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Preliminary wing model tests in the variable density wind tunnel of the National Advisory Committee for Aeronautics

Description: This report contains the results of a series of tests with three wing models. By changing the section of one of the models and painting the surface of another, the number of models tested was increased to five. The tests were made in order to obtain some general information on the air forces on wing sections at a high Reynolds number and in particular to make sure that the Reynolds number is really the important factor, and not other things like the roughness of the surface and the sharpness of the trailing edge. The few tests described in this report seem to indicate that the air forces at a high Reynolds number are not equivalent to respective air forces at a low Reynolds number (as in an ordinary atmospheric wind tunnel). The drag appears smaller at a high Reynolds number and the maximum lift is increased in some cases. The roughness of the surface and the sharpness of the trailing edge do not materially change the results, so that we feel confident that tests with systematic series of different wing sections will bring consistent results, important and highly useful to the designer.
Date: January 1, 1926
Creator: Munk, Max M.
Partner: UNT Libraries Government Documents Department

The Preparation and Properties of Mammalian Ribonucleic Acids

Description: "A method for the preparation of mammalian ribonucleic acids employing high concentrations of guanidine hydrochloride in the fractionation procedure is reported in this paper. Aside from the facility of preparation the method has the advantage of avoiding conditions of acidity and alkalinity which might degrade tissue ribonucleic acids and, by virtue of the protein denaturant action of guanidine salts, of minimizing the possibility for enzymatic degradation" (p. 3).
Date: October 12, 1950
Creator: Volkin, E. & Carter, C. E.
Partner: UNT Libraries Government Documents Department

Preparation and Uses of Tar and its Simple Crude Derivatives

Description: Technical paper issued by the Bureau of Mines over studies of coal tars. As stated in the introduction, "this paper discusses the uses to which some of the various tars are put and shows briefly the usual methods of working up tar into some of its simple or easily prepared derivatives, for which a market can generally be found" (p. 5). This paper includes tables, illustrations, and photographs.
Date: February 1922
Creator: Odell, W. W.
Partner: UNT Libraries Government Documents Department

Preparation Characteristics of Illinois Coals

Description: Report issued by the Bureau of Mines discussing the mechanical coal-preparation characteristics. As stated in the introduction, "this second publication reports the washability and screen analyses of the important Illinois coal beds, showing the quality of product that would result when the raw coal is subjected to preparatory treatment" (p. 1). This report includes tables, maps, and illustrations.
Date: 1949
Creator: Crentz, William L. & Fraser, Thomas
Partner: UNT Libraries Government Documents Department

Preparation Characteristics of Pennsylvania Anthracite from the Bottom Red Ash Bed, Northern Field

Description: Report issued by the Bureau of Mines on the anthracite coal in the Bottom Red Ash Bed in Pennsylvania. The coal samples were analyzed for thickness and geologic structure. The amount of recoverable coal was also estimated. This report includes tables, maps, and illustrations.
Date: July 1967
Creator: Sanner, William S.
Partner: UNT Libraries Government Documents Department

Preparation Characteristics of Some Coals Available for the Synthetic Liquid Fuels Industry

Description: From Introduction: "The first major assignment was the sampling and testing of a series of typical American coals deemed to be suitable for hydrogenation based on early research work conducted by the Bureau of Mines. The first series of tests has been completed and is reported in this paper."
Date: 1950
Creator: Fraser, Thomas; Crentz, William L. & Barrett, Orrin T.
Partner: UNT Libraries Government Documents Department

Preparation of N-Polychloropolyfluoroheptane

Description: From introduction: "Discussion of alternate processes for manufacture of perfluoroxylene as insurance against any eventuality, e.g. disaster, poor quality, required amount of elemental fluorine not obtainable, necessity for further expansion at some future date, or decreasing cost."
Date: 1946
Creator: Babcock, J. H.
Partner: UNT Libraries Government Documents Department

Prereduced Iron Ore Pellets: Preparation, Properties, Utilization

Description: Report discussing the a new agglomerated raw material: partially reduced, hardened iron ore pellets. The pellets are a versatile product suitable for adaptation to both ironmaking and steelmaking. Includes discussion of the technology involved in making prereduced pellets, laboratory techniques, problems of production, data from blast furnace smelting, the economics of production, and the future of the industry.
Date: 1970
Creator: Fine, M. M. & Melcher, N. B.
Partner: UNT Libraries Government Documents Department

Preselect Address Unit for the IBM 1620 Computer

Description: From Abstract: "A device is described which permits the user to stop an IBM 1620 Computer at any preselected instruction address to aid in program debugging. Computer timing considerations are discussed and a circuit description is provided."
Date: December 1963
Creator: Frey, J. J.; Graveson, R. T. & Cassidy, M. E.
Partner: UNT Libraries Government Documents Department

Present status of aircraft instruments

Description: This report gives a brief description of the present state of development and of the performance characteristics of instruments included in the following group: speed instruments, altitude instruments, navigation instruments, power-plant instruments, oxygen instruments, instruments for aerial photography, fog-flying instruments, general problems, summary of instrument and research problems. The items considered under performance include sensitivity, scale errors, effects of temperature and pressure, effects of acceleration and vibration, time lag, damping, leaks, elastic defects, and friction.
Date: January 1, 1932
Partner: UNT Libraries Government Documents Department

The present status of airship construction, especially of airship-framing construction

Description: This work proposes to sketch, in broad outline, the status of airship construction in the various countries, at a time when commerce over great distances might be finally opened up to the airship through the performances of the "Graf Zeppelin." After a short historical review, a survey of the most important rigid and semirigid airships built since 1925, their differences and special problems, is made. In more detailed treatment, the framing construction of the more recent rigid airships and some especially interesting structural questions are investigated.
Date: July 1, 1938
Creator: Ebner, Hans
Partner: UNT Libraries Government Documents Department

Present Status of Lateral-Control Devices for use with Split Flaps, Special Report

Description: The increased use of split flaps for the dual purpose of reducing the landing speed and shortening the landing glide of airplanes has established as acute the problem of obtaining satisfactory lateral control to be used in conjunction with the flaps with out the sacrifice of any of the effectiveness of the flaps. A large amount of work is being done on this problem by various organizations and individuals. Several of the devices developed seem usable, some of them unquestionably so. The present paper attempts to summarize the most promising results obtained to date. Topics covered include ordinary ailerons, external ailerons, floating ailerons, upper-surface ailerons, and spoilers. Although the external ailerons above the trailing edge of the wing and the spoilers at the rear of the wing appear quite promising, it would seem that probably the most satisfactory immediate solution of the problem, including the obtaining of light and smoothly graduated control forces, would in most cases be obtained by the use of the arrangement in which the flap is retracted ahead of ordinary narrow-chord ailerons and is deflected to the rear as well as downward when in use.
Date: August 1933
Creator: Weick, Fred E.
Partner: UNT Libraries Government Documents Department