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[Check for Door Varnish, December 13,1921]

Description: Check from Forestburg School Board and secretary H. B. Caddell in the amount of $2.00 to Lyon Gray Lumber Company; the memo line says "Door, Top, & Varnish". The check is from First State Bank in Forestburg, Texas. The back of the check is stamped December 14, 1921 and is from the First National Bank in Saint Jo, Texas.
Date: December 13, 1921
Creator: Forestburg School Board
Partner: UNT Libraries Special Collections
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Dependence of Propeller Efficiency on Angle of Attack of Propeller Blade

Description: In order to determine the maximum and the most favorable pitch for a propeller, it was found desirable to investigate the dependence of propeller efficiency on the angle of attack of the propeller blade. The results of a few experiments are given to show that propeller blades conduct themselves just like airplane wings with reference to the dependence of their efficiency on their angle of attack.
Date: December 1921
Creator: Borck, Hermann
Partner: UNT Libraries Government Documents Department
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Destructive Distillation of Mixtures of Oil and Coal

Description: Report issued by the U.S. Bureau of Mines on the characteristics and behavior of oil and coal distillation processes. The effectiveness of the distillation processes and the properties of the oil and coal mixtures are presented. This report includes tables, graphs, and illustrations.
Date: December 1921
Creator: Davis, Joseph D.; Place, Palmer B. & Scott, G. S.
Partner: UNT Libraries Government Documents Department
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Effects of Varying the Relative Vertical Position of Wing and Fuselage

Description: "The object of this series of experiments was to determine the influence of the relative vertical position of wing and fuselage on the efficiency of the wing. Since the longitudinal position of the wing can be varied but slightly with reference to the center of gravity in a normal airplane, it was kept constant in the experiments to be described and only the vertical position of the wing with reference to the fuselage was varied" (p. 1).
Date: December 1921
Creator: Prandtl, L.
Partner: UNT Libraries Government Documents Department
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Ground Influence on Aerofoils

Description: The question of ground influence on airplanes has recently attracted some attention in view of the claims made by certain designers that the landing speed of their airplanes is much decreased by an increase in lift coefficient due to the proximity of the ground in landing. The results of wind tunnel tests indicate that ground effect is not entirely beneficial. It decreases the landing speed and cushions the landing shock somewhat. However, it does so at the expense of an increased length of preliminary skimming over the ground.
Date: December 1921
Creator: Raymond, Arthur E.
Partner: UNT Libraries Government Documents Department
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A Mechanical Device for Illustrating Airplane Stability

Description: An instrument is described which will illustrate completely in a qualitative sense the longitudinal stability characteristics of an airplane. The instrument is primarily of use for the lecture room, but it is hoped that ultimately it will be possible to obtain quantitative results from it.
Date: December 1921
Creator: Norton, F. E.
Partner: UNT Libraries Government Documents Department
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Mutual Influence of Wings and Propeller

Description: Report presenting an experiment consisting of an aerofoil and propeller in order to discover the mutual influence between the two components and variations in moment due to the propeller influence.
Date: December 1921
Creator: Prandtl, L.
Partner: UNT Libraries Government Documents Department
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[Check for Drinking Fountain, November 22, 1921]

Description: Check from the Forestburg School Board to the Practical Drawing Company for $21.00; the memo line says "Drinking fount." The check is signed "Forestburg School brd., HB. Caddell, Sec." The back of the check has 3 stamps. One of the stamps is from Southwest National Bank in Dallas Texas, another stamp is from the Banking or Trust Company, dated November 28, 1921 also in Dallas. The third stamp is dated November 29.
Date: November 22, 1921
Creator: Forestburg School Board
Partner: UNT Libraries Special Collections
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The Choice of Wing Sections for Airplanes

Description: "The subject of the choice of an airfoil section is by no means a closed one, and despite the impossibility of making a single rule serve, it is quite practicable to deduce in a strictly rational manner a series of rules and formulas which are capable of being of the greatest use if we but confine ourselves to the consideration of one element of performance at a time. There are seven such elements of performance which are here taken up in turn. The seven are of different relative importance in different types of airplanes. The seven elements are: maximum speed regardless of minimum; maximum speed for given minimum; maximum speed range ratio; maximum rate of climb; maximum absolute ceiling; maximum distance non-stop; and maximum duration non-stop" (p. 1-2).
Date: November 1921
Creator: Warner, Edward P.
Partner: UNT Libraries Government Documents Department
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Drying crude drugs.

Description: Explains the fundamental principles of drying crude vegetable drugs. Provides drawings and instructions for constructing two types of driers.
Date: November 1921
Creator: Russell, G. A.
Partner: UNT Libraries Government Documents Department
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Establishment of Aviation Schools

Description: Report presenting a discussion of the creation of a suitable aviation school and some of the characteristics that should be considered in terms of hiring personnel, creating a curriculum, and obtaining equipment.
Date: November 1921
Creator: Kempe, Erich
Partner: UNT Libraries Government Documents Department
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Experiments With Slotted Wings

Description: Note presenting an investigation of various aspects of slotted wings, including some theoretical and experimental results and characteristics of certain slotted wings currently in production.
Date: November 1921
Creator: Lachmann, G.
Partner: UNT Libraries Government Documents Department
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An Investigation on the Effect of Raked Wing Tips

Description: This investigation was carried out by request of the United States Air Service in the wind tunnel of the Massachusetts Institute of Technology. The results are here published by the National Advisory Committee for Aeronautics as it is thought that they may be of general interest. Wings of the R.A.F. 6 section are tested with various angles of rake, and it is found that although rake has very little effect, a positive or negative rake of 30 degrees is the best.
Date: November 1921
Creator: Norton, F. H.
Partner: UNT Libraries Government Documents Department
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Pressure Measurements During Flight

Description: The general idea was to record the air pressure on the spot, that is, without intervening tubes, by some simple automatic registering device. This was therefore made in such small dimensions that it could be inserted into the wing between the ribs and stand in direct connection with the pressure openings. The results of different experiments are presented along with the best locations for locating the instruments for recording the pressure.
Date: November 1921
Creator: Pröll, A.
Partner: UNT Libraries Government Documents Department
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Traffic Airships With Special Reference to Economy

Description: The first part of this report details the efficiency and economy of airship travel, while the second part presents methods of economic efficiency with regards to construction, cost of upkeep and operation, and the establishment of airship lines.
Date: November 1921
Creator: Leyensetter, Walther
Partner: UNT Libraries Government Documents Department
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Vortices and the Related Principles of Hydrodynamics

Description: Here, conceptions concerning vortices are illustrated by the simplest possible examples. Mathematical formulas and similar means of presentation, which, for the most part, do not help the understanding of persons not versed therein, have been avoided as much as possible. Instead, the author has endeavored to demonstrate the phenomena by means of simple geometrical and mechanical illustrations. For the sake of clarity, the author chiefly considers currents in one plane only, a situation that can be readily represented by diagrams. Some of the peculiarities of vortices in three dimensional flow are briefly discussed.
Date: November 1921
Creator: Betz, A.
Partner: UNT Libraries Government Documents Department
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