Report presenting an investigation of the two-dimensional aerodynamic characteristics of 15 NACA airfoils at four Reynolds numbers. The results indicate that the drag coefficient at the design lift coefficient and the maximum lift coefficient are the most important aerodynamic characteristics and are most affected by Reynolds number changes.

Report presenting an investigation in the two-dimensional low-turbulence pressure tunnel to determine the aerodynamic characteristics of the NACA 8-H-12 airfoil section at four Reynolds numbers. The section lift, drag, and pitching-moment characteristics are presented for smooth and rough surface conditions. Generally, no unusual scale effects are present for either condition.

From Introduction: "Although the aerodynamic characteristics of the components of such configurations may be well known, the mutual interference resulting from combining the wings, as well as the wings and body, may be so great that is desirable to study the aerodynamic properties of the complete configurations. Two methods of handling this problem are presented in this report. The first method is essentially an extension of the theory for slender wing-body combinations of reference 1 to determine the load distribution, forces, and moments exerted on slender cruciform-wing and body combinations inclined simultaneously at small angles in pitch and yaw. "

"Several methods (references 1 and 2) based on gas-dynamic principles are available for reducing such measurements. The results obtained by these methods are subject to the limitation of the gas-dynamic theory which is that the mean free path of the molecules between impacts, is small with respect to the measuring device. Inasmuch as no information on the subject is to present known to be available, the purpose of the present paper is to present a method based on the concept of free-molecule theory for use in connection with this problem" (p. 1).

From Summary: "The purpose of this investigation was to determine whether such airplanes could be made to fly uncontrolled for an indefinite period of time without getting into dangerous attitudes and for a reasonable period of time (one to three minutes) without deviating excessively from their original course. The results of this analysis indicated that the uncontrolled motions of a personal airplane could be made safe as regards spiral tendencies and could be greatly improved as regards maintenance of course without resort to an autopilot."

From Introduction: "The flare assumed is based primarily on reference 1, in which information permitting calculation of the flare characteristics of an airplane was obtained from flight tests. The results of calculations for airplanes having constant lift-drag ratio during the flare are plotted in chart form."

"This report is the second phase of a broad program of study of the transient motions of helicopters in autorotative flight. The first phase (reference 1) dealt with the steady-state condition of autorotative vertical descent. This report is concerned with the the transition from the steady condition of hovering to the steady autorotative descent" (p. 1).

"This report is the result of the first part of a broad program to analyze the transient motions of a helicopter, which occur in the various phases of flight following power failure" (p. 1).

From Summary: "Included in the report are the results of total-pressure surveys made at downstream ends of the mixing tubes."

From Summary: "In order to facilitate the application of miscellaneous airfoil data to the problems of the helicopter designer, a discussion of a number of the problems most frequently arising is presented. A reference list of published papers on airfoil section characteristics (or their application) which experience has shown to be useful in connection with these helicopter problems is included."

Note presenting general methods of solution for the two- and three-dimensional steady-state and two-dimensional unsteady-state equations. Four applications of the general solutions are given.

Note presenting some of the basic general equations governing the three-dimensional compressible flow of gas through a compressor or a turbine in terms of velocity components, total enthalpy, and entropy. The equations are applied to investigate the maximum compatible number of the radial variations of the gas properties between successive blade rows that a designer is free to specify.

Note presenting an approximate method developed to predict the location of detached shock waves ahead of two-dimensional and axially symmetric bodies. The method is based on the continuity relation, which is applied to the air that passes the sonic line.

Note presenting an investigation to determine the fatigue-strength values for 24S-T aluminum alloy when subjected to various ratios of biaxial stresses. The stresses considered were both tensile. The results indicated that uniaxial fatigue-strength values in the longitudinal direction cannot be used to predict the fatigue strength, and that biaxial fatigue strength may be as low as 50 percent of the uniaxial fatigue strength.

Report presenting a wind-tunnel investigation to determine the boundary-layer and stalling characteristics of the NACA 63-009 airfoil section. Pressure distributions, tuft studies, and boundary-layer measurements were obtained. A localized region of flow separation was found to develop on the upper surface of the airfoil near the leading edge.

Report presenting the boundary-layer and stalling characteristics on an NACA 64A006 airfoil section at a Reynolds number of 5,800,000. Data included measurements of lift, drag, and pitching moment, chordwise distributions of pressure, visual studies of the boundary-layer flow, and surveys of the static-pressure and velocity distribution within the boundary layer. Results regarding force and moment characteristics, pressure distributions, and boundary-layer characteristics are provided.

Note presenting an investigation of the problem of the buckling of parallel simply supported tension and compression members connected by equally stiff and equally spaced elastic deflection springs as an approximation to the problem of the effect of finite stiffness of ribs and tension surface on the buckling load of the compression surface of a wing. Charts relating compressive buckling load, deflectional spring stiffness, and the ratio of the flexural stiffness of the members are given for tension and compression members with various numbers of spans.

Report presenting a comparison between the calculated design performance of a gas-turbine stator blade and its performance in a sector of an annular cascade tunnel. The gas velocities on the blade surface were computed by the stress filament method and compared with experimental values, with which they agreed satisfactorily. Results regarding discharge angle, vane-surface-velocity distribution, tangential- and axial-velocity distribution, and radial-equilibrium consideration are provided.

Report presenting a landing investigation with a flying boat with a conventional configuration to determine the applicability of hydrodynamic impact theory in defining full-scale water impact loads. The results indicated that in addition to chine flare and angular rotation, there are many other factors that may affect overall load, such as elasticity effects, sustained pressures on the area behind the chine, and the effect of variation of wing lift during impact.

Report presenting an investigation of pitching moments and center-of-pressure locations obtained from a landing investigation in smooth water of a conventional flying boat as compared to values predicted by general hydrodynamic impact theory. Landings were generally moderate and covered as wide a range of trim and velocities as practical. Results regarding the center of pressure and pitching moments are provided.

Report presenting comparisons of the structural efficiency of panels with straight-web and curved-web Y-section stiffeners. In the high-stress region in which failure is at least in part associated with local buckling, panels with curved-web Y-section stiffeners have higher structural efficiencies than panels with straight-web Y-section stiffeners, which is evidenced by higher average stresses at failure, smaller stiffener heights, or wider average spacing of rivet lines.

Note presenting pressure distribution measurements made on the wing of a fighter-type airplane to determine the span loading and to compare center-of-pressure results with those obtained by strain-gage measurements on the same airplane during a previous flight investigation. Flight tests were all made at a pressure altitude of about 30,000 feet and covered a Mach number range from approximately 0.35 to 0.81. Results regarding additional air load, spanwise center of pressure of additional air load, basic air load distribution, and span loading during a stall and buffeting are provided.

Note presenting a theoretical solution for the problem of the compressive buckling of flat rectangular Metalite type sandwich plates with simply supported loaded edges and clamped unloaded edges. The solution is based on the general small-deflection theory for flat sandwich plates developed in a previous report. Results regarding stability orientation and buckling curves, comparison with approximate solution, correction for plasticity, and comparison of theory and experiment are provided.

"Charts are presented for the analysis of the stability under compression of simply supported rectangular plates with one, two, three, and an infinite number of identical equally spaced longitudinal stiffeners that have zero torsional stiffness" (p. 1).