From Summary: "The results of an experimental investigation of several low-drag wing-nacelle combinations, incorporating internal air-flow systems, are presented. The external-drag increments due to these nacelles are between one-half and two-thirds of those of conventional nacelle forms. This improvement is accomplished with only minor effects on the lift and moment characteristics of the wing. The procedure employed to determine the external shape of such low-drag nacelles is considered in detail. The design of an efficient internal-flow system with or without a blower or throttle, presents no serious problems. The energy losses in the expansion before the engine and the contraction thereafter can be kept small. It is believed that these nacelles have a wide application in housing engine pusher-propeller units and, with some alteration, jet-propulsion devices. It is probable that the low external drags may not be realized if such nacelles are used with a tractor propeller because of the high level of turbulence in the propeller slipstream."

Report discussing the effects of supercharging on the take-off thrust and useful load for a typical helicopter. Performance of the engine with the supercharger and on the rotor thrust is detailed.

Report issued by the U.S. Bureau of Mines discussing the occurrences of tantalum in different areas of the world. The tantalum deposits are described in reference to each individual country that it is found in. This report includes maps, tables, and illustrations.

Note showing that under certain conditions, a two-dimensional subsonic compressible flow around an airfoil profile can be derived from an incompressible flow around another profile. The connection between the two "conjugate flows" is given by a simple conformal transformation of the respective hodograph planes.

Report discusses an investigation into the tensile strength of cast-iron piston rings, NACA microtensile specimens, and bar specimens. Photographs showing the relation between graphite-flake size and tensile strength and radiographs showing the shrinkage cavities in the piston rings are provided. Piston rings tend to be one of the first parts of an aircraft engine to fail, so discovering the ideal material composition and foundry treatment is very important.

This paper reports work carried out to determine the factors necessary to give a filterable precipitation and determine the effects of these factors on the quantitativeness of the precipitation, and how any tendency to increase the tuballoy solubility may be overcome.

The following report presents data from the investigations on discovering factors affecting the precipitation of tubanyl peroxide from Alpha and Beta gunk solutions at reduced temperatures.

Technical report with short reports on (1) Effect of radiation on water and aqueous systems; (2) Gas evolution from uranyl solutions; (3) Effect of radiation on solid compounds; (4) Instruments; and (5) Scattering.

Report discussing an investigation of wing-inlet oil-cooler ducts on a twin-engine airplane to determine internal and external-flow characteristics of the ducting installation. Testing was also performed on revised inlets to attempt to develop a ducting system with low overall losses throughout the operating range.

Report presenting tests to verify and extend ultraviolet spectroscopic techniques for applications to the analysis of aviation fuels for their aromatic constituents. Results regarding photographic absorption spectra, spectrophotometric absorption spectra, and spectrophotometric analyses are provided.

Report discussing tests of a Sikorsky YR-4B helicopter, including photography of a rotor blade in forward-flight conditions at several azimuth angles for several tip-speed ratios. Fabric deformation in the form of sagging and bulging was noted. A reversal in the bending curve near the blade tip was also noted, which was hypothesized to come from losses of lift and high centrifugal force.

"Tests were conducted to develop a slip-ring and brush system that will perform satisfactorily in aircraft-engine, dynamic-strain-measuring applications where resistance-wire strain gages are the means of measuring the strain and to correlate the data obtained from tests in order to provide a basis for predicting the performance of similar slip-ring and brush systems operating under conditions similar to those imposed by these tests." 24 combinations of materials were tested dry and 8 were tested in oil. The five most predictable systems were identified.

Report presenting an investigation of the properties of a 20-inch diameter by 3.25 inch disc of 19-9 DL alloy in the as-forged and stress-relieved condition. Results regarding the hardness survey, short-time tensile properties, rupture test characteristics, time for deformation characteristics under stress, creep strengths, and stability characteristics are provided.

Report discussing testing to determine the cooling effect of modified baffles and auxiliary-cooling ducts on the rear-row cylinders of a double-row radial engine. The modified baffles were found to reduce the temperatures of the exhaust-valve seats, but did not have an effect on the valve-guide temperatures. The auxiliary-cooling ducts reduced temperatures of the exhaust-valve seats and rear spark plug gaskets.

Report presenting an examination of new and used nitrided-steel piston rings by electron and X-ray diffraction in a study of the surface changes produced during engine operation. Both new and used rings, examined after degreasing, gave an electron-diffraction pattern consisting of diffuse bands: those from used rings fell at the usual positions of the bands from polished metal surfaces.

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."

"Results of performance measurements made in level fight with the HNS-1 (Army YR-4B) helicopter are presented. These data include torquemeter measurements of shaft power for both the main rotor and the tail rotor. The power data, in conjunction with full-scale-tunnel date on the lift and drag of the fuselage, are used to calculate the drag-lift ratio for the main rotor" (p. 1).

Report presenting an electric torquemeter that was used to measure the power of an Allison V-1710-93 engine installed in a Bell P-63A-1 airplane. Results of maximum-available-power tests in flight at a range of density altitudes showed good agreement between the measured maximum power output and the maximum power shown on the engine manufacturer's calibration chart.

Abstract. a method of recovering thorium from slag from the bomb process of producing thorium has been developed. HCl and NaOH are the only chemicals required in quantity. Materials required for a representative slag are given.

Report discusses the results of an investigation to determine the effect of extreme changes in mass distribution along each of the three body axes. The effects of individual inertia moment parameters upon spin and recovery characteristics were examined.

Report explores the periodic forces that helicopter rotors are subjected to, both horizontal and vertical, and several configurations and material combinations of blades are described. The vibrations and exciting forces are demonstrated through calculations and explored with combinations of one, two, three, and four blades.

From Summary: "A portion of a PV-2 helicopter rotor blade has been tested in the 6- by 6-foot test section of the Langley stability tunnel to determine if the aerodynamic characteristics were seriously affected by cross flow or fabric distortion. The outer portion of the blade was tested as a reflection plane model pivoted about the tunnel wall to obtain various angles of cross flow over the blade. Because the tunnel wall acts as a plane of symmetry, the measured aerodynamic characteristics correspond to those of an airfoil having various angles of sweepforward and sweepback. Tests were made with the vents on the lower surface open and also with the vents sealed and the internal pressure held at -20 inches of water producing an internal pressure coefficient of -1.059."

From Introduction: "In the present paper a numerical procedure for the stress analysis of flat-sheet and stringer combinations of arbitrary construction and loading is presented and applied to axially loaded panels and to the reinforced covers of box beams."

Report presenting flight tests of an all-movable horizontal tail installed on a Curtiss XP-42 airplane due to its possible advantages as a longitudinal control at high Mach numbers. The elevator control was found to be unsatisfactory with the control arrangements tested.