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Correction of Downwash in Wind Tunnels of Circular and Elliptic Sections

Description: The downwash velocity distribution behind the wing was determined for the free jet and for the closed tunnel of both circular and elliptic cross sections. The wing was placed at the center of the tunnel. The theory makes it possible to determine the downwash at any point in the jet. The computations were performed for points in the plane determined by the jet axis and the center-of-pressure line of the wing.
Date: July 1936
Creator: Lotz, Irmgard
Partner: UNT Libraries Government Documents Department
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Status of Wing Flutter

Description: "This report presents a survey of previous theoretical and experimental investigations on wing flutter covering thirteen cases of flutter observed on airplanes. The direct cause of flutter is, in the majority of cases, attributable to (mass-) unbalanced ailerons. Under the conservative assumption that the flutter with the phase angle most favorable for excitation occurs only in two degrees of freedom, the lowest critical speed can be estimated from the data obtained on the oscillation bench" (p… more
Date: January 1936
Creator: Küssner, H. G.
Partner: UNT Libraries Government Documents Department
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Automatic Stabilization

Description: This report lays more stress on the principles underlying automatic piloting than on the means of applications. Mechanical details of servomotors and the mechanical release device necessary to assure instantaneous return of the controls to the pilot in case of malfunction are not included. Descriptions are provided of various commercial systems.
Date: December 1936
Creator: Haus
Partner: UNT Libraries Government Documents Department
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Experimental Studies of the Effective Width of Buckled Sheets

Description: The object of the present experiments is a more exact determination of the effective width for the case of pure compression and of the sheet clamped at the angle section. From the experimental data of the effective width the calculation of the buckling load of an angle joined to a thin sheet is then deduced. The test material consisted of spring-hardened brass sheet.
Date: December 1936
Creator: Lahde, R. & Wagner, H.
Partner: UNT Libraries Government Documents Department
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The Cetene Scale and the Induction Period Preceding the Spontaneous Ignition of Diesel Fuels in Bombs

Description: In the present report a comparison is made between the scale obtained with mixtures of cetane and l-methyl naphthalene in a bomb, and that obtained with the same fuels in a Waukesha engine. The tests were conducted in a metal bomb heated by a Nichrome spiral. The fuel was injected into the bomb from a Bosch jet by means of a specially constructed plunger pump. The instant injection and the pressure curve in the bomb were registered by a beam of light which was reflected from a mirror connected … more
Date: December 1936
Creator: Michailova, M. N. & Neumann, M. B.
Partner: UNT Libraries Government Documents Department
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The Horsepower of Aircraft Engines and Their Maximum Frontal Area

Description: This adaptation of a Russian report reveals the effect of maximum cross section of an engine as well as the interest attaching to a choice not solely based on horsepower. The tabulation gives a comparison between different engines restored at 5,000 meters. Radial versus inverted in-line engines are also compared.
Date: November 1936
Creator: Précoul, Michel
Partner: UNT Libraries Government Documents Department
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The Impact on Floats or Hulls During Landing as Affected by Bottom Width

Description: For floats and hulls having V bottoms the impact force does not necessarily increase with increasing width. Therefore, the weight of the float landing gear, side walls, and other parts, and of the fuselage construction need not be increased with increasing bottom width, but the weight of the bottom construction itself, on the other hand, does not increase with increase in bottom width and is largely determined by the type of construction.
Date: November 1936
Creator: Mewes, E.
Partner: UNT Libraries Government Documents Department
open access

Tests for the Determination of the Stress Condition in Tension Fields

Description: "The present experiments treat the stress of actual tension fields within the elastic range. They give the magnitude of the flexural stresses due to wrinkling. They also disclose, particularly by slightly exceeded buckling load, the marked unloading - as compared with the tension-field theory - of the uprights as a result of the flexural stiffness of the web plate. The test sheets were clamped at the edges and brought to buckling through shearing and compressive stresses applied in the directio… more
Date: November 1936
Creator: Lahde, R. & Wagner, H.
Partner: UNT Libraries Government Documents Department
open access

