Report presenting an investigation to determine the effects of loading on the performance of axial-flow fan and compressor blades in a test blower. Results regarding verification of the two-dimensional design data and effects of blade roughness are provided.

Note presenting a comparison between the measured take-off ground run of an airplane equipped with seven different propeller-engine gear-ratio combinations and the computed distances by two different methods. Results indicated that the values of ground run calculated by Diehl's approximate method checked experimental values with 7 percent but were in error as much as 10 to 15 percent under certain conditions. Improved methods of thrust computation may be required in order to avoid large errors and before any more rigorous methods can be substituted for Diehl's method.

Results are presented of tests to determine the effect of brake forming in various tempers on the strength of Alclad 75S-T aluminum alloy sheet in the direction parallel to the brake. The tensile and compressive strengths of Alclad 75S-T sheet, formed in the O and W tempers, were either increased or little affected compared with those of similarly treated unformed material. When Alclad 75S-T sheet 'as received' was formed, however, the tensile yield stress was reduced about 7 percent for the with-grain direction and 1 percent for the cross-grain direction, whereas the tensile ultimate and compressive yield stresses were increased somewhat. The elongation was always slightly reduced as a result of forming.

Report presenting a spectrophotometric method for identifying and estimating approximate amounts of naphthalenic-type hydrocarbons, which is suitable for finding differences in the naphthalenic content of kerosene fractions in petroleum.

From Summary: "Previous tests of blower-blade sections have been extended by a series of tests at 52.5 degrees stagger. The results of these tests have been combined with the earlier test results and are presented in new blade design charts which supersede those previously presented. An investigation in a test blower over a range of stagger from 44 degrees to 65 degrees has shown that for blades at a solidity of 1.0, the two-dimensional cascade data predict the turning angle to within 1/2 degrees."

Note presenting tests of 12 wing-fuselage combinations employing triangular and 18 employing elliptical fuselages made in the NACA variable-density tunnel as part of a program to investigate at large values of Reynolds number the aerodynamic effects of wing-fuselage interference. The parameters of combination covered in the investigation were the vertical position of the wing with respect to the fuselage axis, wing shape, and wing-fuselage juncture shape.

Report presenting two-dimensional span-loading tests of a two-foot-chord NACA 65(sub 1)-012 airfoil model in the stability tunnel to determine tunnel-wall boundary-layer effects. Testing indicated that a small loss in average load may be expected. Results regarding tunnel-wall velocity profiles, pressure distributions, spanwise surveys, and force and moment coefficients are provided.

"A general description of the field operations of the U.S. Weather Bureau thunderstorm project conducted in the vicinity of Orlando, Florida during the summer month of 1946 is given. The participation of NACA in this project is described and measurements of atmospheric turbulence taken by NACA are presented for one of the flights. The results indicate that some regions of thunderstorms may present no great hazard to flight, while exceptionally severe conditions of atmospheric turbulence may occur in other regions, or even in the same region, at about the same time" (p. 1).

Report presenting the application of dimensional analysis to the computation of the main bearing of a V-type in-line aircraft engine. Two crankshafts have been considered, one designed for higher operating speed than the other. Two types of engines are considered: one for regular V-type engines and one for production V-type engines.

"The results obtained from a series of flight measurements of atmospheric turbulence within convective-type clouds and from meteorological soundings are presented together with descriptions of the flights and concurrent weather conditions. These results are presented to provide a background of experience for the forecaster and pilot by illustrating the turbulence conditions as indicated by effective gust velocities in convective-type clouds under spring and summer weather conditions along the eastern coast of the United States" (p. 1).

Report presenting comparisons of 24S-T aluminum-alloy flat compression panels with longitudinal Z-section stiffeners and panels with flat FS-1E magnesium-alloy sheet and longitudinal 24S-T aluminum-alloy Z-section stiffeners. The use of the composite magnesium-alloy, aluminum-alloy construction permits wider stiffener spacing with little to not loss in structural efficiency or stress for local buckling. Results regarding stiffener spacing, proportions, and consideration of the different material constructions are provided.

