Report describes the lubrication characteristics of an aircraft-type piston as visually studied in a V-type engine with a glass cylinder. Information about the movement of the piston, the piston rings, and the oil-control rings and their effect on lubrication is included.

From Introduction: "The purpose of this analysis was to investigate the use of function of intake-manifold temperature and pressure, exhaust back pressure, and engine speed in place of a ventri as a means of measuring engine air consumption and to determine if this function is suitable for automatic mixture control."

Report presenting tests made in the 4- by 6-foot vertical wind tunnel of an NACA 0009 airfoil with a 30-percent-chord flap with a medium amount of aerodynamic overhanging balance. In this investigation, the effects of the shape of the flap-nose overhang and the gap at the nose of the flap have been determined. The results indicate that, generally, the lift effectiveness of the aerodynamically balanced flap was increased slightly over that of a plain flap when a blunt or medium flap nose was used on the balanced flap.

Report presenting force-test measurements in two-dimensional flow in the 4- by 6-foot vertical tunnel to determine the characteristics of an NACA 0015 airfoil equipped with a straight-contour plain flap with a chord 30 percent of the airfoil chord. Results regarding the lift, hinge moment of flap, pitching moment, and drag are provided.

Report presenting a method for predicting from basic airplane characteristics the elevator deflection required to maintain optimum landing attitude. Charts for evaluating the components of the equation for elevator deflection and a comparison of computed and measured values for 15 airplanes are included. The computed deflection is considered the minimum value required to maintain landing attitude due to variations in piloting technique.

Report presenting a series of related flying-boat hull forms with various combinations of aerodynamic and hydrodynamic requirements that were tested in an NACA tank and high-speed tunnel. Effects explored included varying the height of the bow, varying the height of the stern, increasing the angle of dead rise at the bow, decreasing the angle of dead rise on the afterbody, increasing the depth of step, increasing the angle of afterbody keel, adding chine flare, adding a third planing surface, and rounded chines at the bow.

Report describing the behavior of the heat meter when it is used in thermal circuits which are under the influence of transient potentials. Three scenarios are considered: a heat meter suddenly placed on a hot surface, a heat meter mounted on the interior surface of the cabin wall of an uninsulated airplane climbing through air of decreasing temperature, and a heat meter mounted on the interior surface of the composite cabin wall of an airplane climbing through air of decreasing temperature.

Report presenting wind-tunnel tests to determine the aerodynamic section characteristics of an NACA 0009 airfoil with a plain flap with a chord 25 percent of the airfoil chord and a balancing tab with a chord 50 percent of the airfoil chord or 200 percent of the flap chord so linked that the tab would deflect at a given rate with respect to the flap. Three linkage ratios were tested on the model. Results regarding theory and test results including lift and hinge moments are provided.

Report presenting a theoretical study of the effects of aileron adverse yawing moment on lateral maneuverability at a high lift coefficient. The study included the effects of changes in effective dihedral angle, vertical-tail area, and tail length.

Report presenting some principles for designing the optimum hull for a large long-range flying boat in order to suit the requirements of minimum drag, seaworthiness, and ability to take off and land at all operational gross weights. The principles include the use of moderate gross-load coefficients, ample forebody lengths, and deep steps and the close adherence of the form to that of a streamline body of revolution with a moderate fineness ratio.

Report presenting a study to determine the effect of several methods of increasing the knock-limited power on critical cylinder temperatures. The knock-limited indicated horsepower and cylinder temperatures were determined for a Wright R-2600-8 cylinder under specified operating conditions. The most satisfactory method of increasing knock limited power was found to be internal cooling with water and the least satisfacotry was increasing the engine speed.

Report presenting vibration tests of six- and eight-blade tractor and seven- and eight-blade pusher dual-rotating propellers conducted in the 16-foot high-speed tunnel to determine the severity of vibrations excited by blade passages. Measurements of vibratory stresses were made for engine-speed ranges at low, intermediate, and high engine powers. Few vibrations caused by blade passages were detected, and those vibrations were not serious.

