Report discussing an investigation of the dynamic stability and control characteristics of a model of the Ryan X-13 jet VTOL airplane in hovering and transition flight. Flight control was smooth and easy without the gyroscopic effects of the engine represented, but adding a simulation of the gyroscopic effects caused the plane to become uncontrollable in hovering flight without artificial stabilization. The transition was found to be easy to perform with and without gyroscopic effects, but the model had a tendency to fly in roll and slideslipped attitudes.

From Summary: "The results of numerous unrelated tests of dive-recovery flaps are collected in this report and presented in a form suitable for use in the preliminary design of dive-recovery flap installations. Since the data were obtained for airplane models of quite widely varying configurations, and are limited largely to a Mach number of 0.80, it is recommended that each new installation be carefully flight-tested before final approval. A flight-test procedure is outlined which will insure a maximum degree of safety."

Memorandum describing preliminary investigations of two 3-inch-diameter slotted test sections over a range of pressure ratios from 1.3 to 10.0. The two test sections varied based on the number of slots and amount of open space, but they showed no appreciable difference in performance. Results regarding the slots with no chamber around the test section and with a closed chamber around the test section are provided.

Report discussing an investigation of the aerodynamic characteristics of an airfoil-forebody swept flying boat hull with a wing and tail swept back 51.3 degrees at the leading edge. The swept hull's minimum drag coefficient was about the same as the parent model or streamline model. Various combinations of flaps were also utilized.

Report presenting wind-tunnel tests that have been conducted to evaluate the independent effects of Reynolds and Mach numbers on the aerodynamic characteristics of a horizontal tail of aspect ratio 4.5 with a plain sealed elevator with a tab. Lift, drag, pitching moment, elevator hinge moment, tab hinge moment, streamwise distribution of static pressure at the midsemispan, and pressure difference across the elevator-nose seal were measured.

NACA instrumentation has been installed in the Northrop X-4 airplane to obtain stability and control data during the Northrop conducted acceptance tests. The results o. the third flight of the X- ll. number 1 airplane are presented in this paper. The results of this flight showed that the directional stability as measured in steadily increasing sideslips was positive and high and that the lateral stability was positive.

Report presenting an investigation in the high-speed tunnel to determine the effect of sweep on the static lateral stability characteristics of wing-fuselage combinations with wings of aspect ratio 4 and taper ratio 0.6 at high subsonic speeds. Results regarding rolling-moment characteristics and lateral-force and yawing-moment characteristics are also provided.

Memorandum presenting measurements of the oscillatory lift force acting on an airfoil vibrated in bending. Results were obtained for an isolated airfoil and for the same airfoil oscillated in a cascade, at low and high angles of attack.

Report presenting an investigation to determine the effect of circumstantial inlet location on the performance of twin half-conical scoop-type inlets with and without boundary-layer removal at several Mach numbers and angles of attack. For positive angles of attack, higher pressure recovery performance was obtained with the inlets mounted on lower fuselage quadrants than on upper quadrants.

An experimental and analytical investigation of the flutter of sweptback cantilever wings is reported. The experiments employed groups of wings swept back by rotating and by shearing. The angle of sweep range from 0 degree to 60 degrees and Mach numbers extended to approximately 0.85. A theoretical analysis of the air forces on an oscillating swept wing of high length-chord ratio is developed, and the approximations inherent in the assumptions are discussed. Comparison with experiment indicates that the analysis developed in the present report is satisfactory for giving the main effects of sweep, at least for nearly uniform cantilever wings of high and moderate length-chord ratios.

Abstract: "The half-life of polonium has been measured by a calorimetric method using samples several thousand times larger than have been previously available. The value is found to be 138.3 +/- 0.1% days."

Abstract: Radiochemical and carrier techniques have been applied to the determination of minute amounts of Fe, Cr, Ni, and Co which appear as corrosion products of Inconel. The results are as follows: Fe, 0.061 per cent; Cr, 0.15 per cent; Ni, 0.037 per cent; and Co, .0005 per cent.

Report discussing progress made by the National Research Corporation in developing preparation of ductile zirconium for the month of August, 1949.