Torsion and Buckling of Open Sections

Description: In this paper is a discussion of the general principles for open sections of any shape. In what follows the torsion will be computed and on the basis of the results it will be possible to obtain a proper design of section in each case. The torsion of buckling members for the case where they are centrally loaded, leads to a problem in pure stability and is similar to that of stressed beams.
Date: October 1936
Creator: Wagner, Herbert
Partner: UNT Libraries Government Documents Department
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The Question of Spontaneous Wing Oscillations: Determination of Critical Velocity Through Flight-Oscillation Tests

Description: Determination of the spontaneous oscillations of a wing or tail unit entail many difficulties, both the mathematical determination and the determination by static wing oscillation tests being far from successful and flight tests involving very great risks. The present paper gives a method developed at the Junkers Airplane Company by which the critical velocity with respect to spontaneous oscillations of increasing amplitude can be ascertained in flight tests without undue risks, the oscillation… more
Date: October 1936
Creator: v. Schlippe, B.
Partner: UNT Libraries Government Documents Department
open access

Impact of a vee-type seaplane on water with reference to elasticity

Description: From Summary: "The theory developed by H. Wagner for the computation of the landing impact on water for a rigid float is extended to include elastic floats by introducing the concept of an equivalent rigid bottom to substitute for the actual elastic bottom."
Date: November 1936
Creator: Weinig, F.
Partner: UNT Libraries Government Documents Department
open access

General Considerations on the Flow of Compressible Fluids

Description: This paper presents an introduction to the subject of the flow of compressible media. Information regarding steady potential flow, flows with "subsonic" velocities, higher approximations of subsonic velocities, flow with supersonic velocities, an approximate method for general two-dimensional supersonic flow, passage through the velocity of sound, and the application to airfoils is provided. Historical development and hydraulics are omitted.
Date: October 1936
Creator: Prandtl, L.
Partner: UNT Libraries Government Documents Department
open access

The stress criterion of a tension member with graded flexural stiffness: contribution to the problem of "clamping effect" outside of the elastic range

Description: The approximate size of the stress criterion of a bar on two supports stressed beyond the elastic range is assessed by an approximation. The calculation proceeds from the premise of "substitute flexural stiffness" so defined that the part stressed beyond the elastic range may be considered as following Hooke's law when determining the flexural deformation quantities. For the determination of the substitute flexural stiffness, it is presumed that the material is already stressed so much beyond t… more
Date: September 1936
Creator: Kaul, Hans W.
Partner: UNT Libraries Government Documents Department
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Details of the Construction and Production of Fuel Pumps and Fuel Nozzles for the Airplane Diesel Engine

Description: This report presents investigations into the design and construction of fuel pumps for diesel engines. The results of the pump tests on the engines showed that, with a good cut-off, accurate injection, assured by the proper adjustment of the pump elements, there is a decrease in the consumption of fuel and hence an increase in the rated power of the engine. Some of the aspects investigated include: cam profile, coefficient of discharge, and characteristics of the injection system.
Date: September 1936
Creator: Lubenetsky, W. S.
Partner: UNT Libraries Government Documents Department
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Automatic Stabilization

Description: This report concerns the study of automatic stabilizers and extends it to include the control of the three-control system of the airplane instead of just altitude control. Some of the topics discussed include lateral disturbed motion, static stability, the mathematical theory of lateral motion, and large angles of incidence. Various mechanisms and stabilizers are also discussed.
Date: August 1936
Creator: Haus
Partner: UNT Libraries Government Documents Department
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Charts for Checking the Stability of Compression Members in Trusses

Description: "The present report contains a set of charts developed for computing the fixity effect on a compression member in a truss through its adjacent members, the amount of fixity being considered variable with the particular total truss load. The use of the charts is illustrated on two- and three-bay systems, as well as on a triangular truss" (p. 1).
Date: July 1936
Creator: Borkmann, K.
Partner: UNT Libraries Government Documents Department
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The Transport of Vorticity Through Fluids in Turbulent Motion: In the Light of the Prandtl and Taylor Theories

