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The Boundary Layer as a Means of Controlling the Flow of Liquids and Gases
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
System:
The UNT Digital Library
Static Longitudinal Stability Of "Ente" Airplanes
The stability conditions of Ente (duck) airplanes are investigated in this report. In developing the formulas, which afford an approximate solution, the unimportant effect of the height of the C.G. and the moment of the residual resistance are neglected. The effect of downwash from the forward horizontal empennage on the wing are also disregarded.
Date:
March 1931
Creator:
Kiel, Heinrich Georg
System:
The UNT Digital Library
Atmospheric Waves and Their Utilization in Soaring Flight
In soaring flight, ascending air currents are utilized and the interesting question is raised whether there are such currents which extend to any considerable distance and which can be utilized practically.
Date:
March 1923
Creator:
Baldit, M. Albert
System:
The UNT Digital Library
Problems Concerning the Stability and Maneuverability of Airplanes
"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" (p. 1).
Date:
March 1932
Creator:
Biche, Jean
System:
The UNT Digital Library
Accurate Calculation of Multispar Cantilever and Semicantilever Wings With Parallel Webs Under Direct and Indirect Loading
In the present report the computation is actually carried through for the case of parallel spars of equal resistance in bending without direct loading, including plotting of the influence lines; for other cases the method of calculation is explained. The development of large size airplanes can be speeded up by accurate methods of calculation such as this.
Date:
March 1932
Creator:
Sänger, Eugen
System:
The UNT Digital Library
A Few More Mechanical-Flight Formulas Without the Aid of Polar Diagrams
The reliability of the assumption of a parabolic shape of the polar curve is investigated and found satisfactory for all practical purposes. It is further shown that the aerodynamically best possible or "ideal" airplane is produced on this assumption. Lastly, detailed suggestions are given on the possibilities of application of this method of calculation. It especially simplifies the design and evaluation of structural changes and the determination of the limits of technical possibilities. The present report deals only with the relations of the airfoils. The mutual action of the airfoils, engine and propeller will be treated in a subsequent report.
Date:
March 1928
Creator:
Schrenk, Martin
System:
The UNT Digital Library
Elmira Soaring Contest, 1930
This report details the Elmira, New York soaring contest of 1930 and provides up-current maps, experiences in piloting, distance flights, and a few details on glider design.
Date:
March 1931
Creator:
Hirth, Wolfram K. E.; Schempp, Martin H. & Herrick, Jack
System:
The UNT Digital Library
Spontaneous Combustion of Hydrogen
It is shown by the author's experiments that hydrogen which escapes to the atmosphere through openings in the system may burn spontaneously if it contains dust. Purely thermal reasoning can not account for the combustion. It seems to be rather an electrical ignition. In order to determine whether the cause of the spontaneous ignition was thermo-chemical, thermo-mechanical, or thermo-electrical, the experiments in this paper were performed.
Date:
March 4, 1922
Creator:
Pothmann, P. & Nusselt, Wilhelm
System:
The UNT Digital Library
The Protection of Duralumin From Corrosion
Different types of coatings to protect duralumin from corrosion are discussed. Plating, etching, brushing, coloring, painting and varnishing are all investigated.
Date:
March 1927
Creator:
Nelson, William
System:
The UNT Digital Library
The vector ruling protractor
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.
System:
The UNT Digital Library
The Practical Difficulties of Commercial Flying
This paper relates some of the problems commercial aircraft companies have in attracting larger numbers of paying customers. The author discusses some remedies such as changing the public perception of flying as dangerous.
Date:
March 1924
Creator:
Courtney, F. T.
System:
The UNT Digital Library
Functioning of Reduction Gears on Airplane Engines
"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" (p. 1).
Date:
March 1926
Creator:
Matteucci, Raffaelli
System:
The UNT Digital Library
Analytical methods for computing the polar curves of airplanes
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
System:
The UNT Digital Library
Voyage of The "Dixmude" Over Northern Africa
This article presents the difficulties and triumphs of the airship Dixmude in its long distance flight over North Africa as described by one of the occupants.
Date:
March 1924
Creator:
Lemaire
System:
The UNT Digital Library
Analysis of flight and wind-tunnel tests on Udet airplanes with reference to spinning characteristics
This report presents an analysis of results of wind-tunnel tests conducted at the D.V.L. Values were determined for the effectiveness of all the controls at various angles of attack. The autorotation was studied by subjecting the rotating model to an air blast.
Date:
March 1929
Creator:
Herrmann, H.
System:
The UNT Digital Library
German Aircraft Accident Statistics, 1930
The investigation of all serious accidents, involving technical defects in the airplane or engine, is undertaken by the D.V.L. in conjunction with the imperial traffic minister and other interested parties. All accidents not clearly explained in the reports are subsequently cleared up.
Date:
March 1932
Creator:
Weitzmann, Ludwig
System:
The UNT Digital Library
Optico-Photographic Measurements of Airplane Deformations
"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" (p. 1).
Date:
March 1931
Creator:
Küssner, Hans Georg
System:
The UNT Digital Library
The Electrodynamometric Balance of the Small Wind Tunnel of the French Service of Aeronautical Research
This investigation shows the attempt to improve the electrodynamomoter designed by Mr. Villey. The force to be measured acts on a flexible steel plate which is placed in front of a fixed plate. The deformation varies the original thickness of the layer of air between the two plates, thus causing a more rapid variation in the coefficient of electrostatic attraction of the two plates than in the capacity of the condenser formed by the dynamometer.
Date:
March 1930
Creator:
Rebuffet, P.
System:
The UNT Digital Library
Suggestions for Courses of Instruction in Aviation
Suggestions are presented for the establishment of lecture courses on aviation. An outline of some courses that have previously been given is provided.
Date:
March 1925
Creator:
Poeschel
System:
The UNT Digital Library
Communications and Beacons on Air Routes
Different systems of navigations beacons are discussed with an emphasis on radiotelegraphy and radiotelephony.
Date:
March 1922
Creator:
Franck
System:
The UNT Digital Library
Mechanical Control of Airplanes
"Before undertaking a detailed description of an automatic-control mechanism, I will state briefly the fundamental conditions for such devices. These are: 1) it must be sensitive at one or more reference values; 2) it must stop the angular motions of the airplane not produced by the pilot; and 3) it must be possible to switch it off and on by a simple hand lever" (p. 1).
Date:
March 1929
Creator:
Boykow, H.
System:
The UNT Digital Library
Effect of Changing the Mean Camber of an Airfoil Section
Methodical experiments with the series of airfoil sections of the same relative thickness and of variable relative cambers can be utilized for determining the effect of the camber on the aerodynamic properties of airfoil sections.
Date:
March 1924
Creator:
Toussaint, A.
System:
The UNT Digital Library
Calculation of Wing Spars of Variable Cross-Section and Linear Load
"The calculation of wing spars of constant cross-section and load has been thoroughly treated by a large number of authors. Such is not the case,however, regarding the calculation of wing spars whose section and linear load diminish toward the ends, as in wings of trapezoidal contour and decreasing section" (p. 1).
Date:
March 1925
Creator:
Kirste, Léon
System:
The UNT Digital Library
Altitude of equilibrium of an airship
This report details the procedure followed in establishing a general formula enabling the calculation of the maximum altitude attainable statically.
Date:
March 1925
Creator:
Nobile, Umberto
System:
The UNT Digital Library