You limited your search to:

  Partner: UNT Libraries Government Documents Department
 Serial/Series Title: NACA Technical Memorandums
 Collection: Technical Report Archive and Image Library
Tail Buffeting

Tail Buffeting

Date: February 1, 1943
Creator: Abdrashitov, G.
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.
Contributing Partner: UNT Libraries Government Documents Department
The Theory of a Free Jet of a Compressible Gas

The Theory of a Free Jet of a Compressible Gas

Date: March 1, 1944
Creator: Abramovich, G. N.
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.
Contributing Partner: UNT Libraries Government Documents Department
Air forces on airfoils moving faster than sound

Air forces on airfoils moving faster than sound

Date: June 1, 1925
Creator: Ackeret, J
Description: We are undertaking the task of computing the air forces on a slightly cambered airfoil in the absence of friction and with an infinite aspect ratio. We also assume in advance that the leading edge is very sharp and that its tangent lies in the direction of motion.
Contributing Partner: UNT Libraries Government Documents Department
Drag measurements of two thin wing sections at different index values

Drag measurements of two thin wing sections at different index values

Date: June 1, 1927
Creator: Ackeret, J
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.
Contributing Partner: UNT Libraries Government Documents Department
Experiments on airfoils with trailing edge cut away

Experiments on airfoils with trailing edge cut away

Date: September 1, 1927
Creator: Ackeret, J
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 their chords.
Contributing Partner: UNT Libraries Government Documents Department
High-speed wind tunnels

High-speed wind tunnels

Date: November 1, 1936
Creator: Ackeret, J
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.
Contributing Partner: UNT Libraries Government Documents Department
Present and future problems of airplane propulsion

Present and future problems of airplane propulsion

Date: May 1, 1941
Creator: Ackeret, J
Description: Some of the problems considered in this report include: thermodynamics of surface friction, application of thick wing sections, special applications of controllable propellers, and gas turbines for aircraft.
Contributing Partner: UNT Libraries Government Documents Department
Recent experiments at the Gottingen Aerodynamic Institute

Recent experiments at the Gottingen Aerodynamic Institute

Date: July 1, 1925
Creator: Ackeret, J
Description: This report presents the results of various experiments carried out at the Gottingen Aerodynamic Institute. These include: experiments with Joukowski wing profiles; experiments on an airplane model with a built-in motor and functioning propeller; and the rotating cylinder (Magnus Effect).
Contributing Partner: UNT Libraries Government Documents Department
Removing boundary layer by suction

Removing boundary layer by suction

Date: January 1, 1927
Creator: Ackeret, J
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.
Contributing Partner: UNT Libraries Government Documents Department
Experimental and Theoretical Investigations of Cavitation in Water

Experimental and Theoretical Investigations of Cavitation in Water

Date: May 1, 1945
Creator: Ackeret, J.
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. The collapse of the bubbles under compression shock produces very high pressures internally, which must be contributory factors to corrosion. The pressure required for purely mechanical corrosion is also discussed.
Contributing Partner: UNT Libraries Government Documents Department
Aerodynamic Heat-Power Engine Operating on a Closed Cycle

Aerodynamic Heat-Power Engine Operating on a Closed Cycle

Date: November 1, 1942
Creator: Ackeret, J. & Keller, D. C.
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 which the internal efficiency of the unit changes but slightly. The effect of pressure and temperature losses is investigated. A general discussion is given of the experimental installation operating at the Escher Wyss plant in Zurich for a considerable time at high temperatures.
Contributing Partner: UNT Libraries Government Documents Department
Investigations of Compression Shocks and Boundary Layers in Gases Moving at High Speed

Investigations of Compression Shocks and Boundary Layers in Gases Moving at High Speed

Date: January 1, 1947
Creator: Ackeret, J.; Feldmann, F. & Rott, N.
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.
Contributing Partner: UNT Libraries Government Documents Department
Experiments with an airfoil from which the boundary layer is removed by suction

