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Results 15391 - 15400 of 18,519
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Comparative flight and full-scale wind-tunnel measurements of the maximum lift of an airplane

Comparative flight and full-scale wind-tunnel measurements of the maximum lift of an airplane

Date: January 1, 1938
Creator: Silverstein, Abe; Katzoff, S & Hootman, James A
Description: Determinations of the power-off maximum lift of a Fairchild 22 airplane were made in the NACA full-scale wind tunnel and in flight. The results from the two types of test were in satisfactory agreement. It was found that, when the airplane was rotated positively in pitch through the angle of stall at rates of the order of 0.1 degree per second, the maximum lift coefficient was considerably higher than that obtained in the standard tests, in which the forces are measured with the angles of attack fixed. Scale effect on the maximum lift coefficient was also investigated.
Contributing Partner: UNT Libraries Government Documents Department
Composition of Coal Tar and Light Oil

Composition of Coal Tar and Light Oil

Date: 1938
Creator: Fisher, C. H.
Description: None
Contributing Partner: UNT Libraries Government Documents Department
Compressible flow about symmetrical Joukowski profiles

Compressible flow about symmetrical Joukowski profiles

Date: January 1, 1938
Creator: Kaplan, Carl
Description: The method of Poggi is employed for the determination of the effects of compressibility upon the flow past an obstacle. A general expression for the velocity increment due to compressibility is obtained. The general result holds whatever the shape of the obstacle; but, in order to obtain the complete solution, it is necessary to know a certain Fourier expansion of the square of the velocity of flow past the obstacle. An application is made to the case flow of a symmetrical Joukowski profile with a sharp trailing edge, fixed in a stream of an arbitrary angle of attack and with the circulation determined by the Kutta condition. The results are obtained in a closed form and are exact insofar as the second approximation to the compressible flow is concerned, the first approximation being the result for the corresponding incompressible flow. Formulas for lift and moment analogous to the Blasius formulas in incompressible flow are developed and are applied to thin symmetrical Joukowski profiles for small angles of attack.
Contributing Partner: UNT Libraries Government Documents Department
Copper Mining in North America

Copper Mining in North America

Date: 1938
Creator: Gardner, E. D.; Johnson, C. H. & Butler, B. S
Description: None
Contributing Partner: UNT Libraries Government Documents Department
The crinkling strength and the bending strength of round aircraft tubing

The crinkling strength and the bending strength of round aircraft tubing

Date: January 1, 1938
Creator: Osgood, William R
Description: The upper limit of the column strength of structural members composed of thin material is the maximum axial stress such members can carry when short enough to fail locally, by crinkling. This stress is a function of the mechanical properties of the material and of the geometrical shape of the cross section. The bending strength, as measured by the modulus of rupture, of structural members is also a function of these same variables. Tests were made of round tubes of chromium-molybdenum steel and of duralumin to determine the crinkling strengths and the bending strengths in terms of the specified yield strength and the ratio of diameter to thickness. Empirical formulas are given relating these quantities.
Contributing Partner: UNT Libraries Government Documents Department
Crushing and Grinding

Crushing and Grinding

Date: 1938
Creator: Gross, John
Description: None
Contributing Partner: UNT Libraries Government Documents Department
Determination of boundary-layer transition on three symmetrical airfoils in the NACA full-scale wind tunnel

Determination of boundary-layer transition on three symmetrical airfoils in the NACA full-scale wind tunnel

Date: January 1, 1938
Creator: Silverstein, Abe & Becker, John V
Description: For the purpose of studying the transition from laminar to turbulent flow, boundary-layer measurements were made in the NACA full-scale wind tunnel on three symmetrical airfoils of NACA 0009, 0012, and 0018 sections. The effects of variations in lift coefficient, Reynolds number, and airfoil thickness on transition were investigated. Air speed in the boundary layer was measured by total-head tubes and by hot wires; a comparison of transition as indicated by the two techniques was obtained. The results indicate no unique value of Reynolds number for the transition, whether the Reynolds number is based upon the distance along the chord or upon the thickness of the boundary layer at the transition point. In general, the transition is not abrupt and occurs in a region that varies in length as a function of the test conditions.
Contributing Partner: UNT Libraries Government Documents Department
A discussion of certain problems connected with the design of hulls of flying boats and the use of general test data

A discussion of certain problems connected with the design of hulls of flying boats and the use of general test data

Date: January 1, 1938
Creator: Diehl, Walter S
Description: Report presents the results of a survey of problems encountered in applying general test data to the design of flying-boat hulls. It is shown how basic design features may be readily determined from special plots of test data. A study of the effect of the size of a flying boat on the probable limits to be covered by the general test data is included and recommendations for special tests and new methods of presenting test data for direct use in design are given.
Contributing Partner: UNT Libraries Government Documents Department
Drag of cylinders of simple shapes

Drag of cylinders of simple shapes

Date: January 1, 1938
Creator: Lindsey, W F
Description: In order to determine the effect of shape, compressibility, and Reynolds number on the drag and critical speed for simple forms, the drag forces on models of various simple geometric cross sections were measured in the NACA 11-inch high-speed wind tunnel. The models were circular, semitubular, elliptical, square, and triangular (isosceles) cylinders. They were tested over a speed range from 5 percent of the speed of sound to a value in excess of the critical speed, corresponding, for each model, approximately to a tenfold Reynolds number range, which extended from a minimum of 840 for the smallest model to a maximum of 310,000 for the largest model.
Contributing Partner: UNT Libraries Government Documents Department
The effect of compressibility on eight full-scale propellers operating in the take-off and climbing range

The effect of compressibility on eight full-scale propellers operating in the take-off and climbing range

Date: January 1, 1938
Creator: Biermann, David & Hartman, Edwin P
Description: Tests were made of eight full-scale propellers of different shape at various tip speeds up to about 1,000 feet per second. The range of blade-angle settings investigated was from 10 degrees to 30 degrees at the 0.75 radius. The results indicate that a loss in propulsive efficiency occurred at tip speeds from 0.5 to 0.7 the velocity of sound for the take-off and climbing conditions. As the tip speed increased beyond these critical values, the loss rapidly increased and amounted, in some instances, to more than 20 percent of the thrust power for tip-speed values of 0.8 the speed of sound. In general, as the blade-angle setting was increased, the loss started to occur at lower tip speeds. The maximum loss for a given tip speed occurred at a blade-angle setting of about 20 degrees for the take-off and 25 degrees for the climbing condition. A simplified method for correcting propellers for the effect of compressibility is given in an appendix.
Contributing Partner: UNT Libraries Government Documents Department