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 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.

"The results are given of an investigation of some of the limitations that now prevent increases in the temperature level of engine cylinder heads, and a review of previous work in the field is included to supplement these results. Attention was given, in particular, to the effects of fuel knock and surface ignition on cylinder temperatures and the effects of cylinder temperatures on performance. Data were obtained from a Wright C9GC air-cooled cylinder and from a Lycoming O-1230 liquid-cooled cylinder" (p. 1).

Report discusses the results of testing conducted to determine the performance of automatic, internal-coolant valves actuated by cylinder temperatures.The performance of the valves with respect to temperature sensitivity, rapidity of response, and hunting characteristics is described. The relative effects on cylinder performance obtained by internally supplying water and additional fuel were also examined.

Report presenting an analysis of cylinder-to-cylinder temperature and mixture distributions of four different aircraft engines to determine the possible economy of automatically supply water or additional fuel to only those cylinders having excessive temperatures. The cooling problem as distinguished from the fuel-knock problem was studied and an analysis limited to those cases in which additional cooling is ordinarily obtained by carburetor enrichment was made.

Report presenting an investigation in two-dimensional flow to determine the effect of leakage past the aileron nose on the aerodynamic characteristics of ailerons. The effects of amount and type of leakage, aileron contour, and Mach and Reynolds number are investigated.

Report presents tables and charts for the evaluation of profile drag from wake surveys at high supersonic speeds. Two methods of evaluation are presented: an exact method that can be used on a wake of any shape and a simple approximate method that can be used when the variation of total-pressure loss across the wave has a typical form.

Report presenting an investigation to obtain blade design data for high-efficiency axial-flow fans and compressors, which were carried out in a two-dimensional low-speed cascade tunnel. The effects of camber, solidity, and stagger on blade turning angle and the shape of pressure distributions were determined for a family of five low-drag airfoils.

Bulletin presenting an investigation of the effects of various camouflage paints and painting procedures on the drag characteristics of a 60-inch-chord low-drag airfoil in the NACA two-dimensional low-turbulence pressure tunnel.

From Summary: "A design chart in coefficient form is presented from which a radiator can be chosen with any desired characteristics, whether for minimum power, particular dimensions, or pressure drop for cooling. The chart is a convenient tool for selecting a practicable radiator for any given set of operating conditions. Because the flow is turbulent in the tubes, the chart is for turbulent-flow conditions."

Report presenting a study of the performance of bombers powered by one, two, four, and six 2000-horsepower engines supercharged to 25,000 feet. The performances are computed and are based on drag coefficients equal to the best obtained on modern airplanes and on weight estimates obtained from modern Army Air Forces airplanes. A chart is provided with the coordinates of power loading and wing loading noted so that all performances can be compared.

Report discussing the icing characteristics of a rectangular-throat pressure-type carburetor. Serious ice was not found to form under the conditions of this particular test, although visible ice and frost formed in certain areas.

"A preliminary analysis has been made of the conditions of stability of free oscillations of a hinged rotor in hovering flight. The case analyzed is a rotor with hinges allowing freedom in flapping and lagging and having a completely reversible cyclic pitch-control system, so that a twisting moment on a blade moves the control stick without hindrance from spring or friction constraint. The principal results of this study are presented in the form of a stability chart" (p. 1).

"Vibrations of rotary-wing aircraft may derive their energy from the rotation of the rotor rather than from the air forces. A theoretical analysis of these vibrations is described and methods for its application are explained herein" (p. 1). Information about self-excited speed range and shaft-critical speed are provided for any rotor with more than two blades.

Report presenting wind tunnel testing of four full-scale seaplane floats to determine the aerodynamic characteristics of the floats and to evaluate several drag-reducing refinements. Four floats were investigated; two differed only in external details like flush rivets, while one was the type used on twin-float installations. The variation of lift, drag, and pitching moment with pitch angle are presented for each float.

Report discussing the effects of various inlet pressures, inlet temperatures, wheel speeds, pressure ratios, and cooling-air flows on the performance of a radial-flow exhaust-gas turbosupercharger turbine with a 12.75-inch tip diameter. Information about efficiency is provided for a given blade-to-jet speed ratio.

Report presenting a series of tests on the Brewster XSBA-1 airplane to determine the effects of various tail modifications. Some of the modifications include variations of the chord of the elevator and rudder while the span and total area of the surfaces are kept constant and variations of the total area of the vertical tail surface. Results regarding the longitudinal stability and control and lateral stability and control are provided.

Report discussing testing to determine the longitudinal stability and control and stalling characteristics of a DeHavilland Mosquito F-8. Special focus is given to the control forces, elevator control, trim changes, and stick fixed and stick free characteristics of the aircraft.

Report presenting a theoretical analysis of the performance of propellers extending to high values. Charts are presented that facilitate the selection of the most efficient propellers over a wide range of operating conditions.

Report presenting a direct comparison between the observed and the calculated longitudinal dynamic stability of a particular dynamic model of a flying boat moving on the water. Good agreement was obtained between experiment and theory for trim angles in the vicinity of lower limit, at one speed a little above the hump.

The effects of jet-motor operation on the stability and control characteristics of two fighter-type airplanes as determined by wind-tunnel tests of 1/5-scale models are presented. It is shown that the action of the jets is to cause a small loss in stick-fixed stability which is predictable from known theories.

"The purpose of this report is to provide designers of airplanes with information that will be helpful in obtaining good ditching characteristics in new designs. The results from a number of model tests and report of actual ditchings are used as a basis for which to draw conclusions as to the effect on ditching performance of general arrangement, interior arrangement, fuselage shape, and other design parameters. The characteristics of several types of ditching aids that could be incorporated in a design are also discussed" (p. 1).

Report presenting data from tests conducted on full-scale propellers with 3155 blade design, which have been used to construct a set of propeller thrust charts for use in the calculation of take-off performance. By using the charts, the thrust of modern single- and dual-rotating propellers may be easily and rapidly calculated through the entire take-off range.

Report presenting an investigation to obtain data on the vertical and horizontal gusts in the atmosphere by reworking accelerometers and airspeed records from past investigations of vertical gusts. The results indicate that the vertical and horizontal gusts are of about equal intensity in the atmosphere.