Experiments with an airfoil from which the boundary layer is removed by suction

Date: August 1, 1926
Creator: Ackeret, J; Betz, A & Schrenk, O
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.
Contributing Partner: UNT Libraries Government Documents Department
Investigations on wings with and without sweepback at high subsonic speeds

Investigations on wings with and without sweepback at high subsonic speeds

Date: November 1, 1951
Creator: Ackeret, Jakob; Rott, Nikolaus & Degen, Max
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 and 0.12 and the results compared with results predicted by von Karman's similarity law.
Contributing Partner: UNT Libraries Government Documents Department
The Magnus effect in theory and in reality

The Magnus effect in theory and in reality

Date: May 1, 1930
Creator: Ahlborn, F
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.
Contributing Partner: UNT Libraries Government Documents Department
Turbulence and mechanism of resistance on spheres and cylinders

Turbulence and mechanism of resistance on spheres and cylinders

Date: January 1, 1932
Creator: Ahlborn, FR
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. The very pronounced changes in pressure distribution connected with it were affirmed by manometric measurements on spheres by Professor O. Krell. The reversal in a homogenous nonvortical flow is brought about by the advance of the stable arrangement of Karman's dead air vortices toward the test object and by the substitution of an alternatingly one-sided or rotating but stable vortex formation in place of the initially symmetrical formation. This also explains the marked variations of the models.
Contributing Partner: UNT Libraries Government Documents Department
Experimental determination of local and mean coefficients of heat transfer for turbulent flow in pipes

Experimental determination of local and mean coefficients of heat transfer for turbulent flow in pipes

Date: February 1, 1954
Creator: Aladyev, I T
Description: An extensive investigation of the changes of the local and mean heat-transfer coefficients along the pipe length, and some results.
Contributing Partner: UNT Libraries Government Documents Department
Air cooling : an experimental method of evaluating the cooling effect of air streams on air-cooled cylinders

Air cooling : an experimental method of evaluating the cooling effect of air streams on air-cooled cylinders

Date: May 1, 1927
Creator: Alcock, J F
Description: In this report is described an experimental method which the writer has evolved for dealing with air-cooled engines, and some of the data obtained by its means. Methods of temperature measurement and cooling are provided.
Contributing Partner: UNT Libraries Government Documents Department
Combustion of liquid fuels in diesel engine

Combustion of liquid fuels in diesel engine

Date: October 1, 1924
Creator: Alt, Otto
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.
Contributing Partner: UNT Libraries Government Documents Department
On the Calculation of Shallow Shells

On the Calculation of Shallow Shells

Date: December 1, 1956
Creator: Ambartsumyan, S. A.
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.
Contributing Partner: UNT Libraries Government Documents Department
On the Theory of Anisotropic Shallow Shells

On the Theory of Anisotropic Shallow Shells

Date: December 1, 1956
Creator: Ambartsumyan, S. A.
Description: A numerical analysis of thin-walled shallow shells is presented. Equations of equilibrium and relations between deformations and stresses are included along with fundamental differential equations.
Contributing Partner: UNT Libraries Government Documents Department
Calculation of tapered monoplane wings

Calculation of tapered monoplane wings

Date: August 1, 1930
Creator: Amstutz, E
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 consideration of these problems.
Contributing Partner: UNT Libraries Government Documents Department
Airplane stability in taxying

Airplane stability in taxying

Date: September 1, 1932
Creator: Anderlik, E
Description: The stability analysis of an airplane while rolling is much more simplified to the extent that it can be obtained for numerical data which can be put to practical use in the design of landing gear dimensions. Every landing gear type attains to a critical ground friction coefficient that decides the beginning of instability, i.e., nosing over. This study has, in addition, a certain interest for the use of wheel brakes.
Contributing Partner: UNT Libraries Government Documents Department
Experiments on autorotation

Experiments on autorotation

Date: September 1, 1926
Creator: Anderlik, E
Description: This article deals principally with Professor Bairstow's experiments on autorotation, in which the wing is free to rotate about an axis in its plane of symmetry, which axis is parallel with the direction of the wind.
Contributing Partner: UNT Libraries Government Documents Department
FIRST PREV 1 2 3 4 5 NEXT LAST