Report presenting a summary of the hydrodynamic qualities of interest in the normal operation of a seaplane, established over a period of years by model testing and by some knowledge of full-size operation. Results regarding longitudinal stability and control, landing stability, seaworthiness, performances, and lateral stability and control are provided.

Note presenting a method for the calculation of bending stresses due to torsion in a tapered box beam. A special taper was assumed in which all flanges, if extended, would meet at a point. The results obtained by this method were compared with experimental data obtained from tests performed on a tapered box beam.

Report presenting a determination of the tunnel-induced velocities for yawed and swept-back airfoils in a closed circular wind tunnel. Calculations were performed for elemental horseshoe vortices with one tip of the bound vortex on the tunnel axis for a range of yaw angles and bound-vortex lengths.

Report presenting calculations of the supersonic wave drag at zero lift for a series of wings with thin symmetrical biconvex sections with untapered plan forms and various angles of sweepback and aspect ratios.

Report presenting charts with coefficients for the stress analysis of a reinforced circular cylinder. They allow for the rapid determination of sheer flows and direct stresses in the sheet of a cylinder as well as the shear forces, axial forces, and bending moments in the rings. Separate charts are also given for three basic ring loadings.

Report presenting the aerodynamic characteristics of 19 isolated tail surfaces, which have been determined by wind tunnel tests. Testing was also made of rectangular airfoils of various aspect ratios with and without double end plates of various shapes. The analysis indicated that the slope of the lift curve could be predicted within 10 percent for all models by use of lifting-surface-theory equations.

Note presenting the rolling moments of one tapered wing and two geometrically similar wings in rolling flow with the wing stationary and in straight flow with forced rotation of the wing to obtain a correlation between the two methods of testing and to determine the rolling characteristics of the wings. The results showed that for unswept wings the rolling characteristics obtained by rotation of the air agreed with those obtained by forced rotation of the wing.

"A solution based upon small-deflection theory is presented for the critical shear stress of curved rectangular panels with simply supported edges. Computed curves which cover a wide range of panel dimensions are presented; these curves are found to be in good agreement with test results. Estimated curves are also given for panels with clamped edges" (p. 1).

Report presenting a method for the calculation of elastic stresses in symmetrical disks typical of those of a high-temperature gas turbine. Illustrative examples are presented to demonstrate how to treat solid disks, disks with central holes, and disks constructed of a single material or two or more welded materials.

Report presenting an analytical treatment of the problem of determining the distribution of reaction forces among multiple plain bearings supporting a shaft subjected to rotating loads. An investigation conducted on a straight shaft operating in a seven-bearing crankcase of an aircraft engine is presented to show the importance of the hydrodynamic effect of the oil film.

Report presenting an investigation of the effects of several spoiler arrangements on the spanwise variation of section twisting moments of a wing of NACA 230-series airfoil sections. Both plain and perforated spoilers were tested at a designated Mach and Reynolds number and force and moment measurements as well as chordwise pressure-distribution measurements at six spanwise stations were obtained.

Wing was tested with full-span, partial-span, or split flaps deflected 60 Degrees and without flaps. Chordwise pressure-distribution measurements were made for all flap configurations.. Peak values of maximum lift coefficient were obtained at relatively low free-stream Mach numbers and, before critical Mach number was reached, were almost entirely dependent on Reynolds Number. Lift coefficient increased by increasing Mach number or deflecting flaps while critical pressure coefficient was reached at lower free-stream Mach numbers.

"The analogy between the distribution of stresses in flat stiffened panels and the distribution of electric current in a ladder-type resistance network is used as the theoretical basis of an electrical computer for the rapid solution of shear-lag problems. The computer, consisting of variable resistors and multiple-current sources, is described; and typical examples are given of its use. The analogy is extended to include bolted-joint problems, and an example is given also" (p. 1).

The aerodynamic characteristics of seven unswept tapered wings were determined by calculation from two-dimensional data and by wind-tunnel tests in order to demonstrate the accuracy of the calculations and to show some of the effects of aspect ratio, taper ratio, and root thickness-chord ratio. The characteristics were calculated by the usual application of the lifting-line theory which assumes linear section lift curves and also by an application of the theory which allows the use of nonlinear lift curves. A correction to the lift for the effect of chord was made by using the Jones edge-velocity factor. The wings had aspect ratios of 8, 10, and 12, taper ratios of 2.5 and 3.5, and NACA 44-series airfoils.

Report presenting tests to determine the damping in roll and aileron rolling effectiveness of three wings with different degrees of sweepback. The results showed that the values of damping in roll decreased with increasing sweepback. The rolling effectiveness of the aileron of the sweptback wing was found to be predicted with fair accuracy from static aileron-rolling-moment tests and wing-damping tests.

Sinusoidal waves excited by random disturbances have been observed in the laminar boundary layer of a rotating disk at Reynolds numbers in a narrow range below the Reynolds number of transition. Their frequency was found to be approximately a constant times the velocity of the disk. The velocity of the waves at the radius of 11 inches was determined and found to be 0.2 linear velocity of the disk in a downstream direction, making an angle of approximately 14 degrees with the outward drawn radius vector.

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 testing of a double-hinged horizontal tail on a small low-speed airplane to determine the longitudinal stability and control characteristics. The flying characteristics of the airplane equipped with the double-hinged horizontal tail surface were generally satisfactory. The primary effect of removal of the elevator seal was a decrease in the elevator effectiveness.

Report presenting power-off flight tests in the free-flight tunnel to determine the dynamic stability characteristics of an airplane model with a 42 degree sweptback wing of aspect ratio 5.9 and taper ratio 0.5. The static-stability and wing-stall characteristics of the model were also determined. Results regarding force tests, flow surveys, and flight tests are provided.

Report presenting a flight investigation in the free-flight tunnel to determine the severity of the dynamic stability and control problems associated with 62 degrees sweepback. In addition to the flight tests, force tests and tuft tests were made to determine the static-stability and wing-stall characteristics, and calculations were made to determine the boundary of zero damping of the lateral oscillation.

Note presenting a determination of friction coefficients for three constant-area vaneless diffusers, used in conjunction with a centrifugal impeller, from static- and total-pressure surveys taken at several radii and from the usual overall measurements of temperature, pressure, and air flow. The average value of the friction coefficient through the entire diffuser was approximately 50 percent higher than that for fully developed turbulent flow in smooth pipes.

Report presenting an investigation of the forward-flight performance characteristics of a typical single-rotor helicopter equipped with main and tail rotors. Testing occurred over a range of tip-speed ratios and thrust coefficients. Results regarding the fuselage effects and rotor characteristics are provided.

Report presenting a set of equations based on the first mode of wing bending for determining the dynamic responses of an airplane wing structure as induced by gusts. The representation of the airplane is such that the aerodynamic damping of the vibratory motion of the wing is separate from that of the vertical motion of the airplane as a whole.

Report presenting a procedure for obtaining the pressure distribution in a two-dimensional, incompressible, and nonviscous flow on an arbitrary airfoil section in cascade.