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Flight Experiences and Tests on Two Airplanes With Suction Slots

Description: Memorandum presenting the flight tests of two airplanes with boundary-layer control are reviewed. The results for take-off and flight test measurements are reported. Suction proved to be an effective means of obtaining high lifts during flights.
Date: January 1950
Creator: Stüper
Partner: UNT Libraries Government Documents Department
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Investigation of the Model Me 210 in the Spin Wind Tunnel of the DVL: Fourth Partial Report - Model With Long Fuselage and With a Vee Tail

Description: "After conclusion of the spin investigation of the model Me 210 with elongated fuselage and central vertical tail surfaces (model condition III; reference 3), tests were performed on the same model with a vee tail (model condition IV). Here the entire tail surfaces consist of only one surface with pronounced dihedral. Since the blanketing of the vertical tail surfaces by the horizontal tail surfaces, which may occur in case of standard tail surfaces, does not occur here, one could expect for th… more
Date: April 1950
Creator: Huffschmid, A.
Partner: UNT Libraries Government Documents Department
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Laws of Flow in Rough Pipes

Description: An experimental investigation is made of the turbulent flow of water in pipes with various degrees of relative roughness. The pipes range in size from 25 to 100 millimeters in diameter and from 1800 to 7050 millimeters in length. Flow velocities permitted Reynolds numbers from about 10 (sup. 4) to 10 (sup. 6). The laws of resistance and velocity distributions were obtained as a function of relative roughness and Reynolds number. Mixing length, as described by Prandtl's mixing-length formula, is… more
Date: November 1950
Creator: Nikuradse, J.
Partner: UNT Libraries Government Documents Department
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The Development of a Hollow Blade for Exhaust Gas Turbines

Description: The subject of the development of German hollow turbine blades for use with internal cooling is discussed in detail. The development of a suitable blade profile from cascade theory is described. Also a discussion of the temperature distribution and stresses in a turbine blade is presented. Various methods of manufacturing hollow blades and the methods by which they are mounted in the turbine rotor are presented in detail.
Date: December 1950
Creator: Kohlmann, H.
Partner: UNT Libraries Government Documents Department
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Dependence of the Elastic Strain Coefficient of Copper on the Pre-Treatment

Description: The effect of various pre-treatments on the elastic strain coefficient (alpha) (defined as the reciprocal of the modulus of elasticity E) (Epsilon) and on the mechanical hysteresis of copper has been investigated. Variables comprising the pre-treatments were pre-straining by stretching in a tensile testing machine and by drawing through a die, aging at room and elevated temperatures and annealing. The variation of the elastic strain coefficient with test stress was also investigated.
Date: August 1950
Creator: Kuntze, Wilhelm
Partner: UNT Libraries Government Documents Department
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Investigations of the Wall-Shearing Stress in Turbulent Boundary Layers

Description: Because of the unsatisfactory state of knowledge concerning the surface shearing stress of boundary layers with pressure gradients, the problem is re-examined. It is found that for general turbulent boundary layers in wall proximity, that is, in the laminar sublayer, in the transition zone and in the part of the completely turbulent zone near the wall, the same universal law applies as for the plate flow.
Date: May 1950
Creator: Ludwieg, Hubert & Tillmann, W.
Partner: UNT Libraries Government Documents Department
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Two-Dimensional Symmetrical Inlets With External Compression

Description: The purpose of inlets like, for instance, those of air-cooled radiators and scoops is to take a certain air quantity out of the free stream and to partly convert the free-stream velocity into pressure. In the extreme case this pressure conversion may occur either entirely in the interior of the inlet (inlet with internal compression) or entirely in the free stream ahead of the inlet (inlet with external compression). In this report a theory for two-dimensional inlets with external compression i… more
Date: March 1950
Creator: Ruden, P.
Partner: UNT Libraries Government Documents Department
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Contribution to the Problem of Buckling of Orthotropic Plates, With Special Reference to Plywood

