Report presenting tests in the two-dimensional low-turbulence pressure tunnel to study the interference effects of various pusher-propeller shaft-housing combinations on a low-drag airfoil. Thirty different combinations were tested, variations being made in shaft size, shape, angle, and fillet.

"In connection with studies of airfoils applicable to large high-speed aircraft, the effects of roughness on three 22-percent-thick airfoils were investigated. The tests were made over a range of Reynolds number from about 6 to 26 x 10(exp 6) for the airfoils smooth and with roughness strips applied to the surfaces. The results indicated that for the roughened models the scale effect was generally favorable" (p. 1).

Tests were made in the NACA two-dimensional low turbulence pressure tunnel of a highly cambered low-drag airfoil (NACA 65,3-618) with a plain flap designed for lift control. The results indicate that such a combination offers attractive possibilities for obtaining low profile-drag coefficients over a wide range of lift coefficients without large reductions of critical speed.

"The effect of two-dimensional bumps and surface waviness on the pressure distribution over airfoils is considered. It is shown that the results of the analysis may be useful in evaluating the effects of accidental or intended surface distortions on the drag and critical Mach number of airfoils" (p. 1).

Report discusses the results of an experimental investigation of two low-drag wing-nacelle units suitable for use with pusher propellers. The benefits of adding a nacelle to the wing are detailed.

The development of the laminar boundary layer in a compressible fluid is considered. Formulas are given for determining the boundary-layer thickness and the ratio of the boundary-layer Reynolds number to the body Reynolds number for airfoils and bodies of revolution. It is shown that the effect of compressibility will profoundly alter the Reynolds number corresponding to the upper limit of the range of the low-drag coefficients.

From Summary: "The results of an experimental investigation of several low-drag wing-nacelle combinations, incorporating internal air-flow systems, are presented. The external-drag increments due to these nacelles are between one-half and two-thirds of those of conventional nacelle forms. This improvement is accomplished with only minor effects on the lift and moment characteristics of the wing. The procedure employed to determine the external shape of such low-drag nacelles is considered in detail. The design of an efficient internal-flow system with or without a blower or throttle, presents no serious problems. The energy losses in the expansion before the engine and the contraction thereafter can be kept small. It is believed that these nacelles have a wide application in housing engine pusher-propeller units and, with some alteration, jet-propulsion devices. It is probable that the low external drags may not be realized if such nacelles are used with a tractor propeller because of the high level of turbulence in the propeller slipstream."

Report presenting tests made on an NACA 23012 airfoil fitted with a 20-percent-chord, true-contour aileron with 35-percent-chord, extreme blunt-nose balance. The primary purpose of the investigation was to determine the variation of the aerodynamic characteristics of this type of aileron with airspeed; the effect of variations of gap width and balance-nose radii was also investigated. Results regarding hinge moments, lift, and pitching-moment coefficients are provided.

From Summary: "An analysis of the nose-inlet shapes developed in previous investigations to represent the optimum from the standpoint of critical speed has shown that marked similarity exists between the nondimensional profiles of inlets which have widely different proportions and critical speeds. With the nondimensional similarity of such profiles established, the large differences in the critical speeds of these nose inlets must be a function of their proportions. An investigation was undertaken in the Langley 8-foot high-speed tunnel to establish the effects of nose-inlet proportions on critical Mach number and to develop a rational method for the design of high-critical-speed nose inlets to meet desired requirements."

Report presenting charts showing the rotor profile drag-lift ratio for a helicopter rotor operating in forward flight and having hinged rectangular untwisted blades. The charts are given for a range of power input covering glides, level flight, and moderate rates of climb. A drag curve was used for preparing the charts, and the curve is compared with experimental curves for typical airfoils.

Report presenting data that show the knock-limited performance of methyl tert-butyl ether obtained from tests made in a 17.6-cubic-inch-displacement engine under supercharged conditions. Tests for temperature sensitivity, speed sensitivity, and lead susceptibility were made on a blend of 20 percent methyl tert-butyl ether and 80 percent S-2 reference fuel.

Report presenting an investigation of the suitability of methyl tert-butyl ether as a component of aviation fuel from considerations of knock-limited performance tests and laboratory inspection tests. Data were obtained from testing on the 17.6 engine under supercharged conditions with fuel blends containing 10 and 20 percent methyl tert-butyl ether. Results regarding small-scale-engine data, full-scale-engine data, and inspection data are provided.