Description: The report studies the problem of the transport of vorticity or of momentum in light of the Taylor and Prandtl theories which are briefly reviewed. It also show how the formulas of Prandtl could be brought into agreement with experimental results in those cases where they agree with the principle of statistic similitude of Karman, and particularly in the problem of the distribution of velocity and temperature in the wake of a heated cylindrical obstacle.
Date: July 1936
Creator: Ferrari, C.
Partner: UNT Libraries Government Documents Department
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Flow Phenomena on Plates and Airfoils of Short Span

Description: "Investigations on the flow phenomena at plates and cambered models were carried out with the aid of force measurements, some pressure distribution measurements, and photographic observation. The experimental methods are described and the results given. Section III of this work gives a comprehensive account of the results and enables us to see how nearly the lift line and lift surface theories agree with the experimental results" (p. 1).
Date: June 1936
Creator: Winter, H.
Partner: UNT Libraries Government Documents Department
open access

Ignition Process in Diesel Engines

Description: This report analyzes the heating and vaporization process of fuel droplets in a compression-ignition engine on the basis of the theory of similitude - according to which, the period for heating and complete vaporization of the average size fuel drop is only a fraction of the actually observed ignition lag. The result is that ignition takes place in the fuel vapor air mixture rather than on the surface of the drop. The theoretical result is in accord with the experimental observations by Rothroc… more
Date: June 1936
Creator: Wentzel, W.
Partner: UNT Libraries Government Documents Department
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Contribution to the problem of airfoils spanning a free jet

Description: After a brief discussion of the work done up to now on an unwarped wing of constant chord spanning a free jet, the computation of the circulation and lift distribution for different forms of warped wings spanning rectangular and circular jets was carried out. The computed values are compared with test values and the agreement is found to be good. The effect of placing the wing eccentrically is slight and may be applied as a correction factor to the data obtained for wing placed in middle of jet. more
Date: June 1936
Creator: Stüper, J.
Partner: UNT Libraries Government Documents Department
open access

Similitude in Hydrodynamic Tests Involving Planing

Description: The problems of using models in planing tests are addressed. If one passes from the model to a hull of linear dimensions n times greater, the speeds are connected by the law of mechanical similitude. The normal forces given by the hydrodynamic equations (perfect fluid) also follow the law of dynamic similitude (Reech's method) and are multiplied by n(exp 3). A series of tests were performed and the actual results were compared to theoretical results.
Date: May 1936
Creator: Gruson, M. F.
Partner: UNT Libraries Government Documents Department
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Chief Characteristics and Advantages of Tailless Airplanes

Description: This study will be concerned with the critical examination of two main questions, mainly, susceptibility of centering and more generally, the conditions of static stability, longitudinal equilibrium, and the question of dynamic stability, or at least the damping of longitudinal vibrations about a position of equilibrium that may result from a small variation in the angle of attack.
Date: May 1936
Creator: Dufaure De Lajarte, A.
Partner: UNT Libraries Government Documents Department
open access

General instability criterion of laminar velocity distributions

Description: The present paper describes the results of a stability investigation on symmetrical velocity profiles in a channel and of boundary-layer profiles. The effect of friction was assumed to be vanishing and did not occur in the stability consideration so far as it had been resorted to for preparatory asymptotic considerations. Proceeding on very general premises as regards the form of the velocity distribution, a proof was deduced of the elementary theorem that velocity profiles with inflection poin… more
Date: April 1936
Creator: Tollmien, W.
Partner: UNT Libraries Government Documents Department
open access

Behavior of Turbulent Boundary Layers on Curved Convex Walls

Description: The system of linear differential equations which indicated the approach of separation and the so-called "boundary-layer thickness" by Gruschwitz is extended in this report to include the case where the friction layer is subject to centrifugal forces. Evaluation of the data yields a strong functional dependence of the momentum change and wall drag on the boundary-layer thickness radius of curvature ratio for the wall. It is further shown that the transition from laminar to turbulent flow occurs… more
Date: April 1936
Creator: Schmidbauer, Hans
Partner: UNT Libraries Government Documents Department
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