Description: Planar stress-strain relations and bending stress-strain relations are presented for elastic orthotropic plates and specialized to plywood. These relations are used to derive the differential equation and energy expression for the buckling of orthotropic rectangular plates whose principal stiffness directions are not parallel to the plate edges. Buckling analyses are made for the case of pure compression and pure shear of a long plate-strip.
Date: August 1950
Creator: Thielemann, Wilhelm
Partner: UNT Libraries Government Documents Department
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Turbulence and Heat Stratification

Description: With applications to meteorology in view, the method of small oscillations is used to investigate the stability of a plane laminar boundary layer in which the density depends in a special way on the distance from the plate. It is found that for a constant Froude number the flow becomes more stable as the Richardson number increases until, at a critical value of the Richardson number that depends on the Froude number, the flow is stable for all disturbance wave lengths and Reynolds numbers. The … more
Date: October 1950
Creator: Schlichting, Hermann
Partner: UNT Libraries Government Documents Department
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On the Theory of the Propagation of Detonation in Gaseous Systems

Description: "The existing theory of detonation is critically examined. It is shown that the considerations with which the steady value of the velocity of detonation is chosen are not convincing. In connection with the problem of the process of the chemical reaction in a detonation wave, the objections raised against the conceptions of Le Chatelier and Vieille of the 19th century with regard to the ignition of the gas by the shock wave are refuted" (p. 1).
Date: November 1950
Creator: Zeldovich, Y. B.
Partner: UNT Libraries Government Documents Department
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General Solution of Prandtl's Boundary-Layer Equation

Description: A method is described by means of which the laminar friction layer at a wall with arbitrary pressure distribution may be calculated from Prandtl's boundary-layer equations.
Date: June 1950
Creator: Mangler, W.
Partner: UNT Libraries Government Documents Department
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The Solution of the Laminar-Boundary-Layer Equation for the Flat Plate for Velocity and Temperature Fields for Variable Physical Properties and for the Diffusion Field at High Concentration

Description: "In connection with Pohlhausen's solution for the temperature field on the flat plate, a series of formulas were indicated by means of which the velocity and temperature field for variable physical characteristics can be computed by an integral equation and an iteration method based on it. With it, the following cases were solved: On the assumption that the viscosity simply varies with the temperature while the other fluid properties remain constant, the velocity and temperature field on the he… more
Date: May 1950
Creator: Schuh, H.
Partner: UNT Libraries Government Documents Department
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Effect of Intense Sound Waves on a Stationary Gas Flame

Description: Intense sound waves with a resonant frequency of 5000 cycles per second were imposed on a stationary propane-air flame issuing from a nozzle. In addition to a slight increase of the flame velocity, a fundamental change both in the shape of the burning zone and in the flow pattern could be observed. An attempt is made to explain the origin of the variations in the flame configuration on the basis of transition at the nozzle from jet flow to potential flow.
Date: July 1950
Creator: Hahnemann, H. & Ehret, L.
Partner: UNT Libraries Government Documents Department
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The Gas Kinetics of Very High Flight Speeds

Description: The aerodynamic forces on bodies of arbitrary shape were investigated under conditions such that the mean free path of the air molecule is greater than the dimensions of the body. Air pressures and friction forces were calculated from gas kinetic theory for surfaces facing both toward and away from the air stream at any angle. Air forces for an atmosphere of definite composition (molecular hydrogen) were calculated as a function of the flight velocity.
Date: May 1950
Creator: Sänger, Eugen
Partner: UNT Libraries Government Documents Department
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Instrument for Measuring the Wall Shearing Stress of Turbulent Boundary Layers

Description: "It is shown that at a smooth wall in a turbulent boundary layer the velocity profile next to the wall is dependent, aside from the material constants of the flowing medium, only on the shearing stress transmitted to the wall, even with pressure rise or with pressure drop. Consequently, the heat transfer of a small element that is built into the wall and has a higher temperature than that of the flowing medium is a measure of the wall shearing stress. Theoretical considerations indicate that th… more
Date: May 1950
Creator: Ludwieg, H.
Partner: UNT Libraries Government Documents Department
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Graphical Determination of Wall Temperatures for Heat Transfers Through Walls of Arbitrary Shape

