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The boundary layer as a means of controlling the flow of liquids and gases

Description: According to one of the main propositions of the boundary layer theory the scarcely noticeable boundary layer may, under certain conditions, have a decisive influence on the form of the external flow by causing it to separate from the wing surface. These phenomena are known to be caused by a kind of stagnation of the boundary layer at the point of separation. The present report deals with similar phenomena. It is important to note that usually the cause (external interference) directly affects only the layer close to the wall, while its indirect effect extends to a large portion of the external flow.
Date: March 1, 1930
Creator: Schrenk, Oskar
Partner: UNT Libraries Government Documents Department

Supplement to Comparison of automatic control systems

Description: This analysis deals with the indirect regulator, wherefrom the behavior of the direct regulator is deduced as a limiting case. The prime mover is looked upon as "independent of the load": a change in the adjusting power (to be applied) for the control link (as, for example, in relation to the adjusting path (eta) with pressure valves or the rudder of vessels) does not modify the actions of the prime mover. Mass forces and friction are discounted; "clearance" also is discounted in the transmission links of the regulator.
Date: August 1941
Creator: Oppelt, W
Partner: UNT Libraries Government Documents Department

The transformation of heat in an engine

Description: This report presents a thermodynamic basis for rating heat engines. The production of work by a heat engine rests on the operation of supplying heat, under favorable conditions, to a working fluid and then taking it away.
Date: April 1929
Creator: Neumann, Kurt
Partner: UNT Libraries Government Documents Department

The critical velocity of a body towed by a cable from an airplane

Description: It is sufficient to consider only the equations of motion of the towed body whereas those of the cable may be left out of consideration. The result obtained makes it possible to determine which factors affect the critical velocity and what modifications of the instrument are necessary for extending the upper limit of that velocity.
Date: July 1937
Creator: Koning, C. & DeHaas, T. P.
Partner: UNT Libraries Government Documents Department

Fire prevention on aircraft

Description: The following discussion is at first restricted to the light-oil engines now in use. We shall consider how far it is possible to reduce fire hazards by changes in the design of the engines and carburetors and in the arrangement of the fuel pipes.
Date: July 1, 1931
Creator: Kuhn, Fritz
Partner: UNT Libraries Government Documents Department

Functioning of reduction gears on airplane engines

Description: In undertaking to analyze the functioning conditions of a reduction gear on an aviation engine, we will consider an ordinary twelve-cylinder V-engine. The reduction gear employed consists either of a pair of spur gears, one of which is integral with the engine shaft and the other with the propeller shaft, or of a planetary system of gears.
Date: March 1926
Creator: Matteucci, Raffaelli
Partner: UNT Libraries Government Documents Department

Optico-photographic measurements of airplane deformations

Description: The deformation of aircraft wings is measured by photographically recording a series of bright shots on a moving paper band sensitive to light. Alternating deformations, especially vibrations, can thus be measured in operation, unaffected by inertia. A handy recording camera, the optograph, was developed by the static division of the D.V.L. (German Experimental Institute for Aeronautics) for the employment of this method of measurement on airplanes in flight.
Date: March 1, 1931
Creator: Kussner, Hans Georg
Partner: UNT Libraries Government Documents Department

Nomogram for correcting drag and angle of attack of an airfoil model in an air stream of finite diameter

Description: In experimenting with airfoil models in a wind tunnel, the magnitude of the forces acting on the model is affected by the fact that the air stream in which the model is suspended, has a restricted cross-section. In order to utilize the results for an airplane in an unlimited quantity of air, a correction must be made. The magnitude of this correction was determined by Prandtl by the application of his wing theory.
Date: December 1924
Partner: UNT Libraries Government Documents Department

Problems concerning the stability and maneuverability of airplanes

Description: The stability of an airplane can be easily determined by wind-tunnel tests, especially by simple tests with models mounted wind-vane fashion. However, each stability curve plotted by this method is valid only for a certain setting of the corresponding control surface, i.e., it characterizes the stability of the airplane with the control stick in a given position. The problems thus defined are studied from the point of view of longitudinal and transverse stability. Directional stability is not included in this study.
Date: March 1, 1932
Creator: Biche, Jean
Partner: UNT Libraries Government Documents Department

Landing impact of seaplanes

Description: The theory of landing impact is briefly stated and the applicability of a previously suggested formula is extended. Theoretical considerations regarding impact measurements on models and actual seaplanes are followed by a brief description of the instruments used in actual flight tests. The report contains a description of the strength conditions and deals exhaustively with force measurements on the float gear of an "HE 9a" with flat-bottom and with V-bottom floats. The experimental data are given and compared with the theoretical results.
Date: June 1, 1931
Creator: Pabst, Wilhelm
Partner: UNT Libraries Government Documents Department

Lecture on Aerodynamics

Description: This lecture deals with four main subjects: methods of studying air resistance, experimental aerodynamics, propellers and stability of airplanes.
Date: September 1923
Creator: Toussaint, A
Partner: UNT Libraries Government Documents Department

Lautal as a material for airplane construction

Description: Lautal is a refinable aluminum alloy which, unlike duralumin, contains no magnesium. According to the statements of the Lauta Works, lautal contains: aluminum, 94%; copper, 4%; silicon, 2%. The use of lautal as a construction material is discussed in relation to specific weight, production methods, and riveting tests.
Date: August 1, 1929
Creator: Brenner, Paul
Partner: UNT Libraries Government Documents Department

Liquid cooling of aircraft engines

Description: This report presents a method for solving the problem of liquid cooling at high temperatures, which is an intermediate method between water and air cooling, by experiments on a test-stand and on an airplane. A utilizable cooling medium was found in ethylene glycol, which has only one disadvantage, namely, that of combustibility. The danger, however is very slight. It has one decided advantage, that it simultaneously serves as protection against freezing.
Date: December 1931
Creator: Weidinger, Hanns
Partner: UNT Libraries Government Documents Department

Load assumptions for calculating the strength of airplanes

Description: The following load assumptions shall be taken as the basis of the strength calculations. Certain definite load conditions (e.g. of flight, control, landing and transport) shall be assumed. The loads shall be assumed to be safe loads, constant or only slowly variable, and the inertia forces due to elastic deformation are accordingly disregarded. The external forces, the force of gravity and the inertia forces on the whole airplane shall produce a condition of equilibrium.
Date: September 1, 1930
Partner: UNT Libraries Government Documents Department