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Reduction Mills in Montana in 1925

Description: List of reduction mills in Montana, compiled in the course of investigations of mineral resources of Montana. It includes information about each loaction including: the process, character of ore, when the mill was operated, and custom work; equipment and power used; and capacity in tons.
Date: March 1927
Creator: Gerry, C. N.
Partner: UNT Libraries Government Documents Department

Practical Underground Education of the Coal Miner

Description: Report describing information that should be provided for miners when they are first being trained on-site, as well as an explanation about the education program offered by the Practical Mining School at Dawson, New Mexico.
Date: November 1927
Creator: Grove, G. W.
Partner: UNT Libraries Government Documents Department

Fifty-Nine Coal-Mine Fires: How They Were Fought and What They Teach

Description: Introduction: "This bulletin abstracts and reviews essential details of reports on 59 fires in different coal mines in the United States, describes the circumstances of origin and the methods of controlling or extinguishing the fires, and points out the lessons taught."
Date: 1927
Creator: Rice, George S.; Paul, J. W. & von Bernewitz, M. W.
Partner: UNT Libraries Government Documents Department

Gases from Blasting in Tunnels and Metal-Mine Drifts

Description: From Introduction: "This paper gives the results of sampling the gases from blasting drift rounds at five mines-the United Verde Extension, Calumet & Arizona, Old Dominion, Mountain Copper, and the United Verde-and of tunnel rounds at the Big Creek water tunnel and Moffat railroad tunnel. The paper also describes the rounds blasted and the methods of sampling and analyzing the gases. In all, 99 rounds were fired and 376 samples were taken."
Date: 1927
Creator: Gardner, E. D.; Howell, S. P. & Jones G. W.
Partner: UNT Libraries Government Documents Department

Drilling and Blasting in Open-Cut Copper Mines

Description: From Introduction: "The drilling and blasting practices described in this bulletin are chiefly those in use at the time of these visits. Information, obtained by correspondence, on recent changes at certain mines is also included. The bulletin is confined to descriptions and comparisons of drilling and blasting methods at the six open-cut mines."
Date: 1927
Creator: Gardner, E. D.
Partner: UNT Libraries Government Documents Department

Coal-Dust Explosion Tests in the Experimental Mine, 1919 to 1924, Inclusive

Description: From Introduction and Summary: "This bulletin describes the third series of coal-dust explosion tests by the Bureau of Mines in its experimental mine and covers a period from 1919 to the end of 1924, inclusive. A few related tests made in 1925 are also included."
Date: 1927
Creator: Rice, George S.; Paul, J. W. & Greenwald, H. P.
Partner: UNT Libraries Government Documents Department

Petroleum Refinery Statistics, 1926

Description: Report discussing petroleum refinery statistics for 1926.
Date: 1927
Creator: Hopkins, G. R.
Partner: UNT Libraries Government Documents Department

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.
Date: March 1, 1927
Creator: Higgins, George J
Partner: UNT Libraries Government Documents Department

A warning concerning the take-off with heavy load

Description: A successful take-off can be made with an airplane so heavily loaded that it cannot climb to a height greater than the span of its wings. The explanation is that the power required to maintain level flight at an altitude of the order of the wing span may be as much as 50 per cent greater than that necessary when the airplane is just clear of the ground. The failure of heavily loaded airplanes to continue climbing at the rate attained immediately after the actual take-off is a grave hazard and has resulted in great risk or catastrophe in three notable cases which are cited.
Date: July 1, 1927
Creator: Reid, Elliott G & Carroll, Thomas
Partner: UNT Libraries Government Documents Department

Technical preparation of the airplane "Spirit of St. Louis."

Description: Given here is a brief history of the design and construction of the "Spirit of St. Lewis", the airplane that Charles Lindbergh flew solo across the Atlantic. Although the plan was to modify a standard model Ryan M-2, it was quickly determined that modification was less practical than redesign. Colonel Lindbergh's active participation in the design of the aircraft is noted. Given here are the general dimensions, specifications, weight characteristics, and man hours required to build the aircraft.
Date: July 1, 1927
Creator: Hall, Donald A
Partner: UNT Libraries Government Documents Department

Method of correcting wind tunnel data for omitted parts of airplane models

Description: Wind tunnel models do not have complete similarity to the full scale airplane. Part of the dissimilarity is due to the difference between the stationary model in the artificial wind stream of the tunnel and the moving airplane in still air. There are a number of other reasons for departing from exact geometrical similitude. For reasons of accuracy and economy, all minor parts of the full scale airplane, such as struts, wires, fittings, control horns and other parts whose scale corrections are large are removed from wind tunnel models. By omitting the minor parts of the airplane in the wind tunnel model and adding to the forces and moments of the model those omitted parts measured full scale and properly reduced, the scale effects of such parts disappear from the model data. Scale effects due to major parts of the airplane, particularly the fuselage and wings, can be corrected by omitting the propeller and making the surface of the model as smooth as possible, two further departures from geometrical similitude between model and full scale that add considerably to the accuracy and economy of model tests.
Date: January 1, 1927
Creator: Smith, R H
Partner: UNT Libraries Government Documents Department

