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 an investigation in the 7- by 10-foot wind tunnel of a large-chord NACA 23021 airfoil with a 15-percent-chord and a 25-percent-chord balanced split flap of Clark Y profile, to determine the aerodynamic section characteristics of the airfoil-flap combinations as affected by the size, nose location, and deflection of the flaps.

Report presenting a thermal ice-prevention system for the B-24D airplane. The report includes a description of the design and an outline of the method of design analysis. Results of performance tests of the installation will be presented in a supplementary report.

Report presenting a method utilizing the Doppler effect on radio signals for determining the speed and distance traveled of an airplane. The method is called the NACA radio ground-speed system and uses the standard radio transmitter already found in most aircraft. Flight tests were made in which the method was used and the results were consisted with calibrated airspeed indications and stop-watch measurements.

"A method that utilizes the Doppler effect on radio signals for determining the speed of an airplane and the distance traveled by the airplane has been developed and found to operate satisfactorily. In this method, called the NACA radio ground-speed system, standard readily available radio equipment is used almost exclusively and extreme frequency stability of the transmitters is not necessary. No complicated equipment need be carried in the airplane, as the standard radio transmitter is usually adequate" (p. 1).

"Preliminary data are presented on the variation of the maximum lift coefficient with Mach number. The data were obtained from tests in the 8-foot high-speed tunnel of three NACA 16-series airfoils of 1-foot chord. Measurements consisted primarily of pressure-distribution measurements in order to illustrate the nature of the phenomena. It was found that the maximum lift coefficient of airfoils is markedly affected by compressibility even at Mach numbers as low as 0.2" (p. 1).

Report presenting an analysis of the pressure drop that is required to cool a typically baffled radial engine, which shows that a total pressure drop of 58 pounds per square foot is necessary at sea level and 112 pounds per square foot is required at an altitude of 40,000 feet.

Report presenting the calculated performance of four-, six-, and eight-blade single-rotating propellers compared with experimental results for blade angles ranging from 25 to 65 degrees. The data were obtained on propellers mounted in front of a streamline body with a spinner housing the hub.

In this report a method is presented for the calculation of the profile drag of airfoil sections. The method requlres only a knowledge of the theoretical velocity distribution and can be applied readily once this dlstribution is ascertained. Comparison of calculated and experimental drag characteristics for several airfoils shows a satisfactory agreement. Sample calculatlons are included.

Report presenting an equation based on simple blade-element theory and the assumption of a fixed wake pattern is derived and fitted to available data to show the first-order relation between the parameters of propeller operation and intensity of wake-excited periodic force acting on the blades of a pusher propeller. The derived equation indicates that the effect of power coefficient on the intensity of the wake-excited periodic force is small. Limited data also indicates that the wake-excited vibratory stress in a propeller increases with the drag of the body producing the wake.

Report presenting a tabular method for determining the span load distribution at high Mach numbers by utilizing high-speed airfoil section data. This method, which is also called the generalized method, is an easily applied process of successive approximations by which a general application of the lifting-line theory may be used to determine the span load distribution for wings composed of sections with arbitrary lift curves. An example is provided to show how the method is used.

Report presenting an investigation of the effectiveness of suction slots as a means of extending the laminar boundary layer in flight at high Reynolds numbers on an NACA 35-215 airfoil. The results showed that, with a slot spacing of about 5 percent of the chord, the laminar boundary layer could be maintained to or slightly beyond 45 percent of the chord.

Report presenting an investigation of the effectiveness of suction slots a a means of extending the laminar boundary layer in flight at high Reynolds numbers using an NACA 35-215 airfoil. Tests were made over a range of indicated airspeeds, lift coefficients, and Reynolds numbers. Results regarding boundary-layer control, air-intake distributions, character of the boundary layer, total-intake rate, and profile-drag coefficient are provided.

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 wind-tunnel testing in two-dimensional flow to investigate the aerodynamic characteristics of a flap balanced by a large overhang linked to deflect more slowly than the flap. Three lengths of blunt-nose overhang were tested linked to a 0.30-airfoil-chord straight-contour flap on an NACA 66-009 airfoil. Results regarding lift, hinge moment, drag, pitching moment, and practical considerations are provided.

From Introduction: "The purpose of this report is to summarize, without extended proofs, the results of a study of a simplified model of nonadiabiatic, compressible fluid flow, both subsonic and supersonic, and to state these results in a form that will make them immediately useful in providing a theoretical background for current technical problems of high-speed combustion.

From Summary: "The results of the analysis showed that the combined efficiency, which is unacceptably low at speeds less than 300 miles per hour, becomes nearly equal to that of conventional power plants of current design at 500 miles per hour. It was also shown that the efficiency will be increased considerably as the physical limitations on cycle temperature and blower speed are raised and as the efficiencies of the system components are improved."

Report presenting an investigation of a P-513 airplane with the propeller removed in flight at Mach numbers up to 0.755 and a comparison of those results with those of a wind tunnel test with a scale model.

Report presenting an iteration method for determining the longitudinal control characteristics of a flexible horizontal tail. The method permits factors such as the actual spanwise variation of elasticity and the aerodynamic induction effects due to three-dimensional flow to be accounted for to any degree of accuracy needed. An analysis is also included of the effects of horizontal-tail flexibility on the tail effectiveness, the hinge-moment characteristics, and the control-force gradients in a dive recovery for two modern fighter airplanes.

Force and flight tests were performance on an all-wing model with windmilling propellers. Tests were conducted with deflected and retracted flaps, with and without auxiliary vertical tail surfaces, and with different centers of gravity and trim coefficients. Results indicate serious reduction of stick-fixed longitudinal stability because of wing-tip stalling at high lift coefficient. Directional stability without vertical tail is undesirably low. Low effective dihedral should be maintained. Elevator and rudder control system is satisfactory.

Report presenting an electron-diffraction examination of cast-iron piston rings used in a single-cylinder test engine, which showed the presence of a layer of graphite covering the surface. The wear curves from the rings studied had shown variation from high rates to very low rates of wear.

Report presenting an investigation of the transition of the boundary layer from the laminar to the turbulent regime on the concave side of a plate with a radius of curvature of 8.5 feet. Results regarding the mean speed distribution, effect of curvature on the position of the transition point, effect of the pressure gradient on transition, and effect of free stream turbulence on transition are provided.

Report presenting the results of a drag investigation of twelve military airplanes in order to increase their speed. The main purpose of the report is to point out undesirable aerodynamic features as a guide to airplane designers. Results regarding the power-plant installation, installations in wings, empennages, armament, canopies, and radio antenna are provided.

Report presenting a large air scoop designed for high critical speed, which has been tested in the 8-foot high-speed tunnel on the fuselage of a scale fighter-type airplane. The effects of boundary layer on scoop characteristics were found to be important at all inlet-velocity ratios. Results regarding the boundary-layer surveys, characteristics of original scoop installation, and characteristics of scoop with boundary-layer passage are provided.