Report presenting a theoretical investigation of the two-dimensional, incompressible potential flow past a symmetrical lattice of airfoils of arbitrary shape. Expressions are given for evaluation of the velocity and pressure distribution at the airfoil boundary.

Report presenting the potential function for flow, with circulation, of a compressible fluid about a circular cylinder, which is obtained in series form including terms of the order of M(exp 4) where M is the Mach number of the free stream. The equations are used to obtain pressure coefficient as a function of Mach number at a point on the surface of the cylinder for different values of circulation.

Report presenting testing in the stability tunnel of two types of spring tab used as balances on a partial-span plain aileron. The tabs were connected to a spring located in the control system so that tab deflection was dependent on the control force.

"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 a determination of the mean effective emissivity as a function of temperature for the surfaces of several metals and insulating materials. A description and discussion of the measuring technique is presented. The results are plotted on a variety of graphs.

Report discusses an analysis of the stability of an airplane with ailerons free, with particular attention to the motions when the ailerons have a tendency to float against the wind. Information about the aerodynamic balance of the plane and oscillations that may be encountered are included. The effects of friction in the control system is also explored.

From Summary: "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. The known approximate results of Chaplygin, Von Karman and Tsien, Temple and Yarwood, and Prandtl and Glauert are unified by means of the analysis of the present paper. Two new types of approximations, obtained from the basic solutions, are introduced; they possess certain desirable features of the other approximations and appear preferable as a basis for extrapolation into the range of high stream Mach numbers and large disturbances to the main stream."

Engine tests, together with estimates made at Langley Memorial Aeronautical Laboratory, indicate that a 25-percent increase in take-off power can be obtained with present-day aircraft engines without increasing either the knock limit of the fuel or the external cooling requirements of the engine. This increase in power with present fuels and present external cooling is made possible through the use of an internal coolant inducted through the inlet manifold. Estimates on aircraft indicate that this 25-percent increase in power will permit an approximate usable increase of 8.5 percent in the take-off load of existing military airplanes. This increase in load is equivalent to an increase in the weight of gasoline normally carried of between 30 and 65 percent.

Report discussing the effect of inlet-air temperature and cylinder displacement on the charge temperature of an internal-combustion engine at the end of the induction stroke. The experiment to test various types of cylinders and their results on the air temperature and pressure is described.

"An analysis of the irregular vertical displacement of the wake from the trailing edge of a tailless airplane is presented, which shows the existence of an effective aerodynamic wing twist that causes an induced drag coefficient of 0.0004. The analysis explains most of the discrepancy between the drag determined from the momentum surveys an the drag measured on the wind-tunnel balance" (p. 1).

From Summary: "As part of a general investigation of propellers at high forward speeds, tests of two 2-blade propellers having the NACA 4-(3)(8)-03 and NACA 4-(3)(8)-45 blade designs have been made in the Langley 8-foot high-speed tunnel through a range of blade angle from 20 degrees to 60 degrees for forward Mach numbers from 0.165 to 0.725 to establish in detail the changes in propeller characteristics due to compressibility effects. These propellers differed primarily only in blade solidity, one propeller having 50 percent and more solidity than the other. Serious losses in propeller efficiency were found as the propeller tip Mach number exceeded 0.91, irrespective of forward speed or blade angle."

Report presenting comparisons between the approximate substitute single-stringer method of shear-lag analysis and the exact solutions, which indicate that for beams of practical proportions the approximate method yields a value for the maximum root stress that exceeds the value obtained by use of the exact solution by less than 10 percent.

"Strain measurements were made on the compression side of two box beams with corrugated aluminum-alloy covers loaded to failure. Angles formed from sheet were used for corner flanges in beam 1; whereas extruded angles were used in beam 2. Failure in each beam occurred in the corner angle at a stress that was above the compressive yield stress for the material" (p. 1).