Interaction between air propellers and airplane structures

Description: The purpose of this investigation was the determination of the character and amount of interaction between air propellers as usually mounted on airplanes and the adjacent parts of the airplane structure - or, more specifically, those parts of the airplane structure within the wash of the propeller, and capable of producing any significant effect on propeller performance. In report no. 177 such interaction between air propellers and certain simple geometrical forms was made the subject of investigation and report. The present investigation aims to carry this general study one stage further by substituting actual airplane structures for the simple geometrical forms. From the point of view of the present investigation, the airplane structures, viewed as an obstruction in the wake of the propeller, must also be viewed as a necessary part of the airplane and not as an appendage which might be installed or removed at will. (author).
Date: January 1, 1927
Creator: Durand, W F
Partner: UNT Libraries Government Documents Department

Meteorological conditions along airways

Description: This report is an attempt to show the kind of meteorological information that is needed, and is in part available, for the purpose of determining operating conditions along airways. In general, the same factors affect these operating conditions along all airways though in varying degree, depending upon their topographic, geographic, and other characteristics; but in order to bring out as clearly as possible the nature of the data available, a specific example is taken, that of the Chicago-Dallas airway on which regular flying begins this year (1926).
Date: January 1, 1927
Creator: Gregg, W R
Partner: UNT Libraries Government Documents Department

Pressure of air on coming to rest from various speeds

Description: The text gives theoretical formulas from which is computed a table for the pressure of air on coming to rest from various speeds, such as those of aircraft and propeller blades. Pressure graphs are given for speeds from 1 cm. Sec. up to those of swift projectiles.
Date: January 1, 1927
Creator: Zahm, A F
Partner: UNT Libraries Government Documents Department

The corrosion of magnesium and of the magnesium aluminum alloys containing manganese

Description: The extensive use of magnesium and its alloys in aircraft has been seriously handicapped by the uncertainties surrounding their resistance to corrosion. This problem has been given intense study by the American Magnesium Corporation and at the request of the Subcommittee on Materials for Aircraft of the National Advisory Committee for Aeronautics this report was prepared on the corrosion of magnesium. The tentative conclusions drawn from the experimental facts of this investigation are as follows: the overvoltage of pure magnesium is quite high. On immersion in salt water the metal corrodes with the liberation of hydrogen until the film of corrosion product lowers the potential to a critical value. When the potential reaches this value it no longer exceeds the theoretical hydrogen potential plus the overvoltage of the metal. Rapid corrosion consequently ceases. When aluminum is added, especially when in large amounts, the overvoltage is decreased and hydrogen plates out at a much lower potential than with pure magnesium. The addition of small amount of manganese raises the overvoltage back to practically that of pure metal, and the film is again negative.
Date: January 1, 1927
Creator: Boyer, J A
Partner: UNT Libraries Government Documents Department

The installation and correction of compasses in airplanes

Description: The saving of time that results from flying across country on compass headings is beginning to be widely recognized. At the same time the general use of steel tube fuselages has made a knowledge of compass correction much more necessary than was the case when wooden fuselages were the rule. This paper has been prepared primarily for the benefit of the pilot who has never studied navigation and who does not desire to go into the subject more deeply than to be able to fly compass courses with confidence. It also contains material for the designer who wishes to install his compasses with the expectation that they may be accurately corrected.
Date: August 1, 1927
Creator: Schoeffel, M F
Partner: UNT Libraries Government Documents Department

Tension experiments on diaphragm metals

Description: Strips of german silver, steel, copper, duralumin, nickel and brass were tested in tension in an apparatus in which the change in deflection with time was measured by means of an interferometer. This change in deflection with time caused by the application and removal of a load is defined as "drift" and "recovery," respectively. It was measured in the time interval from approximately 5 seconds to 5 hours after loading. The data are given in a series of graphs in which the drift and recovery are plotted against time. The proportional drift and recovery in five hours are given for a number of the tests, and in addition are shown graphically for nickel and steel.
Date: August 1, 1927
Creator: Henrickson, H B
Partner: UNT Libraries Government Documents Department

"A L C L A D" : new corrosion resistant aluminum product

Description: Described here is a new corrosion resistant aluminum product which is markedly superior to the present strong alloys. Its use should result in greatly increased life of a structural part. Alclad is a heat-treated aluminum, copper, manganese, magnesium alloy that has the corrosion resistance of pure metal at the surface and the strength of the strong alloy underneath. Of particular importance is the thorough character of the union between the alloy and the pure aluminum. Preliminary results of salt spray tests (24 weeks of exposure) show changes in tensile strength and elongation of Alclad 17ST, when any occurred, to be so small as to be well within the limits of experimental error. Some surface corrosion of the pure metal had taken place, but not enough to cause the specimens to break through those areas.
Date: August 1, 1927
Creator: Dix, E H , Jr
Partner: UNT Libraries Government Documents Department

A load factor formula

Description: The ultimate test of a load factor formula is experience. The chief advantages of a semi rational formula over arbitrary factors are that it fairs in between points of experience and it differentiates according to variables within a type. Structural failure of an airplane apparently safe according to the formula would call for a specific change in the formula. The best class of airplanes with which to check a load factor formula seems to be those which have experienced structural failure. Table I comprises a list of the airplanes which have experienced failure in flight traceable to the wing structure. The load factor by formula is observed to be greater than the designed strength in each case, without a single exception. Table II comprises the load factor by formula with the designed strength of a number of well-known service types. The formula indicates that by far the majority of these have ample structural strength. One case considered here in deriving a suitable formula is that of a heavy load carrier of large size and practically no reserve power.
Date: August 1, 1927
Creator: Miller, Roy G
Partner: UNT Libraries Government Documents Department