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Tail Buffeting

Description: "An approximate theory of buffeting is here presented, based on the assumption of harmonic disturbing forces. Two cases of buffeting are considered: namely, for a tail angle of attack greater and less than the stalling angle, respectively. On the basis of the tests conducted and the results of foreign investigators, a general analysis is given of the nature of the forced vibrations the possible load limits on the tail, and the methods of elimination of buffeting" (p. 1).
Date: February 1943
Creator: Abdrashitov, G.
Partner: UNT Libraries Government Documents Department
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The Theory of a Free Jet of a Compressible Gas

Description: "In the present report the theory of free turbulence propagation and the boundary layer theory are developed for a plane-parallel free stream of a compressible fluid. In constructing the theory use was made of the turbulence hypothesis by Taylor (transport of vorticity) which gives best agreement with test results for problems involving heat transfer in free jets" (p. 1).
Date: March 1944
Creator: Abramovich, G. N.
Partner: UNT Libraries Government Documents Department
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Experimental and Theoretical Investigations of Cavitation in Water

Description: "The cavitation in nozzles on airfoils of various shape and on a sphere are experimentally investigated. The limits of cavitation and the extension of the zone of the bubbles in different stages of cavitation are photographically established. The pressure in the bubble area is constant and very low, jumping to high values at the end of the area. The analogy with the gas compression shock is adduced and discussed" (p. 1).
Date: May 1945
Creator: Ackeret, J.
Partner: UNT Libraries Government Documents Department
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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 whic… more
Date: November 1942
Creator: Ackeret, J. & Keller, D. C.
Partner: UNT Libraries Government Documents Department
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Investigations of Compression Shocks and Boundary Layers in Gases Moving at High Speed

Description: The mutual influences of compression shocks and friction boundary layers were investigated by means of high speed wind tunnels.Schlieren optics provided a clear picture of the flow phenomena and were used for determining the location of the compression shocks, measurement of shock angles, and also for Mach angles. Pressure measurement and humidity measurements were also taken into consideration.Results along with a mathematical model are described.
Date: January 1947
Creator: Ackeret, J.; Feldmann, F. & Rott, N.
Partner: UNT Libraries Government Documents Department
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Axial Superchargers

Description: Improvements, however, have been attained which permit a shortening of the structure without any impairment of the efficiency. The axial supercharger has a better efficiency and a simpler design than the radial supercharger. The relatively narrow range in which it operates satisfactorily should not be a very disturbing factor for practical flight problems. The length of this type of supercharger may be reduced considerably if some impairment in the efficiency is permitted.
Date: August 1944
Creator: Betz, A.
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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Calculation of the Pressure Distribution on Bodies of Revolution in the Subsonic Flow of a Gas Part 1 - Axially Symmetrical Flow

Description: "The present report concerns a method of computing the velocity and pressure distributions on bodies of revolution in axially symmetrical flow in the subsonic range. The differential equation for the velocity potential Phi of a compressible fluid motion is linearized tn the conventional manner, and then put in the form Delta(Phi) = 0 by affine transformation. The quantity Phi represents the velocity potential of a fictitious incompressible flow, for which a constant superposition of sources by … more
Date: July 1947
Creator: Bilharz, Herbert & Hölder, Ernst
Partner: UNT Libraries Government Documents Department
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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.
Partner: UNT Libraries Government Documents Department
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The Monoplane as a Lifting Vortex Surface

Description: "In Prandtl's airfoil theory the monoplane was replaced by a single lifting vortex line and yielded fairly practical results. However, the theory remained restricted to the straight wing. Yawed wings and those curved in flight direction could not be computed with this first approximation; for these the chordwise lift distribution must be taken into consideration. For the two-dimensional problem the transition from the lifting line to the lifting surface has been explained by Birnbaum. In the pr… more
Date: February 1947
Creator: Blenk, Hermann
Partner: UNT Libraries Government Documents Department
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Contribution to the Design of Plywood Shells

Description: "The writer sets out to prove by calculation and experiment that by extensive utilization of the skin to carry axial load (reduction of stringer spacing) the stringer sections can be made small enough to afford a substantial saving in structural weight. This saving ranges from 5 to about 40 percent" (p. 1).
Date: October 1942
Creator: Blumrich, S.
Partner: UNT Libraries Government Documents Department
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The Surface Structure of Ground Metal Crystals

Description: "The changes produced on metallic surfaces as a result of grinding and polishing are not as yet fully understood. Undoubtedly there is some more or less marked change in the crystal structure, at least, in the top layer. Hereby a diffusion of separated crystal particles may be involved, or, on plastic material, the formation of a layer in greatly deformed state, with possible recrystallization in certain conditions" (p. 1).
Date: August 1944
Creator: Boas, W. & Schmid, E.
Partner: UNT Libraries Government Documents Department
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Airscrew Gyroscopic Moments

