UNT Libraries Government Documents Department - 20 Matching Results

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Creep strength of stabilized wrought-aluminum alloys

Description: Rohn-type equipment has been mounted on rubber blocks, for the purpose of damping the vibrations of the ground and of rendering the plastic yielding of the test bars less subject to outside interferences. New equipment also included three shockproof creep-testing machines with the Martens mirror instruments for recording the strain curve of the fatigue-tested specimens.
Date: November 1, 1940
Creator: Muller, W

The Effect of Initial Displacement of the Center Support on the Buckling of a Column Continuous over Three Supports

Description: The test indicate that "an indiscriminate single application of the Southwell method (for analyzing Exp. Observations in problems of elastic stability)--can result in definite and measurable errors" The test also indicate "that the effect of curvature due to bending on the critical load for the compression flange material of a box beam is probably small and can be neglected." We have not found this to be true in our tests. It is believed that the effect of curvature, together with a small amount of fixity at the ribs, tends to force the stiffeners to bow in each bay thus effectively increasing their end fixity and thereby raising their allowable loads.
Date: November 1940
Creator: Lunquist, Eugene E. & Kotanchik, Joseph N.

Feeding dairy cows.

Description: Describes many types of dairy-cow feeds, their nutritive value, and their functions. Includes instructions for feed preparation and feeding recommendations for various situations.
Date: November 1940
Creator: Woodward, T. E. (Thompson Elwyn) & Nystrom, Amer Benjamin, 1885-

A Flight Investigation of Exhaust-Heat De-Icing

Description: The National Advisory Committee for Aeronautics conducted exhaust-heat de-icing tests in flight to provide data needed in the application of this method. The capacity to extract heat from the exhaust gas for de-icing purposes, the quantity of heat required, and other factors were examined. The results indicate that a wing-heating system employing a spanwise exhaust tube within the leading edge of the wing removed 30 to 35 percent of the heat from exhaust gas entering the wing. Data are given from which the heat required for ice prevention can be calculated. Sample calculations have been made on the basis of existing engine power/wing area ratios to show that sufficient heating can be obtained for ice protection on modern transportation airplanes, provided that uniform distribution of the heat can be secured.
Date: November 1, 1940
Creator: Jones, Alun R & Rodert, Lewis A

Flight Tests of Exhaust Gas Jet Propulsion, Special Report

Description: Flight test s were conducted on the XP-41 airplane, equipped with a Pratt & Whitney R1830-19, 14-cylinder, air-cooled engine, to determine the increase in flight speed obtainable by the use of individual exhaust stacks directed rearwardly to obtain exhaust-gas thrust. Speed increases up to 18 miles per hour at 20,000 feet altitude were obtained using stacks having an exit area of 3.42 square inches for each cylinder. A slight increase in engine power and decrease in cylinder temperature at a given manifold pressure were obtained with the individual stacks as compared with a collector-ring installation. Exhaust-flame visibility was quite low, particularly in the rich range of fuel-air ratios.
Date: November 1940
Creator: Pinkel, Benjamin & Turner, L. Richard

General relationships between the various systems of reference axes employed in flight mechanics

Description: The different possibilities of orientation of the systems of axes currently employed in flight mechanics are compiled and described. Of the three possible couplings between the wind and aircraft axes, the most suitable coupling is that in which the y axis is made the principal axis of rotation for one of the two coupling angles (angles of attack). In connection with this coupling, an experimental system of axes is introduced, whose axes x(sub e) and z(sub e) are situated in the plane of symmetry of the airplane and rotate about the airplane lateral axis y = y(sub e). This system of axes enables the utilization of the coefficients obtained in the wind tunnel in the flight-mechanic equations by a simple transformation, with the aid of the angle of attack, measured in the plane of symmetry of the airplane.
Date: November 1, 1940
Creator: Rautenberg, H J

Note on the calculation of boundary layers

Description: The properties of the solutions of the hydrodynamic equations of viscous fluid by "boundary-layer omission" are discussed. A method is indicated for the numerical determination of the solution for a known initial profile u(x(sub o),y) and pressure distribution p(x) within the region.
Date: November 1, 1940
Creator: Prandtl, L

Railway shop battalion.

Description: "This manual explains the organization and operation of railway shop battalion for employment on a standard military railway. Its purpose is to assist railway shop battalion officers in the training and operation of their units, and to guide command and staff officers charged with the employment of railway shop battalions."
Date: November 29, 1940
Creator: United States. War Department. Office of the Chief of Engineers.

Wind tunnel investigation of fuselage stability in yaw with various arrangements of fins

Description: An investigation was made in the 7-by-10 foot wind tunnel to determine the effects of dorsal-type fins and various arrangements of fins on the aerodynamic characteristics of a streamline circular fuselage. Comparative plots of the aerodynamic characteristics of the fuselage alone and the fuselage with various fin arrangements are given to show their effects on coefficients of yawing moment, drag, and lateral force. Results are also given for one case in which a rear fin on a circular fuselage was faired with modeling clay to obtain a fuselage shape with the same side elevation as the fuselage with the unfaired fin but with an elliptical cross section over the rearward portion of the fuselage. The results indicated that fin area to the rear of the center of gravity of the fuselage was beneficial in reducing the magnitude of the unstable yawing moments at large angles of yaw; whereas, fin area forward of the center of gravity was harmful. The dorsal-type fin was more effective for increasing the yawing stability of the fuselage than was a smoothly faired rearward portion with the same side elevation as the fuselage with the unfaired dorsal type fin. The minimum drag coefficient and the slope of the curve of yawing-moment coefficient of the fuselage at zero yaw were unaffected by the addition of the fins, within the experimental accuracy of the tests.
Date: November 1, 1940
Creator: Hoggard, H Page, Jr

Wind tunnel tests of an NACA 23021 airfoil equipped with a slotted extensible and a plain extensible flap

Description: An investigation has been made in the NACA 7- by 10-foot wind tunnel of a large chord NACA 23021 airfoil equipped with two arrangements of a completely extended 15 percent chord extensible flap. One of the flaps had a faired juncture, without a gap; the other was provided with a slot between the trailing edge of the airfoil and the nose of the flap. The results showed that the basic airfoil gave the lowest profile-drag coefficients over the low lift range, the airfoil with the plain extensible flap gave the lowest profile-drag coefficients over the moderate lift range, and the airfoil with the slotted extensible flap gave the lowest profile-drag coefficients over the high lift range. The airfoil with the slotted extensible flap had the same maximum lift at a flap deflection of 25 degrees as the airfoil with the plain extensible flap had at a flap deflection of 60 degrees. The results of comparisons of the airfoil pitching-moment coefficients obtained with the two types of flap are dependent upon the basis chosen for comparison. Complete aerodynamic section characteristics are presented for the various flap deflections for both flap arrangements in the completely extended portion.
Date: November 1, 1940
Creator: Swanson, Robert S & Harris, Thomas A