Description: "A graphical method is given which permits determining of the temperature distribution during heat transfer in arbitrarily shaped walls. Three examples show the application of the method. The further development of heat engines depends to a great extent on the control of the thermal stresses in the walls" (p. 1).
Date: April 1950
Creator: Lutz, Otto
Partner: UNT Libraries Government Documents Department
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Isentropic Phase Changes in Dissociating Gases and the Method of Sound Dispersion for the Investigation of Homogeneous Gas Reactions With Very High Speed

Description: The analytical results of Part I are also applied to sound dispersion by friction and heat conduction, An irreversible change of momentum, energy, and type of particle corresponding to friction, heat conduction, and diffusion effects can appear both in the direction of the sound field and traverse to it. Longitudinal damping, the coupling of longitudinal damping and that due to chemical and physical changes, and coupling of diffusion and compositional changes are treated for a plane sound wave … more
Date: September 1950
Creator: Damköehler, Gerhard
Partner: UNT Libraries Government Documents Department
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Theory of Plane, Symmetrical Intake Diffusers

Description: "The present report ties in with the investigations on the inlet diffusers by P. Ruden. The theory developed by Ruden had produced results which found excellent confirmation in wind-tunnel tests and in spite of certain still-existing defects, are technically very promising. The reasons for the new theory of the diffuser forms indicated by Ruden are twofold: first, the arguments adduced in Ruden's theory deal only with one specific operating condition, that is, a certain ratio of mean velocity w… more
Date: April 1950
Creator: Brödel, Walter
Partner: UNT Libraries Government Documents Department
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Preliminary Results From Fatigue Tests With Reference to Operational Statistics

Description: Simple elements were subjected to repeated loads of variable ampliture, chosen in such a way that they may be regarded as approximations to the operational loads (gust and maneuver) experienced by an airplane. The effect of varying some parameters was investigated briefly. Some discussion is given of the question whether a design according to current (1938 German) requirements for static strength is adequate from the fatigue point of view, and existing requirements on fatigue strength are compa… more
Date: May 1950
Creator: Gassner, E.
Partner: UNT Libraries Government Documents Department
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Amplitude distribution and energy balance of small disturbances in plate flow

Description: From Introduction: "The present report, therefore, deals first, with the distribution of the amplitude of the disturbance over the flow section, that is, the calculation of the characteristic functions and second, with the study of the energy distribution and energy balance of the disturbance motion. The investigations are based upon the disturbances of the laminar flow past a flat plate which are situated exactly at the boundary between amplification and damping (neutral oscillations)."
Date: April 1950
Creator: Schlichting, H.
Partner: UNT Libraries Government Documents Department
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Hydrodynamic Properties of Planing Surfaces and Flying Boats

Description: "The study of the hydrodynamic properties of planing bottom of flying boats and seaplane floats is at the present time based exclusively on the curves of towing tests conducted in tanks. In order to provide a rational basis for the test procedure in tanks and practical design data, a theoretical study must be made of the flow at the step and relations derived that show not only qualitatively but quantitatively the inter-relations of the various factors involved. The general solution of the prob… more
Date: October 1950
Creator: Sokolov, N. A.
Partner: UNT Libraries Government Documents Department
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Equations of Motion of a Rocket

Description: "In considering the motion of the rocket, at each instant of time only the state of those material particles which at that instant are within the control surface passing through the exterior surface of the body of the rocket and the exit section of the nozzle shall be included. In order to obtain the equations of motion of the rocket, the following procedure is used. An arbitrary but fixed instant of time is considered" (p. 1).
Date: April 1950
Creator: Gantmacher, F. R. & Levin, L. M.
Partner: UNT Libraries Government Documents Department
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