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 Decade: 1940-1949
 Year: 1947
 Month: June
 Collection: National Advisory Committee for Aeronautics Collection
Airfoil in sinusoidal motion in a pulsating stream

Airfoil in sinusoidal motion in a pulsating stream

Date: June 1, 1947
Creator: Greenberg, J Mayo
Description: The forces and moments on a two-dimensional airfoil executing harmonic motions in a pulsating stream are derived on the basis of non-stationary incompressible potential flow theory, with the inclusion of the effect of the continuous sheet of vortices shed from the trailing edge. An assumption as to the form of the wake is made with a certain degree of approximation. A comparison with previous work applicable only to the special case of a stationary airfoil is made by means of a numerical example, and the excellent agreement obtained shows that the wake approximation is quite sufficient. The results obtained are expected to be useful in considerations of forced vibrations and flutter of rotary wing aircraft.
Contributing Partner: UNT Libraries Government Documents Department
Calculation of compressible flows past aerodynamic shapes by use of the streamline curvature

Calculation of compressible flows past aerodynamic shapes by use of the streamline curvature

Date: June 1, 1947
Creator: Perl, W
Description: A simple approximate method is given for the calculation of isentropic irrotational flows past symmetrical airfoils, including mixed subsonic-supersonic flows. The method is based on the choice of suitable values for the streamline curvature in the flow field and the subsequent integration of the equations of motion. The method yields limiting solutions for potential flow. The effect of circulation is considered. A comparison of derived velocity distributions with existing results that are based on calculation to the third order in the thickness ratio indicated satisfactory agreement. The results are also presented in the form of a set of compressibility correction rules that lie between the Prandtl-Glauert rule and the von Karman-Tsien rule (approximately). The different rules correspond to different values of the local shape parameter square root sign YC sub a, in which Y is the ordinate and C sub a is the curvature at a point on an airfoil. Bodies of revolution, completely supersonic flows, and the significance of the limiting solutions for potential flow are also briefly discussed.
Contributing Partner: UNT Libraries Government Documents Department
Calibration and Measurement in Turbulence Research by the Hot-Wire Method

Calibration and Measurement in Turbulence Research by the Hot-Wire Method

Date: June 1, 1947
Creator: Kovasznay, Kaszlo
Description: The problem of turbulence in aerodynamics is at present being attacked both theoretically and experimentally. In view of the fact however that purely theoretical considerations have not thus far led to satisfactory results the experimental treatment of the problem is of great importance. Among the different measuring procedures the hot wire methods are so far recognized as the most suitable for investigating the turbulence structure. The several disadvantages of these methods however, in particular those arising from the temperature lag of the wire can greatly impair the measurements and may easily render questionable the entire value of the experiment. The name turbulence is applied to that flow condition in which at any point of the stream the magnitude and direction of the velocity fluctuate arbitrarily about a well definable mean value. This fluctuation imparts a certain whirling characteristic to the flow.
Contributing Partner: UNT Libraries Government Documents Department
Charts for the minimum-weight design of multiweb wings in bending

Charts for the minimum-weight design of multiweb wings in bending

Date: June 1, 1947
Creator: Schuette, Evan H & Mcculloch, James C
Description: None
Contributing Partner: UNT Libraries Government Documents Department
A Comparison of Three Theoretical Methods of Calculating Span Load Distribution on Swept Wings

A Comparison of Three Theoretical Methods of Calculating Span Load Distribution on Swept Wings

Date: June 9, 1947
Creator: VanDorn, Nicholas H. & DeYoung, John
Description: Three methods for calculating span load distribution, those developed by V.M Falkner, Wm. Mutterperl, and J. Weissinger, have been applied to five swept wings. The angles of sweep ranged from -45 degrees to +45 degrees. These methods were examined to establish their relative accuracy and case of application. Experimentally determined loadings were used as a basis for judging accuracy. For the convenience of the readers the computing forms and all information requisite to their application are included in appendixes. From the analysis it was found that the Weissinger method would be best suited to an over-all study of the effects of plan form on the span loading and associated characteristics of wings. The method gave good, but not best, accuracy and involved by far the least computing effort. The Falkner method gave the best accuracy but at a considerable expanse in computing effort and hence appeared to be most useful for a detailed study of a specific wing. The Mutterperl method offered no advantages in accuracy of facility over either of the other methods and hence is not recommended for use.
Contributing Partner: UNT Libraries Government Documents Department
Compression Shocks of Detached Flow

Compression Shocks of Detached Flow

Date: June 1, 1947
Creator: Eggink
Description: It is known that compression shocks which lead from supersonic to subsonic velocity cause the flow to separate on impact on a rigid wall. Such shocks appear at bodies with circular symmetry or wing profiles on locally exceeding sonic velocity, and in Laval nozzles with too high a back pressure. The form of the compression shocks observed therein is investigated.
Contributing Partner: UNT Libraries Government Documents Department
Critical combinations of shear and longitudinal direct stress for long plates with transverse curvature

Critical combinations of shear and longitudinal direct stress for long plates with transverse curvature

Date: June 1, 1947
Creator: Batdorf, S B; Schildcrout, Murry & Stein, Manuel
Description: None
Contributing Partner: UNT Libraries Government Documents Department
Critical combinations of torsion and direct axial stress for thin-walled cylinders

Critical combinations of torsion and direct axial stress for thin-walled cylinders

Date: June 1, 1947
Creator: Batdorf, S B; Stein, Manuel & Schildcrout, Murry
Description: None
Contributing Partner: UNT Libraries Government Documents Department
Critical shear stress of long plates with transverse curvature

Critical shear stress of long plates with transverse curvature

Date: June 1, 1947
Creator: Batdorf, S B; Schildcrout, Murry & Stein, Manuel
Description: None
Contributing Partner: UNT Libraries Government Documents Department
Critical stress of thin-walled cylinders in torsion

Critical stress of thin-walled cylinders in torsion

Date: June 1, 1947
Creator: Batdorf, S B; Stein, Manuel & Schildcrout, Murry
Description: None
Contributing Partner: UNT Libraries Government Documents Department
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