Note presenting an experimental study of friction coefficients near the inlet of smooth, round tubes with bellmouth entrances. Four different combinations of approach section and bellmouth entry were used. Results regarding the apparent local friction coefficient, integrated friction coefficient, effect of induced turbulence, laminar inlet zone, developed friction coefficient, and application to discharge coefficients for rounded-entrance flow nozzles are provided.

Report presenting theoretical results for the surface-velocity-potential functions, surface-pressure distributions, and stability derivatives for various motions at supersonic speeds of thin flat rectangular wings without dihedral. The investigation included steady and accelerating vertical and longitudinal motions and steady rolling, yawing, sideslipping, and pitching for Mach numbers are provided.

Report presenting a general method of analysis developed for the two-dimensional, steady, compressible flow through mixed-flow compressors in which the center line of the passage generates a right circular cone about the axis of the compressor. The two-dimensional, radial-discharge compressor is a special case in which the cone angle is equal to 180 degrees. The general analysis also applies to inward-flow turbines.

Report presenting an investigation in the two-dimensional low-turbulence pressure tunnel on an NACA 64(sub 1)A212 airfoil with various extents of permeable surface area between the leading edge and 12.5 percent chord to determine the effectiveness of area suction in eliminating leading-edge separation at high lift coefficients. The results indicated that not only was leading-edge separation prevented, but turbulent separation moving forward from the trailing edge was also delayed.

Report presenting the calculated performance of three series of ducted-fan turbojet engines designed for obtaining maximum thrust per pound of air handled, minimum net-thrust specific fuel consumption, and maximum flight range. Results regarding the maximum-thrust engines, maximum-economy engines, and maximum-range engine are provided.

Report presenting an investigation of the effects of compressibility on the flow about the NACA 0012 airfoil in a wind tunnel and in free air using the relaxation method. The solutions cover a wide variety of flow conditions.

Report presenting a solution for the coupled and uncoupled modes and frequencies of wings (swept or unswept) mounted on a fuselage. Characteristic equations describing symmetrical and antisymmetrical modes of vibrations are created and applied to various types of wing vibration in numerical examples.

Report presenting a study of tunnel-induced upwash field for a point element of lift in a rectangular tunnel, which is shown to consist of three superimposed fields that, except for relative position, are independent of the lateral or longitudinal location of the lift element in the tunnel. A contour chart is given of the first field. For tunnels that are not rectangular, the corresponding procedure requires the preparation of a chart for each of several spanwise locations of the lifting element.

"Solutions are developed for shear flows in multicell sandwich sections for various cell-twist distributions. The problems of twisting and bending of a cantilever beam are first considered. More general cell-twist distributions are then considered, including the arbitrary distribution" (p. 1).

Report presenting an investigation in the gust tunnel to determine the effectiveness of a fixed spoiler, forwardly located on the upper surface of a wing, in reducing the loads imposed on airplanes in flight through gusty air. Testing occurred through a sharp-edge and a gradient gust with and without spoilers. The results indicate that the model has roughly the same maximum acceleration with and without spoilers in a sharp-edge gust.

Note presenting an experimental investigation made to validate a theoretical parabolic interaction curve for the elastic buckling of flat rectangular plates under combined shear and longitudinal compression loads. The four flat rectangular plates tested formed the sides of a square box with corner angles.

"The buckling of an infinitely long square tube under combined torsion and compression is investigated by means of an exact energy method utilizing Lagrangian multipliers. An interaction curve is obtained from which it is possible to determine the amount of one loading required to produce buckling when a given amount of the other loading is present" (p. 1).

Note presenting numerical values of the calculated boundary-induced-upwash velocities necessary for the determination of the jet-boundary corrections for swept reflection-plane models mounted vertically in 7- by 10-foot, closed, rectangular wing tunnels in chart form. Results regarding the correction factors for accurate calculations are also provided.

Report presenting flight measurements to determine the low-speed flying qualities of an airplane with a wing sweptback 35 degrees at the quarter-chord line. The lateral and directional stability and control characteristics of the airplane without slots and with 80-percent-span slots on the wing are provided.

Report presenting an experimental investigation of a blowdown turbine installed in the exhaust stream of a 12-cylinder liquid-cooled engine of 1710-cubic-inch displacement. Results regarding turbine performance and performance of complete engine systems are provided.

Note presenting a theoretical method for obtaining the aerodynamic forces acting on a thin wing in an irrotational nonuniform supersonic stream. The method is applied to determine lift and moments acting on a rectangular tail surface due to a spanwise parabolic distribution of upwash. Lift and moments due to a linear upwash distribution are also evaluated.

Report presenting an experimental investigation to determine the effect of varying the rivet diameter and pitch on the compressive strength of flat 24S-T aluminum-alloy Z-stiffened panels of the type for which design charts are available. The current investigation is concerned with panels which have various values of width-to-thickness ratio of the webs of the stiffeners and have such length that failure is by local buckling.

Report presenting a wind-tunnel investigation of the low-speed lateral control characteristics of a tapered, low-drag, semispan wing model equipped with 20-percent-chord sealed ailerons with spans of 0.954, 0.583, and 0.294 percent of a full-span aileron, each with trailing edge angles of 6, 14, and 25 degrees. The investigation included tests with the ailerons unsealed, simulating symmetrical lift-flap configurations with spans of 0.954 and 0.660 percent of a full-span flap. The results indicated that the existing theoretical method tends to give satisfactory results with the exception of ailerons with a trialing-edge angle of 25 degrees.

"Strength tests were made on 24S-T and Alclad 75S-T aluminum-alloy sheet in diagonal tension. These tests indicated that the ultimate shear stress was essentially independent of the rivet factor if the rivet factor was greater than 0.6, which covers most of the practical range. Curves showing the effect of diagonal tension on the ultimate shear stress in the gross section are presented. These curves supersede those given in NACA TN No. 1364" (p. 1).

Report presenting performance characteristics of conical jet nozzles in an investigation covering a range of pressure ratios from 1.0 to 2.8, cone half-angles from 5 degrees to 90 degrees, and outlet-inlet diameter ratios from 0.50 to 0.91.

From Introduction: "This paper summarizes the results of an analysis of V-G records taken on Douglas DC-2 airplanes during the period from June 1935 to December 1940. The operational life is compared with the operational lives of other airplanes flown on different routes during the corresponding period."

Report presenting an examination of the development of low-turbulence wind tunnels, which was greatly dependent on the development of the hot-wire anenometer, measurements of the decay of turbulence behind screens, measurements of the effect of damping screens on turbulence, measurements of flow near a flat plate in air streams of varying turbulence, and measurements of the drag of specially designed low-drag airfoils.

Report discussing a test program to provide data at 1200 degrees Fahrenheit for 19-9DL alloy bar stock in three typical conditions of treatment: hot-rolled, hot-cold-rolled, and solution-treated conditions. The highest strengths were shown by the hot-cold-worked stock for short time periods and high stresses, while the solution treatment was best for long time periods and low stresses. Results regarding physical properties, rupture test characteristics, time-deformation characteristics, creep characteristics, and stability characteristics are provided.

Report presenting a study of the properties of EME alloy in the form of contour-forged discs for the rotors of gas turbines. The investigation was undertaken because the properties of promising alloys are dependent to a considerable extent on the conditions of fabrication and the size and shape of the rotor discs introduced fabrication procedures for which information was not available. Results regarding hardness surveys, short-time tensile properties, rupture test characteristics, time-deformation characteristics, creep strengths, stability characteristics, and data from tests in other laboratories are provided.