Report presenting theoretical pressure distributions and experimental aerodynamic characteristics at low speeds for a group of NACA four-digit series airfoil sections. Results regarding lift, drag, and pitching moment are provided.

From Introduction: "Thrust augmentation of an axial-flow-type turbojet engine by burning fuel in the tail pipe is discussed in references 1 to 3. Thrust augmentation of the same turbojet engine by water injection at the compressor inlet is reported in reference 4."

From Summary: "This paper describes a method for the determination of drop size and free water in clouds, based on the interpretation of an artificially created rainbow. Details of the design and operation of an optical instrument employing this method are presented."

From Introduction: "In references 1, 2, and 3, flight measurements of the performance of a conventional, single-rotor helicopter equipped with its production fabric-covered main rotor blades are presented."

"In order to understand the operation and the interaction of jet-engine components during engine operation and to determine how component characteristics may be used to compute engine performance, a method to analyze and to estimate performance of such engines was devised and applied to the study of the characteristics of a research turbojet engine built for this investigation. An attempt was made to correlate turbine performance obtained from engine experiments with that obtained by the simpler procedure of separately calibrating the turbine with cold air as a driving fluid in order to investigate the applicability of component calibration. The system of analysis was also applied to prediction of the engine and component performance with assumed modifications of the burner and bearing characteristics, to prediction of component and engine operation during engine acceleration, and to estimates of the performance of the engine and the components when the exhaust gas was used to drive a power turbine" (p. 1).

From Introduction: "In the present paper, the variation of effective gust velocity in convective-type clouds with altitude is investigated. Data obtained during 1941 and 1942 at altitudes up to 34,000 feet and data obtained more recently from the Thunderstorm Project (reference 5) at altitudes up to 26,000 feet are utilized for this purpose. Consideration is given in analyzing the results both to data for the range

Note presenting an investigation conducted to determine the applicability of statistical methods as an approach to the evaluation of materials for use in gas turbines by determining the frequency distribution of time until failure of gas-turbine blades. Two wheels, each incorporating 142 inserted blades of a cast cobalt-base heat-resistant alloy, were tested. The results indicated that the time for first failure may not generally be taken as an accurate indication of the performance of the average blade.

Report presenting computations of the horsepower and specific fuel consumption of a compound engine composed of an exhaust-gas turbine and an auxiliary supercharger geared to the crankshaft of a 12-cylinder liquid-cooled engine. Results regarding the engine exhaust pressure, engine speed, fuel-air ratio, inlet-manifold pressure, turbine, auxiliary-supercharger, and drive-gear efficiency, effect of altitude, comparison of compound and turbosupercharged engines, performance at high-power levels, effect of afterburning, and characteristics of a modified system are provided.

Report presenting a method consistent with the assumptions of small perturbation theory, which provides a means of determining the downwash behind a wing in supersonic flow for a known load distribution. The analysis is based on the use of supersonic doublets, which are distributed over the plan form and wake of the wing in a manner determined from wing loading.

Abstract: The rate of extraction of PuIV in either direction between benzene-TTA and aqueous HNO3 solutions is shown in the present study to be fast enough so that application of the chelate process to continuous operation should be feasible. This conclusion is based on two primary considerations: 1. The mechanism limiting the rate of extraction appears to be diffusion and not chemical-reaction-limiting. 2. The extraction may be controlled by adjustment of the system conditions to give almost any desired specifications of rate and/or equilibrium. A continuous process involving multiple extraction stages with a controlled pH gradient is proposed for obtaining maximum decontamination and plutonium recovery.

Note presenting pressure measurements on a triangular wing with an aspect ratio of 2 and an NACA 0012 airfoil section parallel to the center line. The wing angle of attack was varied from 4.3 to 48.1 degrees with the airspeed held constant at approximately 100 miles per hour. Results regarding chordwise pressure distribution, section lift characteristics, span load distribution, centers of pressure, and comparison of pressure data with force-test data are provided.

