UNT Libraries Government Documents Department - 38 Matching Results

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Investigation of Lubricants Under Boundary Friction

Description: Numerous observations of such lubrication processes within range of boundary friction on journal bearings and gear tooth profiles have strengthened the supposition that it should be possible to study the attendant phenomena with engineering methods and equipment. These considerations formed the basis of the present studies, which have led to the discovery of relations governing the suitability of bearing surfaces and the concept of "lubricating quality.".
Date: May 1942
Creator: Heidebroek, E. & Pietsch, E.

On the Symmetrical Potential Flow of Compressible Fluid Past a Circular Cylinder in the Tunnel in the Subcritical Zone

Description: "The two-dimensional symmetrical potential flow of compressible fluid past a circular cylinder placed in the center line of a straight tunnel is analyzed in second approximation according to the Jansen-Rayleigh method. The departure of the profile from the exact circular shape can be kept to the same magnitude as for the incompressible flow. The velocities in the narrowest section of the tunnel wall and at the profile edge are discussed in detail" (p. 1).
Date: June 1942
Creator: Lamla, Ernst

Statics of Circular-Ring Stiffeners for Monocoque Fuselages

Description: "For circular-ring stiffeners in monocoque fuselages the bending moments, axial forces, and shear forces under the action of applied external forces or a moment are accurately computed by known methods. Circular-ring stiffeners with variable moments of inertia are likewise considered. In comparison with the step-by-step and partially graphical procedure, the one here described is a more accurate and at the same time a simpler method" (p. 1).
Date: February 1942
Creator: Stieda, W.

The Design of Propeller Blade Roots

Description: Predicated on the assumption of certain normal conditions for engine and propeller, simple expressions for the static and dynamic stresses of propeller blade roots are evolved. They, in combination with the fatigue strength diagram of the employed material, afford for each engine power one certain operating point by which the state of stress serving as a basis for the design of the root is defined. Different stress cases must be analyzed, depending on the vibration tendency of engine and use of propeller. The solution affords an insight into the possible introduction of different size classes of propeller.
Date: January 1942
Creator: Cordes, G.

Prediction of Downwash and Dynamic Pressure at the Tail From Free-Flight Measurements

Description: "The present measurements form a continuation of earlier flight tests published in a previous report for predicting the downwash at the tail of an airplane. The method makes use of the tail itself as integrating contact surface to the extent that, beginning from the measurement of the self-alignment of the elevator, the mean downwash angle and dynamic pressure at the tail are determined. The instrumental accuracy is considerably improved if the elevator is completely separate from the controls during the tests, because the effect of friction on the self-alignment of the elevator is then reduced to a minimum and a finer elevator weight balance is rendered possible" (p. 1).
Date: July 1942
Creator: Eujen, E.

Strength Tests on Hulls and Floats

Description: "The present report deals with strength tests on hulls and floats intended in part for the collection of construction data for the design of these components and in part for the stress analysis of the finished hulls and floats" (p. 1).
Date: June 1942
Creator: Matthaes, K.

Theory of Heat Transfer and Hydraulic Resistance of Oil Radiators

Description: "In the present report the coefficients of heat transfer and hydraulic resistance are theoretically obtained for the case of laminar flow of a heated viscous liquid in a narrow rectangular channel. The results obtained are applied to the computation of oil radiators, which to a first approximation may be considered as made up of a system of such channels. In conclusion, a comparison is given of the theoretical with the experimental results obtained from tests on airplane oil radiators" (p. 1).
Date: June 1942
Creator: Mariamov, N. B.

The resistance coefficient of commercial round wire grids

Description: From Summary: "The resistance coefficients of commercial types of round wire grids were examined for the purpose of obtaining the necessary data on supercharger test stands for throttling the inducted air to a pressure corresponding to a desired air density. The measurements of the coefficients ranged up to Reynolds numbers of 1000. In the arrangement of two grids in tandem, which was necessary in order to obtain high resistance coefficients with the solidity, that is, mesh density of grid, was found to be accompanied by a further relationship with the mutual spacing of the individual grids."
Date: January 1942
Creator: Eckert, B. & Pflüger, F.