Report presenting data obtained when a float with both horizontal and vertical velocity contact on a water surface. The report is confined to a presentation of the relationship between resultant velocity and impact normal acceleration for various float weights when all other parameters are constant.

Report presenting determinations of boundary-layer transition on the NACA 0012 and 23012 airfoils in the high-speed wind tunnel over a range of Reynolds numbers. For all of the lift coefficients that testing occurred at, transition occurred in the region of estimated laminar separation at low Reynolds numbers and approached the point of minimum static pressure as a forward limit at high Reynolds numbers.

Report presenting testing in the high-speed wind tunnel to determine the drag characteristics of several types of radial-engine nacelle on a low-drag airfoil. The drag coefficients of nacelles incorporating cowling-nose shapes shown by previous tests to be efficient and afterbodies of adequate length were about the same magnitude as commonly obtained for comparable installations on conventional wings. Results regarding the reduction of data, effect of nacelles on lift, and pressures at wing-nacelle juncture are provided.

Report presenting force tests of the NACA 23012 and 23012-64 airfoils of 24-inch chord in the high-speed wind tunnel at a range of Mach numbers. The results show the variation with mach number of lift, drag, and pitching-moment coefficients at a range of angles of attack.

Report presenting testing in the 8-foot high-speed wind tunnel to determine the effect on external drag and pressure distribution of air inlet openings on the stagnation point of a streamline body. The results showed that external drag of the body with suitably designed nose-inlet and tail-outlet openings over a wide range of rates of internal air flow was no higher than the drag of the streamline body. Specific results for the streamline body, nose-inlet openings, outlet openings, and inlet-outlet combinations are provided.

Test of a ducted body with Internal flow were made in the 8-foot high-speed wind tunnel for the purpose of studying the effects on external drag and an critical speed of the addition of efficient inlet and outlet openings to a basic streamline shape. Drag tests of a 13.6- inch-diameter streamline body of fineness ratio 6.14 were made at Mach numbers ranging from 0.20 to 0.75. The model was centrally mounted on a 9-percent-thick airfoil and was designed to have an efficient airfoil-body juncture and a high critical speed.

Report presenting simple curves by which the basic pressure-drop characteristics of unheated tubular radiators can be corrected to operating conditions in which the radiator is heated and in which the Mach number of the tube flow is of appreciable magnitude. The only data required for the use of the curves are the radiator dimensions, the rate of heat input, the pressure and temperature ahead of the radiator, and the rate of mass flow of air through the radiator.

Report presenting tests conducted in the 8-foot high-speed wind tunnel of a scale model pursuit-type fuselage with practicable internal duct arrangement designed to meet all of the air requirements of a 1000-horsepower radial engine submerged at the maximum section. The results showed that the required internal flow can be obtained with negligible ducting losses provided that basic principles are observed in designing the air passages.

Report presenting a flight investigation made to determine the effectiveness of dive-recovery flaps installed on the XP-51 airplane as a safety device for recovery from contemplated terminal-velocity dives. The flap installation is described and results are presented of measurements obtained during stick-free pull-ups and pull-outs made by deflecting the dive-recovery flaps to two selected values of flap angle .

Report presenting investigations to determine the knock-limited performance of blends of 90 percent by volume AN-F-28, Amendment-2 fuel, and 10 percent by volume of the following fuels: tert-amyl alcohol, 2,6-dimethyl-1, 4-dioxane, methyl tert-butyl ether, methyl tert-butyl ketone, methyl isobutyl ketone, mesityl oxide, acetone, and diisopropyl ketone.

Report presenting the effect of internal cooling on the knock-limited performance of AN-F-28 fuel in a CFR engine with the following internal coolants: water, methyl alcohol-water mixture, ammonia-methyl alcohol-water mixture, monomethyllamine-water mixture, dimethylamine-water mixture, and trimethylamine-water mixture.

Report presenting an investigation to determine the knock-limited performance of AN-F-28, Amendment-2, fuel in a DCFR engine when water solutions of the following aliphatic amines were added as internal coolants: monomethylamine, dimethylamine, ethylendiamine, diethylamine, triethylamine, and butylamine. Results regarding the mean effective pressure, indicated specific fuel competition, indicated specific liquid consumption, and knock-limited inlet-air pressure plotted against fuel-air ratio are presented for each fuel and amine combination.