Report presenting direct-reading tables and charts for determining the drag or thrust coefficients from wake-survey measurements in the subsonic speed range. Additionally, numerical examples are provided using information from the tables.

"The effect on the propulsive efficiency of locking or windmilling one propeller of a six-blade dual-rotating propeller installation was determined in the Langley propeller-research tunnel. Tests were made of both pusher and tractor configurations, with the unpowered propeller both leading and following the powered propeller, which was set at a blade angle of 40 degrees. The maximum propulsive efficiency of the powered propeller in combination with the locked or windmilling propeller was, in all cases, lower than that of the powered propeller operating alone" (p. 1).

Report presenting an exact solution and a closely concurring approximate energy solution for the buckling of an infinitely long flat plate under combined shear and transverse direct stress with edges elastically restrained against rotation. An appreciable fraction of the critical stress in pure shear may be applied to the plate without any reduction in the transverse compressive stress necessary to produce buckling.

Report presenting testing to determine the influence of propeller rotation and vertical-tail design on the trim characteristics of a model of a twin-engine airplane with one engine inoperative. The tests showed that the effect of mode of propeller rotation on the directional trim characteristics of the model operating with asymmetric power was considerable. Results regarding the effect of mode of propeller rotation and effect of vertical-tail design are provided.

Report presenting an investigation to determine the nature and extent of the reversal of flow, which occurs at the inlet of centrifugal superchargers over a considerable portion of the operating range. Results regarding lampback patterns, tuft studies, backflow surveys, and effect of impeller tip speed on backflow are provided.

"Tank tests were made of a flying-boat model having various types of fairing with and without ventilation ducts behind the main step to investigate the hydrodynamic characteristics of the model. All the types were designed to reduce significantly the air drag chargeable to the main step. The configuration that combined the best stability with a good aerodynamic form consisted of a shallow step and an adjoining ventilation aperture having an area about 7 percent of the square of the beam" (p. 1).

"As part of an investigation of the cooling characteristics of liquid-cooled engines, tests were conducted with an electrically heated single-tube heat exchanger to determine the heat-transfer characteristics of AN-E-2 ethylene glycol and other ethylene glycol-water mixtures. Similar tests were conducted with water and commercial butanol (n-butyl alcohol) for check purposes. The results of tests conducted at an approximately constant liquid-flow rate of 0.67 pound per second (Reynolds number, 14,500 to 112,500) indicate that at an average liquid temperature 200 degrees f, the heat-transfer coefficients obtained using water, nominal (by volume) 30 percent-70 percent and 70 percent-30 percent glycol-water mixtures are approximately 3.8, 2.8, and 1.4 times higher, respectively, than the heat-transfer coefficients obtained using an-e-2 ethylene glycol.

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 presenting tests to study the effectiveness of small pressure differences in removing the dust boundary layer through slots in the duct wall of airplane ducts and reducing separation losses. Two-dimensional diffusers of 15 and 30 degrees included angles and some 90 degree bends were tested. The 30 degree diffuser was tested with and without an intercooler.

Report presenting testing to determine the effect of special baffles on the temperatures and cooling-air requirements of the Wright 1820 G200 and R-2600-8 cylinders. Nine baffles were tested with the 18020 cylinder and two were tested with the R-2600-8 cylinder. Results indicated that the internal cylinder surfaces with good thermal connection with the external-cooling means respond to changes in external cooling.

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 an analysis of the thermopile radiometer as used in the measurement of irradiation and radiant power interchange is given. The theory of the instrument when used to measure irradiation and net radiant power interchange is developed, and the precautions to be observed when using it for these measurements are presented.

Report presenting data on the thermal performance and static and total pressure drop characteristics of a fluted-type exhaust gas and air heat exchanger. Results regarding heat transfer, pressure drop, and non-isothermal pressure drop are provided.

Report presenting results of tests of the thermal performance and the static pressure drop characteristics of a flat-plate type exhaust gas and air heat exchanger. The ventilating air shroud built into the heat exchanger gives characteristics of cross flow and parallel flow.

Report presenting data on the thermal performance and static pressure drop of a finned-type cast-aluminum exhaust gas and air heat exchanger. Results regarding heat transfer, isothermal pressure drop, and heater surface temperature are provided.

Report presenting data on the thermal performance and the static pressure drop characteristics of a flattened-tube type crossflow exhaust gas and air heat exchanger. The measured thermal outputs and static pressure drops are compared with predicted magnitudes.

Report presenting a summary of a series of reports regarding heat exchangers, and in particular, the design of exhaust gas and air heat exchangers. The four parts included are a summary of heat transfer equations, single pass heat exchangers, heater performance in flight, and appendicies with additional aerodynamic information.

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.

Report presenting knock-limited small-scale-engine tests of isopropyl-benzene, benzene, and o-xylene blended individually in various concentrations with selected base fuels. Data were obtained to determine the blending sensitivity, lead susceptibility, and sensitivity of the blends to inlet-air temperatures. Isopropylbenzene was found to be the most effective overall.

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 discusses the shear and normal stresses caused by a load applied until failure on the tension side of an open box beam with a flat stiffened cover. The maximum strain was found to be much less than in solid tensile specimens of the same material. Special attention is paid to the variation in strains at various parts on the beam and the potential effects of rivet holes and riveting, which requires further testing.

Report presenting tests to verify and extend ultraviolet spectroscopic techniques for applications to the analysis of aviation fuels for their aromatic constituents. Results regarding photographic absorption spectra, spectrophotometric absorption spectra, and spectrophotometric analyses are provided.

Report presenting an investigation to determine the suitability and precision of a modified, routine-model, infrared spectrophotometer for analyzing binary and ternary mixtures of aircraft-fuel components. Analyses by means of infrared measurements are described for the following hydrocarbon mixtures: 12 known mixtures of 2,2,3-trimethylbutane (triptane) and cyclohexane, 4 known mixtures of triptane and benzene, and 4 known mixtures of triptane, cyclohexane, and benzene.

Report presenting pressure-distribution measurements made on the right wing of a P-39N-1 airplane at values of Mach number up to 0.80. A considerable portion of the lift was carried by components of the airplane other than the wings, and the proportion carried by the wing varies considerably with Mach number. Results regarding the variation of wing loads and moments with Mach number, internal wing pressure, and airplane lift-curve slope are provided.