Report presenting the results of flight measurements of performance and cooling characteristics of the XP-42 airplane equipped with a short-nose low-inlet-velocity cowling. Testing included measurements in level flight and climb of the effects of a spinner-mounted axial-flow fan without propeller cuffs, no fan or cuffs, and two different sets of propeller cuffs.

Report presenting flight measurements of the performance and cooling characteristics of a short-nose high-inlet-velocity cowling on the XP-42 for conditions of climb with and without propeller cuffs and for high speed without cuffs. The speed of the airplane was approximately 1 mile per hour greater without propeller cuffs than the previously measured value with cuffs. Results regarding maximum speed, pressures and temperatures, and ground cooling are provided.

From Introduction: "The purpose of this report is to gather together in one place information on the skipping characteristics of number of flying boats. A graph showing the influence of the hull form on the skipping characteristics is given which should be useful in laying out the proportions of the hull in preliminary design to insure good landing behavior."

Report presenting results from a series of flight tests of the performance and cooling characteristics in high-speed level flight and in climb of the XP-42 airplane equipped with a short-nose low-inlet-velocity cowling and an axial-flow fan mounted on the spinner. Results regarding maximum speed and pressures and temperatures are provided.

Report presenting tests made in the 7- by 10-foot tunnel to determine the effect of direction of propeller rotation on the static longitudinal and lateral stability characteristics of the scale model of the North American B-28 airplanes. The results of the present investigation indicate that the mode of propeller operation has a considerable effect upon lateral and longitudinal stability and may have an effect upon propulsive efficiency.

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 a procedure for the shear-lag analysis of box beams, such as wing structures. It is based off of a previous method but allows for the separation of the most essential part of the shear-lag analysis.

Report discusses an investigation into the spray characteristics of a twin-engine flying boat model similar to the Boeing XPBB-1 but with a modified length-beam ratio of the hull. The spray characteristics of the modified model compared favorably with the standard XPBB-1 flying boat and no adverse effects on spray characteristics were introduced by modifying the length-beam ratio and hull.

"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).

"This paper studies the effect of altitude on the ratings of rotating electric machines and after determining the fundamental principles involved, discusses these in relation to the application of such machines in modern aircraft" (p. 1).

Report presenting knock-limited small-scale-engine tests of isopropyl-benzene, benzene, and o-xylene blended individually in various concentrations with selected base fuels. Data were obtained to determine the blending sensitivity, lead susceptibility, and sensitivity of the blends to inlet-air temperatures. Isopropylbenzene was found to be the most effective overall.

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.

"The two-dimensional incompressible potential flow over corrugations and bumps of arbitrary shape is derived by conformal transformation. The results are compared with those obtained by the methods of thin-airfoil theory. Some discussion is included of the flow over bumps that protrude both inward and outward from a wall" (p. 1).

"Equations have been derived for the change in the quantities that define the thermodynamic state of air - pressure, density, and temperature - at an abrupt increase in cross-sectional area of flow of compressible air. Results calculated from these equations are given in a table and are plotted as curves showing the variation of the calculated qualities with the area expansion ratio in terms of the initial Mach number as parameter. Only the subsonic region of flow is considered" (p. 1).

"Methods are given for making the necessary corrections to the strains indicated by multiple-strand resistance-type wire strain gages used singly or as rosettes to measure strains at an angle to the principal strain. The results of tests to determine the validity of the methods of correction are reported" (p. 1).

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. "

"A method is developed for calculating the tunnel-wall corrections to rolling and yawing moments due to aileron deflection on models in closed rectangular wing tunnels. Graphs are presented which permit a rapid determination of these corrections for models mounted in 7- by 10-foot or 8- by 12-foot wind tunnels. The method is so developed that the corrections may be calculated for the deflection of either aileron alone or both ailerons simultaneously" (p. 1).

"The effect on the propulsive efficiency of locking or windmilling one propeller of a six-blade dual-rotating propeller installation was determined in the Langley propeller-research tunnel. Tests were made of both pusher and tractor configurations, with the unpowered propeller both leading and following the powered propeller, which was set at a blade angle of 40 degrees. The maximum propulsive efficiency of the powered propeller in combination with the locked or windmilling propeller was, in all cases, lower than that of the powered propeller operating alone" (p. 1).

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.

Report of a study to develop a method of obtaining gas temperatures from the frequency of knock-induced gas vibrations in an internal-combustion engine cylinder. Temperatures calculated from frequency data were in agreement with temperatures measured by the spectral line-reversal method in previous investigations and were about 700 degrees Fahrenheit lower than temperatures obtained from thermodynamic charts.

Report presenting knock-limited performance tests made with eight representative fuels rated at 100-octane number using the CFR aviation method. All eight fuels were mixtures of representative blending agents and bases. Results regarding the effect of inlet-temperature air changes, effect of octane numbers in a full-scale single-cylinder engine, effect of addition of aromatics to the fuels, and type of spark plug used are provided.