"In the present paper, under the same lineaeizing assumptions as are made in the derivation in reference 1 but with the explicit consideration and simplification of the form of the wake extending from the rear of the airfoil, the methods of Theodorsen (reference 2) have been extended to obtain the forces on the airfoil not only at a fixed angle of attack but also in arbitrary motion" (p. 1).

"A simple approximate method is given for the calculation of isentropic irrotational flows past symmetrical airfoils, including mixed subsonic-supersonic flows. The method is based on the choice of suitable values for the streamline curvature in the flow field and the subsequent integration of the equations of motion. The method yields limiting solutions for potential flow. The effect of circulation is considered" (p. 1).

Report presenting a method for the calculation of the buckling stress of a multiweb wing in bending as well as design charts based on this method for the minimum-weight design of 24S-T aluminum alloy sheets, extruded 75S-T aluminum alloy, and extruded 0-1HTA magnesium alloy. An example of the use of the charts is also provided.

Note presenting a theoretical solution for the buckling stresses of long plates with transverse curvature loaded in shear and longitudinal direct stress. The theoretical critical-stress combinations for plates with either simply supported or clamped edges are given in figures and tables and a comparison is made with previous theoretical solutions. Results regarding the theoretical results, empirical results and design curves, and some interaction formulas are provided.

"A theoretical solution is presented for the determination of the combinations of direct axial stress and torsion which cause thin-walled cylinders with either simply supported or clamped edges to buckle. This theoretical solution is used in conjunction with available test data to develop empirical curves and formulas for use in design. Comparisons are made with theoretical and empirical solutions obtained in other investigations" (p. 1).

"A theoretical solution is presented for the buckling stress of long plates with transverse curvature loaded in shear. The results are given in the form of curves and formulas for plates with simply supported or clamped edges for a wide range of plate dimensions. Comparisons are made with theoretical solutions obtained in previous investigations" (p. 1).

"Empirical design curves are presented for the critical stress of thin-walled cylinders loaded in axial compression. These curves are plotted in terms of nondimensional parameters of small-deflection theory and are compared with theoretical curves derived for the buckling of cylinders with simply supported and clamped edges. An empirical equation is given for the buckling of cylinders having a length-radius ratio greater than about 0.75" (p. 1).

Note presenting a theoretical solution for the critical stress of thin-walled cylinders loaded in torsion. The results are presented in terms of simple formulas and curves which are applicable to a wide range of cylinder dimensions. The theoretical results are found to be in fairly good agreement with experimental results.

Note presenting an investigation to determine the reduction in drag that could be obtained for a conventional-type flying-boat hull by means of aerodynamic refinements. For comparisons, tests were made on a streamline body simulating the fuselage of a modern transport airplane.

Report presenting flutter tests of two wind-tunnel-fan models, one with conventional Clark Y airfoil sections and one with high-camber blade sections. The results indicated that higher flutter speeds were present for high lift coefficients for high-camber blades. Results regarding lift coefficients, blade-tip twisting, power loading, critical Mach numbers, flutter point, vibrational frequencies, and stall-flutter tip Mach number are provided.

Report presenting a review of literature to determine the frequency of sound of a given source strength that is loudest at various distances from the source. Frequencies in the range from 500 to 1000 cycles per second were found to be the easiest to hear, even at a distance of several miles. Sound data obtained from a light trainer airplane showed good agreement with predictions.

Report presenting an investigation in the free-spinning tunnel to determine the effect of horizontal-tail position on rudder hinge moments in simulated spinning conditions. Hinge-moment measurements were made on an unbalanced rudder on a rectangular vertical tail at six positions on the horizontal tail. Results regarding rudder hinge moments, tuft tests, and application of the hinge-moment data are provided.

Report presenting a wind-tunnel investigation to determine the effect of length-beam ratio on the aerodynamic characteristics of a family of flying-boat hulls in the presence of a wing. The hulls were designed to have approximately the same hydrodynamic performance with respect to spray and resistance characteristics. Results regarding the two-dimensional and three-dimensional mounting setups, drag reduction, and aerodynamic refinement effects are provided.

Report presenting calculations to determine the influence of changes in temperature distribution and elastic material properties on calculated elastic stresses for a typical gas-turbine disk. Severe temperature gradients caused thermal stresses of sufficient magnitude to reduce the operating safety of the disk.

Note presenting a description of the improvements in the design of equipment associated with the hot-wire anemometer for the measurement of fluctuating-air flow quantities. An improved technique and an electronic circuit for the frequency compensation of a hot wire are presented.

Report presenting a method for estimating the control forces of spring-tab ailerons from nonlinear wind-tunnel data. Two principal arrangements of the ailerons and spring unit were used, one with the ailerons interconnected and a central spring unit and an arrangement with no interconnection between the ailerons with individual preloaded spring units for each aileron.

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.

"A detailed table of the standard equilibrium velocity and standard equilibrium time is presented for bodies falling in the standard atmosphere. This table gives the velocity at various altitudes and the time of fall from sea level to -4000 feet and from 80,000 feet to sea level. In addition to this standard table, there are given short tables and charts of an open-parachute descent and free-falls; the terminal velocity at sea level, and the variation of the weight-to-drag ratio (2w/cds)1/2 for various weight jumpers from 90 to 30 feet in open-parachute descent; and estimations of drag coefficients of silk and nylon parachutes" (p. 1).

Report presenting an investigation involving a prismatic-float forebody of 30 degrees angle of dead rise subjected to impacts in smooth water as part of a series of impact tests to investigate the effects of angle of dead rise on hydrodynamic loads of floats and hulls. Results indicated that the loads encountered during impacts can be predicted within the limits of experimental accuracy by curves and equations.

Note presenting tests of three types of boundary-layer-control suction slots in a two-dimensional diffuser to investigate design criterions and to evaluate the practical minimum total-pressure losses. Testing occurred at a velocity of about 100 feet per second with a boundary layer with a displacement thickness of 0.85 inch and a shape parameter of about 1.8.

Report presenting a method of predicting the dynamic response of airplane wings to gusts by considering only the fundamental mode of bending along with the results of model tests to evaluate the method. Results regarding experimental results and associated calculations, limitations of calculations, and results calculated for effect of change of certain parameters are provided.

Report presenting a method for calculating the local buckling strength of lipped Z-columns with a small lip width. Some experimental data are presented to show agreement between theoretical and experimental results.

"The results obtained from a series of flight measurements of atmospheric turbulence within convective-type clouds and from meteorological soundings are presented together with descriptions of the flights and concurrent weather conditions. These results are presented to provide a background of experience for the forecaster and pilot by illustrating the turbulence conditions as indicated by effective gust velocities in convective-type clouds under spring and summer weather conditions along the eastern coast of the United States" (p. 1).

Note presenting a derivation of a modified form of Donnell's equation for the equilibrium of thin cylindrical shells which is equivalent to Donnell's equation but has certain advantages in physical interpretation and in ease of solution, particularly in the case of shells with clamped edges. The modified equation can be solved for the buckling stresses of curved sheet having either simply supported or clamped edges by established methods essentially equivalent to those in use for flat sheet.