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 an exact solution and a closely concurring approximate energy solution for the buckling of an infinitely long flat plate under combined shear and transverse direct stress with edges elastically restrained against rotation. An appreciable fraction of the critical stress in pure shear may be applied to the plate without any reduction in the transverse compressive stress necessary to produce buckling.

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 an experiment regarding tank and float venting conditions that exist on diving airplanes undergoing rapid changes in altitude. The results indicated that large pressure differences build up between the outside and inside of tanks and floats on diving airplanes unless the correct size of venting tube is used.

Report presenting equations relating the wing and tail loads are derived for a unit elevator displacement. The equations are converted into a nondimensoinal form and charts are given that can be used to predict wing- and tail-load-increment variation for any type of elevator motion and for degrees of airplane stability.

Report presenting a program of icing tests conducted on an aircraft-engine induction system consisting of a Wright R-1820, G-200 blower section, Holley 1375-F carburetor and adapter, and specially built air scoop. The primary purpose of the investigation was to determine the effect of a number of possible factors on icing of engine-induction systems, including carburetor-air temperature, air-moisture content, water-droplet size, throttle opening, mixture ratio, rate of air flow, altitude, and others.

Report presenting a series of single-cylinder engine tests run to determine a satisfactory method of reducing oil consumption in radial air-cooled engines with flat-face compression rings as standard parts and equipped with cylinder barrels salvaged by porous chrome plating. Testing was conducted using porous chrome-plated cylinders with straight and choke bores with standard flat-face compression rings.

Wing pressure distribution diagrams for several angles of attack and flap deflections of 0 degrees, 20 degrees, and 40 degrees are presented. The normal force coefficients agree with lift coefficients obtained in previous test of the same model, except for the maximum lifts with flap deflection. Pressure distribution measurements were made at Reynolds Number of about 6,000,000.

Report presenting pressure distribution measurements on two 24-inch chord models equipped with Fowler flaps in the two-dimensional low-turbulence pressure tunnel. Results regarding pressure-distribution diagrams and normal-force and moment coefficients are provided.

Report presenting force-test measurements in two-dimensional flow in the 4- by 6-foot vertical tunnel to determine the characteristics of several different shaped overhang-type aerodynamic balances applied to a straight-contour flap mounted on an NACA 0015 airfoil. The flap with blunt-nose overhang was overbalanced throughout certain ranges of flap deflection. Results regarding precision, lift, flap hinge moments, pitching moment, and drag are provided.

Report presenting force-test measurements in two-dimensional flow made in the 4- by 6-foot vertical tunnel to determine the aerodynamic effects of changing the alignment of the cover plates on a sealed internally balanced flap. Manufacturing imperfections in the alignment of the cover plates with the airfoil contour may have serious effects on the resultant hinge moment of a flap with a sealed internal balance. Results regarding lift, flap hinge moments, pitching moment, and drag are provided.

Report presenting flight testing of an improved type of all-movable tail surface. The particular arrangement tested provides control-free stability and a stable variation of the control forces during maneuvers. Results regarding rudder effectiveness, directional stability, rudder-free lateral motion, and rudder-free turns are provided.

Report discussing an investigation into several types and sizes of flaps and spoilers located forward of the elevators on the upper surface of the horizontal stabilizer of a model of a radial-engine pursuit airplane. Information about the elevator characteristics, elevator-fixed and elevator-free balance lift coefficient, and trim drag coefficient for a range of Mach numbers is provided.

"At the request of the Bureau of Aeronautics, Navy Department, tests were made in the variable-density wind tunnel of a tapered wing of 3-10-18 plan form and based on the NACA 4400R series sections. The wing was also tested with 0.2 chord split flaps, deflected 60 degrees, in the center of the wing and having flat span to wing span ratios of 0.3, 0.5, 0.7, and 1.0, respectively" (p. 1).

From Introduction: "The results of the load tests and some additional aerodynamic characteristics of perforated double split flaps on a rectangular NACA 23012 airfoil are given in the present report."

Report presenting an analysis of available data on vee-tail surfaces. The analysis indicated that a vee tail designed to provide values of stability and control parameters equal to those provided by a conventional tail would probably provide no reduction in area unless the conventional vertical tail is in a bad canopy wake or unless the vee tail has a higher effective aspect ratio than the conventional vertical and horizontal tails.

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.

Aerodynamics data are obtained for the design of linked balancing tabs and effect of varied tab span and location to produce suitable lateral control characteristics with reasonable stick pressures for high-speed aircraft. Simple and spring-linked balancing tabs may considerably reduce control pressures if aileron system is designed for low maximum aileron deflection. Spring-linked tabs also decrease variation of stick pressure with speed and impart better controlllability at low speeds.

"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 an investigation in the 7- by 10-foot tunnel of various modifications of the trailing-edge portion of a 0.20-chord plain aileron on a partial-span model of a tapered low-drag wing. The modifications tested included various amounts of symmetrical and unsymmetrical thickening and beveling of the aileron trailing edge. Results regarding coefficients and corrections, characteristics with ailerons neutral, characteristics with ailerons deflected, aileron trim characteristics, and estimated aileron-control characteristics are provided.

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 presenting an analysis of the effect of wing loading of the landing flare, which indicated that it had an important effect on landing technique and distance. Results regarding the approach and flare path and ground run are provided.

Report presenting tests in the 8-foot high-speed wind tunnel to determine the loads and the load distributions at high speeds for a number of windshields of the cockpit-canopy type. Ten windshields of various designs similar to those in general use were included in these tests. Results regarding drag, loads, and design considerations are provided.

"Flight measurements have been made of the individual aileron hinge moments, aileron rolling effectiveness pb/2V ,and stick-force characteristics in abrupt aileron rolls with a P-40F airplane (AAF No. 41-14119) over an indicated airspeed range from 108 to 304 miles per hour. Three methods for measuring the rate of change of hinge moment with angle of attack were investigated. Presented for comparison with the flight results are data from two-dimensional wind-tunnel tests of the wing-aileron profile as measured at the center aileron hinge" (p. 1).