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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

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" (p. 1).
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

Lift Theory of Supporting Surfaces: Second Article

Description: Memorandum presenting a description of the hydrodynamic lift theory of supporting services. This report is mainly about the task of finding suitable wing sections for given lift conditions. Formulas are given for lift magnitude and moment, which make it possible to obtain solutions of great simplicity and clearness.
Date: September 1921
Creator: von Mises, R.
Partner: UNT Libraries Government Documents Department

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 1930
Creator: Schrenk, Oskar
Partner: UNT Libraries Government Documents Department

Downwash measurements behind wings with detached float

Description: This investigation, which was made in the small wind tunnel having a diameter of 1.2 m (3.94 feet), embraced three wing models, behind which, at various angles of attack between 0 and 60 degrees, the static pressure and the total pressure along vertical lines (perpendicular to the direction of the undisturbed wind and to the wing span) were measured. The location of these vertical lines are indicated in Figure 1. Moreover, the wing polars were determined by the customary three-component measurements. For testing the pressure field, a Pitot tube and a static probe, both of 2 mm (0.08 in.) in diameter, were mounted 40 mm (1.57 in.) apart on the end of a shaft 1 m (39.37 in.) long.
Date: August 1931
Creator: Petersohn, E.
Partner: UNT Libraries Government Documents Department

Analytical methods for computing the polar curves of airplanes

Description: This report presents a method of calculating polar curves which is at least as precise as graphical methods, but it more rapid. Knowing the wind tunnel test of a wing and the performances of an airplane of the same profile, it is easy to verify the characteristic coefficients and, at the same time, the methods determining induced resistances.
Date: March 1921
Creator: Le Sueur
Partner: UNT Libraries Government Documents Department

Combined pitching and yawing motion of airplanes

Description: This report treats the following problems: The beginning of the investigated motions is always a setting of the lateral controls, i.e., the rudder or the ailerons. Now, the first interesting question is how the motion would proceed if these settings were kept unchanged for some time; and particularly, what upward motion would set in, how soon, and for how long, since therein lie the dangers of yawing. Two different motions ensue with a high rate of turn and a steep down slope of flight path in both but a marked difference in angle of attack and consequently different character in the resultant aerodynamic forces: one, the "corkscrew" dive at normal angle, and the other, the "spin" at high angle.
Date: May 1931
Creator: Baranoff, A. V. & Hopf, L.
Partner: UNT Libraries Government Documents Department

Fire prevention on airplanes. Part 2

Description: This part of the report presents a detailed examination of spark prevention, fire extinguishers, and fuel tank location and design. A continued program of investigations and research is also proposed.
Date: October 1929
Creator: Sabatier, J.
Partner: UNT Libraries Government Documents Department

Researches on ailerons and especially on the test loads to which they should be subjected

Description: Aileron calculations have hitherto given greatly differing results according to different authors. It seems to be the general opinion that it is only necessary to give the ailerons such dimensions that the airplane can maneuver well, that the stresses they must undergo are relatively small, and that they are strong enough if their framework is of the order of strength as the wings to which they are attached. This article will show that the problem is really quite complex and that it should receive more attention.
Date: February 1927
Creator: Sabatier, J.
Partner: UNT Libraries Government Documents Department

Fire prevention on airplanes. Part 1

Description: Various methods for preventing fires in airplanes are presented with most efforts centering around prevention of backfires, new engine and carburetor designs, as well as investigations on different types of fuels.
Date: October 1929
Creator: Sabatier, J.
Partner: UNT Libraries Government Documents Department

On the stability of oscillations of an airplane wing

Description: During a flight with a Van Berkel W. B. seaplane it was observed that the wing could perform violent oscillations. A theoretical and experimental investigation led to the conclusion, that in some cases an unstable oscillation of the wing-aileron system under the influence of the elastic and aerodynamic forces is possible without further external causes.
Date: August 1923
Creator: Von Baumhauer, A. G. & Koning, C.
Partner: UNT Libraries Government Documents Department

The vector ruling protractor

Description: The theory, structure and working of a vector slide rule is presented in this report. This instrument is used for determining a vector in magnitude and position when given its components and its moment about a point in their plane.
Date: March 1924
Creator: Zahm, A. F.
Partner: UNT Libraries Government Documents Department

Aeronautical education and research at the Swiss Institute of Technology in Zurich

Description: Progress in the scientific and practical fields of aviation has caused the Swiss Institute of Technology to organize lectures and practical training courses in all three branches of aeronautics and to found centers of scientific research, laboratories, etc., in order to supply the government and industries with scientifically and technically trained engineers.
Date: April 1931
Creator: Karner, L. & Ackeret, J.
Partner: UNT Libraries Government Documents Department

Approximation method for determining the static stability of a monoplane glider

Description: The calculations in this paper afford an approximate solution of the static stability. A derivation of the formulas for moment coefficient of a wing, moment coefficient of elevator, and the total moment of the combined wing and elevator and the moment coefficient with reference to the center of gravity are provided.
Date: November 1927
Creator: Lippisch, A.
Partner: UNT Libraries Government Documents Department

Technical report of the 1928 Rhon soaring-flight contest

Description: Report presenting some information on the gliders that participated in the 1928 Rhön soaring flight contest. Almost all of the gliders represented an improvement over gliders used in the previous years. A great increase in the skill of the glider pilots is also noted.
Date: May 1929
Creator: Lippisch, A.
Partner: UNT Libraries Government Documents Department

The vortex theory and its significance in aviation

Description: This report will present ideas closely related to the vortex conception and illustrate them in the simplest possible terms. In addition to these general considerations, this report will attempt to show the application of the vortex theory in connection with the wing theory.
Date: July 1930
Creator: Betz, A.
Partner: UNT Libraries Government Documents Department

Aerial photography : obtaining a true perspective

Description: Report discussing a demonstration was given within the last few days at the British Museum by Mr. J. W. Gordon, author of "Generalized Linear Perspective" (Constable and Co.), a work describing a newly-worked-out system by which photographs can be made available for the purpose of exactly recording the dimensions of the objects photographed even when the objects themselves are presented foreshortened in the photograph.
Date: April 1923
Partner: UNT Libraries Government Documents Department

Hydrodynamic tests for determining the take-off characteristics of seaplanes

Description: The resistance of water, even at low speeds, may be such as to render it impossible to take off. For this type of aircraft, it is therefore especially important to determine the take-off characteristics. A new and simple graphical method is given and appears to be the only one for the complete solution of the problem.
Date: May 1923
Creator: Verduzio, R.
Partner: UNT Libraries Government Documents Department

Application of the theory of free jets

Description: Based upon Kirchoff's theory of free jets the flow through different screen arrangements of flat plates, as chiefly encountered with turbines in the cavitation zone is defined. It is shown by experiments that these theoretical results are very well representative in most cases of the conditions of discharge from water in air and consequently by cavitation. In addition, the experiments reveal a picture of the discrepancies between the actual flow and the theory of discharge of air in air (of water in water without cavitation). These discrepancies are explained qualitatively by the mingling processes between the jets and the dead air zones.
Date: April 1932
Creator: Betz, A. & Petersohn, E.
Partner: UNT Libraries Government Documents Department