Report presenting an investigation of the maximum hovering time, or the time that a helicopter can sustain itself without motion, for helicopters using a reciprocating engine, by ramjet engines at the tips of rotor blades, and by pulse-jet engines at the tips of rotor blades. Testing showed that the reciprocating engine permitted much longer hovering time than the jet-propulsion engines, but the jet-propulsion engines were much lighter and could lift greater disposable loads.

Report presenting an investigation of the variables pertinent to the control of gas temperatures of gas-turbine engines during starting conducted by obtaining time records of the variables involved during actual starting conditions. Poor control of gas temperatures during starting was found to be caused by an accumulation of fuel in the engine before ignition and excessive fuel-flow rates at the time of ignition.

Note presenting an extensive investigation of the cooling characteristics of a multicylinder, liquid-cooled aircraft engine of 1710-cubic-inch displacement. The results of the investigation are presented showing the variation of the cylinder-head temperature and the coolant heat rejection with the pertinent engine and coolant variables. Results regarding the relations between cylinder temperatures, effect of engine variables on average cylinder-head temperature between exhaust valves, coolant-flow distribution, effect of engine variables on heat rejection to coolant, and effect of coolant variables on coolant heat rejection are provided.

Report presenting an extension of a finite-difference method to include the computation of disk stresses when plastic flow and creep are considered. The results of numerical examples indicate qualitatively that plastic flow markedly alters the elastic-stress distribution and that, if the amount of creep is small, the effect on stress distribution is also small.

Memorandum presenting a theoretical analysis of the effect of aerodynamic hysteresis on stalling flutter. The results were applied to a given airfoil and correlation of the experimental and theoretical results was found possible by assuming that the angle of aerodynamic lag varies as the slope of the static-lift curve. It was shown that the phenomenon of stalling flutter can at least in some cases be explained on the basis of an aerodynamic lag or hysteresis effect.

Report presenting theoretical calculations made by means of semirigid-flutter theory to determine the effect of centrifugal force on the critical flutter speed of a uniform cantilever beam. Calculations are made on airfoils with fundamental bending frequencies up to 2000 radian per second. Centrifugal force can under certain conditions reduce the critical flutter speed.

Report presenting an investigation to determine the effect of exhaust pressure on the knock-limited performance of an air-cooled aircraft-engine cylinder. Results are presented in the form of curves showing the relation between the ratio of exhaust pressure to inlet-manifold pressure, the inlet-manifold pressure, and the inlet mixture temperature at incipient knock.

Report presenting the results of flame-speed measurements of quiescent fuel-air mixtures in a 2.5-centimeter horizontal glass tube of 16 straight-chain hydrocarbons of paraffin, olefin, diolefine, and acetylene series and four cyclic hydrocarbons presented in graphical form. Results regarding peak flame velocity and uniform flame velocity are provided.

Report presenting the effect of landing flaps and landing gear on the spin and recovery characteristics of airplanes as determined from investigations of the spinning characteristics of 58 models in the 15-foot and 20-foot free-spinning tunnels. Lowering flaps was generally found to cause an increase in inward sideslip, an increase in the angle of attack, and a decrease in the rate of rotation of the model in the spin.

"An investigation was made to determine the effect of longitudinal stiffeners on the buckling load of long flat plates under shear. Tests were made of long flat plates reinforced by one and by two longitudinal stiffeners. A theoretical study of the buckling load of such plates, made by the energy method, is presented in the appendix. The results of the tests and the results of the theory are compared and are found to be in fair agreement" (p. 1).

Report presenting an investigation using a cylinder of a V-type liquid-cooled engine to observe the behavior of the cylinder when operated under preignition conditions. The effects of fuel-air ratio, power output, aromatic content of fuel, engine speed, mixture temperature, and preignition source are provided.

Report presenting an experimental investigation of a 62 degree valve overlap, 18-cylinder, air-cooled, radial engine modified with 40 degree-valve-overlap cams to determine the effect of a change in valve overlap on engine performance. Computations were made to show the effect of change in valve overlap on compound-engine performance.

Report presenting an experimental investigation to determine the effect of design factors on the performance of collectors for axial-flow compressors, which consisted of airflow studies of an experimental collector on which six different outlet configurations were used. The size and number of outlet pipes had little effect on the static-pressure distribution at the collector inlet.