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Corrections on the Thermometer Reading in an Air Stream

Description: A method is described for checking a correction formula, based partly on theoretical considerations, for adiabatic compression and friction in flight tests and determining the value of the constant. It is necessary to apply a threefold correction to each thermometer reading. They are a correction for adiabatic compression, friction and for time lag.
Date: October 1940
Creator: Van der Maas, H. J. & Wynia, S.
Partner: UNT Libraries Government Documents Department
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Correlation of Data on the Statistical Theory of Turbulence

Description: The statistical theory of turbulence affords an excellent medium for representing the kinematic conditions in turbulent flow and also serves as a valuable aid to exact experimental research. But it is still not developed enough for solving dynamic processes. Even in the simplest case of isotropic turbulence the calculation of the correlation curve or of the decrement of turbulence invariably reaches a point where clear-cut assumptions, such as omission of the inertia terms, or, earlier, mixing … more
Date: March 1942
Creator: Wieghardt, K.
Partner: UNT Libraries Government Documents Department
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The Coupling of Flexural Propeller Vibrations with the Torsional Crankshaft Vibrations

Description: The exact mathematical treatment of the problem is possible by replacing the propeller blade by a homogeneous prismatic rod. Conclusions can them be drawn as to the behavior of an actual propeller, since tests on propeller blades have indicated a qualitative agreement with the homogeneous rod. The natural frequencies are determined and the stressing of the systems under the various vibration modes are discussed.
Date: December 1943
Creator: Meyer, J.
Partner: UNT Libraries Government Documents Department
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The Creep of Laminated Synthetic Resin Plastics

Description: "The long-time loading strength of a number of laminated synthetic resin plastics was ascertained and the effect of molding pressure and resin content determined. The best value was observed with a 30 to 40 percent resin content. The long-time loading strength also increases with increasing molding pressure up to 250 kg/cm(exp 2); a further rise in pressure affords no further substantial improvement" (p. 1)..
Date: November 1941
Creator: Perkuhn, H.
Partner: UNT Libraries Government Documents Department
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Creep Strength of Stabilized Wrought-Aluminum Alloys

Description: Rohn-type equipment has been mounted on rubber blocks, for the purpose of damping the vibrations of the ground and of rendering the plastic yielding of the test bars less subject to outside interferences. New equipment also included three shockproof creep-testing machines with the Martens mirror instruments for recording the strain curve of the fatigue-tested specimens.
Date: November 1940
Creator: Müller, W.
Partner: UNT Libraries Government Documents Department
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Description of Russian Aircraft Engines "AM 35" and "AM 38"

Description: The Russian AM 35 and AM 38 aircraft engines have superchargers with a swirl throttle, which appears to be a purely Russian development. This paper gives the results of test runs of the two engines, including the effects of the swirl throttle on engine performance.
Date: June 1947
Creator: Denkmeier, H. & Gross, K.
Partner: UNT Libraries Government Documents Department
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The Design of Jet Pumps

Description: This report shows that by applying both energy and impulse theorems the optimum throat dimension of the mixing nozzle and the best shape of intake can be predicted approximately in a relatively simple manner. The necessary length of the mixing nozzle follows from Prandtl's turbulent mixing theory. The calculations are carried out for the mixing of similar and dissimilar fluids.
Date: July 1941
Creator: Flügel, Gustav
Partner: UNT Libraries Government Documents Department
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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… more
Date: January 1942
Creator: Cordes, G.
Partner: UNT Libraries Government Documents Department
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Determination of the Actual Contact Surface of a Brush Contact

Description: "The number of partial contact surfaces of a brush-ring contact is measured by means of a statistical method. The particular brush is fitted with wicks - that is, insulated and cemented cylinders of brush material, terminating in the brush surface. The number of partial contact surfaces can be computed from the length of the rest periods in which such wicks remain without current" (p. 1).
Date: August 1944
Creator: Holm, Ragnar
Partner: UNT Libraries Government Documents Department
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Determination of the Bending and Buckling Effect in the Stress Analysis of Shell Structures Accessible From One Side Only

Description: "The present report describes a device for ascertaining the bending and buckling effect in stress measurements on shell structures accessible from one side only. Beginning with a discussion of the relationship between flexural strain and certain parameters, the respective errors of the test method for great or variable skin curvature within the test range are analyzed and illustrated by specimen example" (p. 1).
Date: December 1941
Creator: Dose, A.
Partner: UNT Libraries Government Documents Department
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Determination of the Mass Moments and Radii of Inertia of the Sections of a Tapered Wing and the Center-of-Gravity Line Along the Wing Span

Description: "For computing the critical flutter velocity of a wing among the data required are the position of the line of centers of gravity of the wing sections along the span and the mass moments and radii of inertia of any section of the wing about the axis passing through the center of gravity of the section. A sufficiently detailed computation of these magnitudes even if the weights of all the wing elements are known, requires a great deal of time expenditure. Thus a rapid competent worker would requ… more
Date: December 1943
Creator: Savelyev, V. V.
Partner: UNT Libraries Government Documents Department
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Determination of the Stress Concentration Factor of a Stepped Shaft Stressed in Torsion by Means of Precision Strain Gages

Description: The stress distribution in stepped shafts stressed in torsion is determined by means of the electric precision strain gage the stress concentration factor is ascertained from the measurements. It is shown that the test values always are slightly lower than the values resulting from an approximate formula.
Date: September 1947
Creator: Weigand, A.
Partner: UNT Libraries Government Documents Department
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Determination of the Stresses Produced by the Landing Impact in the Bulkheads of a Seaplane Bottom

