Abstract. Measurements were made to determine the effect of thermal cycling on heat transfer from slug to jack using a slug with a sand blasted surface. The value of the transfer coefficient h decreased from initial values ranging from 10 to [formula], to values and [formula] after 1700 cycles, and to a range of 0.15 to 0.45 [formula] after 3200 cycles. Comparisons are made with the results found for slugs with different surfaces.

Abstract. Irradiated Whiting graphite possesses a small negative or a positive Hall constant, depending upon the dosage. Annealing at 500 degrees C for 1 hour in helium results in a Hall constant which is large in magnitude and negative in sign. The properties of the annealed graphite are presumably close to those of the original unirradiated material. Unirradiated AGOT-K graphite has a large, negative Hall constant. A mechanism is suggested which accounts for the change in sign of the Hall constant as a result of neutron bombardment.

Summary: A method is presented for the precipitation of tuballoy, apparently as a tubanyl ammonium sulfite, from gunk solutions containing the contaminants encountered in the recovery cycle. The impurities are not precipitated under the conditions employed, and their amounts in the product are reduced to values which can be attributed to occlusion. The recovery of tuballoy on one precipitation ranges from 99.5% to 99.9%.

Report discussing tests on three sets of elevators with various combinations of section contour, balancing tabs, bobweights, and control-system mechanical advantage on an SB2C-1C airplane. Effects on maneuvering stability, a comparison of production elevators and recommended arrangement, and internal elevator pressures are described.

Report presenting a boundary-layer transition and profile-drag investigation on an experimental low-drag wing installed on a P-47 airplane designated the XP-47F and supplied by the Army Air Forces. Measurements were made at a section outside the propeller slipstream with smooth and with standard camouflage surfaces and on the upper surface of a section in the propeller slipstream with the surface smoothed.

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.

Report presenting an analysis of the thermopile radiometer as used in the measurement of irradiation and radiant power interchange is given. The theory of the instrument when used to measure irradiation and net radiant power interchange is developed, and the precautions to be observed when using it for these measurements are presented.

Report presenting data on the thermal performance and the static pressure drop characteristics of a flattened-tube type crossflow exhaust gas and air heat exchanger. The measured thermal outputs and static pressure drops are compared with predicted magnitudes.

Report presenting data on the thermal performance and static pressure drop of a finned-type cast-aluminum exhaust gas and air heat exchanger. Results regarding heat transfer, isothermal pressure drop, and heater surface temperature are provided.

Report discussing testing on a retractable spoiler aileron on the NACA 66(215)-216 airfoil with a 25-percent-chord slotted flap. The effects of spoiler thickness, spoiler gap, spoiler bevel angle, spoiler roughness, and flap deflection on aerodynamic characteristics are described.

Report discussing the aerodynamic characteristics of the wing and isolated tail of the Bell XP-83 airplane in attitudes simulating spin conditions. Information about the the aileron hinge moment, angle of attack, and elevator hinge-moment is provided.

Flat-plate flaps with no wing cutouts and flaps having Clark Y sections with corresponding cutouts made in wing were tested for various flap deflections, chord-wise locations, and gaps between flaps and airfoil contour. The drag was slightly lower for wing with airfoil section flaps. Satisfactory aileron effectiveness was obtained with flap gap of 20% wing chord and flap-nose location of 80 percent wing chord behind leading edge. Airflow was smooth and buffeting negligible.

Report describing power-off tests in the 6- by 6-foot test section of the stability tunnel to determine the variation of the static lateral stability characteristics with vertical-tail area, fuselage length, and wing dihedral. Two NACA 23012 rectangular wings with rounded tips and dihedral angles of 0 and 5 degrees were tested alone and in combination with three circular fuselages of different lengths. Results regarding the interference effects, effect of horizontal tail, effect of changes in fuselage length, effect of changes in vertical-tail area, effect of changes with constant tail volume, effect of changes in dihedral, and a comparison of data from 7- by 10-foot and stability tunnels are provided.

Report presenting a theoretical study of a diesel engine-compressor-turbine combination for aircraft application. The performance characteristics of the compressor and turbine chosen for analysis are believed to be attainable on present aircraft equipment.

Report discusses the results of bench testing on a German BMW 301D2 to determine the relation between the control parameters and any special methods by which the control principles are adapted to the control of the engine. Characteristics are presented for a variety of simulated manifold pressures, charge-air temperatures, engine speeds, and altitudes. Special attention is paid to the pressure characteristics of the servo-oil system and the potential effects of its failure on the operation of the automatic engine-control system.

"The NACA has conducted a flight investigation to improve the cooling characteristics of the installation of a double-row radial engine. The tests reported herein concern the use of the NACA injection impeller and ducted head baffles in various combinations on both the port inboard and the port outboard engines. The performance of the modified installation was evaluated by comparing it with that of the standard engines" (p. 1).

Report discussing a cooling-correlation equation based on the average temperature of exhaust-valve seats of a large double-row radial engine. From the equation, predicts can be made about the cooling-air pressure drop required to cool the critical region of engine cylinders. Using a modified carburetor to improve the fuel-air-ratio distribution to the cylinders increased the accuracy of the equation's predictions.

Report presenting a boundary-layer-transition and profile-drag investigation conducted on an experimental low-drag wing installed on a P-47 airplane designated the XP-47F. Measurements were made at a section outside the propeller slipstream with smooth and with standard camouflage surfaces and on the upper surface of a section in the propeller slipstream with the surface smoothed. Results regarding the right wing section outside the slipstream and left wing section in the propeller slipstream are provided.

Report discussing the effect of valve clearance on valve-lift diagrams, knock-limited performance, and engine cooling. The performance of single-cylinder and multicylinder engines was also compared across these variables.

Report discussing basic performance data obtained on the PV-2 helicopter rotor. Blade motion, rotor forces, and power were measured for static-thrust condition and a limited range of forward-flight conditions. Recommendations are provided for further testing to obtain blade-motion data and force-test data in order to develop a more detailed analysis.

Report presenting efficiency tests on a single-stage impulse turbine with an 11.0-inch pitch-line diameter wheel and a fabricated nozzle diaphragm with air at moderate temperature as the driving fluid. Results regarding the variation of turbine efficiency with blade-to-jet speed ratio over a range of turbine pressure ratios and maximum efficiency are provided.

Report discussing testing of an HNS-1 (Army YR-4B) helicopter to determine the hovering data in the ground-effect region and at altitude with an original set of rotor blades and an alternate set with different aerodynamic design and surface condition.

Report presenting a method for showing, by means of three curves, the locations of points of tangency to the envelope of the main-spray blisters generated by flying boat hull models obtained from general testing. Three equations are applied to data from general spray testing on seven models.