Aerodynamic Heat-Power Engine Operating on a Closed Cycle

Description: "Hot-air engines with dynamic compressors and turbines offer new prospects of success through utilization of units of high efficiencies and through the employment of modern materials of great strength at high temperature. Particular consideration is given to an aerodynamic prime mover operating on a closed circuit and heated externally. Increase of the pressure level of the circulating air permits a great increase of limit load of the unit. This also affords a possibility of regulation for which the internal efficiency of the unit changes but slightly. The effect of pressure and temperature losses is investigated" (p. 1).
Date: November 1942
Creator: Ackeret, J. & Keller, D. C.

Contribution to the ideal efficiency of screw propellers

Description: From Summary: "The stipulation of best thrust distribution is applied to the annular elements of the screw propeller with infinitely many blades in frictionless, incompressible flow and an ideal jet propulsion system derived possessing hyperbolic angular velocity distribution along the blade radius and combining the advantage of uniform thrust distribution over the section with minimum slipstream and rotation losses. This system is then compared with a propeller possessing the same angular velocity at all blade elements and the best possible thrust distribution secured by means of an induced efficiency varying uniformly over the radius. Lastly, the case of the lightly loaded propeller also is discussed."
Date: January 1942
Creator: Hoff, Wilhelm

New method of extrapolation of the resistance of a model planing boat to full size

Description: "The previously employed method of extrapolating the total resistance to full size with lambda(exp 3) (model scale) and thereby foregoing a separate appraisal of the frictional resistance, was permissible for large models and floats of normal size. But faced with the ever increasing size of aircraft a reexamination of the problem of extrapolation to full size is called for. A method is described by means of which, on the basis of an analysis of tests on planing surfaces, the variation of the wetted surface over the take-off range is analytically obtained. The friction coefficients are read from Prandtl's curve for turbulent boundary layer with laminar approach. With these two values a correction for friction is obtainable" (p. 1).
Date: March 1942
Creator: Sottorf, W.

Statistical analysis of service stresses in aircraft wings

Description: On the wing structures of modern high speed aircraft, in particular, the comparatively high-service stresses and the consistently increasing number of hours of operation during the life of the separate airplane parts make the studies of strength requirement under recurrent stresses appear of major concern. The DVL has therefore made exhaustive studies for this structural group of airplanes, some results of which are reported here.
Date: June 1942
Creator: Kaul, Hans W.

The Stability of Laminar Flow Past a Sphere

Description: "As a contribution to the problem of turbulence on a surface of rotation, the method of small oscillation is applied to the flow past a sphere. It was found that the method developed for two-dimensional flow is applicable without modifications. The frictional layer in the vicinity of the stagnation point of a surface of rotation is less stable against small two-dimensional disturbances than in the stagnation point itself, as proved from an analysis of the velocity distribution made by Homann" (p. 1).
Date: June 1942
Creator: Pretsch, J.

Analytical Theory of the Campini Propulsion System

Description: "The present report deals exclusively with the particular jet-propulsion system mentioned in the cited reports. The discussion is limited, for the present, to the analytical study of the efficiency and the consumption for the case of application to aircraft and to the plotting of the practical operating curves secured theoretically by the use of suitable experimental factors" (p. 1).
Date: March 1942
Creator: Campini, S.

Theoretical Solution of Profile Drag

Description: "After a survey of the customary procedures for appraising the profile drag in which pressure drag was discounted and the methods for computing the laminar and turbulent friction flow, the author proposes a method by which the pressure drag can be computed with the aid of the displacement thickness of the frictional layer. The method is restricted to the case where the effects, caused by separation of frictional layer, are small. Then the total profile drag can be expressed solely by quantities derived from the velocity distribution in the frictional layer immediately at the trailing edge" (p. 1).
Date: April 1942
Creator: Pretsch, J.

