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 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."

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.

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.

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.

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.

Report presenting a theoretical investigation of the effects of steady rolling on the longitudinal and directional stability of aircraft. Simplifying assumptions have been made with regard to the longitudinal and lateral motions of the airplane in order to obtain a solution which shows the principal effects of rolling motion.

Report presenting an investigation to study the effects of changes in fuel-nozzle carbon deposition on the combustion efficiency of a single tubular-type, reverse-flow, turbojet combustor. The investigation was conducted because of the need to improve the reproducibility of combustion data for fuel-research purposes.

Report presenting an investigation of the interference effects between an airfoil of high critical speed with no sweepback and a nacelle of high critical speed mounted in various positions with respect to the wing. The main objective was to obtain a wing-nacelle combination which has the force break occurring at a Mach number as high as for the wing alone. Results regarding the wings alone, pressure contours on wing and nacelle, influence of wing on nacelle, influence of nacelle on wing, and leading-edge modifications are provided.

"A simplified compound-pendulum method for the experimental determination of the moments of inertia of airplanes about the x and y axes is described. The method is developed as a modification of the standard pendulum method reported previously in NACA report, NACA-467. A brief review of the older method is included to form a basis for discussion of the simplified method" (p. 1).

Report presenting results to show the effects on the flutter characteristics of mounting concentrated weights at various positions on an untapered wing model. The moment of inertia, chordwise position of the weight, and spanwise position of the weight were varied. Results regarding the flutter parameters, flutter-speed ratio, flutter-velocity coefficients, and curves of ratio of first-bending frequency to torsion frequency and second-bending frequency to torsion frequency and provided.

"The average low-speed jet-boundary constriction correction is presented for a large model spanning a closed circular tunnel. The experimentally determined variation of the local constriction correction with spanwise and chordwise location is also shown. A brief comparison with existing theory is given for the constriction correction and the induced-curvature correction resulting from lifting section" (p. 1).

Note presenting a theoretical investigation made of the hydrodynamic pitching moments experienced by V-bottom seaplanes during step-landing impacts. The entire immersion process is analyzed from the instant of initial contact until the seaplane rebounds from the water surface.