Report presenting the horizontal and vertical components of the induced velocity in front of an inclined propeller in a horizontal stream obtained by a magnetic-analogy method. The problem was formulated in terms of the linear theory of the acceleration potential of an incompressible nonviscous fluid.

Report presenting the effects of large variations of lateral area on the lateral stability and control characteristics of a free-flying model when ailerons are used as the principal control as determined by flight tests. The effects of the lateral-force parameter were investigated for a wide range of values of the directional-stability parameter and the rotary-damping-in-yaw parameter.

"In conjunction with a program of research on the general problem of stability of airplanes in the climbing condition, tests have been made of a spring-loaded tab, which is referred to as a "springy tab," installed on the elevator of a low-wing scout bomber. The tab was arranged to deflect upward with decrease in speed which caused an increase in the pull force required to trim at low speeds and thereby increased the stick-free static longitudinal stability of the airplane. It was found that the springy tab would increase the stick-free stability in all flight conditions, would reduce the danger of inadvertent stalling because of the definite pull force required to stall the airplane with power on, would reduce the effect of center-of-gravity position on stick-free static stability, and would have little effect on the elevator stick forces in accelerated flght" (p. 1).

Report presenting a series of dynamic tests undertaken on a model of a hull of JRM-1 in order to provide information on the probable water loads during rough water landings. The impact acceleration and trim data are analyzed to show the trend of accelerations with wave size and length-height ratio.

Report presenting an investigation of the antiknock effectiveness of N-methyl-aniline and xylidines as fuel additives under severe engine operating conditions. 5-percent concentrations by weight were blended with an alkylate blending agent and a virgin-base gasoline.

Report discusses a series of force tests of a NACA 0009 elliptical semispan wing equipped with a flap that is either 50 percent of the wing area or 30 percent of the wing area. Information about the lift, hinge moment, and drag and pitching moment is provided.

Report presenting an attempt to establish a correlation of the cooling characteristics of the Wright R-2600-8 engine with water as an internal coolant and to investigate methods of introducing the water. A cooling correlation, including the effect of water as an internal coolant, was established by use of the NACA cooling-correlation method. Results regarding the cooling-performance predictions and engine condition are provided.

Report presenting an investigation of a special single-cylinder test engine constructed with provision for operation with three different lengths of piston stroke. Results regarding the air capacity of the engine, extent to which the spark must be retarded in order to prevent detonation, and brake mean effective pressure are provided.

Report presenting the results of tests to determine the extent to which the knocking tendency of an air-cooled engine cylinder is increased when the cylinder head is poorly cooled and when the cylinder temperature exceeds the maximum specified by the engine manufacturer. The tests showed that, when the cylinder-head temperature was increase from 400 to 600 degrees Fahrenheit, the knock-limited indicated mean effective pressure was reduced 3 percent at a fuel-air ratio of 0.097 and 39 percent at a fuel-air ratio of 0.065.

"An exhaust-port design was developed that provides a heat-flow path of increased area from the valve stem to the outside surface of a Wright C9GC cylinder. The effects of the new port design on exhaust-valve temperature and volumetric efficiency were determined from single-cylinder engine tests. A reduction of 70 degrees Fahrenheit in the exhaust-valve temperature was obtained with no decrease in volumetric efficiency or power output" (p. 1).

Report presenting an investigation of the effect of progressive ring failure on piston life. Two endurance runs were conducted on an Allison single-cylinder engine at high power output until destruction of the pistons occurred at 33.1 and 84.25 hours.

Report presenting results of tests conducted with an air-cooled, radial aircraft engine to determine the reduction in the brake specific fuel consumption that would result from operating with a very low fuel-air ratio and an increased spark advance. Computed values of the brake specific fuel consumption corrected for cooling-air drag are also given.

