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"The results are given of an investigation of some of the limitations that now prevent increases in the temperature level of engine cylinder heads, and a review of previous work in the field is included to supplement these results. Attention was given, in particular, to the effects of fuel knock and surface ignition on cylinder temperatures and the effects of cylinder temperatures on performance. Data were obtained from a Wright C9GC air-cooled cylinder and from a Lycoming O-1230 liquid-cooled cylinder" (p. 1).

The effects of mass distribution on lateral stability and control characteristics of an airplane have been determined by flight tests of a model in the NACA free-flight tunnel. In the investigation, the rolling and yawing moments of inertia were increased from normal values to values up to five times normal. For each moment-of-inertia condition, combinations of dihedral and vertical-tail area representing a variety of airplane configurations were tested. The results of the flight tests of the model were correlated with calculated stability and control characteristics and, in general, good agreement was obtained.

"Vibrations of rotary-wing aircraft may derive their energy from the rotation of the rotor rather than from the air forces. A theoretical analysis of these vibrations is described and methods for its application are explained herein" (p. 1). Information about self-excited speed range and shaft-critical speed are provided for any rotor with more than two blades.

Report presenting wind tunnel testing of four full-scale seaplane floats to determine the aerodynamic characteristics of the floats and to evaluate several drag-reducing refinements. Four floats were investigated; two differed only in external details like flush rivets, while one was the type used on twin-float installations. The variation of lift, drag, and pitching moment with pitch angle are presented for each float.

The objective of this report is to investigate the feasibility of obtaining uranium from the carnotite sludge in such a form as o permit its use in the brown oxide purification process.

Report presenting a direct comparison between the observed and the calculated longitudinal dynamic stability of a particular dynamic model of a flying boat moving on the water. Good agreement was obtained between experiment and theory for trim angles in the vicinity of lower limit, at one speed a little above the hump.

Report presenting data from tests conducted on full-scale propellers with 3155 blade design, which have been used to construct a set of propeller thrust charts for use in the calculation of take-off performance. By using the charts, the thrust of modern single- and dual-rotating propellers may be easily and rapidly calculated through the entire take-off range.

Report presenting a method for obtaining exact potential-flow patterns in a compressible fluid. The method is based on a complex-function theory developed for the solutions of the simultaneous first-order partial differential equations in the hodograph variables.

Report presenting force tests in two-dimensional flow made on an NACA 66-009 airfoil with a flap having a chord 30 percent of the airfoil chord and a tab having a chord 20 percent of the flap chord. A plain flap and flaps having overhangs of 35 and 50 percent of the flap chord were tested with two gap variations: sealed and unsealed. Results regarding lift, flap hinge moments, pitching moments, drag, and tab characteristics are provided.

Tests were made to determine the column strength of extruded magnesium alloy AM-57S. Column specimens were tested with round ends and with flat ends. It was found that the compressive properties should be used in computations for column strengths rather than the tensile properties because the compressive yield strength was approximately one-half the tensile yield strength. A formula for the column strength of magnesium alloy AM-57S is given.

This memorandum discusses means to extinguish magnesium fires in metal turnings at the Hanford Engineer Works 300 Area. The storage of metal turnings in 55 gallon drums presented a fire hazard, for which an effective means for extinguishing the fire had not been presented. This memorandum is dated July 1943. (JL)

Report describes the standard procedure that NACA used for evaluating the aileron characteristics of airplanes. The variables measured in the testing are rolling velocity, aileron positions, aileron stick forces or tangential wheel force, indicated airspeed, altitude, free-air temperature, and rudder position. The step-by-step flight procedure is described and information regarding evaluation of the control data and general suggestions is included.

Report presenting tests of the flow of air through brass tubes with the friction coefficient and incompressible flow relation as the main focus. The analytical relation between friction coefficient, tube length, and Mach number is shown for flow without shock and the conditions for flow with and without shock are delimited.

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A report discussing a possible new volatile compound of uranium, its probable properties, and attempts to synthesize it. Though the possible new compound was not successfully synthesized, the author provides suggestions for future work.

Report discusses the results of yawing tests on a model of the complete hull of the XPB2M-1. The tests indicated that there was a tendency toward directional instability in the vicinity of the hump. The researchers concluded that at a certain range, the curves of yawing moment are discontinuous, and this has led to difficulty in preliminary test flights.

Report presenting a study of oil coolers, especially in regards to three factors: the congealing tendency of the cooler, the power cost chargeable to the installation, and the performance characteristics of the oil cooler in operation at altitude.

This report follows research done at the Purdue Research Foundation and Department of Chemistry on fluorocarbons done by the Office of Scientific Research and Development.

Report presenting testing to determine the effect of xylidines of the corrosiveness of aircraft-engine oil toward engine bearings as part of an investigation on the suitability of xylidines as an antiknock component in aviation gasoline. Results regarding the loss in bearing weight, corrosion losses, temperature characteristics, and types of corrosion are provided.

Report presenting an investigation for the purpose of developing a target which can be towed satisfactorily at high speeds. Testing included drag measurements and visual observations of the stability characteristics of several full-scale and scale models of sleeve-type tow targets. The drag coefficients obtained for the currently used targets were found to be excessively high.

Report presenting testing to determine methods for reducing the temperatures of the hot cylinders on air-cooled aircraft engines. A Pratt & Whitney R-1830-43, 14-cylinder engine used for the tests. Results regarding the cooling-air ducts, mixture-enriching tests, additional cooling area, baffle modifications, and an application of the information are provided.

Report presenting determination of air-flow quantity in front of and behind three orifice plates to determine the errors introduced in the quantity measurements by the turbulence behind the orifice plates. For the orifice plates tested, the results showed that the measurements must be taken 40 to 60 hole diameters downstream from the plates to ensure accuracy.

"The results of tests of round heat-treated chromium-molybdenum-steel tubing are presented. Tests were made on tubing under axial load, bending load, torsional load, combined bending and axial load, combined bending and torsional load, and combined axial, bending, and torsional load. Tensile and compressive tests were made to determine the properties of the material. Formulas are given for the evaluation of the maximum strength of this steel tubing under individual or combined loads" (p. 1).