Report presenting a theory regarding engine-cooling variables from a previous report, which was used as a basis for the development of a semi-empirical equation to correlate exhaust-valve temperature with engine conditions. Results regarding the determination of constants, influences of operating variables on mean effective gas temperatures, thermal-resistance factor, and accuracy of correlating equation are provided.

Report presenting pressure-distribution measurements obtained from the horizontal tail surfaces of the Curtiss P-40K airplane during low-speed pull-ups to abrupt stall in which tail buffeting was experienced. The chordwise load distributions during buffeting are similar to those experienced during angle-of-attack changes. The location of the stall and frequency of stall disturbances are also described.

Report discussing the use of variable-ratio geared tabs with an experimental elevator to improve stick-force characteristics in turning flight. The stick forces with the tabs were found to be satisfactory for a variety of center-of-gravity ranges. The ability of pilots to use the controls is also described.

"In Mach range of 0.25 - 0.69, boundary-layer measurements were made on upper wing surface at 25% semi-span, pressure-distribution measurements made on upper surface at 63% semi-span, and wake surveys made at 63% semi-span. The minimum profile-drag coefficient of 0.0062 was indicated for smooth section at 63% semi-span. Critical mach number was exceeded by 0.04, but no compressibility shocks appeared. In slipstream, boundary layer transition occurred as far back as 20% chord on upper surface at low lift coefficients" (p. 1).

Report presenting an analysis to compare longitudinal stability and control characteristics obtained with a conventional fixed-stabilizer, an adjustable-stabilizer, and an all-movable horizontal tail. The tail-area requirements, control forces required in the critical landing condition, static margin, control-force gradients in a dive recovery, and elevator-free stability are investigated.

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 testing of two deep inducers as separate components and in combination with an impeller as part of an investigation to correlate design requirements of inducers and impellers. Both inducers, when tested as separate components at a speed corresponding to an impeller tip speed of 1000 feet per second, had a peak adiabatic efficiency of approximately 82 percent. Results regarding the inducers as separate components, inducer-impeller units, and a comparison of inducer performance as a separate and as an integral impeller component are provided.

Report presenting a program of tests to determine the effect of an integral front shroud on the performance characteristics of a centrifugal supercharger impeller. The impellers tested included a modification of a commercial semishrouded impeller and a fully shrouded impeller, which was the same as the semishrouded one except for an integral front shroud.

Report presenting a flight investigation made of boundary-layer and profile-drag characteristics of smooth wing sections of a P-47D airplane. Measurements were made at three stations on the wing: boundary-layer measurements, pressure-distribution measurements, and wake surveys. The results indicated that a minimum profile-drag coefficient of 0.0062 for the smooth section at 63 percent semispan was obtained.

Investigations were made to determine the cowling and cooling characteristics of the Ranger V-770-8 engine installation in an observation seaplane. Final cowl configurations possessed ample engine and oil-cooler pressure drops for cooling in the critical normal-power climb condition with any of the three baffle configurations tested. The indicated critical Mach number of the cowling was found to be 0.70 as determined by the pressure on the lower lip of the inlet.

Report presenting an investigation to develop a general method of determining bearing loads for crankpins. Results regarding the idea design of the bearing, bearing operating temperature, and the calculations for determining ideal operating conditions for V-type engines and production V-type engines are provided.

Report presenting a dimensional analysis method of analyzing bearing loads as applied to the blade bearing of a V-type aircraft engine.

Report presenting tests conducted with two liquid-cooled cylinders in order to isolate the effects of the various engine and coolant variables on cylinder temperatures and to obtain engine-cooling data required for a fundamental study of the heat-transfer processes in liquid-cooled engines. Cylinder temperatures were obtained for a large range of engine speeds, manifold pressures, carburetor-air temperatures, fuel-air ratios, spark advances, coolant-flow rates, average coolant temperatures, and coolant pressures with water and AN-E-2 ethylene glycol and other ethylene glycol-water mixtures as coolants.

