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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.
Item Type: Refine your search to only Report
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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.
Item Type: Refine your search to only Report
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Drag measurements of two thin wing sections at different index values

Description: It is stated that the index value 6000, as found in normal tests of wing sections with a 20 cm chord, falls in the same region where the transition of laminar to turbulent flow takes place on thin flat plates. It is to be expected that slightly cambered, thin wing sections will behave similarly. The following test of two such wing sections were made for the purpose of verifying this supposition.
Date: June 1927
Creator: Ackeret, J.
Item Type: Refine your search to only Report
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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.
Item Type: Refine your search to only Report
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Experiments on airfoils with trailing edge cut away

Description: "Airfoils with their trailing edge cut away are often found on aircraft, as the fins on the hulls of flying boats and the central section of the wings for affording better visibility. It was therefore of some interest to discover the effect of such cutaways on the lift and drag and on the position of the center of pressure. For this purpose, systematic experiments were performed on two different airfoils, a symmetrical airfoil and an airfoil of medium thickness, with successive shortenings of t… more
Date: September 1927
Creator: Ackeret, J.
Item Type: Refine your search to only Report
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High-speed wind tunnels

Description: Wind tunnel construction and design is discussed especially in relation to subsonic and supersonic speeds. Reynolds Numbers and the theory of compressible flows are also taken into consideration in designing new tunnels.
Date: November 1936
Creator: Ackeret, J.
Item Type: Refine your search to only Report
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Removing boundary layer by suction

Description: "Through the utilization of the "Magnus effect" on the Flettner rotor ship, the attention of the public has been directed to the underlying physical principle. It has been found that the Prandtl boundary-layer theory furnishes a satisfactory explanation of the observed phenomena. The present article deals with the prevention of this separation or detachment of the flow by drawing the boundary layer into the inside of a body through a slot or slots in its surface" (p. 1).
Date: January 1926
Creator: Ackeret, J.
Item Type: Refine your search to only Report
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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.
Item Type: Refine your search to only Report
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Experiments With an Airfoil From Which the Boundary Layer Is Removed by Suction

Description: "Our attempts to improve the properties of airfoils by removing the boundary layer by suction, go back to 1922. The object of the suction is chiefly to prevent the detachment of the boundary layer from the surface of the airfoil. At large angles of attack, such detachment prevents the attainment of the great lift promised by the theory, besides greatly increasing the drag, especially of thick airfoils. This report gives results of those experiments" (p. 1).
Date: August 1926
Creator: Ackeret, J.; Betz, A. & Schrenk, O.
Item Type: Refine your search to only Report
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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.
Item Type: Refine your search to only Report
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Investigations on Wings With and Without Sweepback at High Subsonic Speeds

Description: Drag tests at zero lift have been made at Mach numbers from 0.7 to approximately 0.95 in the high speed wind tunnel of the Institute of Aerodynamics, ETH, Zurich, on a group of untapered wings of aspect ratio 3.25, having sweep angles of 0 degree and 35 degrees. For each sweep angle, a series of geometrically similar models was tested at a constant Reynolds number to provide a verification of computed tunnel blocking corrections. Tests were also made for wings having thickness ratios of 0.09 an… more
Date: November 1951
Creator: Ackeret, Jakob; Degen, Max & Rott, Nikolaus
Item Type: Refine your search to only Report
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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.
Item Type: Refine your search to only Report
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The Magnus Effect in Theory and in Reality

Description: A discussion of the Flettner rotor is presented from a nautical and economic viewpoint, and although it was a failure, the experimental and theoretical inventions cannot be disregarded. The following critical and experimental investigation will show the relations and applicability of the theories and practical applications. The Magnus effect is described in detail and a discussion and critical review of the Magnus effect is included.
Date: May 1930
Creator: Ahlborn, F.
Item Type: Refine your search to only Report
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Turbulence and Mechanism of Resistance on Spheres and Cylinders

Description: The nature of turbulent flow through pipes and around obstacles is analyzed and illustrated by photographs of turbulence on screens and straighteners. It is shown that the reversal of flow and of the resistance law on spheres is not explainable by Prandtl's turbulence in the boundary layer. The investigation of the analogous phenomena on the cylinder yields a reversal of the total field of flow.
Date: January 1932
Creator: Ahlborn, F.
Item Type: Refine your search to only Report
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Aerodynamic characteristics of the X-15/B-52 combination

Description: Report presenting an investigation to determine the carry loads and mutual aerodynamic interference effects from high-speed wind-tunnel tests and the drop characteristics of the X-15 through the B-52 flow field from low-speed dynamic-model drop tests and six-degree-of-freedom calculations. The X-15 installation was found to increase drag at cruise conditions by approximately 15 percent.
Date: 1959
Creator: Alford, William J., Jr. & Taylor, Robert T.
Item Type: Refine your search to only Report
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Combustion of Liquid Fuels in Diesel Engine

Description: Hitherto, definite specifications have always been made for fuel oils and they have been classified as more or less good or non-utilizable. The present aim, however, is to build Diesel engines capable of using even the poorest liquid fuels and especially the waste products of the oil industry, without special chemical or physical preparation.
Date: October 1924
Creator: Alt, Otto
Item Type: Refine your search to only Report
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On the Calculation of Shallow Shells

Description: This paper considers a sufficiently thin shallow shell of nonzero Gaussian curvature. It also presents a system of symmetrically constructed differential equations, constructed by the mixed method through the stress function and the displpacement function.
Date: December 1956
Creator: Ambartsumyan, S. A.
Item Type: Refine your search to only Report
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Calculation of Tapered Monoplane Wings

Description: The tapered wing shape increases the lift in the middle of the wing and thus reduces the bending moment of the lifting forces in the plane of symmetry. Since this portion of the wing is the thickest, the stresses of the wing material are reduced and desirable space is provided for stowing the loads in the wing. This statically excellent form of construction, however, has aerodynamic disadvantages which must be carefully weighed, if failures are to be avoided. This treatise is devoted to the con… more
Date: August 1930
Creator: Amstutz, E.
Item Type: Refine your search to only Report
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