"The effects of lip thickness on inlet performance are estimated as functions of mass flow for subsonic and supersonic flight speeds. At subsonic speeds, pressure-recovery losses and additive drag are shown to decrease linearly with increasing lip frontal area if the maximum suction force is attained. At supersonic speeds, inlet drag increases linearly with inlet lip frontal area at full mass flow. For reduced mass flow, some reduction in additive drag is possible with lips of moderate thickness, but the magnitude of this reduction becomes negligible as flight speed increases" (p. 1).

Report presenting surveys made through a turbulent boundary layer on a flat plate by means of a pitot probe, an X-ray densitometer, and hot-wire and cold-wire probes. Results were analyzed to determine the reliability of basic data and how well the distributions of properties in the boundary layer compare with those assumed in theoretical analyses.

"A mathematical procedure is herein developed for obtaining exact solutions of shear-lag problems in flat panels and box beams: the method is based on the assumption that the amount of stretching of the sheets in the direction perpendicular to the direction of essential normal stresses is negligible. Explicit solutions, including the treatment of cut-outs, are given for several cases and numerical results are presented in graphic and tabular form. The general theory is presented in a from which further solutions can be readily obtained" (p. 1).

"A simplified compound-pendulum method for the experimental determination of the moments of inertia of airplanes about the x and y axes is described. The method is developed as a modification of the standard pendulum method reported previously in NACA report, NACA-467. A brief review of the older method is included to form a basis for discussion of the simplified method" (p. 1).

Report presenting testing of a 16-inch-diameter supersonic impulse rotor with guide vanes in Freon-12. Results regarding the overall performance and blade-element performance are provided.

Report presenting results to show the effects on the flutter characteristics of mounting concentrated weights at various positions on an untapered wing model. The moment of inertia, chordwise position of the weight, and spanwise position of the weight were varied. Results regarding the flutter parameters, flutter-speed ratio, flutter-velocity coefficients, and curves of ratio of first-bending frequency to torsion frequency and second-bending frequency to torsion frequency and provided.

"The average low-speed jet-boundary constriction correction is presented for a large model spanning a closed circular tunnel. The experimentally determined variation of the local constriction correction with spanwise and chordwise location is also shown. A brief comparison with existing theory is given for the constriction correction and the induced-curvature correction resulting from lifting section" (p. 1).

"Experimental results of lifts and moments about the quarter chord of a two-dimensional wing at subsonic Mach numbers are presented. A comparison of the experimental magnitude of the lift vector with the theory as given by Dietze showed good agreement. Comparisons of the moments and the quadrature component of lift with theory indicated that some refinements in the testing technique are necessary for the experimental determination of these quantities in the transonic range" (p. 1).

From Summary: "Interferometric measurements were made of the density profiles of an unsteady turbulent boundary layer on the flat wall of a shock tube. The investigation included both subsonic and supersonic flow (Mach numbers of 0.50 and 1.77) with no pressure gradient and with heat transfer to a cold wall. Velocity profiles and average skin-friction coefficients were calculated. Effects on the velocity profile of surface roughness and flow lengths are examined."

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.

"Two straight mineral oils and a polymer-containing oil have been tested in a rotating-cylinder viscometer at high shear rates (maximum 0.25 million reciprocal seconds) and the accompanying heat effects have been investigated. The torque measurements are of low accuracy and fail to establish the moderately non-Newtonian behavior of the polymer-containing oil, but the temperature measurements, which are in good agreement with a thermal analysis, do indicate the presence of temporary viscosity decrease at high shear rates for this oil" (p. 1).

Report presenting skin-friction measurements for three bodies of revolution of fineness ratio 12.2 with different shapes and pressure distributions: an ogive-cylinder, a cone-cylinder, and a parabolic body. Tests were made at zero angle of attack and over a range of Reynolds numbers based on body length. Results regarding transition and skin friction, surface-temperature surveys, and correlation of pressure-gradient effects are provided.

