UNT Libraries Government Documents Department - 13 Matching Results

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Concerning the Flow About Ring-Shaped Cowlings 12: Two New Classes of Circular Cowls

Description: "For application in practice for annular radiator fairings and similar arrangements, two new classes of circular cowls are developed by theoretical method, and investigated in a systematic test series regarding their behavior under various working conditions" (p. 1).
Date: October 1953
Creator: Küchemann, Dietrich & Weber, Johanna
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Deplacement Effect of the Laminar Boundary Layer and the Pressure Drag

Description: The displacement effect of the boundary layer on the outer frictionless flow is discussed for both steady and unsteady flows. The analysis is restricted to cases in which the potential flow pressure distribution remains valid for the boundary-layer calculation. Formulas are given for the dependence of the pressure drag, friction drag, and total drag of circular cylinders on the time from the start of motion for cases in which the velocity varies as a power of the time. Formulas for the location… more
Date: October 1951
Creator: Görtler, H.
open access

Experiments on a Tail-Wheel Shimmy

Description: "Model tests on the "running belt" and tests with a full-scale tail wheel were made on a rotating drum as well as on a runway in order to investigate the causes of the undesirable shimmy phenomena frequently occurring on airplane tail wheels, and the means of avoiding them. The small model (scale 1:10) permitted simulation of the mass, moments of inertia, and fuselage stiffness of the airplane and determination of their influence on the shimmy, whereas by means of the larger model with pneumati… more
Date: October 1954
Creator: Dietz, O. & Harling, R.
open access

From Linear Mechanics to Nonlinear Mechanics

Description: Consideration is given to the techniques used in telecommunication where a nonlinear system (the modulator) results in a linear transposition of a signal. It is then shown that a similar method permits linearization of electromechanical devices or nonlinear mechanical devices. A sweep function plays the same role as the carrier wave in radio-electricity. The linearizations of certain nonlinear functionals are presented.
Date: October 1955
Creator: Loeb, Julien
open access

General Solutions of Optimum Problems in Nonstationary Flight

Description: "A general method concerning optimum problems in nonstationary flight is developed and discussed. Best flight techniques are determined for the following conditions: climb with minimum time, climb with minimum fuel consumption, steepest climb, descending and gliding flight with maximum time or with maximum distance. Optimum distributions of speed with altitude are derived assuming constant airplane weight and neglecting curvatures and squares of path inclination in the projection of the equatio… more
Date: October 1955
Creator: Miele, Angelo
open access

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.
open access

On the Design of Airfoils in Which the Transition of the Boundary Layer Is Delayed

Description: Memorandum examining the phenomenon of airfoil drag, which is related almost exclusively to skin friction at high speed flight conditions. The primary way to reduce drag is to delay the transition from laminar to turbulent flow in the boundary layer along the surface. A particular airflow design that may delay transition and therefore have fewer problems related to drag are provided.
Date: October 1952
Creator: Tani, Itiro
open access

On the Theory of Thin and Thin-Walled Rods

Description: Through the work of V. Z. Vlasov a theory of thin-walled rods has been established that is widely applicable in practice. This theory was extended by A. A. Umanski to thin-walled rods of closed profile section. This report attempts to construct a theory of thin-walled rods, including the classical theory of deformation of thin rods, by making use of a kinematic assumption.
Date: October 1951
Creator: Dzhanelidze, G. Y.
open access

On the Turbulent Friction Layer for Rising Pressure

Description: Among the information presented are included displacement, momentum, and kinetic energy thicknesses, shearing stress distributions across boundary layer, and surface friction coefficients. The Gruschwitz method and its modifications are examined and tested. An energy theorem for the turbulent boundary layer is introduced and discussed but does not lead to a method for the prediction of the behavior of the turbulent boundary layer because relations for the shearing stress and the surface frictio… more
Date: October 1951
Creator: Wieghardt, K. & Tillmann, W.
open access

The Theories of Turbulence

Description: "The theory of turbulence reached its full growth at the end of the 19th century as a result of the work by Boussinesq and Reynolds. It then underwent a long period of stagnation which ended under the impulse given to it by the development of wind tunnels caused by the needs of aviation. Numerous researchers, attempted to put Reynolds' elementary statistical theory into a more precise form. During the war, some isolated scientists - von Weizsacker and Heisenberg in Germany, Kolmogoroff in Russi… more
Date: October 1955
Creator: Agostini, L. & Bass, J.
open access

Theory of Thin-Walled Rods

Description: Starting with the Love equations for bending of extensible shells, "principal stress states" are sought for a thin-walled rod of arbitrary but open cross section. Principal stress states exclude those local states arising from end conditions which damp out with distance from the ends. It is found that for rods of intermediate length, long enough to avoid local bending at a support, and short enough that elementary torsion and bending are not the most significant stress states, four principal st… more
Date: October 1951
Creator: Goldenveizer, A. L.
open access

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
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