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The Law Relating to Air Currents

Description: In the subdivided wing section profile, the diagram of the current is entirely changed and the harmful formation of eddies is avoided through premature deflection. Pressure equalization does not occur between the upper and under sides. This report presents a discussion of the various laws relating to wing design with the conclusion being that lift increases with more acute angles of attack.
Date: March 1921
Partner: UNT Libraries Government Documents Department
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The Goebel Rotary Engine

Description: This report presents a table of specifications of the rotary engine and a very brief description of some of the notable features such as the exhaust valves controlled by means of a fixed cam gear.
Date: March 1921
Partner: UNT Libraries Government Documents Department
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Abacus Giving the Variation of the Mean Pressure of an Aviation Engine as a Function of its Speed of Rotation

Description: Comparing the results of the calculations for computing the mean pressure of an aviation engine for any number of revolutions, with those of experiment, the writer, by numerous examples, shows the perfect agreement between them. This report will show that, by means of a special abacus, an engineer can instantly plot the characteristics of an engine.
Date: March 1921
Creator: Margoulis, W.
Partner: UNT Libraries Government Documents Department
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Hydrostatic Test of an Airship Model

Description: An airship model made by the Goodyear Rubber Company was filled with water and suspended from a beam. The deformations of the envelope were studied under the following conditions: 1) both ballonets empty; 2) forward ballonets filled with air; 3) rear ballonets filled with air; and 4) both ballonets filled with air. Photographs were taken to record the deflections under each of these conditions, and a study was made to determine the minimum head of water necessary to maintain the longitudinal axis of the envelope under these conditions. It was concluded that any pressure sufficient to keep the airship full may be used. It appears that a pressure of one inch of water would provide a suitable factor of safety, and therefore it is the pressure that is recommended.
Date: March 1922
Partner: UNT Libraries Government Documents Department
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The Choice of the Speed of an Airship

Description: The favorable speed of an airship is chiefly determined by the condition of the consumption of the least amount of fuel per unit of traveled distance, although other conditions come into play. The resulting rules depend on the character of the wind and on the variability of the efficiency of the engine propeller units. This investigation resulted in the following rules. 1) Always keep the absolute course and steer at such an angle with reference to it as to neutralize the side wind. 2) In a strong contrary wind, take a speed one and one half times the velocity of the wind. 3) As a general rule, take the velocity of the wind and the velocity of the course component of the wind. Add them together if the wind has a contrary component, but subtract them from each other if the wind has a favorable component.
Date: March 1922
Creator: Munk, Max M.
Partner: UNT Libraries Government Documents Department
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New Data on the Laws of Fluid Resistance

Description: Thus far, all attempts at the quantitative determination of drag, on the basis of the theory of viscous fluids, have met with but slight success. For this reason, whenever a more accurate knowledge of the drag is desirable, it must be determined by experiment. Here, a few experimental results are given on the drag of a cylinder exposed to a stream of air at right angles to its axis. It is shown that the drag depends on the absolute dimensions of the body and the velocity and viscosity of the fluid in a much more complex manner than has heretofore been supposed.
Date: March 1922
Creator: Wieselsberger, C.
Partner: UNT Libraries Government Documents Department
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Influence of Span and Load Per Square Meter on the Air Forces of the Supporting Surface

Description: "It should be clear that in order to obtain a lift it is necessary that the air which flows past an aerofoil be given a downward acceleration; indeed the lift can be only the reaction produced by the downward acceleration of the flowing air. The motion of the air in the neighborhood of an aerofoil may be followed theoretically with great exactness. In the following, it will be undertaken to make understood, through the simplest possible considerations, the effect of span and loading on the air force on an aerofoil, and while these do not form a strong proof of the correctness of the formulae developed, yet they explain the essential features of the phenomena" (p. 1).
Date: March 1921
Creator: Betz, A.
Partner: UNT Libraries Government Documents Department
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Standardization and Aerodynamics

Description: Report presenting suggestions for the standardization of the study of aerodynamics in laboratories in the United States and Europe. A report by each of the different scientists, all of whom are working in a variety of different labs and countries, is provided, and each discusses the progress made in their respective labs and their suggestions for standardization and progress in the field.
Date: March 1923
Creator: Knight, William; Prandtl, L.; von Karman; Costanzi, G.; Margoulis, W.; Verduzio, R. et al.
Partner: UNT Libraries Government Documents Department
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Static stability of seaplane floats and hulls

Description: Values of lateral and longitudinal metacentric heights for various seaplanes were calculated by means of approximate formulae derived here. The data are given in tabular form. Upon plotting these metacentric heights against the corresponding gross weights, it appears that the metacentric height is approximately a straight line function of the gross weight.
Date: March 1924
Creator: Diehl, W. S.
Partner: UNT Libraries Government Documents Department
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Note on Vortices on Their Relation to the Lift of Airfoils

Description: "This note, prepared for the NACA, contains a discussion of the meaning of vortices, so often mentioned in connection with the creation of lift by wings. The action of wings can be more easily understood without the use of vortices" (p. 1).
Date: March 1924
Creator: Munk, Max M.
Partner: UNT Libraries Government Documents Department
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Evolution of the Helicopter

Description: Report presenting an investigation of problems related to helicopters. Also included are the history of the evolution of the helicopter and a series of propeller experiments.
Date: March 1923
Creator: Balaban, Karl
Partner: UNT Libraries Government Documents Department
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The Calculation of Wing Float Displacement in Single-Float Seaplanes

Description: Note presenting an exploration of the calculation of wing float displacement in single-float seaplanes. An explanation of a formula that can be used is provided.
Date: March 1925
Creator: Warner, Edward P.
Partner: UNT Libraries Government Documents Department
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Note on the Air Forces on a Wing Caused by Pitching.