From Introduction: "The self-shielding characteristics of a number of absorbers and of U-235 and U-238 have been investigated in PPA-20 (66°). Most of the measurements have been made in Ring 3 at the core mid-plane. The foil doubling technique was employed. Particular attention was given to 'thin' foil regions for the purpose of extrapolating the data to zero thickness."

The following report summarizes the data taken from a series of measurements on the combustion and ignition properties of hexone. The experiments were taken at the Bureau of Mines Central Experiment Station by their personnel, and the samples were given to them by KAPL and Hanford.

One of the oldest properties of electrons is their emission of x-rays (discrete and continuous spectra) when impinging on matter. Cloud-chamber tracks show light ionization, and considerable multiple scattering, except for fast electrons. Tracks are long and range indefinite.

Very little information and data are available on the various physical properties of Zircaloy tubing, especially the high temperature- high pressure failure aspects. As greater use is being made of the low cross-sectional properties of this material in the design and development of reactor components, it was considered desirable to determine the type of failure that would be experienced under conditions of a localized over-heating. This hot-spot could be caused by "cocked" or warped fuel elements coming in direct contact with the process tube, thereby preventing adequate cooling media at the particular location.

From Introduction: "The purpose of the present paper is to show in more detail the possibilities end the limitations of the use of regeneration as a means of effecting greater fuel economy and of reducing the net weight of the power plant and fuel of compressor-turbine-propeller aircraft engines."

"An investigation of a decoupler and a controlled-feathering device incorporated with the YT-56A turboprop engine has been made to determine the effectiveness of these devices in reducing the high negative thrust (drag) which accompanies power failure of this type of engine. Power failures were simulated by fuel cut-off, both without either device free to operate, and with each device free to operate singly. The investigation was made through an airspeed range from 50 to 230 mph" (p. 1).

Report presenting a wind-tunnel investigation to determine the effect of propeller operation on the characteristics of submerged inlets. The tests were performed with a model of a hypothetical fighter airplane powered by a turbine-propeller unit. The propeller had eight blades with thin airfoil shanks and dual rotation and the submerged inlets were placed in the fuselage behind the propeller and forward of the wing.

From Summary: "A single-stage modification of the turbine from a Mark 25 torpedo power plant was investigated to determine the performance with two nozzles and three rotor-blade designs. The performance was evaluated in terms of brake, rotor, and blade efficiencies at pressure ratios of 8, 15 (design), and 20. The blade efficiencies with the two nozzles are compared with those obtained with four other nozzles previously investigated with the same three rotor-blade designs."

Report presents the results of a study made of the effects of known end restraint on commercially available round and streamline tubing of chromium-molybdenum steel, duralumin, stainless steel, and heat-treated chromium-molybdenum steel; and a more accurate method than any previously available, but still a practical method, was developed for designing compression members in riveted or welded structures, particularly aircraft. Two hundred specimens were tested as short, medium-length, and long columns with freely supported ends or elastically restrained ends. Tensile and compressive tests were made on each piece of original tubing from which column specimens were cut.

An investigation was conducted to determine the effects of three design modifications of the original NACA injection impeller on the performance of an R-3350 engine. Different methods of injecting the fuel into the impeller air stream were studied and evaluated from the individual cylinder fuel-air ratios and the resulting cylinder temperatures. Each impeller was tested for a range of engine powers normally used in flight operation. The relatively simple design of the original injection impeller produced approximately the same mixture- and temperature-distribution characteristics as the modified impellers of more complex design. None of the modifications appreciably affected the manifold pressure, the combustion-air flow, nor the throttle angle required to maintain a given engine power,.

The geometry of the magnetic pole structure in the cloverleaf cyclotron suggests the use of three dees excited by three phase rf placed in the valleys out of the way of the beam. Experience with the model machines indicates that it is desirable to be able to vary the phase angles between the three dee voltages through 30 or 40 degrees and to be able to maintain them at any given value within plus or minus one degree. It is desirable, also, to be able to vary the phase angle independently of the amplitude of the dee voltages. There are several possible ways of meeting these requirements. The one which was chosen appears to be the most flexible and to best meet the problems presented by the center geometry of the machine.