"The cavitation in nozzles on airfoils of various shape and on a sphere are experimentally investigated. The limits of cavitation and the extension of the zone of the bubbles in different stages of cavitation are photographically established. The pressure in the bubble area is constant and very low, jumping to high values at the end of the area. The analogy with the gas compression shock is adduced and discussed" (p. 1).

Abstract. to estimate the oxygen picked up by thorium in casting a rapid method of running the acid insoluble content was developed. the quickest procedure consists of reacting with mixed acids, fuming with perchloric and filtration to separate the "free" thorium from the "combined". The precipitate is ignited and weighed as thorium dioxide.

The lubricant (Calel A-60) used to reduce pushing forces when discharging slugs from pile tubes forms a cloudy emulsion with water. During the initial period of operation at 100 B and D areas, spillage of lubricant during discharge produced so much cloudiness in the basin water that it interfered with sorting operations. An investigation was started to see if a lubricant could be found that would effectively lubricate tubes during discharge and which would form optically clear systems when mixed with water. This report presents the data on a number of lubricants which were suggested for test.

Report presenting a flight investigation made to determine the effectiveness of dive-recovery flaps installed on the XP-51 airplane as a safety device for recovery from contemplated terminal-velocity dives. The flap installation is described and results are presented of measurements obtained during stick-free pull-ups and pull-outs made by deflecting the dive-recovery flaps to two selected values of flap angle .

"The knock-limited performance of blends containing General Motors triptane in S reference fuel and in an S plus M base fuel was determined in 17.6, F-3, F-4, and full-scale (single cylinder) engines. The results obtained are presented and are compared with published data from similar tests of 12 aromatics, 10 paraffins (including highly purified triptane), and 2 olefins. The comparison of fuels - which is based on a consideration of (a) antiknock blending sensitivity, (b) lead susceptibility, (c) temperature sensitivity, and (d) comparison of small-scale and full-scale engine data - is presented by means of bar graphs" (p. 1).

Report discussing a study of automatic nonreturn air valves for use in an intermittent-jet engine. Four valve-spring materials, three valve-grill materials, and five types of valves were used. Valve A, which was made out of aluminum, was found to perform the best and last the longest.

The following report describes findings from a reconnaissance mission in Alabama, Georgia, and North Carolina on radioactive trace elements in a variety of rocks.

Report issued by the U.S. Bureau of Mines discussing the iron-ore mining accident experience in the Lake Superior District. Frequency and severity rates of accidents between 1940 and 1943 are presented. This report includes tables.

Report discussing an investigation to determine whether the crank angle for maximum rate of pressure rise can be used to indicate maximum-economy spark advance. Information about spark-advance tests at constant inlet-air pressure and fuel-air-ratio test results are provided.

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As part of a general investigation of propellers at high forward speeds, tests of two-blade propellers having the NACA 4-(5)(08)-03 and NACA 4-(10)(08)-03 blade designs were made in the Langley 8-foot high-speed tunnel through a range of blade angle from 20 degrees to 60 degrees for forward Mach numbers from 0.165 to 0.70 to determine the effect of camber and compressibility on propeller characteristics. Results previously reported for similar tests of a two-blade propeller having the NACA 4-(3)(08)-03 blade design are included for comparison.

Report presenting a method of correlating the effects of compression ratio and inlet-air temperature on the knock limits of aviation fuels. Knock-limited performance tests of several fuels were run to check the method.

Technical report discussing that the deuterium concentration of heavy water can be determined by equilibrating the water with deuterium gas in the presence of a catalyst with subsequent analysis of the equilibrated gas on the mas spectrometer. The apparatus for equilibration analyses maybe be considered in three parts: 1) apparatus for introducing the ingredients into the reaction chambers; 2) the reaction chambers; 3) the mass spectrometer for analysis of the equilibrated gas. The isotopic composition of the deuterium gas to be used as the starting material is primarily governed by what gases are available. In general it is best to use gas within about one percent on either side of the final equilibrium composition. No reaction takes place between deuterium gas and water molecules in the absence of a catalyst. Platinum oxide is used as the catalyst.

This report is the second in the series of reports carried by the Geological Survey on rare or uncommon elements and their possible sources. The report discusses xenon, an element belonging in a group of elements known as the inert gases, characterized by its lack of reactivity.

The results of an investigation of submerged-duct entrances are presented. It is shown that this type of entrance possesses the following characteristics: 1) very high-critical-compressibility speeds throughout the range of high-speed inlet velocity ratios; 2) very low pressure losses for the air entering the duct at all inlet-velocity ratios; and, 3) low external drag. These characteristics are obtained by the proper shaping of the contour of the upstream approach to the submerged inlets and by proper alignment of the duct lip. Design data are presented and the application of these data to a specific high-speed fighter-airplane design is discussed.

Report presenting an investigation of the effect of compressibility on the drag of a Bell P-39N-1 airplane in flight as part of a drag study on several high-speed airplanes for a range of Mach numbers.

Report discussing the changes in static longitudinal stability due to tilting the propeller axis of an SB2C-3 airplane downward. Tilting the propeller was found to be beneficial for stability, but only if the pilot was in a forward center-of-gravity position with a tilted engine. Installing a tilted engine reduced trim forces due to the changes in power up to 25 percent.

The data presented have no bearing on performance characteristics of airplane, which were considered exceptionally good in previous tests. Some of the undesirable features of lateral and directional stability and control characteristics of the F-8 are listed. Directional stability, with rudder fixed, did not sufficiently restrict aileron yaw; rudder control was inadequate during take-off and landing, and was insufficient to fly airplane with one engine; in clean condition, power of ailerons was slightly below minimum value specified; it was difficult to trim airplane in rough air.

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Note presenting an instrument that measures small absolute humidity changes by photoelectric examination of the 9440 angstrom units absorption band of water vapor. The instrument consists of a small source of light which sends its radiation over an air path of less than 1.5 meters to a dispersing system.

The results of this analysis indicate that isothermal pressure losses can be predicted analytically in the type of ducting system which may be broken down into the elementary forms of elbows, diffusers, and straight ducts for which pressure-loss data are published.

The primary purpose of the corrosion work was to find a tuballoy alloy which would be sufficiently corrosion resistant to be useful for canned slugs even if some of the can were to leak. The secondary purpose was to obtain general corrosion data on tuballoy alloys.

Report presenting performance charts for gliders and twin-engine tow planes with different degrees of aerodynamic and structural refinement. The glider charts display the gliding angle, useful load, stalling speeds, power required for level flight at various speeds, and power required for level flight while climbing at various speeds. The tow-plane charts show the stalling speeds, power required for level flight at various speeds, and power required for level flight while climbing at various speeds.