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Lift on a Bent, Flat Plate
The lift on a bent, flat plate is calculated exactly by the use of conformal mapping. Results are presented in terms permitting direct determination of the angle of zero lift, the lift coefficient, and the lift-curve slope for any flap-chord ratio, flap-deflection angle, and angle of attack.
Date:
February 1955
Creator:
Keune, F.
Object Type:
Report
System:
The UNT Digital Library
Some Measurements of Time and Space Correlation in Wind Tunnel
Results are presented of research obtained by means of an apparatus for measurement of time and space correlation and of a spectral analyzer in the study of the longitudinal component of turbulence velocities in a wind tunnel downstream of a grid of meshes. Application to the case of a flat-plate boundary layer is illustrated. These researches were made at the Laboratoire de Mecanique de l'Atmosphere de l'I.M.F.M. for the O.N.E.R.A.
Date:
February 1955
Creator:
Favre, A.; Gaviglio, J. & Dumas, R.
Object Type:
Report
System:
The UNT Digital Library
Contribution to the Theory of Tail-Wheel Shimmy
A basic theoretical and experimental investigation is made of the shimmy behavior of a swiveling landing gear, the experimental tests being conducted with a small wheel mounted over a continuous belt. Effects of wheel loading, rolling velocity, rearward position of the wheel with respect to the swivel axis, tire elasticity, and torsional flexibility of the fuselage are investigated both experimentally and theoretically. A major theoretical conclusion is that the motion of a landing gear moving in a straight line without fuselage elasticity is stable for a sufficiently large rearward position of the wheel behind the swivel axis, and this conclusion is well verified quantitatively by the experimental data.
Date:
December 1954
Creator:
Melzer, M.
Object Type:
Report
System:
The UNT Digital Library
Determination of the Elastic Constants of Airplane Tires
For determination of the elastic constants of airplane tires which are required for the numerical calculations of the shimmy properties of nose and tail wheels, deformation measurements were carried out on four different tires. For this purpose, the tires were loaded in each case with a normal load and then with a lateral force, a tangential force, and a moment. Moreover, the weight and the mass moment of inertia about a vertical axis were determined for the various tires.
Date:
November 1954
Creator:
Boeckh
Object Type:
Report
System:
The UNT Digital Library
Heat Transfer by Free Convection From Horizontal Cylinders in Diatomic Gases
"The case of the horizontal cylinder is of particular importance in the study of heat transfer by free convection for the following reasons: In the first place, next to the rectangular plate it represents the simplest two-dimensional case; and second, a very wide range of measurements is possible, from the finest electrically heated glow lamp wires to pipes heated by liquids or gases flowing through them" (p. 1).
Date:
November 1954
Creator:
Hermann, R.
Object Type:
Report
System:
The UNT Digital Library
On Force-Deflection Diagrams of Airplane Shock Absorber Struts: First, Second, and Third Partial Reports
This paper, which is presented in three parts, is an analytical study of the behavior of landing gear shock struts, with various types of assumptions for the shock-strut characteristics. The effects of tire springing are neglected. The first part compares the behavior of struts with linear and quadratic damping. The second part considers struts with nonlinear spring characteristics and linear or quadratic damping. The third part treats the oleo-pneumatic strut with air-compression springing without damping and with damping proportional to velocity.
Date:
November 1954
Creator:
Schlaefke, Karlhans
Object Type:
Report
System:
The UNT Digital Library
On the Determination of Certain Basic Types of Supersonic Flow Fields
A discussion is given of the application of Fourier series techniques to the problems of linearized supersonic flow. The formulation presented is an extension of the doublet type of "fundamental solution" to higher order types of singularity. The equations developed have application to wing theory but are primarily of importance in wing-body interaction problems. A specific example of a wing-body interference problem is discussed in light of the presented methods.
Date:
November 1954
Creator:
Ferrari, Carlo
Object Type:
Report
System:
The UNT Digital Library
Experiments on a Tail-Wheel Shimmy
"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 pneumatic tires (scale 1:2) more accurate investigations were made on the tail wheel itself. The results of drum and road tests show good agreement with one another and with model values" (p. 1).
Date:
October 1954
Creator:
Dietz, O. & Harling, R.