Note presenting an electromagnetic-analogy model of the vortex load, estimated from lifting-line theory with an arbitrary fairing near the elevator tip, on a thin elliptic horizontal tail surface of aspect ratio 3 with a 0.5-chord 0.85-span plain elevator was constructed and tested. A comparison of the aspect-ratio corrections for the partial-span elevators was made with those previously presented for full-span elevators. Wind-tunnel results for a tail surface of the some plan form are presented.

Report presenting measurements in sideslipping flight of the pressure distribution over the horizontal tail surface of a tractor-propeller-driven pursuit airplane to determine the effects of angle of sideslip and propeller operation on the tail-load distribution. Results regarding the reduction of data, effect of sideslip and power on tail loads, effect of sideslip and power on tail moments, and a comparison of the calculated loading with experimental results.

Research was undertaken to ascertain the properties of better wrought heat resisting alloys in the form of large discs required for gas turbine rotors. The properties of large discs of low carbon N-155 alloy in both the as-forged and water-quenched and aged conditions were determined by means of stress-rupture and creep tests for time periods up to about 2000 hours at 1200, 1350, and 1500 F. Short-time tensile test, impact test, and time-total deformation characteristics are included.

Report presenting flight tests to evaluate an elevator stick-force bungee and engine tilt as methods of improving the longitudinal-control characteristics of an existing airplane. The stick-force bungee was found to be the simplest and most effective modification.

Report presenting the effects of various catalysts used to cure resinous adhesives on the strength properties of plywood, especially in regard to the degree of solidity developed by the catalysts in the resin film and the plywood. Six resins were tested with birch wood, which is the most commonly used wood in aircraft construction.

Report presenting a series of tests with a single-cylinder engine in order to determine the effect on volumetric efficiency and on engine performance of changing the ratio of exhaust-valve flow capacity to inlet-valve flow capacity when operating with exhaust pressure equal to inlet pressure.

Report presenting a series of tests made with a CFR engine to determine the effect of inlet-valve capacity, inlet and exhaust pressure, and valve timing on the volumetric efficiency at various speeds. Three combinations of inlet and exhaust pressures and seven valve-timing arrangements were used.

Report presenting the results of an investigation of a specific tail configuration in the 15-foot free-spinning tunnel in order to supplement the existing published data on hinge moments of elevators and rudders in spins. Hinge-moment measurements are presented for a balanced elevator equipped with trim tabs and for a balanced rudder. Results regarding elevator hinge moments, rudder hinge moments, and application of hinge-moment data are provided.

Report presenting a dynamometer-stand investigation to determine the effect of exhaust pressure on the performance of a 12-cylinder liquid-cooled aircraft engine equipped with a conventional exhaust collector. The results are presented in the form of curves that show the effect of exhaust pressure on engine power, charge-air flow, volumetric efficiency, inlet-manifold mixture temperature, exhaust-gas temperature, cylinder-head temperature, and heat rejected to the coolant.

Report presenting theoretical and experimental data for NACA 6A-series basic thickness airfoils, which were designed to eliminate the trailing-edge cusp present in NACA 6-series sections. Results indicated that the section minimum-drag and maximum-lift characteristics of the 6-series and 6A-series airfoil sections are essentially the same. Drag, lift, pitching-moment characteristics, and aerodynamic center are also provided.

Note presenting force tests of two isolated vee-tail surfaces with various amounts of dihedral made to provide an experimental verification of a simplified vee-tail theory and the results are presented which were found to be in good agreement with calculations of previous reports. Plots of the basic test data and summaries of the data in the form of plots of the variation of static-stability derivatives and control-effectiveness parameters with dihedral angle are included.

Report presenting a correlation of the experimental and calculated effects of the product of inertia on the stability of lateral oscillations of airplanes. The experimental and calculated boundaries were in good agreement with one another, but neglecting the product of inertia led to wide discrepancies. Results regarding stability and its influence on general flight behavior are provided.

Report presenting a set of charts for the convenient determination of flow conditions behind a shock wave and at the surface of inclined planes and axially symmetric cones located in a uniform frictionless supersonic air stream. Shock angle, static-pressure coefficient, static-pressure ratio, total-pressure ratio, Mach number ratio, and velocity ratio for two-dimensional and conical flow fields are plotted for a range of free-stream Mach numbers.