Description: Report containing information on the air forces on a wing produced by its pitching at a finite rate of angular velocity. The condition of smooth flow at the region of the trailing edge is maintained. The wing then experiences the same lift as if moving with the momentary velocity of the rear edge.
Date: March 1925
Creator: Munk, Max M.
Partner: UNT Libraries Government Documents Department
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Disturbing Effect of Free Hydrogen on Fuel Combustion in Internal Combustion Engines

Description: "Experiments with fuel mixtures of varying composition, have recently been conducted by the Motor Vehicle and Airplane Engine Testing Laboratories of the Royal Technical High School in Berlin and at Fort Hahneberg, as well as at numerous private engine works. The behavior of hydrogen during combustion in engines and its harmful effect under certain conditions, on the combustion in the engine cylinder are of general interest. Some of the results of these experiments are given here, in order to elucidate the main facts and explain much that is already a matter of experience with chauffeurs and pilots" (p. 1).
Date: March 1923
Creator: Riedler, A.
Partner: UNT Libraries Government Documents Department
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Wall interference in closed type wind tunnels

Description: "A series of tests has been conducted by the National Advisory Committee for Aeronautics, in the variable density wind tunnel on several airfoils of different sizes and sections to determine the effect of tunnel wall interference and to determine a correction which can be applied to reduce the error caused thereby. The use of several empirical corrections was attempted with little success. The Prandtl theoretical correction gives the best results and its use is recommended for correcting closed wind tunnel results to conditions of free air" (p. 1).
Date: March 1927
Creator: Higgins, George J.
Partner: UNT Libraries Government Documents Department
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The Lateral Failure of Spars

Description: It was concluded that after the critical span or depth-breadth ratio has been reached, the modulus of rupture varies approximately inversely as the first power of the span and of the depth-breadth ratio. The direction of the lateral deflection is alternate between successive supports. For this reason, we believe that rib spacing along the spar is more important in reducing lateral deflection than the distance between supports at the strut points.
Date: March 1926
Creator: Bromley, Stevens & Robinson, William H., Jr.
Partner: UNT Libraries Government Documents Department
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The Rumpler Passenger Airplane

Description: This report details the Rumpler Limousine which was a further development of the well known type 5 A 2. The fuselage, engine, cabin, wings, controls, and landing gear are all discussed.
Date: March 1921
Creator: Langsdorff, Werner v.
Partner: UNT Libraries Government Documents Department
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Variation in the Number of Revolutions of Air Propellers

Description: Note describing the variation in the number of revolutions per minute and provides simple formulas that allow for advanced calculation to be made of the variation of propeller speed with variation of one or more dimensions of the propeller and allow the necessary corrections to be applied.
Date: March 1923
Creator: Achenbach, W.
Partner: UNT Libraries Government Documents Department
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The Increase in Dimensions of Airplanes - Weight, Area, and Loading of Wings

Description: Note presenting an investigation of the increase in the dimensions of airplanes, including the weight, area, and loading of wings, and how increasing the size of different components may affect these aerodynamic factors.
Date: March 1923
Creator: Everling, E.
Partner: UNT Libraries Government Documents Department
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Notes on Aerodynamic Forces on Airship Hulls

Description: "For a first approximation the air flow around the airship hull is assumed to obey the laws of perfect (i.e. free from viscosity) incompressible fluid. The flow is further assumed to be free from vortices (or rotational motion of the fluid). These assumptions lead to very great simplifications of the formulae used but necessarily imply an imperfect picture of the actual conditions. The value of the results depends therefore upon the magnitude of the forces produced by the disturbances in the flow caused by viscosity with the consequent production of vortices in the fluid" (p. 1).
Date: March 1923
Creator: Tuckerman, L. B.
Partner: UNT Libraries Government Documents Department
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The Factors That Determine the Minimum Speed of an Airplane

Description: The author argues that because of a general misunderstanding of the principles of flight at low speed, there are a large number of airplanes that could be made to fly several miles per hour slower than at present by making slight modifications. In order to show how greatly the wing section affects the minimum speed, curves are plotted against various loadings. The disposition of wings on the airplane slightly affects the lift coefficient, and a few such cases are discussed.
Date: March 1921
Creator: Norton, F. H.
Partner: UNT Libraries Government Documents Department
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Airplane Crashes: Engine Troubles: A Possible Explanation

Description: The aim was to bring attention to what might be the cause of some aircraft accidents for which there was no satisfactory explanation. The author notes that in testing aircraft accidents at the Bureau of Standards, it happened frequently that the engine performance became erratic when the temperature of the air entering the carburetor was between 0 C and 20 C. Investigation revealed the trouble to have been caused by the formation and collection of snow somewhere between the entrance to the carburetor and the manifold, probably at the throttle.
Date: March 1921
Creator: Sparrow, Stanwood W.
Partner: UNT Libraries Government Documents Department
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Extract From a Report on the Resistance of Spheres of Small Diameter in an Airstream of High Velocity

Description: Much attention is given here to the design of the wind tunnel and the experimental set-up. In comparing their results on the wind resistance of spheres to the results of other researchers, the authors find wide discrepancies. They are unable to explain the cause of the discrepancies, concluding, as they do, that the differing results could not be explained by the action of the wind tunnel walls.
Date: March 1921
Creator: Toussaint & Hayer
Partner: UNT Libraries Government Documents Department
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