Object Type:
Report
System:
The UNT Digital Library
Kinetic Treatment of the Nucleation in Supersaturated Vapors
The equations of the individual processes of self nucleation are utilized through an electrical analogy to obtain the nucleation frequency. This process is shown to be shorter and less subject to error than that of previous investigators since the appearance of indeterminant integration constants is completely avoided. With the nucleation frequencies of crystals and spheres the Ostwald law of stages is reviewed and modified.
Date:
September 1954
Creator:
Becker, R. & Döring, Werner
Object Type:
Report
System:
The UNT Digital Library
Papers on Shimmy and Rolling Behavior of Landing Gears Presented at Stuttgart Conference October 16 and 17, 1941
Report presenting a compilation of papers on shimmy and rolling behavior of landing gears.
Date:
August 1954
Creator:
Fromm, H.; Hoffman, E.; Harling, R.; Schrode, H.; Kraft, P.; Scheubel, Franz Nikolaus et al.
Object Type:
Report
System:
The UNT Digital Library
Drop Hammer Tests With Three Oleo Strut Models and Three Different Shock Strut Oils at Low Temperatures
"Drop hammer tests with different shock strut models and shock strut oils were performed at temperatures ranging to -40 C. The various shock strut models do not differ essentially regarding their springing and damping properties at low temperatures; however, the influence of the different shock strut oils on the springing properties at low temperatures varies greatly" (p. 1).
Date:
July 1954
Creator:
Kranz
Object Type:
Report
System:
The UNT Digital Library
On the Three-Dimensional Instability of Laminar Boundary Layers on Concave Walls
Memorandum presenting a study of the stability of laminar boundary layer profiles on slightly curved walls relative to small disturbances, in the shape of vortices, whose axes are parallel to the principal direction of flow. The result in an eigenvalue problem by which, for a given undisturbed flow at a prescribed wall, the amplification or decay is computed for each Reynolds number and each vortex thickness.
Date:
June 1954
Creator:
Görtler, H.
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
On the Sound Field of a Point-Shaped Sound Source in Uniform Translatory Motion
A rigorous analysis presented of the excitation of sound by point sources moving in uniform translatory motion at subsonic or supersonic velocities through a two- or three-dimensional medium at rest. The construction of surfaces of constant phase is based upon Huyghens' principle in such a manner that the propagation in the medium at rest of the elementary waves emanating from the sound source is independent of the momentary state of motion of the sound source. Hence, characteristic traits of the sound propagation may be understood even on the basis of simple geometric constructions.
Date:
April 1954
Creator:
Hönl, H.
Object Type:
Report
System:
The UNT Digital Library
Heat Transfer, Diffusion, and Evaporation
Memorandum presenting an investigation of the equations that relate heat transfer, diffusion, and evaporation. The report shows that more accurate equations must be substituted for those used in previous investigations of the relation between the quantity of matter exchanged by diffusion and the quantity of heat transferred by conduction.
Date:
March 1954
Creator:
Nusselt, Wilhelm
Object Type:
Report
System:
The UNT Digital Library
Experimental Determination of Local and Mean Coefficients of Heat Transfer for Turbulent Flow in Pipes
An extensive investigation of the changes of the local and mean heat-transfer coefficients along the pipe length, and some results.
Date:
February 1954
Creator:
Aladyev, I. T.
Object Type:
Report
System:
The UNT Digital Library
The Plane Problem of the Flapping Wing
"In connection with an earlier report on the lifting vortex sheet which forms the basis of the following investigations this will show how the methods developed there are also suitable for dealing with the air forces for a wing with a circulation variable with time. The theory of a propulsive wing flapping up and down periodically in the manner of a bird's wing is developed. This study shows how the lift and its moment result as a function of the flapping motion, what thrust is attainable, and how high is the degree of efficiency of this flapping propulsion unit if the air friction is disregarded" (p. 1).
Date:
January 1954
Creator:
Birnbaum, Walter
Object Type:
Report
System:
The UNT Digital Library
A New Simple Interferometer for Obtaining Quantitatively Evaluable Flow Patterns
"The method described in the present report makes it possible to obtain interferometer records with the aid of any one of the available Schlieren optics by the addition of very simple expedients, which fundamentally need not to be inferior to those obtained by other methods, such as the Mach-Zehnder interferometer, for example. The method is based on the fundamental concept of the phase-contrast process developed by Zernike, but which in principle has been enlarged to such an extent that it practically represents an independent interference method for general applications. Moreover, the method offers the possibility, in case of necessity, of superposing any apparent wedge field on the density field to be gauged" (p. 1).
