Note presenting a description of the synthesis of isobutylbenzene, sec-butylbenzene, and tert-butylbenzene in 11-gallon quantities. The physical properties are tabulated and freezing curves are plotted for the five hydrocarbons.

"The gross weight, beam, and afterbody length of 12 contemporary flying boats and amphibians with pointed afterbodies are tabulated and correlated. For most of the hulls considered, the afterbody length-beam ratios are shown to be directly proportion to the gross-load coefficients" (p. 1).

From Introduction: "An investigation of the power-plant installation of a single-engine torpedo-bomber-type airplane has been conducted in the NACA Cleveland altitude wind tunnel at the request of the Bureau of Aeronautics, Navy Department. A similar investigation was previously conducted on a three-tenths scale mock-up of the forward portion of the fuselage of this airplane in the Langley 20-foot tunnel. (See reference 1)."

Report discussing the results of accelerated erosion tests to determine the separate effects of the passage of fuel, water, and ice particles through a supercharger. Recommendations for preventing erosion are provided, including materials choice and joint design.

A numerical procedure is presented for the calculation of the stresses in a monocoque cylinder with a cutout. In the procedure the structure is broken up into a great many units; the forces in these units corresponding to specified distortions of the units are calculated; a set of linear equations is established expressing the equilibrium conditions of the units in the distorted state; and the simultaneous linear equations are solved. A fully worked out numerical example, corresponding to the application of a pure bending moment, gave results in good agreement with experiments carried out earlier at the Polytechnic Institute of Brooklyn.

"Ten 24S-T alclad cylinders of 20-inch diameter, 45- or 58-inch length, and 0.012-inch wall thickness, reinforced with 24S-T aluminum alloy stringers and rings were tested in pure bending. In the middle of the compression side of the cylinders there was a cutout extending over 19 inches in the longitudinal direction, and over an angle of 45 degrees, 90 degrees, or 135 degrees in the circumferential direction. The strain in the stringers and in the sheet covering was measured with metal electric strain gages. The stress distribution in the cylinders deviate considerably from the linear law valid for cylinders without a cutout" (p. 1).

Report presenting charts for calculating the combustion temperatures and temperature changes involved in constant-pressure thermodynamic processes of air and the products of combustion of air and hydrocarbon fuels. Examples for different types of fuel and temperature calculation using the charts are also provided.

Report presenting the results of calibrations to determine axial and transverse strain sensitivities for 15 types of single-element, multistrand wire strain gages. The gages were separated into those which had positive average ratios of transverse sensitivity and those which had negative transverse sensitivity.

Note presenting an investigation to compare the effectiveness of two basic methods of cooling a turbosupercharger and to obtain data on the temperature level and distribution in the turbine wheel. Turbine-wheel temperatures were obtained for various conditions of cooling-air mass flow, exhaust-gas temperature, and exhaust-gas mass flow. Modified forms of the standard cooling caps were used to allow for the installation of temperature-measuring devices.

Report presenting an investigation to determine whether stall will occur at certain combinations of thrust, forward speed, and rotational speed, and to establish the amount of stalling that could be present without severe control effects. Results regarding the stall, practical limits of stall, extent of agreement of experimental and theoretical data, and areas for future study are provided.

Testing of a 10-foot-diameter three-blade Curtiss 89301-15 propeller with Clark Y blade sections was conducted in the 16-foot high-speed tunnel to determine the effect of simulated ice on the aerodynamic characteristics of the propeller. The propellers were tested on a 2000-horsepower dynamometer at rotational speed 1800 rpm at several blade angles and airspeeds. Results regarding the effect of icing and constant-power propeller operation are provided.

Report presenting tests of three airplanes in an effort to develop elevators that would provide stick forces in steady turns within the limits required by the Army and Navy handling-qualities specifications over a large range of center-of-gravity positions.

Report presenting an investigation in the full-scale tunnel to determine the thickness and shape of profile of the boundary layer on the fuselage of a typical monoplane fighter airplane with a single liquid-cooled engine. The results indicate that the maximum displacement thickness was nearly 1.2 inches and was at the most rearward station.

