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National Advisory Committee for Aeronautics, Technical Notes - Pressure Distributions for Representative Airfoils and Related Profiles

Selected pressure-distribution diagrams for a
number of conventional and special airfoils are pre—".
sented. The conventional airfoils include the f
NACA 22*, hh—, and ZED—series airfoils and the Clark Y-
family. The special airfoils consist of"dircularéarc
sections of several thicknesses and curvatures'afid a
number of synthetic airfoils, including several with
‘zero-moment coefficient. The pressure distributions
are in most cases given for several lift coefficients
including that at the ideal angle of attack.

In the last decade the importance of obtaining a
Smooth and continuous pressure distribution on an air—
foil has. been increasingly recognized. With improve-
ments in the experimental technigue of measuring pres—
sure distributions, the agreement between experimental
and theoretical pressure distributiOns .has Steadily
improved. A low-drag airfoil has a distributicn_Which
is in almost perfect agreement with thegretically calcu-
lated values, since little allowance has-tovbe‘made for
the boundary layer. Furthermore, it is possible to
determine by inepection in what manner an airfoil may be
improved, particularly if peaks or fluctuations are
evidentxin the pressure curVe.

The early development of the pressure—distribution “
theory is contained in the works of Hunk and Glauert.
The theory of arbitrary, thick airfoils was published,
in 1951 (reference 1). Further details of the theory
of arbitrary airfoils were presented in reference 2,
particularly in regard to the calculation of moment:
coefficients.

The present paper contains an analysis of three _
groups of airfnils with their associated pressure dis—
tributions; that is, conventional airfoils, circular—arc
airfoil sections, and synthetic airfoils, including .
several with zero moment coefficient. The purpose of
this paper is.to present data on a wide selection of
airfoils that—are suitable for general purposes or as
a basis for variations.