Memorandum presenting investigation on reductions of friction on wings, especially by means of boundary-layer suction. The report is broken up into several sections, including: causes of transition, laminar profiles with the transition taking place, laminar boundary-layer suction, investigation of the laminar pressure increase, investigation of the slot flow for laminar boundary-layer suction with single slots, tests about keeping a boundary layer for high Reynolds laminar with the aid of boundary-layer suction, and an investigation of a slightly-cambered laminar suction profile of 10.5-percent thickness.

"Results of measurements are given as a supplement to earlier tests for a laminar profile with nose flap; magnitude, form, and angle of attack of the flap were systematically changed. The experiments were carried out at an effective Reynolds number of 8.2 x 10(exp 5). A comparison with measurements on other profiles shows that the effect of a nose flap is essentially dependent upon magnitude of the nose radius coefficient of the profile" (p. 1).

"Maintenance of a laminar boundary layer by suction was suggested recently to decrease the friction drag of an immersed body, in particular an airfoil section. The present treatise makes a theoretical contribution to this question in which, for several cases of suction and blowing, the stability of the laminar velocity profile is investigated. Estimates of the minimum suction quantities for maintaining the laminar boundary layer and estimates of drag reduction are thereby obtained" (p. 1).

"The problem of the intake of air is treated for a missile flying at supersonic speeds and of changing the kinetic energy of the air into pressure with the least possible losses. Calculations are carried out concerning the results which can be attained. After a discussion of several preliminary experiments, the practical solution of the problem at hand is indicated by model experiments. The results proved very satisfactory in view of the results which had been attained previously and the values which were anticipated theoretically" (p. 1).

"This report contains a theoretical discussion of the load distribution in bolted or riveted joints in light-alloy structures which is applicable not only for loads below the limit of proportionality but also for loads above this limit. The theory is developed for double and single shear joints. The methods given are illustrated by numerical examples and the values assumed for the bolt (or rivet) stiffnesses are based partly on theory and partly on known experimental values" (p. 1).

Based upon a simplified representation of the mode of operation of the pulse-jet tube, the effect of the influences mentioned in the title were investigated and it will be shown that, for a jet tube with a form designed to be aerodynamically favorable, the ability to operate is at least questionable. This investigation will account for the important practical observation made by Paul Schmidt that the ratio of the effective valve cross-sectional area to the tube cross section may not be of any random magnitude and will explain why at too great flight speeds the jet tube ceases to operate. Chemical an thermodynamic processes (for example, constituents or mode of fuel-air-mixture formation or heat losses) are unimportant in this regard.

Memorandum presenting the coefficient of friction, oil flow, and heat balance of a full-journal bearing.

"The present report deals with the effect of turbulence on the propagation of the flame. Being based upon experiments with laminar as well as turbulent Bunsen flames, both the physico-chemical and the hydro-dynamical aspects of the problem are analyzed. A number of new deductions, interesting from the point of view of engine combustion and other very rapidly changing flame reactions, are made" (p. 1).

"The present report contains the results of a series of observations obtained for a wing of symmetrical profile for different angles of yaw. The shock tunnel with 0.4m x 0.4m cross section, of the Institute for Gas Dynamics at L.F.A. - Braunchweig was available for this work. The profile used was a 9 percent, thick hyperbolic profile with maximum thickness 40 percent aft, which was calculated by the method of F. Ringleb (2). Since the conformal transformation of this profile is known, the theoretical pressure distribution could be determined exactly for the case of incompressible flow. Then by the use of the Prandtl rule one may extend the comparison of theory and experiment to the case of higher velocity of incident flow" (p. 1).

This article explains results developed from the following research: 'The Stability of Plates and Shells beyond the Elastic Limit.' A significant improvement is found in the derivation of the relations between the stress factors and the strains resulting from the instability of plates and shells. In a strict analysis, the problem reduces to the solution of two simultaneous nonlinear partial differential equations of the fourth order in the deflection and stress function, and in the approximate analysis to a single linear equation of the Bryan type.

Wind-tunnel measurements on projectiles are discussed. Tests at the Gottingen Tunnel are described. The tunnel operates on the Prandtl principle, that is, a brief stationary air stream produced in an evacuated tank by induction of atmospheric air.

A calulation of the flow in turbine blading is reported that includes the calculation of effect of centrifugal force. Frictional losses on the stator blades and rotor blades are allowed.

This report addresses a method for the approximate calculation of compressible flows about profiles with local regions of supersonic velocity. The flow around a slender profile is treated as an example.

"Two procedures for calculating the lift distribution along the span are given in which a better account is taken of the distribution of circulation over the area than in the Prandtl lifting-line theory. The methods are also applicable to wing sweepback. Calculated results for the two methods were in agreement" (p. 1).

The present report contains three-component forces and mass-flow measurements on a jet nacelle at small inlet-velocity ratios v(sub A)/v(sub o) < 1. The mass-flow measurement on two cross sections of the nacelle demonstrate the local-velocity distribution with varying flow and angle of attack.

The mutual influences of compression shocks and friction boundary layers were investigated by means of high speed wind tunnels.Schlieren optics provided a clear picture of the flow phenomena and were used for determining the location of the compression shocks, measurement of shock angles, and also for Mach angles. Pressure measurement and humidity measurements were also taken into consideration.Results along with a mathematical model are described.

The calculation of infinitesimal conical supersonic flow has been applied first to the simplest examples that have also been calculated in another way. Except for the discovery of a miscalculation in an older report, there was found the expected conformity. The new method of calculation is limited more definitely to the conical case.

It is known that the compressibility shocks accompanying local or total supersonic flows lead to pronounced flow separations which result in unusually high energy losses on airplane wings, vanes, and in diffusers. These phenomena were investigated experimentally and theoretically.

"A selection of measurements obtained on experimental impellers for axial blowers will be reported. In addition to characteristic curves plotted for low and for high peripheral velocities, proportions and blade sections for six different blower models and remarks on the design of blowers will be presented" (p. 1).

Axial blowers are gaining importance as aircraft engine superchargers. However, the pressure head obtainable per stage is small. Due to the necessary great number of stages, the physical length of the blower becomes too great for an airworthy device. This report discusses several types of construction that permit a reduction in the length of the blower.

In the vicinity of a body in a wind tunnel the displacement effect of the wake, due to the finite dimensions of the stream, produces a pressure gradient which evokes a change of drag. In incompressible flow this change of drag is so small, in general, that one does not have to take it into account in wind-tunnel measurements; however, in compressible flow it beoomes considerably larger, so that a correction factor is necessary for measured values. Correction factors for a closed tunnel and an open jet with circular cross sections are calculated and compared with the drag - corrections already bown for high-speed tunnnels.

"On the basis of the investigations so far completed on the behavior of PTL power plants under various operating conditions, in which the influence of the propeller characteristics is of considerable importance, the most important aspects of a control system for turbine-propeller jet power plants are deduced. A simple possible means for its concrete realization, which is also applicable to TL [NACA comment: TL, jet] power plants, is presented by means of examples. A control device of this kind is now being developed" (p. 1).

"With an approach of the velocity of flight of a ship to the velocity of sound, there occurs a considerable increase of the drag. The reason for this must be found in the boundary layer separation caused by formation of shock waves. It will be endeavored to reduce the drag increase by suction of the boundary layer. Experimental results showed that drag increase may be considerably reduced by this method" (p. 1).

The Russian AM 35 and AM 38 aircraft engines have superchargers with a swirl throttle, which appears to be a purely Russian development. This paper gives the results of test runs of the two engines, including the effects of the swirl throttle on engine performance.