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  Partner: UNT Libraries Government Documents Department
 Collection: Technical Report Archive and Image Library
Results 15251 - 15260 of 17,329
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Recent efforts and experiments in the construction of aviation engines

Recent efforts and experiments in the construction of aviation engines

Date: September 1, 1920
Creator: SCHWAGER
Description: It became evident during World War I that ever-increasing demands were being placed on the mean power of aircraft engines as a result of the increased on board equipment and the demands of aerial combat. The need was for increased climbing efficiency and climbing speed. The response to these demands has been in terms of lightweight construction and the adaptation of the aircraft engine to the requirements of its use. Discussed here are specific efforts to increase flying efficiency, such as reduction of the number of revolutions of the propeller from 1400 to about 900 r.p.m. through the use of a reduction gear, increasing piston velocity, locating two crankshafts in one gear box, and using the two-cycle stroke. Also discussed are improvements in the transformation of fuel energy into engine power, the raising of compression ratios, the use of super-compression with carburetors constructed for high altitudes, the use of turbo-compressors, rotary engines, and the use of variable pitch propellers.
Contributing Partner: UNT Libraries Government Documents Department
The dynamometer hub

The dynamometer hub

Date: September 1, 1920
Creator: Stieber, W
Description: The construction of the dynamometer hub is illustrated and explained, and its electrical and aviation motor tests, as well as those in free flight, described.
Contributing Partner: UNT Libraries Government Documents Department
Design of recording wind tunnel balances

Design of recording wind tunnel balances

Date: December 1, 1920
Creator: Norton, F H
Description: Given here is a description of the design of a scientific recording wind tunnel balance. It was decided that the most satisfactory arrangement would be a rigid ring completely surrounding the tunnel or wind stream, so that the model could be supported from it by wires or any arrangement of spindles. The forces and moments acting on this ring can then be recorded by suitable weighing apparatus. The methods available for recording forces on the arms are explained. The proposed type of balance will support the model rigidly in a variety of ways, will make a complete test without attention, and will plot the results so that all computations are avoided.
Contributing Partner: UNT Libraries Government Documents Department
Horizontal buoyancy in wind tunnels

Horizontal buoyancy in wind tunnels

Date: November 1, 1920
Creator: Zahn, A F
Description: None
Contributing Partner: UNT Libraries Government Documents Department
The steadiness factor in engine sets

The steadiness factor in engine sets

Date: January 1, 1920
Creator: Margoulis, W
Description: None
Contributing Partner: UNT Libraries Government Documents Department
High thermal efficiency in airplane service

High thermal efficiency in airplane service

Date: December 1, 1920
Creator: Sparrow, S W
Description: Described here is a method by which high average fuel economy has been achieved in aircraft engines. Details are given of the design of certain foreign engines that employ an unusual type of fuel-air ratio control in which the change in power produced by a mixture change is due almost entirely to the change in the power producing ability of the unit weight of the mixture. The safety and performance features of this type of control are explained.
Contributing Partner: UNT Libraries Government Documents Department
The effect of the nature of surfaces on resistance as tested on struts

The effect of the nature of surfaces on resistance as tested on struts

Date: February 1, 1921
Creator: Wieselsberger, Ing C
Description: The chief concern was to measure the variations of resistance brought about by the nature of the surface of the struts. The struts were spanned with aviation linen, and then covered with one coat of varnish. The top surface was not perfectly smooth after this treatment, being slightly rough owing to the threads and raised fibers of the fabric. The results of the measurements of the surfaces are shown by the dotted lines of the curves plotted in several figures. The resistance is given in terms of the characteristic value. Next, the surface was altered by the removal of any roughness on it by means of filing with sandpaper. The measurements of surfaces thus treated gave values represented by extended lines. The increase of resistance with increasing characteristic value, more or less marked in the first series of measurements, was no longer observable. Resistance always decreases with the increase of characteristic value, excepting in the case of strut 7, which shows a slight tendency to rise again. The reasons for this phenomenon have not yet been fully explained.
Contributing Partner: UNT Libraries Government Documents Department
Causes of cracking of ignition cable

Causes of cracking of ignition cable

Date: February 1, 1921
Creator: Silsbee, F B
Description: The experiments described here show that the cracking at sharp bends, observed in the insulation of internal combustion engine high tension ignition wires after service, is due to a chemical attack upon the rubber by the ozone produced by the electric discharge that takes place at the surface of the cable. This cracking does not occur if the insulating material is not under tension, or if the cable is surrounded by some medium other than air. But it does occur even if the insulation is not subjected to electric stress, provided that the atmosphere near the cable contains ozone. The extent of this cracking varies greatly with the insulating material used. The cracking can be materially reduced by using braided cable and by avoiding sharp bends.
Contributing Partner: UNT Libraries Government Documents Department
Crippling strength of axially loaded rods

Crippling strength of axially loaded rods

Date: October 1, 1921
Creator: Natalis, FR
Description: A new empirical formula was developed that holds good for any length and any material of a rod, and agrees well with the results of extensive strength tests. To facilitate calculations, three tables are included, giving the crippling load for solid and hollow sectioned wooden rods of different thickness and length, as well as for steel tubes manufactured according to the standards of Army Air Services Inspection. Further, a graphical method of calculation of the breaking load is derived in which a single curve is employed for determination of the allowable fiber stress. Finally, the theory is discussed of the elastic curve for a rod subject to compression, according to which no deflection occurs, and the apparent contradiction of this conclusion by test results is attributed to the fact that the rods under test are not perfectly straight, or that the wall thickness and the material are not uniform. Under the assumption of an eccentric rod having a slight initial bend according to a sine curve, a simple formula for the deflection is derived, which shows a surprising agreement with test results. From this a further formula is derived for the determination of the allowable load on an eccentric rod. ...
Contributing Partner: UNT Libraries Government Documents Department
Note on vortices on their relation to the lift of airfoils

Note on vortices on their relation to the lift of airfoils

Date: March 1, 1924
Creator: Munk, Max M
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.
Contributing Partner: UNT Libraries Government Documents Department