Date:
November 1953
Creator:
Erdmann, S. F.
Object Type:
Report
System:
The UNT Digital Library
Supersaturation in the Spontaneous Formation of Nuclei in Water Vapor
"According to experience, a certain supersaturation is required for condensation of water vapor in the homogeneous phase; that is, for inception of the condensation, at a prescribed temperature, the water vapor partial pressure must lie above the saturation pressure. The condensation starts on so-called condensation nuclei. Solid or liquid suspended particles may serve as nuclei; these particles may either a priori be present in the gas phase (dust, soot), or may spontaneously be formed from the vapor molecules to be condensed themselves" (p. 1).
Date:
November 1953
Creator:
Sander, Adolf & Damköhler, Gerhard
Object Type:
Report
System:
The UNT Digital Library
Concerning the Flow About Ring-Shaped Cowlings 12: Two New Classes of Circular Cowls
"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
Object Type:
Report
System:
The UNT Digital Library
Concerning the Flow on Ring-Shaped Cowlings Part 13: The Influence of a Projecting Hub
"The influence of thickness and length of a hub projecting from an inlet opening was investigated on one of the two new classes of circular cowls reported in NACA TM 1360" (p. 1).
Date:
October 1953
Creator:
Küchemann, Dietrich
Object Type:
Report
System:
The UNT Digital Library
Air Admixture to Exhaust Jets
From Introduction: "The problem of thrust increase for jet engines by air mixture to the exhaust jet was introduced into aviation techniques by the suggestions of Melot (ref.1). Due to a too general interpretation of several theoretical investigations of A. Busemann (ref.2), so far no practical use has been made of these suggestions. The following considerations show that, in the case of low-pressure mixing according to Melot's suggestions, probably no thrust increase of technical significance will occur for the flight speeds of interest (however, the low-pressure mixture is highly promising for ground test setups and for special power plants of relatively slow sea and land vehicles."
Date:
July 1953
Creator:
Sänger, Eugen
Object Type:
Report
System:
The UNT Digital Library
Air-Water Analogy and the Study of Hydraulic Models
From Summary: "The author first sets forth some observations about the theory of models. Then he established certain general criteria for the construction of dynamically similar models in water and in air, through reference to the perfect fluid equations and to the ones pertaining to viscous flow. It is, in addition, pointed out that there are more cases in which the analogy is possible than is commonly supposed."
Date:
July 1953
Creator:
Supino, Giulio
Object Type:
Report
System:
The UNT Digital Library
The Microstructure of Turbulent Flow
"In 1941 a general theory of locally isotropic turbulence was proposed by Kolmogoroff which permitted the prediction of a number of laws of turbulent flow for large Reynolds numbers. The most important of these laws, the dependence of the mean square of the difference in velocities at two points on their distance and the dependence of the coefficient of turbulence diffusion on the scale of the phenomenon, were obtained by both Kolmogoroff and Obukhoff in the same year. At the present time these laws have been experimentally confirmed by direct measurements carried out in aerodynamic wind tunnels in the laboratory, in the atmosphere, and also on the ocean" (p. 1).
Date:
June 1953
Creator:
Obukhoff, A. M. & Yaglom, A. M.
Object Type:
Report
System:
The UNT Digital Library
Some Problems on the Theory of Creep
"The term creep of metals is applied to the phenomenon in which, at temperatures beyond a certain limit, the metal subjected to a load slowly undergoes deformation with time. Very slow deformations for a prolonged period are cumulative and lead either to inadmissible changes in the dimensions of a structural part or to its failure. The theory of creep constitutes part of the mechanics of dense media and the mechanical formulation of the problem may be given as the following: a body is subjected to the action of a given system of forces, or initial displacements are prescribed on its surface" (p. 1).
Date:
April 1953
Creator:
Rabotnov, Y. N.
Object Type:
Report
System:
The UNT Digital Library