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Downwash and Wake Behind Plain and Flapped AirfoilsExtensive experimental measurements have been made of the downwash angles and the wake characteristics behind airfoils with and without flaps and the data have been analyzed and correlated with the theory. A detailed study was made of the errors involved in applying lifting-line theory, such as the effects of a finite wing chord, the rolling-up of the trailing vortex sheet, and the wake. The downwash angles, as computed from the theoretical span load distribution by means of the Biot-Savart equation, were found to be in satisfactory agreement with the experimental results. The rolling-up of the trailing vortex sheet may be neglected, but the vertical displacement of the vortex sheet requires consideration. By the use of a theoretical treatment indicated by Prandtl, it has been possible to generalize the available experimental results so the predictions can be made of the important wake parameters in terms of the distance behind the airfoil trailing edge and the profile-drag coefficient. The method of application of the theory to design and the satisfactory agreement between predicted and experimental results when applied to an airplane are demonstrated.
Document ID
19930091726
Acquisition Source
Legacy CDMS
Document Type
Other
Authors
Silverstein, Abe
Katzoff, S
Bullivant, W Kenneth
Date Acquired
September 6, 2013
Publication Date
January 1, 1939
Report/Patent Number
NACA-TR-651
Accession Number
93R21016
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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