<DOC>
<DOCNO>
443
</DOCNO>
<TITLE>
calculated and measured pressure distributions over the midspan section
of the naca 4412 airfoil .
</TITLE>
<AUTHOR>
pinkerton, r. m.
</AUTHOR>
<BIBLIO>
naca r. 563, 1936 .
</BIBLIO>
<TEXT>
pressures were simultaneously measured in the variable-density tunnel
at 54 orifices distributed over the midspan section of a 5 by 30 inch
rectangular model of the n.a.c.a. 4412 airfoil at 17 angles of attack
ranging from -dash 20degree to 30degree at a reynolds number of approximately
3,000,000 . accurate data were thus obtained for studying the
deviations of the results of potential-flow theory from measured results
technique are presented .
it is shown that theoretical calculations made either at the effective
angle of attack or at a given actual lift do not accurately describe the
 observed pressure distribution over an airfoil section . there is
therefore developed a modified theoretical calculation that agrees reasonably
well with the measured results of the tests of the n.a.c.a. 4412
 section and that consists of making the calculations and evaluating the
 circulation by means of the experimentally obtained lift at the effective
angle of attack,. i.e., the angle that the chord of the model makes
 with the direction of the flow in the region of the section under
consideration . in the course of the computations the shape parameter
is modified, thus leading to a modified or an effective profile shape
that differs slightly from the specified shape .
</TEXT>
</DOC>
