Note presenting an investigation to study the stress distribution within cemented and riveted metal joints by use of an analogous joint constructed of a highly flexible material. By means of displacement measurements obtained from foam-rubber analogs, it is shown that the distribution of shear in these joints is not uniform over the length of the joint, but that it is greater near the ends than it is in the middle.

Droplet trajectories about a sphere in ideal fluid flow were calculated. From the calculated droplet trajectories the droplet impingement characteristics of the sphere were determined. Impingement data and equations for determining the collection efficiency, the area, and the distribution of impingement are presented in terms of dimensionless parameters. The range of flight and atmospheric conditions covered in the calculations was extended considerably beyond the range covered by previously reported calculations for the sphere.

From Summary: "The trajectories of water droplets in the air flowing past an NACA 6511004 airfoil at a n angle of attack of 0 deg were determined. The amount of water in droplet form impinging on the airfoil, the area of droplet impingement, and the rate of droplet impingement per unit area on the airfoil surface were calculated from the trajectories and presented t o cover a large range of flight and atmospheric conditions. These impingement characteristics are compared briefly with those previously reported for the same airfoil at angles of attack of 4 deg and 8 deg."

From Introduction: "The surging of a system containing a centrifugal- or axial-flow compressor (e.g., refs. 1 to 4) is an example of self-sustained oscillation. Inlets designed for supersonic jet engines also have been observed to induce oscillations (e.g., refs. 5 to 11) which are usually referred to as "buzz." The origin of buzz in ram-jet engines is the subject of the present report."

Report presenting an investigation of the stall operation of an annular cascade under varied conditions of geometry and air flow. Controlled variables included angle of attack, blade chord and spacing, number of blades in the cascade, and air velocity. Results regarding stalling flutter, vibratory stress, aerodynamic damping characteristics, nature of vibrations, and presence of rotating stall are provided.

Note presenting the inflow distributions, azimuth and spanwise, as determined analytically from measured pressure distributions and blade-motion data on a model helicopter rotor blade under hovering and simulated forward-flight conditions. Pressures and corresponding blade flapping were recorded for various rotor conditions at tip-speed ratios of 0.10 to 1.00. Results regarding the general considerations of blade flapping motion, zero-offset rotor, and offset rotor are provided.

Note presenting an analysis carried out for a 6:1 elliptical airfoil at the angle of attack for maximum lift that requires specification of a dynamic lift curve for the airfoil section at or near stall, presumably including the effect of lift hysteresis. Consideration of the familiar experimental fact of Magnus lift on a rotating cylinder indicates a theoretical approach to the question of aerodynamic hysteresis which, although not definitive, may prove helpful.

Report presenting the effects of increased damping in roll, pitch, and yaw on the flying qualities of a single-rotor helicopter for precision flight as studied using visual maneuvers and instrument approaches. For a representative single-rotor helicopter, increased damping can reduce random deviations fro the desired flight path and can decrease the effort required of the pilot. Some operational aspects of helicopter instrument approaches are also included.

Note presenting a summary of the effects of plan form and thickness on the lift and drag characteristics of wings at transonic speeds. The data were obtained in the high-speed 7- by 10-foot tunnel by the transonic-bump method over a range of Mach numbers. Results regarding lift, drag at zero lift, and drag due to lift are provided.

From Summary: "Mass flow and momentum for various fractions of a turbulent boundary layer are presented in chart form for a range of velocity profiles and for Mach numbers from 0.2 to 5.0. These charts are intended to assist the analyst and designer of boundary-layer removal systems. Application of the charts to inlets of arbitrary shape and to the determination of the pressure recovery of rectangular, normal-shock inlets immersed in boundary layer is described."

Note presenting an investigation to determine the effects of airspeed and angle of attack on the lift, drag, and pitching moment of a shrouded-propeller model with a shroud length of about two-thirds the propeller diameter over an angle of attack from 0 to 90 degrees. Tests were made of the complete model with the propeller operating and also of the shroud and motor combination with the propeller removed.

Report presenting low-speed measurements of the lift, drag, pitching moment, and pressure distribution of 4 airfoil sections over a range of Reynolds numbers. Results indicated that the nature of the stalls depends on the Reynolds number. Low Reynolds numbers tend to be favorable to the thin-airfoil type of stall while high Reynolds numbers are favorable to to the leading-edge type of stall.

Report presenting formulas for the forces and moments due to vortex interference on slender wing-body-tail combinations of general cross section in terms of positions and strengths of shed vortices. The analysis is applicable to steady motion and motions which can be considered to be made up of a succession of steady states.

Report presenting the calibrations of four airspeed systems installed in a North American F-86A airplane as determined in flight at Mach numbers up to 1.04 by the NACA radar-phototheodolite method. The nose-boom installation was found to be most suitable for research at transonic and low supersonic speeds. Two different wing-tip booms were also tested.

Results of an exploratory free-flight investigation at zero lift of several rocket-powered drag-research models having rectangular 6-percent-thick wings are presented for a Mach number range of 0.6 to 1.7. Wings having diamond, circular-arc, and blunt-trailing-edge airfoil sections were tested. Pressures over the base of the blunt-trailing-edge airfoil were measured. The drags of all the models were measured and are compared with theory in this paper.

Report presenting an exploratory free-flight investigation at zero lift of several rocket-powered drag-research models with tapered 4-percent-thick wings for a range of Mach numbers. Results regarding the total-drag coefficient, wing drag coefficients, and drag-coefficient components are provided.

Note presenting an analysis of the laminar compressible boundary layer and heat transfer over an isothermal semi-infinite flat plate moving with a time-dependent velocity. First-order deviations from the quasi-steady velocity and temperature profiles and boundary-layer characteristics have been computed.

Note presenting a theoretical study of the sound field from a random noise source above ground as measured by a receiver with finite band width. The study represents one phase of a general program of research in atmospheric acoustics.

Note presenting a review of experiments on biaxial alternating stresses and simple combinations of static stress with alternating stress, which is shown to lead to a general criterion for the effect of static stress on the permissible amplitude of alternating stress. Tests were performed to determine the effect of static compression on alternating torsion, which is the one simple combination that had not been previously investigated. The results agree with the criterion.