Report presenting an equation by which the overall performance of any number of oil coolers when operating in series can be related to their performance when operating singly. A comparison was made of the experimental overall performance of two conventional type 15-inch-diameter oil coolers, selected according to the analysis and equipped first with spring-loaded valves and then with rotary valves, with the desired overall performance.

Report presenting a study to determine the effect of a carburetor and an inlet elbow on the flow at the supercharger impeller inlet. Tests were conducted on a commercial vaned supercharger inlet-elbow assembly to determine the effect on the velocity distribution at the elbow outlet. Results indicated that the velocity profile obtained at the outlet of the vaneless elbow was better than that with the vaned elbow at all throttle settings.

Report details the methods of determining the heat-transfer rate, pressure drop, and drag power of high-altitude radiators. Performance charts are provided for a wide range of design variables.

Report presenting a paper in a series about the cooling of aircraft-engine installations with special reference to the difficulties of cooling at high altitudes. This particular paper discusses the properties of NACA standard air and Army summer air, with corresponding stagnation conditions for a range of flight speed, as summarized in tables and figures.

Report presenting the heat-transfer theory for air-cooled engines and an analysis of the cooling pressure drop for the case in which the pressure drop is an appreciable fraction of the absolute pressure. A chart is given for the simple determination of the cooling pressure drop predicted on the basis of the usual type of sea-level cooling-correlation tests.

Report presenting a detailed analysis to take account of the high cooling-air velocity occurring in high-altitude radiators. Methods are developed for determining the heat-transfer rate, the pressure drop, and the drag power. Radiator performance charts based on the analysis are presented for a wide range of the design variables.

From Summary: "Efficiency tests have been conducted on a single-stage impulse turbine having a 13.2-inch pitch-line diameter wheel and a cast nozzle diaphragm over a range of turbine speeds from 3000 to 17,000 rpm, pressure ratios from 1.5 to 5.0, inlet total temperatures from 1200 deg to 2000 deg R, and inlet total pressures from 18 to 59 inches of mercury absolute. The effect of inlet temperature and pressure on turbine efficiency for constant pressure ration and blade-to-jet speed ration is correlated against a factor derived from the equation for Reynolds number. The degree of correlation indicates that the change in turbine efficiency with inlet temperature and pressure for constant pressure ration and blade-to-jet speed ration is principally a Reynolds number effect."

Report presenting the fatigue data obtained at the Aluminum Research Laboratories from tests of various types of 17S-T and 53S-T specimens. The specimens were large enough to represent actual service conditions, but the repetition of loading was more rapid than would occur in ordinary service.

Report presenting efficiency tests on a single-stage gas turbine with an 11.0-inch pitch-line diameter wheel and a nozzle diaphragm with cast airfoil-shaped nozzle blades using atmospheric air as the driving fluid. A comparison is made with the same turbine but with different nozzle blades. Results regarding the efficiency curves and further information about velocity effects are provided.

Report discusses the results of testing of measurements of the static-thrust performance of six sets of rotor blades mounted on a helicopter fuselage. The blades differed in surface condition, pitch distribution, airfoil section, plan form, and solidarity. Results indicated that rotor-blade surface condition is important for performance and the optimum performance will only be obtained if the blades have a smooth, accurately contoured surface that will not deform during flight.

Report presenting a flight investigation made on a wing section of a P-47D airplane to determine the effect of roughness on wing profile drag with transition fixed far forward. Surveys of the wake were made for two surface conditions with transition fixed by a thread at 5 percent chord back of the leading edge on the upper and lower surfaces. Below the Mach number at which shock occurred, variations in Mach number of as much as 0.16 appeared to have no appreciable effect on the section profile-drag coefficients of either the smooth or roughened surfaces with transition fixed.

From Introduction: "The lift increments of different flap arrangements were determined by the method of reference 1 with a simple chord correction factor being applied. This procedure is somewhat similar in basic principles to the method of reference 2. The accuracy of the present method was determined by calculating by means of this method the lift and moment increments of flaps on 10 different finite wing-flap combinations for which wind-tunnel data were available."