Description: "When flying in a turn or pulling out of a dive, the airscrew exerts a gyroscopic moment on the aircraft, In the case of airscrews with three or more blades, arranged symmetrically, the value of the gyroscopic moment is J(sub x) omega(sub x) omega(sub y), where J(sub x) denotes the axial moment of inertia about the axis of rotation of the airscrew, omega(sub x) the angular upeed of the airscrew about its axis, and omega (sub Y) the rotary speed of the whole aircraft about an axis parallel to th… more
Date: September 1946
Creator: Bock, G.
Partner: UNT Libraries Government Documents Department
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Factors Influencing the Fatigue Strength of Materials

Description: "A number of factors are considered which influence the static and fatigue strength of materials under practical operating conditions as contrasted with the relations obtaining under conditions of the usual testing procedure. Such factors are interruptions in operation, periodically fluctuating stress limits and mean stresses with periodic succession of several groups and stress states, statistical changes and succession of stress limits and mean stresses, frictional corrosion at junctures, and… more
Date: September 1941
Creator: Bollenrath, F.
Partner: UNT Libraries Government Documents Department
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The Further Development of Heat-Resistant Materials for Aircraft Engines

Description: "The present report deals with the problems involved in the greater utilization and development of aircraft engine materials, and specifically; piston materials, cylinder heads, exhaust valves, and exhaust gas turbine blading. The blades of the exhaust gas turbine are likely to be the highest stressed components of modern power plants from a thermal-mechanical and chemical standpoint, even though the requirements on exhaust valves of engines with gasoline injection are in general no less string… more
Date: September 1946
Creator: Bollenrath, Franz
Partner: UNT Libraries Government Documents Department
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Italian High-Speed Airplane Engines

Description: This paper presents an account of Italian high-speed engine designs. The tests were performed on the Fiat AS6 engine, and all components of that engine are discussed from cylinders to superchargers as well as the test set-up. The results of the bench tests are given along with the performance of the engines in various races.
Date: June 1940
Creator: Bona, C. F.
Partner: UNT Libraries Government Documents Department
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Maintaining Laminar Flow in the Boundary Layer Using a Swept-Back Wing

Description: "The positions of boundary-layer transition were ascertained experimentally for a swept-back wing and a wing without sweepback which were alike in all other respects and were compared for the same angle of attack (R(sub e) = 5.6 x 10(exp 5)). The swept-back wing in a definite range of angle of attack resulted in a backward shift of the transition point on the suction side of the wing. The favorable effect of sweepback on the position of the transition point is confirmed, consequently" (p. 1).
Date: February 1948
Creator: Brennecke
Partner: UNT Libraries Government Documents Department
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On the Installation of Jet Engine Nacelles on a Wing Fourth Partial Report: Pressure-Distribution Measurements on a Sweptback Wing with Jet Engine Nacelle

Description: "The present report, which deals with pressure-distribution measurements made on a sweptback wing with a jet engine nacelle, is similar to a report on pressure-distribution measurements on a rectangular wing with a jet engine nacelle (second partial report). Here, in investigations preliminary to high-speed measurements, as in the second partial report, useful arrangements and fillet designs have been discovered" (p. 1).
Date: July 1949
Creator: Buschner, R.
Partner: UNT Libraries Government Documents Department
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Compression Shocks in Two-Dimensional Gas Flows

Description: "The following are arguments on the compression shocks in gas flow start with a simplified representation of the results of the study made by Th. Meyer as published in the Forschungsheft 62 of the VDI, supplemented by several amplifications for the application. In the treatment of compression shocks, the equation of energy, the equation of continuity, the momentum equation, the equation of state of the particular gas, as well as the condition Of the second law of thermodynamics that no decrease… more
Date: February 1949
Creator: Busemann, A.
Partner: UNT Libraries Government Documents Department
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Infinitesimal Conical Supersonic Flow

Description: The calculation of infinitesimal conical supersonic flow has been applied first to the simplest examples that have also been calculated in another way. Except for the discovery of a miscalculation in an older report, there was found the expected conformity. The new method of calculation is limited more definitely to the conical case.
Date: March 1947
Creator: Busemann, Adolf
Partner: UNT Libraries Government Documents Department
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Rockets Using Liquid Oxygen

Description: "It is my task to discuss rocket propulsion using liquid oxygen and my treatment must be highly condensed for the ideas and experiments pertaining to this classic type of rocket are so numerous that one could occupy a whole morning with a detailed presentation. First, with regard to oxygen itself as compared with competing oxygen carriers, it is known that the liquid state of oxygen, in spite of the low boiling point, is more advantageous than the gaseous form of oxygen in pressure tanks, there… more
Date: April 1947
Creator: Busemann, Adolf
Partner: UNT Libraries Government Documents Department
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Measurement of Oil-Film Pressures in Journal Bearings under Constant and Variable Loads

Description: "In a study of journal bearings, the measurement of the oil-film strength produces some significant information. A new instrument is described by means of which the pressure of the oil film in bearings (under constant or alternating load) can be measured and recorded. With this device, the pressure distribution in the lubricating film of a bearing bushing was measured (under different operating conditions on a journal bearing) in the pulsator-bearing-testing machine" (p. 1).
Date: November 1949
Creator: Buske, A. & Rolli, W.
Partner: UNT Libraries Government Documents Department
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