Report presenting force-test measurements in two-dimensional flow made in the 4- by 6-foot vertical tunnel to determine the aerodynamic characteristics of an NACA 66(215)-014 airfoil equipped with true-contour, straight-contour, and beveled-trailing-edge flaps with chords 30 percent of the airfoil chord. The results are presented in the form of aerodynamic section characteristics for several flap deflections and for a sealed and unsealed gap at the flap nose.

Report discusses the results of testing of flap position and deflection on the aerodynamic characteristics of a NACA 23012 airfoil with a double slotted flap with a chord 30 percent of the airfoil chord. The maximum lift coefficient, profile-drag coefficients, pitching-moment coefficients, lift, and drag are provided at several positions of the flap. The results were also compared to previous testing on several flap configurations.

Report presenting hinge-moment parameters for several typical ailerons, which were calculated from section data with the aspect-ratio correlation as usually determined from lifting-line theory. The calculations showed that the agreement between experimental and calculated results was unsatisfactory.

Report discusses the results of testing on several models of flying boats, the XPB2M-1, the XPBB-1, the JRM-1, and 11 other models to determine the effect of bow form on the amount of spray thrown onto the windshield of a flying boat in rough water. Several recommendations for reducing the height and volume of spray are provided. Any change in the hull form that softens the impact between the hull and waves seems to reduce the spray.

Report presenting flight testing using a North American XP-51 airplane with several arrangements of beveled-trailing-edge ailerons to determine the most satisfactory arrangement. Results regarding the aileron configuration, trimming tabs, and factors affecting symmetry of aileron characteristics are provided.

Report presenting lift and hinge-moment characteristics of various types of airplane control surface. The data can be used to determine curves correlating the results of many tests of the various types of aerodynamic balance.

Several tail modifications of the Brewster XSBA-1 scout-bomber were investigated and results compared. Modifications consisted of variation of the chord of the elevator and rudder while the total area of the surfaces is kept constant and variations of the total area of the vertical tail surface. Configuration number 2 reduced trim changes by 50 percent and reduced average elevator control force gradient from 30 to 27 pounds/g. Stick travel required to stall in maneuver was 4.6 inches.

Report presenting the propeller forces due to an angular velocity of pitch, which are analyzed and shown to be very small for the pitching velocities that may actually be realized in maneuvers, with the exception of the spin. A dual-rotating propeller in yaw was found to develop up to one-third more side force than a single-rotating propeller.

Report discusses a proposal for propeller manufacturers to consider the side-force factor with the activity factor as a fundamental parameter for all blade designs and for the side-force factor to be included in all reports of powered models in wind tunnels. The proposal includes a method for calculating the side-force factor and how it can be used in propeller development. It is shown to be a good index of the relative effectiveness per blade of a yawed propeller in developing side force.

Note presenting a theory that is meant to include all factors that are commonly present when determining the stability of isotropic or orthotropic cylinders or flat or curved panels under a variety of characteristics. The theory is based on the energy method and involves a number of approximations, some rather rough. It is a theory of elastic stability and, like other theories, assumes a construction with no imperfections of shape or elasticity.

Note presenting tensile and compressive stress-strain curves, stress-deviation curves, and secant modulus-stress curves for longitudinal and transverse specimens of magnesium alloy J-1 sheets 0.032 and 0.102 inch thick. Significant differences were found between the tensile and compressive stress-strain curves and between the compressive stress-strain curves for the longitudinal and transverse questions.

Report presenting an investigation of the effect of various surface finishes on the endurance of normalized X4130 and 4140 steels and 25S-T aluminum alloy. All mechanically formed surfaces tested were stronger than electropolished surfaces.

"The purpose of this report is to show by analysis of existing data, pending direct experimental determination, the extent to which nonuniform distribution of fuel to cylinders of a multicylinder engine can produce temperature deviation and the benefits to be anticipated from attainment of uniform fuel distribution" (p. 1).

Report presenting an equation in which it is possible to correlate the cooling characteristics of an engine. Results regarding engine cooling, engine performance, and estimated cooling-pressure-drop requirements are provided.

Report discusses the results of an investigation to study the effect of the height of a rivet head on the number of cycles required to cause failure of a machine-countersunk flush-riveted joint under a combined static and alternating shear load. A tight joint and a loose joint were tested and the number of cycles to failure and location of fatigue failure were compared.

Report presenting an investigation that is part of a research program to obtain structures suitable for low-drag wings. The purpose of this particular investigation was to study the drag characteristics of an NACA 66(215)-(1.25)16 airfoil specimen of two-spar construction with hat-section chordwise stiffeners after a compressive load comparable with the maximum applied flight load of a modern military airplane has been applied and removed. Results regarding the variation of section drag coefficient with Reynolds number for the wing specimen of the airfoil, variation of section drag coefficient with section lift coefficient, and drag coefficients at specified Reynolds numbers are provided.

Report presenting flight tests of a Navy F2A-2 specially equipped with full-scale slotted flaps and two sets of lateral controls: internally balanced, sealed ailerons on the flap trailing edge for use with the flaps up and slot lip ailerons for use with the flaps down. Results regarding aileron characteristics, maximum lift coefficients and stalling characteristics, and longitudinal stability and control are provided.

Report presenting methods and charts for computing stability derivatives of a longitudinally straight V-bottom planing surface representing the forebody of a seaplane float or a flying-boat hull without chine flare. The charts for computing hydrodynamic derivatives were used in calculating the trim limit of stability for angles of dead rise of 10, 20, and 30 degrees.

Report presenting testing of models of medium-bomber designs to investigate the relative characteristics of thickened wing roots with propeller-shaft fairings and wings with nacelles. Incremental drag coefficients due to thickened wing roots and due to propeller-shaft fairings through a range of Mach numbers at lift coefficient 0.10. Results regarding force tests, pressure-distribution tests, effect of thickening and filleting, nacelles and propeller-shaft fairings, and a comparison of submerged engines and engine-nacelle combinations are provided.

Report presenting the stability, lateral-control, and stalling characteristics of an airplane modified to accommodate full-span Zap flaps.The static and dynamic longitudinal and lateral stability was satisfactory, but there were some undesirable lateral-control characteristics, including excessive friction and elasticity.

Report presenting an investigation on spot-welded 24S-T Alclad. The report is divided into five parts, including an investigation of tension fatigue measurements, lap-joint samples spot-welded by different companies, fatigue strengths of wire-stitched lap-joint samples, data on similar samples with different spot spacings, and the results of compression fatigue tests for stiffened panels with purposely overheated spot welds.

"A thermocouple was installed in the crown of a sodium-cooled exhaust valve. The valve was then tested in an air-cooled engine cylinder and valve temperatures under various engine operating conditions were determined. A temperature of 1337 F was observed at a fuel-air ratio of 0.064, a brake mean effective pressure of 179 pounds per square inch, and an engine speed of 2000 rpm" (p. 1).

Report presenting instructions for winding, baking, and mounting a phanolic resin-impregnated, bobbin-type wire strain gage that consists of Advance wire wound around a paper form. A description of some test equipment useful for establishing the merits of the techniques used in gage construction has been included.

"Report discusses the results of inverted-spin tests in 44 airplane models in the NACA free-spinning tunnel. Spins were normally steep and recovery by rudder reversal was generally rapid. Pulling the stick back, deflecting ailerons and rudder together, and crossing them all had an effect on the amount of spin encountered and ease of recovery from spin" (p. 1).