Technical Report Archive and Image Library (TRAIL) - 117 Matching Results

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Theory of flapping flight

Description: Before attempting to construct a human-powered aircraft, the aviator will first try to post himself theoretically on the possible method of operating the flapping wings. This report will present a graphic and mathematical method, which renders it possible to determine the power required, so far as it can be done on the basis of the wing dimensions. We will first consider the form of the flight path through the air. The simplest form is probably the curve of ordinary wave motion. After finding the flight curve, we must next determine the change in the angle of attack while passing through the different phases of the wave.
Date: October 1, 1925
Creator: Lippisch, Alexander
Partner: UNT Libraries Government Documents Department

A method for the direct determination of wing-section drag

Description: In order that the method may be more easily understood, we will first consider the simpler case when there is no lift, but only drag, and when the streamlines at the measuring point behind the obstacle are nearly parallel. Moreover, the flow is assumed not to deviate much from the two-dimensional flow.
Date: November 1925
Creator: Betz, A.
Partner: UNT Libraries Government Documents Department

Strength calculations on airplanes

Description: Every strength calculation, including those on airplanes, must be preceded by a determination of the forces to be taken into account. In the following discussion, it will be assumed that the magnitudes of these forces are known and that it is only a question of how, on the basis of these known forces, to meet the prescribed conditions on the one hand and the practical requirements on the other.
Date: December 1, 1925
Creator: Baumann, A
Partner: UNT Libraries Government Documents Department

Wire suspensions in wind tunnel experiments

Description: The elimination of the rigid supports for models and their replacement by wires constitute a great improvement by rendering negligible the interactions of support. There are disadvantages to wire, namely, the aerodynamic resistance is very large and their use is rather difficult because the whole suspension lacks rigidity and easily becomes distorted. We will here investigate the nature of these distortions, evaluate the errors they entail and describe the methods for taking account of or avoiding them.
Date: December 1, 1925
Creator: Kerneis, Jean
Partner: UNT Libraries Government Documents Department

Potential flow in engine valves

Description: The extensive applicability of the hydrodynamic theory to the problems of engine construction is clearly shown in the following attempt to determine by exact methods the nature of the flow in valves under variously restricted conditions. Observation shows that two principal kinds of flow occur in simple flat-seated valves. For small valve lifts, the flow is along the horizontal wall and is therefore deflected 90 degrees, but for greater valve lifts the flow separates and forms a free stream, whose angle of deflection naturally increases with increasing lift. Both these kinds of flow can, in fact, be theoretically explained.
Date: December 1, 1925
Creator: Eck, Bruno
Partner: UNT Libraries Government Documents Department

The "Navigraph"

Description: Commander Le Prieur, whose flight experience in a low-speed seaplane we related in our number of September 27, 1924, invented, four years ago, an instrument destined to render very great service to aviators, namely, the "navigraph", designed to correct errors of orientation due to the effect of the winds during flight.
Date: June 1, 1925
Creator: Le Prieur, Ives
Partner: UNT Libraries Government Documents Department

Computation of cantilever airplane wings

Description: The purpose of this treatise is, first of all, the determination of the effect of variously loaded spars on one another, since the neglect of this effect would present an economically very unfavorable computation method. The system of spars and cross-bars alone (whether solid or built-up) does not matter at first, the original assumption being that the spars are rigidly braced by the cross-bars.
Date: July 1, 1925
Creator: Thalau, K
Partner: UNT Libraries Government Documents Department

Airplane parachutes

Description: The "Bulletin Technique", of March, 1919, gave the results of tests and studies made up to that date in connection with airplane parachutes. This work has been continued.
Date: August 1925
Creator: Mazer
Partner: UNT Libraries Government Documents Department

Recent experiments at the Gottingen Aerodynamic Institute

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).
Date: July 1, 1925
Creator: Ackeret, J.
Partner: UNT Libraries Government Documents Department

Relation of "Lilienthal effect" to dynamic soaring flight

Description: In this article, the phenomena of the upward component in the case of flat surfaces will be referred to as the "Lilienthal effect." The Lilienthal effect will be distinguished from the Knoller-Betz effect which is explained by means of vertical wind oscillations, at the basis of which, however, there lie air motions which the Lilienthal effect could not produce. It will be shown that the same cause, which can produce the Lilienthal effect on flat airfoils, considerably strengthens the thrust due to the Knoller-Betz effect.
Date: July 1, 1925
Creator: Fick, Roderich
Partner: UNT Libraries Government Documents Department

Pitot-static tubes for determining the velocity of air

Description: On the occasion of the formulation of the rules for testing the efficiency of ventilators and compressors, experiments were instituted by the subcommittee on ventilators for the production of suitable tubes for velocity and pressure measurements.
Date: February 1, 1925
Creator: Kumbruch, H.
Partner: UNT Libraries Government Documents Department

Calculation of wing spars of variable cross-section and linear load

Description: 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.
Date: March 1, 1925
Creator: Kirste, Leon
Partner: UNT Libraries Government Documents Department

Preliminary investigation of the effect of a rotating cylinder in a wing

Description: Into the leading edge of a wing with arbitrary cross-section, there is introduced a cylinder, which can be rotated by an electric motor by means of a cord. Observations were made in the wind tunnel on how the lift at different wind velocities was affected by rotating this cylinder.
Date: March 1, 1925
Creator: Wolff, E B
Partner: UNT Libraries Government Documents Department

Law of similitude for the surface resistance of lacquered planes moving in a straight line through water

Description: The proof of the validity of the Reynolds law of similitude for the surface resistance of planes has been developed with an accuracy hitherto unattained and for a large range of lengths and speeds. It has been shown that, in addition to the form resistance, the resistance of the longitudinal edges must be taken into account.
Date: April 1, 1925
Creator: Gebers, Friedrich
Partner: UNT Libraries Government Documents Department

Light aeroplane engine development

Description: It has frequently been stated and written that in order to popularize light aircraft the first essential is the production of a reliable engine capable of being easily maintained and having a long life, at the same time selling at a low figure. It is desired to point out the difficulties in the way of realizing this ideal before remarking on the claims of the various types for adoption.
Date: April 1, 1925
Creator: Fell, L. F. R.
Partner: UNT Libraries Government Documents Department

European commercial aeronautics

Description: During the months of June to September, 1924, I personally visited the principal airports of Europe and traveled as a passenger some 6500 air miles on English, French, Romanian, Polish, German and Dutch air lines in order to investigate the development of commercial aviation abroad. The results of the investigation are embodied in a series of reports, of which a summary of the general findings is given below.
Date: May 1, 1925
Creator: Van Zandt, J Parker
Partner: UNT Libraries Government Documents Department