Engine temperature data and cooling correlating analyses of the engine and oil cooler are presented in connection with an investigation of the cowling and cooling of the ranger V-770-8 engine installation in the Edo XOSE-1 airplane. Three types of baffles were installed in the course of the tests: the conventional, the turbulent-flow, and the NACA diffuser baffles. Each of the types was of merit in cooling a different region on the cylinder. Incorporation of the best features of the three types into one baffle, a method which appears to be feasible, would provide improvements in cylinder cooling.

"A test-stand investigation was conducted to determine the mixture distribution of a conventional double-row radial engine for a wide range of engine speeds, powers, and fuel-air ratios and to evaluate its effect on engine performance. The fuel was injected into the combustion-air stream by a rotating spray ring located near the impeller entrance. Fuel-air ratios of the individual cylinders were determined from chemical analyses of the exhaust gas" (p. 1).

"Information published in chemical journals from 1933 to 1939 on the thermodynamic properties of the component gases of exhaust gases based on spectroscopic measurements were used as data for computing the ideal values of work, mass flow, nozzle velocity, power, and temperature change involved in the thermodynamic properties of a gas turbine. Curves from which this information can conveniently be obtained are given. An additional curve is included from which the heat flow may be calculated for nonadiabatic processes" (p. 1).

From Summary: "This report suggests a method whereby information on the strength under repeated stresses of aircraft materials or structural parts can be used in conjunction with information on service loadings as a means of comparing alternative designs."

Report discussing testing of six airfoil sections for the wing of the Vega XP2V-1 airplane in a smooth condition and with standard leading-edge roughness. Information about the lift, drag, pitching-moment characteristics, and sensitivity to roughness is provided. No airfoil was found to be superior to the others in all categories.

Report presenting comparisons of measured and calculated loads on the wing and horizontal tail in pull-up maneuvers for six airplanes over a range of weights. Good agreement was obtained between calculated and measured loads under certain circumstances, but the agreement in some cases was only fair, which may be attributed to poor quantitative knowledge of the aerodynamic parameters or to violation of the assumptions on which the method is based.

Report presenting flight tests of a twin-engine midwing attack bomber and a single-engine low-wing fighter, which indicate that both have moderately high effective dihedral but different directional stability and control characteristics. The pilots had a harder time controlling the fighter airplane, while the attack bomber was found to have a higher degree of directional stability and low directional trim forces, which the pilots preferred.

Report presenting wind-tunnel tests made to determine the aerodynamic characteristics of a scale model of a high-speed bomber with a dual pusher propeller aft of the empennage. Some of the results discussed include longitudinal, lateral, and directional stability and control, the empennage design, and ground effects on the aerodynamic characteristics. The results indicate that this particular airplane has several advantages with regard to stability and control over the conventional-type single-engine airplane configuration.

Report discussing the results of testing on a flying boat model with an afterbody length-beam ratio of 4.7 to determine its takeoff and landing stability and resistance characteristics.The range of stable trims was smaller than models with a conventional afterbody, but the range of stable positions for the center of gravity was about the same. Landing stability was satisfactory, and the hump resistance and trim is less than a boat with a smaller ratio.

Report presents correlation of data obtained from several independent length-beam-ratio investigations to determine the general effect of length-beam ratio on the resistance characteristics of three series of flying-boat hulls. An optimum length-beam ratio was found beyond which no further reduction in hydrodynamic resistance occurred. The optimum ratio depended on the hull lines of any given mode series.

"Dimensional analysis and the principle of similitude are applied to the computation of the crankpin-bearing loads of radial engines having nine cylinders per crankpin." All values of engine speed up to 5000 rpm and all values of indicated mean effective pressure to 500 pounds per square inch have been charted and presented. The effects of several engine dimensions, including reciprocating weight, rotating weight, connecting-rod length, stroke, bore, and compression ratio on the crankpin-bearing loads are also included.