From Summary: "An investigation was carried out in the NACA low-turbulence tunnel to develop low-drag airfoil sections suitable for admitting air at the leading edge. A thickness distribution having the desired type of pressure distribution was found from tests of a flexible model. Other airfoil shapes were derived from this original shape by varying the thickness, the camper, the leading-edge radius, and the size of the leading-edge opening. Data are presented giving the characteristics of the airfoil shapes in the range of lift coefficients for high-speed and cruising flight."

Report presenting a preliminary investigation to determine the suitability of ejectors actuated by the exhaust of a radial air-cooled aircraft engine for providing engine cooling air at the ground condition. Various length and diameter ejectors were tested for varying engine power for nine ejectors actuated by the exhaust of individual cylinders and three ejectors actuated by the exhaust of groups of three cylinders.

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).

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.

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."

"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).

"A unit injector was operated under various test conditions with a cam outline giving a high rate of plunger displacement. The rate of discharge of the unit injector followed the plunger displacement for the outwardly opening injection valve (open nozzle) except under conditions of high fuel pressures when the effect of fuel compressibility decreased the rate of discharge as the pressure increased. The rate of discharge for the inwardly opening injection valve (closed nozzle) did not directly follow the plunger displacement" (p. 1).

Report presenting a study of oil coolers, especially in regards to three factors: the congealing tendency of the cooler, the power cost chargeable to the installation, and the performance characteristics of the oil cooler in operation at altitude.

Report discusses the results of bending tests on an open box beam designed to fail on the highly cambered tension side. Results in the elastic range and ultimate-strength test are provided. The stringer stresses near the root were in fair agreement with stresses calculated by shear-lag theory and the ultimate tensile strength developed by the beam was only a little higher than the tensile yield stress of the material.

Report discusses the results of yawing tests on a model of the complete hull of the XPB2M-1. The tests indicated that there was a tendency toward directional instability in the vicinity of the hump. The researchers concluded that at a certain range, the curves of yawing moment are discontinuous, and this has led to difficulty in preliminary test flights.

Report presenting an analysis of records of more than 134,000 flying hours, which have been received and evaluated in order to bring the V-G recorder data up to date. The analysis of the records is contained in the report. Results indicate that the maximum effective gust velocities for both the land transport airplanes and the flying boats have approached values of 40 feet per second.

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.

Propellers with trailing-edge extensions were studied to determine aerodynamic characteristics. Trailing-edge extension increased power absorbed by propeller with little loss in efficiency. Power coefficient for maximum efficiency was greater for 20% camber type extension than for 20% straight type extension over range of advance ratio of 1.0 to 2.5 although camber type was less efficient. Efficiency was about the same for cruising and high-speed at a high power coefficient for propeller with extension.

Report presenting testing of cooling blowers for air-cooled engine installations and an exploration of the methods used in the blower design and operating characteristics of the blowers over a range of flight speeds and altitudes. The results indicate that the blowers operate as a more efficient type of propeller cuff and in many cases provide considerably more pressure boost than using a cuff.

Report discusses the maximum load, time to reach maximum load, and variation of load with time for prismatic floats in order to improve understanding of hydrodynamic theory for the landing impact of seaplane floats. Comparison of theoretical and experimental results and their applicability to flight impact are provided.

"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 investigations to determine the effect of xylidines on the saturation concentration of water in aviation gasoline. The saturation concentration of water in gasoline containing 0, 1, and 3 percent xylidines was determined using fresh water at two temperatures and sea water at one temperature.

Report presenting an investigation of a plain aileron and a balanced aileron on a tapered wing with full-span duplex flaps, which consisted of an inboard NACA slotted flap and an outboard balanced split flap. Increments of maximum lift coefficient of 0.82 and 1.04 were obtained from the inboard flap alone and from the duplex-flap combination.

Report presenting an investigation in the 7- by 10-foot wind tunnel of several arrangements of a plug-type spoiler-slot aileron on a tapered wing model of a typical fighter airplane with a full-span slotted flap. When the aileron is deflected, the plug projects from the upper surface of the wing as a spoiler and makes a slot appear behind the spoiler.

Report presenting an investigation in the 7- by 10-foot wind tunnel to determine the aerodynamic section characteristics of several arrangements of an NACA full-span high-lift lateral-control combination. The combination consists of a full-span flap of airfoil profile that retracts ahead of a narrow-chord full-span aileron. Results regarding coefficients, precision, plain airfoil, determination of optimum aileron-flap arrangement, section aerodynamic characteristics, and lateral-control characteristics are provided.

Report presenting force tests in two-dimensional flow in the 4- by 6-foot vertical tunnel of the characteristics of an NACA 0015 airfoil with a balanced flap having a chord of 30 percent of the airfoil chord, a flap-nose overhang 50 percent of the flap chord, and a tab having a chord 20 percent of the flap chord. Results regarding the precision and presentation of data, lift, hinge moment of flap, pitching moments, drag, tab characteristics, and balancing effectiveness of various overhangs are provided.

Report presenting an analysis of the probable aerodynamic section characteristics of a plain flap with various arrangements of internal balance. The results of the calculations previously obtained were found to be in agreement with the experiment. Some possible applications of the data to balancing tabs are also provided.

Report presenting force tests in two-dimensional flow made on an NACA 66-009 airfoil with a flap having a chord 30 percent of the airfoil chord and a tab having a chord 20 percent of the flap chord. A plain flap and flaps having overhangs of 35 and 50 percent of the flap chord were tested with two gap variations: sealed and unsealed. Results regarding lift, flap hinge moments, pitching moments, drag, and tab characteristics are provided.