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Report presenting tail-surface characteristics calculated from wind-tunnel data, which have been reported to not correspond with flight-test measurements. The primary problem under consideration is the calculation of the effect of tab deflection on the free-floating angle of the elevator, as in a servocontrol.

Report presenting a mathematical analysis of plate-type intercooler design for both turbulent and laminar flow. Charts are presented to show how the plate-type intercooler volume, weight, plate area, frontal area, and linear dimensions can be varied without changing the intercooler operating conditions. An experimental investigation was also carried out with a plate-type intercooler unit to check the validity of the heat-transfer and pressure-drop theories for the airflow between very closely spaced plates.

"The equations that describe the operation of a heat exchanger - the equations for pressure drop, rate of heat transfer, and power expenditure - have been put into nondimensional, generalized form. These generalized equations can be used for constructing selection charts for various types of aircraft heat exchangers. Such charts would facilitate choice of heat-exchanger dimensions for any given set of operating conditions. A typical selection chart is presented" (p. 1).

"This report describes the material, cutting-tool development, and machining procedure used in constructing an air-cooled cylinder barrel having a cooling muff with 2-inch fins spaced 1/8 inch. Details of two types of thread form used for the barrel to head assembly with the cooling muff are also presented" (p. 1).

Report presenting an investigation of the flying qualities of a Hawker Hurricane airplane. Thirteen flights and approximately 17 hours of flying time were required to complete the tests, which included extensive measurements of stability, controllability, and stalling characteristics. The results were similar to the flying qualities of other previously studied pursuit airplanes.

Report presenting calculations to determine the effects of spring and gravity moments in the control system on the longitudinal-stability characteristics of the Brewster XSBA-1 airplane, and the computed results have been verified by flight tests.

Report presenting a practical and relatively rapid method of compensating for shear lag in box-beam analysis with accuracy sufficient for design purposes. Effectiveness curves for box beam elements are derived for an ideal, symmetrical structure. Tabular computation forms for rapid, accurate calculations of axial stresses, shear center, and shear stresses for beam with shear lag are induced.

Report presenting the results of a series of flight tests of the maximum speed and cooling characteristics in high-speed level flight and in climb of the XP-42 airplane equipped with a long-nose high-inlet-velocity cowling. The results indicated that a maximum speed of 338 miles per hour at 870 horsepower at 17,000 feet was achievable, which is above the engine critical altitude. Pressure measurements in the entrances in the cylinder baffles showed a uniform distribution of pressure on the front of the engine in high-speed level flight and a fairly uniform distribution in full-power climb.

"On July 31, 1941 a turbulence survey was made with the XC-35 airplane of a large cumulus congestus cloud near Langley Field, Va. This bulletin presents a general description of conditions and the maximum gust intensities recorded during the flight" (p. 1).

Report presenting a study of the design of an air-heated wing and the results of tests performed on a model air-heated leading edge, which were made to determine the validity of the proposed wing design.

"Three Franz-type temperature probes and a pitot-static tube for use in supercharger passages have been calibrated in the NACA 24-inch high-speed wind tunnel. These instruments were designed for use in supercharger investigations" (p. 1).

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The following document describes the analysis on an attempt at separating mercury isotopes by making their environments as widely different as possible.

Report presenting an investigation to determine the flow losses that occur as a result of locating the axis of an intercooler at various angles with respect to the supply-duct axis and also to determine the flow pattern throughout the intercooler. The flow losses were found to be small for angles of inclination up to about 70 degrees. The distribution of flow through the intercooler also appeared to be fairly uniform up to about this angle.

"Two stress-strain curves are presented for both tension and compression. In addition, the results of a number of flat-end column tests are presented. The more apparent conclusions regarding extruded magnesium alloy J-1 are: it has a very low proportional limit in relation to the yield and ultimate strengths and it has a very low yield point for compression as compared with tension" (p. 1).

"The concept of the effective ejection velocity of a rocket engine is explained and the magnitude of the attainable ejection velocity theoretically and experimentally investigated. Velocities above 3000 meters per second (6700 mph) are actually measured and the possibilities of further increases shown" (p. 1).

"The series of pressure distribution measurements at three test sections on NACA airfoils 2212 and M6 within 170 to 210 angles of attack in reversed flow proved to be largely independent of the profile form. In contradiction to the pressure distribution in normal flow considerable negative pressure from the upper surface spills over onto the lower surface, and vice versa, even in the zone of sound flow. The results are presented as chord-wise pressure and load distribution" (p. 1).

"After a survey of the customary procedures for appraising the profile drag in which pressure drag was discounted and the methods for computing the laminar and turbulent friction flow, the author proposes a method by which the pressure drag can be computed with the aid of the displacement thickness of the frictional layer. The method is restricted to the case where the effects, caused by separation of frictional layer, are small. Then the total profile drag can be expressed solely by quantities derived from the velocity distribution in the frictional layer immediately at the trailing edge" (p. 1).

To determine whether or not the (n,2n) reaction in Be would produce a net increase in fission neutrons in a power plant, the distribution of In resonance neutrons slowed down from fission energies in a graphite block was measured with and without a 2" of Be in front of a U3O8 slab undergoing fission. The thermal neutrons producing the fissions were obtained by slowing down neutrons from a cyclotron source. The observed distribution without Be was well represented by a Gaussian source range 36 cm. (corresponding to an initial fission energy of 3 MeV) and a similar sink of range 7.8 cm. The total In resonance intensity with Be was 5% less than without Be. On the assumption that the effect of the Be is entirely due to its different mean free path and moderating power, the In distribution with Be was calculated. Since the m.f.p. as a function of energy is not known for Be, two separate calculations were made using the highest (2.9 cm.) and the lowest (1.80 cm.) possible values for the effective Be m.f.p. Both calculated curves were found to be higher than the observed Be distribution, indicating that at least 10% of the fission neutrons …