Report presenting an analysis which shows that, when account is taken of sideslip and wing flexibility, the calculated rolling maneuverability of an airplane is in good agreement with the results obtained from flight tests. The method used avoids the complications of successive approximations but is nevertheless believed to be more nearly accurate than other methods based on semirigid-wing assumptions. The method is applied to a wing of tubular shell construction and the procedure is illustrated for a modern pursuit airplane.

Report presenting tests made in order to determine the differences in high-speed aerodynamic characteristics between models of a four-engine transport airplane and a similar bomber airplane. The main conclusion found is that the critical Mach number of the transport model is about 0.05 less than that of the bomber model.

"Flights were made in natural icing conditions at the NACA Ice Research Project, Minneapolis, Minn. to test several designs of thermal-electric propeller de-icing blade shoes and a hub-generator design. It was found that a minimum average unit power of 2.5 watts per square inch of blade-shoe area would protect the propeller blades at the test conditions. The most satisfactory blade shoe of the three designs tested extended to the 20-percent-chord point and to 90 percent of the blade radius" (p. 1).

Report presenting an investigation of a large variety of different metals used as an intermediate metal between aluminum and steel for the purpose of securing a good bond both from the viewpoint of strength and thermal conductivity. The principal result was that it was found possible to secure a satisfactory bond between aluminum and steel by electroplating the steel with a layer of silver of proper thickness.

Report presenting an investigation in the 7- by 10-foot wind tunnel of the effects of various modifications to the profile of a 0.20-chord plain sealed aileron and a 0.15-chord plain sealed aileron on an NACA 66,2-216 airfoil. Thickening of the aileron was found to reduce the aileron effectiveness, reduce the slope of the wing section lift curve, and reduce the hinge-moment coefficients. Results regarding the section data, aileron effectiveness, aileron hinge moments, lift, pitching moment, drag, and Reynolds number are provided.

Report presenting tests of the Northrop MX-334 airplane in the full-scale tunnel. The results are of particular interest since the MX-334 is an all-wing glider-type airplane without a conventional fuselage or vertical surfaces. The primary purpose was to obtain sufficient data with which to determine the longitudinal and lateral stability and control characteristics of the airplane.

"Compression tests were made of 63 panels stiffened with corrugated sheet. The specimens were constructed from artificially aged alclad 24S-T aluminum alloy with minimum guaranteed yield strengths of 57 and 48 kips per square inch for the flat- and corrugated-sheet materials, respectively. Results of the tests are presented in charts which show the average stresses at the maximum load and at buckling of the sheet" (p. 1).

Report presenting tests of airplane models that included investigations to determine the longitudinal stability and control, effects of various constituent parts or their modification on longitudinal stability and control, critical speed, and distribution of wing load. Some of the changes made in attempts to improve longitudinal control and to increase critical speed included auxiliary control flaps on the lower surface of the wing, revision of the windshield, increase in dimensions of outboard nacelles, and alteration in profile of wing leading edge.

Report presenting an investigation in the 7- by 10-foot wind tunnel of the effects of modifications to the trailing edge of a 0.20-chord plain sealed aileron on an NACA 66,2-216 airfoil. The modifications considered consisted of various amounts of symmetrical thickening and beveling of the aileron trailing edge. Results regarding aileron effectiveness, aileron hinge moments, aileron control forces, lift, pitching moment, drag, and Reynolds number are provided.

From Introduction: "A typical ice formation on a wing leading-edge-type light installation is shown in figure 1. Although the primary purpose of this analytic investigation was to determine the practicability of providing a landing-light thermal ice-prevention system which could be incorporated with the wing leading-edge thermal ice-prevention system of the B-17 F airplane, the analysis has been developed in a general form for future application to similar deigns. "

Report presenting an investigation of the existence of energy dissipations in gas dynamics, which must be attributed to a lag in the vibrational heat capacity of the gas, and most specifically the flow about a very small impact tube. A new method of measuring the relaxation time of gases is introduced in which the total-head defects observed with a specially shaped impact tube are compared with theoretical considerations.