Report presenting a theory regarding engine-cooling variables from a previous report, which was used as a basis for the development of a semi-empirical equation to correlate exhaust-valve temperature with engine conditions. Results regarding the determination of constants, influences of operating variables on mean effective gas temperatures, thermal-resistance factor, and accuracy of correlating equation are provided.

Report presenting tests to verify and extend ultraviolet spectroscopic techniques for applications to the analysis of aviation fuels for their aromatic constituents. Results regarding photographic absorption spectra, spectrophotometric absorption spectra, and spectrophotometric analyses are provided.

Report describes the lubrication characteristics of an aircraft-type piston as visually studied in a V-type engine with a glass cylinder. Information about the movement of the piston, the piston rings, and the oil-control rings and their effect on lubrication is included.

Report presenting an exact solution and a closely concurring approximate energy solution for the buckling of an infinitely long flat plate under combined shear and transverse direct stress with edges elastically restrained against rotation. An appreciable fraction of the critical stress in pure shear may be applied to the plate without any reduction in the transverse compressive stress necessary to produce buckling.

Report presenting an experimental investigation of rectangular exhaust-gas ejector pump to provide data that would serve as a guide to the design of ejector applications for aircraft engines with marginal cooling. With a decrease in the quantity of air pumped and an increase in the length of an ejector, the ejector pressure rise increases to optimum values. Results regarding straight ejectors, diffuser ejectors, curved ejectors, ejector aspect ratio, divided ejectors, multistage ejectors, and nozzle-exit effects are provided.

Report presenting flight tests conducted to evaluate the effect of a thermal ice prevention system on the aerodynamic performance of a C-46 cargo airplane. The installation of the thermal ice-prevention system was found to reduce the indicated airspeed by about 6 miles per hour. Results regarding the overall performance change resulting from the installation of the thermal system, reduction of power attributed to heat-exchanger exhaust-gas back pressure, reduction of power attributed to the internal and external drag of the thermal system, and the additional airplane gross weight attributed to the thermal system are provided.

Report presenting an investigation of a thermal ice-prevention system for a Curtiss-Wright C-46 airplane, including the equipment for the wings, empennage, and windshield. The report is the third in a series and focuses on the revisions to the components for thermal ice prevention, the temperature- and pressure-measurement equipment installed in the airplane to determine the performance of the system, and the results of static-load structural tests of a specimen of the wing outer-panel leading edge.

Report presenting an investigation of a thermal ice-prevention system for a C-46 cargo airplane, which involved flight tests in dry-air and natural-icing conditions at two different laboratories. The purpose of the investigation was to determine the effectiveness of the C-46 airplane ice-prevention system and to continue the develop of thermal ice-prevention equipment. Results regarding the wing outer panel, wing tips, wing center panel, horizontal stabilizers, vertical fin, windshields, ice-removal tests, unprotected surfaces, and heat exchangers are provided.

Report discussing the use of two types of geared spring tabs for elevator control: ordinary (or ungeared) spring tabs and geared spring tabs. Their use in airplanes of various sizes and in comparison to conventional control systems is described.

From Summary: "A general representation of fan and turbine arrangements on a single classification chart is presented which is made possible by a particular definition of the stage of an axial-flow fan or turbine. Several unconventional fan and turbine arrangements are indicated and the applications of these arrangements are discussed."

Report presenting flight tests to establish the dry-air-performance characteristics of a thermal ice-prevention system at various operating conditions and altitudes. Results regarding twin-engine tests and single-engine tests of characteristics such as skin temperatures and location of heating are provided.

Report presenting an investigation of an exhaust-air heat exchanger, which has been designed, constructed, and flight-tested for a C-46 cargo airplane. The primary purpose of the investigation was to provide the C-46 airplane with a satisfactory source of heated air and to continue the development of the heat exchanger as a part of thermal ice-prevention equipment. Results indicated that the required thermal output and desired air-temperature rise have been achieved and that the exchanger is suitable for use in the C-46 airplane.

