"The preignition characteristics of a number of fuels have been studied under conditions similar to those encountered in an engine. These conditions were simulated by suddenly compressing a fuel-air mixture in contact with an electrically heated hot spot in the cylinder head of the NACA combustion apparatus. Schlieren photographs and indicator cards were taken of the burning, and the hot-spot temperatures necessary to cause ignition under various conditions were determined" (p. 121).

In connection with the general problem of providing air flow to an aircraft power plant located within a fuselage, an investigation was conducted in the Langley 8-foot high-speed tunnel to determine the effect on external drag and pressure distribution of air inlet openings located at the nose of a streamline body. Air outlet openings located at the tail and at the 21-percent and 63-percent stations of the body were also investigated. Boundary layer transition measurements were made and correlated with the force and the pressure data. Individual openings were investigated with the aid of a blower and then practicable combinations of inlet and outlet openings were tested. Various modifications to the internal duct shape near the inlet opening and the aerodynamic effects of a simulated gun in the duct were also studied. The results of the tests suggested that outlet openings should be designed so that the static pressure of the internal flow at the outlet would be the same as the static pressure of the external flow in the vicinity of the opening.

From Introduction: "In order to afford a means of comparison and to obtain a clear understanding of the results, a study of the effects of normal angular deflections of the ailerons, with and against the spin, was included in the investigation. Ailerons deflected with the spin means that the ailerons are deflected with right aileron up and left aileron down in a right spin. The results of the investigation are discussed in this paper."

From Summary: "This paper does not attempt to establish criterions for directional stability and control; rather, the emphasis is placed on providing some basis for design to specified criterions. An example applying the design methods has been included."

The report given here is for the sixteenth biennium of the texas library and history commission.

"The present report deals with a comparison of mathematically and experimentally defined buckling loads of a spar-rib grill, on the assumption of constant spar section, and infinitely closely spaced ribs with rigidity symmetrical to the grill center. The loads are applied as equal bending moments at both spar ends, as compression in the line connecting the joints, and in the spar center line as the assumedly uniformly distributed spar weight" (p. 1).

The National Advisory Committee for Aeronautics has conducted exhaust-heat de-icing tests inflight to provide data needed in the application of this method of ice prevention. The capacity to extract heat from the exhaust gas for de-icing purposes, the quantity of heat required, and other factors were examined. The results indicate that a wing-heating system employing a spanwise exhaust tube within the leading edge of the wing will make available for de-icing purposes between 30 and 35 percent of the exhaust-gas heat.

"The ionization in the knock zone of an internal-combustion engine was investigated. A suspected correlation between the intensity of knock and the degree of ionization was verified and an oscillation in the degree of ionization corresponding in frequency to the knock vibrations in the cylinder pressure was observed" (p. 1).

The limits of the single-stage compression in superchargers at the present state of development are determined by five factors. 1) by the rotor material; 2) by the formation of the flow; 3) by the manufacture of double shrouded rotors; 4) by the bearing problem; 5) by the drive method.

This book was designed to use as a text on air navigation on private ground course of the Civilian Pilot Training Program, and is the fourth edition of the publication "Practical Air Navigation and the Use of Aeronautical Charts of the U.S. Coast and Geodetic Survey" by Thoburn C. Lyon.

A preliminary investigation made to study the hydrodynamic properties and general behavior of simple hydrofoils. Six plain, rectangular hydrofoils were tested in a tank at various speeds, angles of attack, and depths below the water surface. The results are presented as curves of the lift and drag coefficients plotted against speed for various angles of attack and depths for which the hydrofoils were tested.

Report discusses an investigation into the hydrodynamic properties and general behavior of simple hydrofoils. The experimental results are presented as curves of the lift and drag coefficients plotted against speed for angles of attack and depths. Properly designed hydrofoil sections were determined to have excellent characteristics and a significant reduction in the speed of cavitation.

"With the further development of the supercharger, requirements with regard to measuring accuracy increase while at the same time the conditions under which the measurements must be carried out become more difficult. The present paper is a contribution toward the improvement and refinement of the measuring methods. For pressure measurements some suggestions are made with regard to design and location of the measuring stations" (p. 1).

The following standards give the standardized forms for two throttling devices, standard nozzles and standard orifices, and enable them to be used in circular pipes without calibration. The definition of the standards are applicable in principle to the calibration and use of nonstandardized throttling devices, such as the venturi tube. The standards are valid, likewise, as a basis for discharge measurements in the German acceptance standards.

"The present report deals with the variation of a turbulent velocity profile in flow from rough to smooth wall and vice versa. Expressions obtained for the shear-stress distribution with respect to the distance from the point of junction of the different roughnesses and from the wall distance, are utilized to ascertain the developing velocity distributions. Under simplified assumptions, the use of these formulas renders possible the integration of the motion equations for the shear stress. This calculation is carried out and compared with the experiments" (p. 1).

"A preliminary investigation of a number of duct entrances of rectangular shape installed in the leading edge of a wing was conducted in the NACA 20-foot tunnel to determine the external drag, the available pressure, the critical Mach numbers, and the effect on the maximum lift. The results showed that the most satisfactory entrances, which had practically no effect on the wing characteristics, had their lips approximately in the vertical plane of the leading edge of the wing" (p. 1).

"An investigation has been made in the NACA 7- by 10-foot wind tunnel of a large chord NACA 27-212 airfoil with a 20% chord split flap and with two arrangements of a 25.66% chord slotted flap to determine the section lift characteristics as affected by flap deflection for the split flap and as affected by flap deflection, flap position, and slot shape for the slotted flap. For the two arrangements of the slotted flap, the flap positions for maximum section lift are given. Comparable data on the NACA 23012 airfoil equipped with similar flaps are also given" (p. 1).