Report reviews published data and presents some new data on heat transfer to air flowing in round tubes, in rectangular ducts, and around finned cylinders. The available data for heat transfer to air in straight ducts of rectangular and circular cross section have been correlated in plots of Stanton number versus Reynolds number to provide a background for the study of the data for finned cylinders. Equations are recommended for both the streamlined and turbulent regions, and data are presented for the transition region between turbulent and laminar flow.

Report presenting the relative cooling performance of water, commercial Prestone, and several ethylene-glycol and diethylene-glycol derivatives obtained from tests conducted with a small electrically heated heat exchanger.

Report presenting testing to determine the effect of special baffles on the temperatures and cooling-air requirements of the Wright 1820 G200 and R-2600-8 cylinders. Nine baffles were tested with the 18020 cylinder and two were tested with the R-2600-8 cylinder. Results indicated that the internal cylinder surfaces with good thermal connection with the external-cooling means respond to changes in external cooling.

Report presenting testing to determine the influence of propeller rotation and vertical-tail design on the trim characteristics of a model of a twin-engine airplane with one engine inoperative. The tests showed that the effect of mode of propeller rotation on the directional trim characteristics of the model operating with asymmetric power was considerable. Results regarding the effect of mode of propeller rotation and effect of vertical-tail design are provided.

Report presenting an investigation of an exhaust-air heat exchanger, which has been designed, constructed, and flight-tested for a C-46 cargo airplane. The primary purpose of the investigation was to provide the C-46 airplane with a satisfactory source of heated air and to continue the development of the heat exchanger as a part of thermal ice-prevention equipment. Results indicated that the required thermal output and desired air-temperature rise have been achieved and that the exchanger is suitable for use in the C-46 airplane.

Report presenting an investigation of a thermal ice-prevention system for a Curtiss-Wright C-46 airplane, including the equipment for the wings, empennage, and windshield. The report is the third in a series and focuses on the revisions to the components for thermal ice prevention, the temperature- and pressure-measurement equipment installed in the airplane to determine the performance of the system, and the results of static-load structural tests of a specimen of the wing outer-panel leading edge.

Report presenting an investigation of a thermal ice-prevention system for a C-46 cargo airplane, which involved flight tests in dry-air and natural-icing conditions at two different laboratories. The purpose of the investigation was to determine the effectiveness of the C-46 airplane ice-prevention system and to continue the develop of thermal ice-prevention equipment. Results regarding the wing outer panel, wing tips, wing center panel, horizontal stabilizers, vertical fin, windshields, ice-removal tests, unprotected surfaces, and heat exchangers are provided.

Report presenting strain-gage measurements made on the crankshaft of a Wright R-1820-73 test engine while under power. Bakelite-bonded wire strain gages were installed on the front half of the crankshaft and the connecting wires were brought out through the oil passages and connected to slip rings at the rear of the engine. The inertia-excited bending and tensile-compressive stresses increased almost directly with speed.

Report presenting an investigation made to determine the effectiveness of various oxides and oxide mixtures in oxidizing at room temperature the exhaust gases from an internal-combustion engine for the determination of fuel-air ratio. The oxides of silver, copper, manganese, cobalt, nickel, iron, cerium, lead, bismuth, and mercury were tested individually and in various combinations.

Report presenting testing of a German superchrager from a Junkers Jumo 211F engine. The supercharger differed from conventional American superchargers in that it had a fully shrouded impeller, which discharged through a very short vaneless diffuser into a scroll-collector case. Tests were run at impeller tip speeds from 400 to 1200 feet per second at increments of 100 feet per second for a wide range of air flows.

Report discusses the shear and normal stresses caused by a load applied until failure on the tension side of an open box beam with a flat stiffened cover. The maximum strain was found to be much less than in solid tensile specimens of the same material. Special attention is paid to the variation in strains at various parts on the beam and the potential effects of rivet holes and riveting, which requires further testing.

Report discussing the use of two types of geared spring tabs for elevator control: ordinary (or ungeared) spring tabs and geared spring tabs. Their use in airplanes of various sizes and in comparison to conventional control systems is described.