"An experimental investigation of the general instability of reinforced thin-walled metal cylinders was carried out at the California Institute of Technology. The basic parameters involved were the spacing and sectional properties of the stiffening elements, the wall thickness, and the diameter of the cylinder. An analysis of the experimental data led to a suitable parameter for estimating the general instability stress of reinforced metal cylinders when subjected to pure torsion loading" (p. 1).

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 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 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.

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.

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.

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.

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 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.

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.

Report presenting an investigation of the NACA 64(sub 1)A212 airfoil section equipped with a leading-edge slat, a double slotted flap, and a boundary-layer-control suction slot at 0.40 chord to determine the maximum lift coefficients attainable with the high-lift devices alone and in conjunction with one another. Results regarding the effect of suction-slot location on the characteristics of a plain airfoil, plain airfoil characteristics, effect of irregularities caused by slat installation, characteristics of the airfoil with slat extended, characteristics of the airfoil with double slotted flap, characteristics of the airfoil with leading-edge slat and double slotted flap, and a comparison of maximum lift coefficients obtained with various high-lift devices are provided.

"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).

"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).

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 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.

Report presenting a proposal for the isosceles triangle twisted into a screw surface about its axis as a propeller for transonic flight speeds. The purpose is to attain the drag reduction associated with a large sweepback in a structurally practicable configuration.

Note presenting a wind-tunnel investigation of the effect of span, spanwise location, and chordwise location of spoilers on the lateral control characteristics of an unflapped semispan wing equipped with a simple spoiler with a projection 5 percent of the chord. The chordwise investigation involved moving a 50-percent-semispan spoiler from the 50-percent-chord station to the 80-percent-chord station. Results regarding the plain-wing characteristics, spanwise investigation, and chordwise investigation are provided.

Report presenting wind tunnel measurements of the air load distribution on a canard-type model. Two combinations of lifting surface and fuselage were obtained by removing the wing and stabilizer of the model. Results regarding the fuselage pressure distribution, spanwise loading curves, and variation of lift, drag, and pitching-moment coefficients with angle of attack are provided.

Report presenting tests of a modified NACA 65(sub 1)-012 airfoil with a 30-percent airfoil-chord flap with contours simulating various distorted surface-covering shapes for the purpose of investigating practicability of reducing distortion effects to a negligible amount by maintaining an undistorted contour over a small part of the flap chord.

Note presenting an investigation to determine the effect of variations in the lateral-stability derivatives, wing loading, altitude, and radii of gyration on the combination of directional stability and effective dihedral required for lateral stability at the landing and cruising condition. The results of the investigation showed that an airplane with a high wing loading designed for high-speed and high-altitude flight would be laterally stable if the moments of inertia, the location of the principal longitudinal axis of the airplane, and the value of the damping-in-roll derivative were properly selected.

"A description is presented of the Langley two-dimensional low-turbulence pressure tunnel and a history is given of the work done at the Langley Memorial Aeronautical Laboratory which led to the achievement of a remarkably low level of turbulence in the air stream of this wind tunnel. The types of investigations to which the tunnel is suited and the methods of obtaining and correcting data are also discussed" (p. 1).

Report presenting an investigation made in the 300 mph 7- by 10-foot tunnel to determine at low speed in the longitudinal stability characteristics of a 60 degree sweptback, tapered, low-drag wing of aspect ratio 2.55. The results show undesirably large changes in the longitudinal stability characteristics of the 60 degree sweptback wings.