Report discussing a research program to investigate ice prevention and elimination on airships in order to develop suitable airship ice-prevention equipment. A Naval K-type airship was equipped with photographic and meteorological tools in order to record ice formation and the propellers were outfitted with electrically heated blade shoes. Testing discovered that an airship can be flown successfully in wet snow and freezing rain with only the propellers and induction systems protected from the weather.

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.

An investigation was conducted to correlate the knock limited performance of flight and single-cylinder engines under a variety of operating conditions.

Variable charge-air flow, cooling-air pressure drop, and fuel-air ration investigations were conducted to determine the cooling characteristics of a full-scale air-cooled single cylinder on a CUE setup. The data are compared with similar data that were available for the same model multicylinder engine tested in flight in a four-engine airplane. The cylinder-head cooling correlations were the same for both the single-cylinder and the flight engine. The cooling correlations for the barrels differed slightly in that the barrel of the single-cylinder engine runs cooler than the barrel of te flight engine for the same head temperatures and engine conditions.

Report discussing the results of testing to determine the operating life of a 22-inch-diameter pulse-jet engine equipped with a neoprene-coated valve grid. The valve grid was found to extend the operating life and only reduced the performance slightly.

Report on sea-level performance tests of a 22-inch-diameter pulse-jet engine on a thrust stand. The tests were conducted at several ram pressures and the entire range of fuel flows that the engine can operate at. Information about the maximum-thrust operation, operating frequency, maximum combustion chamber pressures, and operating lives is provided.

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."

"Column and plate compressive strengths of extruded R303-T aluminum alloy were determined both within and beyond the elastic range form tests of thin-strip columns and local-instability tests of H-, Z-, and channel-section columns. These tests are part of an extensive research investigation to provide data on the structural strength of various aircraft materials. The results are presented in the form of curves and charts that are suitable for use in the design and analysis of aircraft structures" (p. 1).

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 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.

"A comparison was made between the energy and the accelerometer methods of computing drag coefficients from flight tests of the P-51B and the P-39N airplanes. The energy method was found to be unreliable with the present types of instrumentation except under the practically unattainable conditions of very steady flight at constant indicated airspeed within a vertically stationary air mass" (p. 1).

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 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.

"As a part of a program of the NACA directed toward increasing the efficiency of compressors and turbines, data were obtained for application to the design of entrance vanes for axial-flow compressors or turbines. A series of blower-blade sections with relatively high critical speeds have been developed for turning air efficiently from 0 deg to 80 deg starting with an axial direction. Tests were made of five NACA 65-series blower blades (modified NACA 65(216)-010 airfoils) and of four experimentally designed blower blades in a stationary cascade at low Mach numbers" (p. 1).

Report presenting some model tests that will be used to guide the relation of length of afterbody and depth of step. Results indicated that an increase in length of afterbody requires an accompanying increase in depth of step to maintain adequate landing stability.

"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 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.

"Flight tests were made to determine the cause and correction for the unusual stick-free instability of the original production P-63 airplane in high-speed straight flight." The rib spacing and stabilizer incidence of the original design were found to increase instability. When they were both altered, stability was improved and fabric deflection was reduced, but stick forces were not substantially altered.

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 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.

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.

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 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.