Description: "The present report deals with the determination of the impact stresses in the bulkhead floors of a seaplane bottom. The dynamic problem is solved on the assumption of a certain elastic system, the floor being assumed as a weightless elastic beam with concentrated masses at the ends (due to the mass of the float) and with a spring which replaces the elastic action of the keel in the center. The distributed load on the floor is that due to the hydrodynamic force acting over a certain portion of … more
Date: January 1944
Creator: Darevsky, V. M.
Partner: UNT Libraries Government Documents Department
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Development and Construction of an Interferometer for Optical Measurements of Density Fields

Description: "A method of interference is described in the present report which promises profitable application in aeronautical research. The physical foundation of the method and a simple method of adjustment are briefly discussed. The special technical construction of the instrument is described which guarantees its use also in the case of vibrations of the surrounding space and permits the investigation of unsteady phenomena" (p. 1).
Date: September 1947
Creator: Zobel
Partner: UNT Libraries Government Documents Department
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DFS Dive-Control Brakes for Gliders and Airplanes and Analytical Study of the Drag of the DFS Dive-Control Brake

Description: These two reports are surveys on the progress and present state of development of dive-control flaps for gliders and airplanes. The second article describes how on the basis of wind tunnel and free-flight tests, the drag increase on brake flaps of the type DFS, can be predicted. Pressure records confirm a two-dimensional load distribution along the brake-flap surface.
Date: January 1940
Creator: Jacobs, Hans & Wanner, Adolf
Partner: UNT Libraries Government Documents Department
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Diagrams for Calculation of Airfoil Lattices

Description: "The field for curved blades is represented by a vortex series with a vortex removed at the blade point. Further, an example of calculation of a curved blade from this series is given, whereby the necessary accuracy required of the different methods in practice is shown according to the case considered" (p. 1).
Date: July 1942
Creator: Betz, Albert
Partner: UNT Libraries Government Documents Department
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The Distribution of Loads on Rivets Connecting a Plate to a Beam Under Transverse Loads

Description: "This report gives theoretical discussion of the distribution of leads on rivets connecting a plate to a beam under transverse leads. Two methods of solution are given which are applicable to loads up to the limit of proportionality; in the first the rivets are treated as discrete members, and in the second they are replaced by a continuous system of jointing. A method of solution is also given which is applicable to the case when nonlinear deformations occur in the rivets and the plate, but no… more
Date: April 1947
Creator: Vogt, F.
Partner: UNT Libraries Government Documents Department
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Distribution of Structural Weight of Wing Along the Span

Description: "In the present report the true weight distribution law of the wing structure along the span is investigated. It is shown that the triangular distribution and that based on the proportionality to the chords do not correspond to the actual weight distribution, On the basis of extensive data on wings of the CAHI type airplane formulas are obtained from which it is possible to determine the true diagram of the structural weight distribution along the span from a knowledge of only the geometrical d… more
Date: August 1946
Creator: Savelyev, V. V.
Partner: UNT Libraries Government Documents Department
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Drag Corrections in High-Speed Wind Tunnels

Description: In the vicinity of a body in a wind tunnel the displacement effect of the wake, due to the finite dimensions of the stream, produces a pressure gradient which evokes a change of drag. In incompressible flow this change of drag is so small, in general, that one does not have to take it into account in wind-tunnel measurements; however, in compressible flow it beoomes considerably larger, so that a correction factor is necessary for measured values. Correction factors for a closed tunnel and an o… more
Date: July 1947
Creator: Ludwieg, H.
Partner: UNT Libraries Government Documents Department
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Drag Reduction by Suction of the Boundary Layer Separated Behind Shock Wave Formation at High Mach Numbers

Description: "With an approach of the velocity of flight of a ship to the velocity of sound, there occurs a considerable increase of the drag. The reason for this must be found in the boundary layer separation caused by formation of shock waves. It will be endeavored to reduce the drag increase by suction of the boundary layer. Experimental results showed that drag increase may be considerably reduced by this method" (p. 1).
Date: July 1947
Creator: Regenscheit, B.
Partner: UNT Libraries Government Documents Department
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DVL Angular Velocity Recorder

Description: "In many studies, especially of nonstationary flight motion, it is necessary to determine the angular velocities at which the airplane rotates about its various axes. The three-component recorder is designed to serve this purpose. If the angular velocity for one flight attitude is known, other important quantities can be derived from its time rate of change, such as the angular acceleration by differentiations, or - by integration - the angles of position of the airplane - that is, the angles f… more
Date: August 1944
Creator: Liebe, Wolfgang
Partner: UNT Libraries Government Documents Department
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Dynamic Similitude in Internal-Combustion Engines

Description: In this report it will be seen that the piston speed - as, moreover, any other speed, such as bearing velocity - must be independent of the quantity dimensions and must be a representative quantity similar to the high speed and the specific weight per horsepower.
Date: May 1941
Creator: Lutz, O.
Partner: UNT Libraries Government Documents Department
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Effect of the Acceleration of Elongated Bodies of Revolution Upon the Resistance in a Compressible Flow

Description: The problem of the motion of an elongated body of revolution in an incompressible fluid may, as is known, be solved approximately with the aid of the distribution of sources along the axis of the body. In determining the velocity field, the question of whether the body moves uniformly or with an acceleration is no factor in the problem. The presence of acceleration must be taken into account in determining the pressures acting on the body. The resistance of the body arising from the accelerated… more
Date: May 1949
Creator: Frankl, F. I.
Partner: UNT Libraries Government Documents Department
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