Report presenting calculations based on dynamometer test-stand data on an 18-cylinder radial engine made to determine the improvement in fuel consumption that can be obtained by gearing an exhaust-gas turbine to the engine crankshaft in order to increase the engine shaft work.

Report presenting a summary of a series of reports regarding heat exchangers, and in particular, the design of exhaust gas and air heat exchangers. The four parts included are a summary of heat transfer equations, single pass heat exchangers, heater performance in flight, and appendicies with additional aerodynamic information.

Report discussing an open box joined to a closed box subjected to torsional loading. A stiff bulkhead and a flexible bulkhead were tested at the discontinuity and the results were compared to a previously published theory. Stress distribution was found to not be sensitive to bulkhead stiffness when the stiffness is large, but the calculations became sensitive to errors in estimating when the stiffness was small.

Report presenting flight tests of an all-movable horizontal tail installed on a Curtiss XP-42 airplane due to its possible advantages as a longitudinal control at high Mach numbers. The elevator control was found to be unsatisfactory with the control arrangements tested.

Report presenting wind-tunnel testing in two-dimensional and three-dimensional flow to investigate the aerodynamic characteristics of spoilers on tail surfaces for low-speed flight. Test results indicated that spoilers on tail surfaces showed little possibility of replacing conventional control surfaces. Results regarding a flap alone, rear spoiler alone, forward spoiler alone, forward spoiler and flap, and a combination of forward and rear spoilers on upper and lower surfaces in both types of flow are provided.

Report discusses the results of testing on a linked differential flap system upon the effective-dihedral characteristics of an airplane scale model. The negative dihedral changes caused by power can be materially reduced or eliminated by use of a differential flap system. The static directional stability also increased with differential flap action.

Report presenting tests in a seal test chamber to determine the hinge moments contributed by the fabric seal in an internal-balance arrangement employing a thin-plate overhang. The tests were performed with various widths of fabric sealing various widths of flap-nose gap, with a horizontal, a vertical, and a circular type of wing structure forward of the balance, and with various heights of balance chamber. Results regarding seal-profile photographs, desired seal-moment characteristics, experimental seal-moment characteristics, effect of the balance configuration on the seal-moment characteristics, comparison of analytical and experimental seal-moment characteristics, computation of seal-moment characteristics by the approximate method, and application of the data are provided.

Report presenting the results of a theoretical analysis of the hinge-moment characteristics of various sealed-internal-balance arrangements for control surfaces. The results of the investigation indicated that the most nearly linear control-surface hinge-moment characteristics can probably be obtained from a flexible seal over a narrow gap, which is so installed that the motion of the seal is restricted to a region behind the point of attachment of the seal to the wing structure.

Report presenting a comparison of two flight-test procedures for the determination of the aileron control capabilities of an airplane. The procedures consist of performing rudder-fixed aileron rolls from straight unbanked flight and from steady turning flight. Results regarding rate of roll comparison and sideslip-angle comparison are provided.

"In Mach range of 0.25 - 0.69, boundary-layer measurements were made on upper wing surface at 25% semi-span, pressure-distribution measurements made on upper surface at 63% semi-span, and wake surveys made at 63% semi-span. The minimum profile-drag coefficient of 0.0062 was indicated for smooth section at 63% semi-span. Critical mach number was exceeded by 0.04, but no compressibility shocks appeared. In slipstream, boundary layer transition occurred as far back as 20% chord on upper surface at low lift coefficients" (p. 1).

Report presenting data on the thermal performance and static and total pressure drop characteristics of a fluted-type exhaust gas and air heat exchanger. Results regarding heat transfer, pressure drop, and non-isothermal pressure drop are provided.

Report presenting results of tests of the thermal performance and the static pressure drop characteristics of a flat-plate type exhaust gas and air heat exchanger. The ventilating air shroud built into the heat exchanger gives characteristics of cross flow and parallel flow.