"Dynamic yawing effects on vertical tail loads are considered by a theory of flat yawing maneuvers. A comparison is shown between computed loads and the loads measured in flight in a fighter airplane. The dynamic effects were investigated on a large flying boat for both an abrupt rudder deflection and a sinusoidal rudder deflection" (p. 1).

Note presenting a method by which the directional stability derivative, which is the rate of change of yawing-moment coefficient with sideslip angle, can be evaluated for a conventional airplane from flight records of a lateral or directional oscillation. When applied to conventional airplanes flying at low to moderate lift coefficients, the assumptions involved in this simplified method produce negligible error.

Note presenting an extension of the method of computing the pressure distribution along a symmetrical profile of arbitrary shape given in a previous technical note under the assumption of a linearized pressure-volume relation to the case of an everywhere subsonic flow satisfying the rigorous adiabatic equation of state. The actual applicability of the method depends on the development of efficient procedures for numerical integration of linear partial differential equations with variable coefficients. Tables and graphs of functions needed for the computation are given.

Report presenting a method for determining the jet-boundary and plan-form corrections necessary for application to test data for a partial-span model with a reflection plane, an end plate, or no end plate in a closed circular wind tunnel. Good agreement with three different conditions was obtained with flaps neutral at values of lift coefficient below the stall and somewhat less satisfactory agreement in the region of maximum lift coefficient or with flaps deflected.

From Summary: "A pressure-distribution investigation was made in the Langley 7- by 10-foot tunnel of a plug-type spoiler-slot aileron on a semispan tapered-wing model of a typical fighter airplane equipped with full-span slotted flaps. The results of the investigation indicate peak pressure on a plug-type spoiler-slot aileron that may result in a compressibility shock on the plug aileron at high speed. The maximum loads on the plug aileron occurred in the high-speed condition for maximum up aileron deflection."

Note presenting an investigation of the heat transfer to a surface from plane heated-air jets discharged tangentially to the surface to provide heat-transfer relationships required in the design of heated-air jet installations for aircraft windshield fog prevention. Experimental temperature, velocity, and heat-transfer data were obtained by tests in which the initial jet temperature and velocity were varied.

"Charts are presented for computing thrust, fuel consumption, and other performance values of a turbojet engine for any given set of operating conditions and component efficiencies. The effects of pressure losses in the inlet duct and the combustion chamber, of variation in physical properties of the gas as it passes through the system, of reheating of the gas due to turbine losses, and of change in mass flow by the addition of fuel are included. The principle performance chart shows the effects of primary variables and correction charts provide the effects of secondary variables and of turbine-loss reheat on the performance of the system" (p. 599).

"Tests have been made at high speeds to determine the drag of models, simulating propeller shanks, in the form of a circular cylinder and three airfoils, the NACA 16-025, the NACA 16-040, and the NACA 16-040 with the rear 25 percent chord cut off. All the models had a maximum thickness of 4 1/2 inches to conform with average propeller-shank dimensions and a span of 20 1/4 inches. For the tests the models were supported perpendicular to the lower surface of the wing of an XP-51 airplane (p. 277).

"Flight tests were conducted on a twin-engine fighter airplane at pressure altitudes up to 10,000 feet with simulated conditions of moderate, heavy, and excessive rain to determine the increase in enthalpy of the charge air due to the turbosupercharger, to determine the rate of enthalpy increase of the charge air resulting from a sudden increase of engine power, and to compare the conditions that caused induction-system icing in flight with those that resulted in icing of the same carburetor and supercharger inlet elbow in laboratory tests" (p. 1).

Report discussing measurements of the overall drag coefficient of the XP-51 in dives using three different methods. The three instruments used to measure drag variation are compared for accuracy. A comparison of the drag results obtained from this test are also compared to the results obtained from previous wind tunnel testing.

Report presenting an investigation for the determination of the behavior of ceramic bodies in tension at elevated temperatures for the purpose of determining data for the design of ceramic blades for gas turbines. Observations were made of six special ceramic bodies in order to determine their tensile strength and creep during prolonged loading under a range of stresses and temperatures.