Tests were made in 8-ft high-speed wind tunnel to determine the drag reduction possible by eliminating the barrel jacket of a protruding 50-caliber aircraft gun. It was found that the drag of a standard aircraft gun protruding into the air stream at right angles to the flow can be reduced by 23% by discarding the barrel jacket. At 300 mph and sea-level conditions, this amounts to a decrease in drag of from 83 to 64 pounds. A rough surface finish on the barrel was found to have no adverse effects on the drag of the barrel, the drag being actually less at high Mach Numbers.

Report discussing a comparison between a centrifugal-flow-type turbojet engine with an adjustable-area exhaust nozzle and with a series of fixed-area nozzles of various throat diameters. The adjustable-area nozzle was found to be as efficient as the fixed-area nozzles in testing. Information about the corrected static thrust, fuel flow, and tail-pipe gas temperature for both types of nozzles is provided.

Report presenting the performance of a 22-inch-diameter pulse-jet engine using a net of low-loss modified air valves at ram pressures equivalent to simulated flight speeds. Results regarding combustion-air weight flow, flight thrust, maximum combustion-chamber pressure, specific fuel consumption, pressure cycle, and valve life are provided.

Report presenting an analysis of data on fuel-vapor loss from fuel tanks during simulated flight obtained by six laboratories to show the effects of individual variables such as altitude, initial fuel temperature, rate of climb, booster-pump agitation, fuel depth, fuel-surface area, types of fuel, and vent-line pressure drop on fuel-vapor loss.

Report discussing an investigation to determine the effect of omitting some of the fuel constituents in AN-F-28 Amendment 2 fuel that are normally lost in flight on fuel-vapor loss. Removing the components was found to decrease the fuel-vapor loss and increase the critical altitudes.

Report discussing an investigation of 24 aromatic amines as antiknock additives in aircraft gasolines and their low-temperature solubility.

"An investigation was conducted to determine the knock-limited blending characteristics of leaded fuels containing selected aromatic fuel components (benzene, toluene, mixed xylenes, and cumene). Each of the aromatics was blended with an alkylate blending agent and with a virgin base stock. The blending characteristics of the resulting fuels were determined in a full-scale aircraft-engine cylinder" (p. 1).

Report discussing tests to determine the effect of 2-percent additions of six aromatic amines on the knock-limited performance of 28-R fuel. All of the aromatic amine blends increased the performance and power of the base fuel. Different blends performed better at different fuel-air ratios.

"Tests were conducted to determine the effect of several flight variables and several types of fuel agitation on fuel-vapor loss from a fuel tank during flight. Data were obtained from simulated-flight tests, in which the effects of rate of climb, altitude, initial fuel temperature, weathering of fuel, and fuel agitation were investigated; and a correlation between the simulated-flight and actual-flight data was established" (p. 1).

Report discusses the thrust and power characteristics of several single- and dual-rotating propellers with differing blade width and number of blades for negative-thrust operation from -45 degrees to 145 degrees blade angle. From Summary: "The tests indicate that it is possible to predict for a given propeller design characteristics in the negative-thrust range from known characteristics at a different activity factor. Adequate negative thrusts were indicated for extremely high positive as well as negative blade angles."

Report discusses an investigation into the behavior of a cantilever beam in transverse motion with a mass at its tip when the root is suddenly brought to rest. Equations for determining the stresses, deflections, and accelerations that arise in the beam are also provided. This testing can be applied to the shock created in an airplane when landing and the vibrations that result.

Report discussing testing on triptane, hot-acid octane, diisopropyl, neohexane, mixed xylenes, cumene, benzene, toluene, and methyl tert-butyl ether in several blends to determine their knock-limited performance data in F-3 and F-4 engines at standard operating conditions. All of the blending agents examined were found to be usable, with concentrations varying depending on various thermodynamic properties.

Report presenting an investigation of the suitability of 27 aromatic amines for overwater storage of their gasoline blends. The program is also meant to determine the antiknock effectiveness and low-temperature solubility in gasoline.

Report presenting testing to determine the effect of xylidines on the load-carrying capacity of aircraft-engine oil in several test devices. Lubricating oil and lubricating oil with xylidines added was tested in four different testing machines. In all of the experiments, adding the xylidines made the oil a poorer lubricant in the boundary region of lubrication, where metal-to-metal contact occurs.

Report presenting testing of the effect of xylidines on the load-carrying capacity of an aircraft-engine oil in several test devices. There is also interest in the suitability of xylidines as an antiknock component in aviation gasoline, so xylidines were added to the gasoline mixes used in several different machines.

Report presenting tests to determine the effect of xylidines on the stability of an aircraft-engine lubricating oil. The Indiana oxidation test and measurements of the oxygen absorption rate of the oil samples were performed on Navy 1120 oil, Navy 1120 oil plus 0.5 percent by weight of xylidines, and Navy 1120 oil used in piston-ring-sticking tests both with and without xylidines. Results regarding the Indiana oxidation test, the Davis oxidation test, the automatic oil-oxidation apparatus, and a laboratory inspection are provided.

Report discussing the cooling characteristics of a modified 14-cylinder double-row radial air-cooled engine installed in a four-engine airplane at a pressure altitude of 7000 feet. Testing of the variable charge-air flow, variable cooling-air pressure drop, and variable fuel-air ratio was conducted. The cooling equation, temperature-limited performance, maximum engine temperatures, and other information predicted by calculations is described.

Report discussing tests on three fuels in a 14-cylinder double-row radial air-cooled engine at different engine speeds, blower ratios, and spark settings.

"A comparison has been made in flight of the antiknock characteristics of 33-R fuel with that of 28-R and a triptane blend. The knock-limited performance of the three fuels - 33-R, a blend of 80 percent 28-R plus 20 percent triptane (leaded to 4.5 ml TEL/gal), and 28-R - was investigated in two modified 14-cylinder double-row radial air-cooled engines. Tests were conducted on the engines as installed in the left inboard nacelle of an airplane. A carburetor-air temperature of approximately 85 deg F was maintained" (p. 1).

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.

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

Report discussing tests in a combustion chamber to obtain smoking characteristics data on a variety of hydrocarbon fuels. Details about the smoking tendencies and burning rates of the fuels in uncontrolled and controlled tests are provided.

Report discussing testing on 22 inch-diameter pulse-jet engines to determine the effect on performance of a change in combustion-air temperature from approximately 80 degrees to 130 degrees. The effects on jet thrust, combustion-air flow, and engine thrust are described.

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.