Results are presented showing the effects of gap, elevator, nose shape, balance, cut-out, and tabs on the aerodynamic characteristics of a horizontal tail surface tested in the NACA full-scale tunnel.

An investigation to determine and correlate the experimental surface heat-transfer coefficients of finned cylinders with different air-stream cooling arrangements was conducted at the Langley Memorial Aeronautical Laboratory from 1932 to 1938. The investigation covered the determination of the effect of fin width, fin space, fin thickness, and cylinder diameter on the heat transfer. Wind-tunnel tests were made in the free air stream with and without baffles and also with various devices for creating a turbulent air stream. Tests were also made with blower.

"In order to determine the effect of shape, compressibility, and Reynolds number on the drag and critical speed for simple forms, the drag forces on models of various simple geometric cross sections were measured in the NACA 11-inch high-speed wind tunnel. The models were circular, semitubular, elliptical, square, and triangular (isosceles) cylinders. They were tested over a speed range from 5 percent of the speed of sound to a value in excess of the critical speed, corresponding, for each model, approximately to a tenfold Reynolds number range, which extended from a minimum of 840 for the smallest model to a maximum of 310,000 for the largest model" (p. 169).

Report presents the results of flight tests comparing the relative effectiveness of conventional ailerons of the same size on wings of rectangular and tapered plan forms made with a Fairchild 22 airplane. Information is included comparing conventional and floating wing-tip ailerons on a tapered wing. The results showed that the conventional ailerons were somewhat more effective on the tapered than on the rectangular wing. The difference, however, was so small as to be imperceptible to the pilots. The floating wing-tip ailerons were only half as effective as the conventional ailerons and, for this reason, were considered unsatisfactory.

This report presents the results of wind tunnel tests to determine the effect of wing-tip shape and dihedral on some of the aerodynamic characteristics of Clark Y wings that affect the performance and lateral stability of airplanes. Force tests at several angles of yaw and rotation tests at zero yaw were made. From these tests the rates of change of rolling moment, yawing moment, and cross-wind force coefficients with angle of yaw and the rate of change of rolling moment coefficient with rolling were determined.

This report presents the results of measurements of flow in the boundary layer of a 1/40-scale model of the U. S. Airship "Akron" (ZRS-4) made with the object of determining the boundary-layer thickness, the point of transition from laminar to the turbulent flow, and the velocity distribution in the boundary layer.

This report presents the results of an investigation to determine the variations in intensity and spectral distribution of the radiant energy emitted by the flames during normal and knocking explosions in an engine. Radiation extending into the infrared was transmitted by a window of fluorite, placed either near the spark plug or over the detonation zone at opposite ends of the combustion chamber. Concave, surface-silvered mirrors focused the beam, first at the slit of a stroboscope which opened for about 2 degrees of crank angle at any desired point in the engine cycle, and then upon the target of a sensitive thermocouple for measuring radiation intensity.

"Experimental results on the effect of the length-diameter ratio of the orifice on the spray characteristics, together with a brief analysis of the factors affecting these characteristics, are presented in this report. The length-diameter ratios tested ranged from 0.5 to 10; the orifice diameters from 0.008 to 0.040 inch; and the injection pressures from 2,000 to 8,000 pounds per square inch. The density of the air into which the fuel was discharged was varied from 0.38 to 1.35 pounds per cubic foot" (p. 79).

This report presents the results of wind tunnel tests conducted to determine the aerodynamic characteristics of airship models. Eight Goodyear-Zeppelin airship models were tested in the original closed-throat tunnel. After the tunnel was rebuilt with an open throat a new model was tested, and one of the Goodyear-Zeppelin models was retested. The results indicate that much may be done to determine the drag of airships from evaluations of the pressure and skin-frictional drags on models tested at large Reynolds number.