Report presenting an experimental investigation concerned primarily with the extension of test data on the drag of revolving disks, cylinders, and streamline rods to high Mach numbers and Reynolds numbers. The tests generally confirm earlier theories and add in some new results. One of the primary findings of interest is that skin friction does not depend on Mach number.

"The results of flight investigations of the profile drag of several carefully finished conventional and low-drag airfoils are presented. The results indicated that in all cases lower profile-drag coefficients were obtained with the low-drag than with the conventional airfoils over the range of lift coefficient tested and that, for comparable conditions of lift coefficient and Reynolds number, the low-drag airfoils may have profile-drag coefficients which are at least 27 percent lower than the profile-drag coefficients of the conventional airfoils" (p.1).

Report presenting elementary basic solutions of the equations of motion of a compressible fluid in the hodograph variables are developed and used to provide a basis for comparison in the form of velocity correction formulas, of corresponding compressible and incompressible flows.

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 tests on an exhaust-gas turbine with four separate nozzle boxes each covering a 90 degree arc of the nozzle diaphragm and each connected to a pair of adjacent cylinders in a Pratt & Whitney R-1340-12 nine-cylinder radial engine. Results regarding the power output of the engine and turbine, effect of the turbine on engine power, turbine power output and speed characteristics, mean turbine efficiency, effect of the blowdown turbine on exhaust-gas temperature, and condition of the blowdown turbine after tests are provided.

Report presenting an investigation in the 19-foot pressure tunnel to determine the nacelle drag, the cowling-air flow, and the propeller characteristics of a model of a high-performance military airplane. The model is fitted with NACA D(sub S)-type engine cowlings and with propellers embodying NACA 16-series airfoil sections. Results regarding the propeller characteristics, drag and cowling-air flow with the propeller removed, the effect of propeller on flow through cowling, and the influence of cooling requirements on airplane performance are provided.

Report presenting the utilization of the differential equation of Chaplygin's jet problem to give a systematic development of particular solutions of the hodograph flow equations, which extends the treatment of Chaplygin into the supersonic range and completes the set of particular solutions. The solutions serve to place on a reasonable basis the use of velocity correction formulas for the comparison of incompressible and compressible flows.

"Following a brief history of the NACA investigation of jet-propulsion, a discussion is given of the general investigation and analyses leading to the construction of the jet-propulsion ground-test mock-up. The results of burning experiments and of test measurements designed to allow quantitative flight-performance predictions of the system are presented and correlated with calculations. These calculations are then used to determine the performance of the system on the ground and in the air at various speeds and altitudes under various burning conditions. The application of the system to an experimental airplane is described and some performance predictions for this airplane are made" (p. 1).

Report presenting a convenient technical method to evaluate changes in the airfoil characteristics resulting from an extension of the chord at the trailing edge of a propeller blade section. The method determines the change in the angle of zero lift, the ideal angle of attack, and the difference in these angles as a function of the angle and length of the trailing-edge extension.

Report presenting pressure distribution tests of six NACA 16-series propeller sections with 1-foot chords in the 8-foot high-speed tunnel to determine the compressibility effects on peak section pitching-moment coefficients. Data is presented as curves of peak section pitching-moment coefficient against Mach number, thickness ratio, and camber. The peak pitching-moment coefficients were found to occur in the regions of positive and negative stall.

Report presenting force tests in two-dimensional flow in the 4- by 6-foot vertical tunnel to determine the aerodynamic characteristics of an NACA 0009 airfoil with flaps having chord at 3 locations of the airfoil chord and three degrees of the beveled trailing edges. The results indicated that, with a smooth leading edge, the increased trailing-edge angle on the flaps with sealed gaps decreased the slope of the control-fixed lift curve and the lift effectiveness.

From Introduction: "The present paper deals with control surfaces having plain-overhang and Frise balances."

Pressure distribution measurements were made over an airfoil with slotted Frise aileron up to 0.76 Mach at various angles of attack and aileron defections. Section characteristics were determined from these pressure data. Results indicated loss of aileron rolling power for deflections ranging from -12 Degrees to -19 Degrees.

From Introduction: "As a part of the general lateral-control investigation by the NACA, the large amount of two- and three-dimensional data on the rolling effectiveness of ailerons without exposed overhang balance is collected and analyzed in the present paper."

"Test data of balanced ailerons have been collected from NACA and British sources. These data, which are presented in the form of charts, are grouped as A - ailerons with Frise balances, B - ailerons with blunt-nose balances, C - ailerons with internal balances, D - ailerons with contour modifications, and E - ailerons with tabs. Results of flight tests and of wind-tunnel tests in both two- and three-dimensional flow are presented but no correlation nor resume of the data has been included" (p. 1).

Report presenting methods for estimating pressure distributions over protuberances such as cockpit canopies, gun turrets, blisters, scoops, and sighting domes. The methods are applied to the estimation of the pressure distributions over spherical segment and faired gun turrets and over the protuberances on the Brewster SB2A-1 airplane. The effects of compressibility, interference, and flow separation are discussed.

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.

Report presenting wind-tunnel tests in two-dimensional flow to investigate the aerodynamic characteristics of a double flap with an internal and overhang balance. Three sizes of each type of balance were tested with three relative rates of deflection of the two flaps. Results regarding lift, hinge moment, drag, and pitching moment are provided.

Results of subject tests indicate the difficulty of obtaining closely balanced rudder surfaces for most tail assemblies with shielded horns and maintaining a near zero rate-of-change of hinge-moment coefficient without an additional balancing device. A comparison is made between shielded and unshielded horn test results. Pressure distribution and tuft tests of flow over different shaped horns showed higher critical speed for medium-taper nosed horn. The trim tab nose shape had little effect on tab test results.

Wind-tunnel tests, investigating low drag wing performance in small-scale tests, showed a large increase in minimum drag coefficient, and a decrease of maximum lift coefficient occurred with decreasing Reynolds Number above certain designated values. The lift-curve slope varied up to 6% between high and low turbulence levels. Low Reynolds Number test data are unreliable for low drag airfoils either to estimate full-scale characteristics or to determine merits of airfoils for higher Reynolds numbers.

Report presenting the effect of Reynolds number on the aerodynamic characteristics of a low-drag airfoil section tested under conditions of relatively high stream turbulence. The data are presented as curves of section angle of attack, section profile-drag coefficient, and section pitching-moment coefficient against section lift coefficient for various flap deflections.

Report presenting problems relating to the stability and control of tailless airplanes in consideration of contemporary experience and practice. Some observations in regards to small and large airplanes are provided.

From Summary: "The results of an analytical investigation to determine the qualitative effects of elevator-fabric distortion on the stick-force characteristics of an airplane are presented. These results indicate that serious alteration of intended stick-force characteristics can be produced by elevator-fabric distortion."

Report presenting the magnitude of slipstream contraction, which provides information about the conditions of the ultimate wake. Curves and tables are given for the contraction coefficient of two-blade and four-blade propellers for various values of the advance ratio; the contraction coefficient is defined as the contraction in the diameter of the wake helix in terms of the wake diameter at infinity.