range of air flows.

Report discussing an investigation of the progressive accumulation of load deposits on spark plugs under nonvarying operating conditions. Deposit-weight determinations and photographic observations are presented, and the specific characteristics of deposit accumulation are described.

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.