Thermal Theory of Combustion and Explosion 3: Theory of Normal Flame Propagation

Description: The technical memorandum covers experimental data on flame propagation, the velocity of flame propagation, analysis of the old theoretical views of flame propagation, confirmation of the theory for simple reactions (theory of combustion of explosive substances and in particular nitroglycol), and check of the theory by example of a chain oxidizing reaction (theory of flame propagation in carbon monoxide, air and carbon monoxide - oxygen mixtures).
Date: September 1942
Creator: Semenov, N. N.

The Compressible Potential Flow Past Elliptic Symmetrical Cylinders at Zero Angle of Attack and with No Circulation

Description: "For the tunnel corrections of compressible flows those profiles are of interest for which at least the second approximation of the Janzen-Rayleigh method can be applied in closed form. One such case is presented by certain elliptical symmetrical cylinders located in the center of a tunnel with fixed walls and whose maximum velocity, incompressible, is twice the velocity of flow. In the numerical solution the maximum velocity at the profile and the tunnel wall as well as the entry of sonic velocity is computed" (p. 1).
Date: October 1942
Creator: Hantzsche, W. & Wendt, H.

Control of Torsional Vibrations by Pendulum Masses

Description: "Various versions of pendulum masses have been developed abroad within the past few years by means of which resonant vibrations of rotating shafts can be eliminated at a given tuning. They are already successfully employed on radial engines in the form of pendulous counterweights. Compared with the commonly known torsional vibration dampers, the pendulum masses have the advantage of being structurally very simple, requiring no internal damping and being capable of completely eliminating certain vibrations" (p. 1).
Date: November 1942
Creator: Stieglitz, Albert

Electrical Equipment for the Experimental Study of the Dynamics of Fluids

Description: "This report contains the description of electric anemometers and their application to the study of turbulent fluid flows, of electric tanks for the realization of the analogies between electrology and aerodynamics and their application to the study of varied technical problems, and lastly of the electric condenser type dynamometer and its application to the prediction of the aerodynamic forces on wing and airplane models in wind-tunnel tests and in controlled and spontaneous rotations" (p. 1).
Date: March 1942
Creator: Ferrari, Carlo

Recording Rapidly Changing Cylinder-Wall Temperatures

Description: "The present report deals with the design and testing of a measuring plug suggested by H. Pfriem for recording quasi-stationary cylinder wall temperatures. The new device is a resistance thermometer, the temperature-susceptible part of which consists of a gold coating applied by evaporation under high vacuum and electrolytically strengthened. After overcoming initial difficulties, calibration of plugs up to and beyond 400 degrees C was possible" (p. 1).
Date: May 1942
Creator: Meier, Adolf

[Memorandums on the Subject of Turbulent Boundary Layers in Compressible Gas at High Speeds]

Description: "The Reynolds law of heat transfer from a wall to a turbulent stream is extended to the case of flow of a compressible gas at high speeds. The analysis is based on the modern theory of the turbulent boundary layer with laminar sublayer. The investigation is carried out for the case of a plate situated in a parallel stream. The results are obtained independently of the velocity distribution in the turbulent boundar layer" (p. 1).
Date: October 1942
Creator: Frankl, F. & Voishel, V.

The Formation of Ice on Aircraft

Description: "The phenomenon accompanying the formation of ice on aircraft has been frequently discussed. The consequences of ice formation have been briefly analyzed in an article , but a definite physical solution of the problem has not been reached up to the present. Most of the authors agree that subcooled water droplets play a prominent part, but they fail to specify the exact manner in which this occurs" (p. 1).
Date: August 1942
Creator: Bleeker, W.

The Icing of Aircraft

Description: This technical memorandum presents a theoretical study of the processes accompanying the formation of ice on solid bodies. It discusses vapor pressure and sublimation in two air masses separated by a boundary area.
Date: September 1942
Creator: Robitzsch, M.