"An exploratory wind-tunnel investigation has been made to determine the lift effects of blowing from nacelles over the upper surface of flaps on a model having a delta wing of aspect ratio 3. Several flap conditions were examined. High-pressure air was blown from an external-pipe arrangement supported above the wing to simulate jet-engine exhaust. The jet momentum- coefficient range was from 0 to 3.0 and the model angle of attack was 0 degrees" (p. 1).

Report presenting an exploratory wind-tunnel investigation to determine the lift effects of blowing from nacelles over the upper surface of flaps on a model with a delta wing of aspect ratio 3. The results indicate that the values of jet-circulation lift coefficient larger than the jet reaction were produced with blowing over flaps fro nacelles mounted above the wing. Results regarding lift coefficients, pitching-moment coefficients, and drag coefficients are provided.

Note presenting a study of the improvement of the performance of airfoils by abrupt changes in contour.

Note presenting fatigue tests at zero mean load on 190 multiple-rivet joints with 1/8 inch diameter A17S-T3 100 degree countersunk-head rivets. Joints made by dimpling showed marked superiority in both fatigue and static strengths to those made by machine countersunking. The relationships between measured static properties of lap joints and fatigue life for the four materials are given.

Report presenting fatigue testing in rotating bending on severely notched bars machined from 2024-T4 aluminum-alloy extruded round rods. Two sizes of specimens were studied.

Note presenting an investigation to determine the influence of biaxial tensile stresses on the fatigue strength of a 14S-T4 aluminum alloy when subjected to various ratios of biaxial stresses. The effect on the fatigue strength of varying the ratio of the biaxial stresses was studied. Anisotropy of the material was found to be the main characteristics that affected fatigue strength.

From Summary: "This reports presents of axial-load fatigue tests on notched specimens of three sheet materials: 24S-T3 and 75S-T6 aluminum alloys and normalized SAE 4130 steel. Each specimen was notched by edge notches designed to have a theoretical stress-concentration factor of 5.0. Tests were run at four levels of nominal mean, stress: 0, 10,000, 20,000, and 30,000 psi. Results of these tests extend information previously reported from tests on unnotched specimens and on specimens less severely notched."

Report presenting the results of axial-load fatigue tests on notched specimens of three sheet materials: 24S-T3 and 75S-T6 aluminum alloys and SAE 4130 steel. Fatigue tests were run at several levels of nominal mean stress, including a zero nominal mean stress. Fatigue tests for notched specimens are compared with previously reported unnotched specimens of the same materials.

From Summary: "As a preliminary step in an investigation of control-stick vibration in direct-control autogiros, the periodic variations in the moments transmitted through the control system of a YG-1B autogiro were recorded in flight. The results of the measurements are presented in the form of coefficients of Fourier series expressing the varying part of the lateral and the longitudinal moments acting between rotor and fuselage at the control trunnions. The most important component of the variation in stick force was found to have frequency of three times the rotor speed and an amplitude that rose from negligible values at tip-speed ratio below 0.20 to +/-5.2 pounds longitudinally and +/-3.2 pounds laterally at tip-speed ratios of 0.35. Variations in stick force at all other frequencies were small in comparison with those at three times the rotor speed."

Report presenting a flight investigation on a four-engine bomber airplane to determine the effects of wing flexibility on wing strains developed in flight through clear-air turbulence. Amplification of the effects appeared to be a function of gust-gradient distance and was not significantly affected by airspeed or weight.

Flight tests were made to demonstrate the particularity of employing fixed tabs in conjunction with a suitably designed differential linkage to reduce the force required to operate ailerons. The tests showed the system to be practicable with tabs of the inset type. The relative ineffectiveness of attached tabs for changing the aileron floating angle rendered them unsuitable. Experience gained in the investigation has indicated that the use of the system is limited to maximum deflections of one aileron relative to the other of less than 30 degrees and that the differential linkage should always be designed on the basis of the highest probable floating angle.

Note presenting vibratory stress measurements obtained in flight on a modified supersonic propeller for forward mach numbers up to 0.95. The magnitude of the vibratory bending stress was low in relation to the strength of the material throughout the flight range of the airplane. Results of a propeller feathering operation at a Mach number of 0.95 indicated no excessive stresses.