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National Advisory Committee for Aeronautics, Technical Notes - Pressure Distribution Over a Clark Y-H Airfoil Section with a Split Flap

An investigation was made in the N.A.C.A. 7— by 10—
foot wind tunnel of the distributions of air pressure
over one chord section of a Clark Y—H airfoil with a
split flap. he results obtained are giVen in the form
of diagrams showing the chordwise distribution of pressure
on both airfoil and flap and as plots of Calculated aero—
dynamic coefficients for both airfoil and flap.

The Clark Y— H airfoil section (frequently designated
the N.A.C.A. CYE- airfoil) is a development of the Clark Y
section obtained by modifying the trailing—edge por_tion so
as to reduce the center— of—pressure t.ravel and the pitch~
ing moments. Aerodvnamic characteristics of_the Clark Y—H
airfoil, obtained from force tests made several years ago
in the variable density wind tunnel, are giVen in refer-
enccs l and 2.

Because of numerous renuests for pressure—distribu—__
tion data for the Clark Y—H airfoil, a short series of
tests to obtain such information was recently made in the
7— by lO~foot wind tunnel in connection with another proj—
ect. The present report gives the results of the pressure—'
distribution tests at a single chord location on a rec_tr .n-
gular Clark Y—H airfoil with a simple split flap for a few_
flap deflections and several angles of attack.

The airfoil used for the present investigation was
built of laminated mahogany to the Clark‘Y—H section
(table I) and has a span of 60 inches and a chord of 10
inches. The wooden trailing edge was cut off at 85 per—
cent of the chord from the leading edge and_was replaced
by two strips of thin metal, one completing the upper sur~
face and the other, the lower surface of the model. The
strip on the lower surface was hinged at its leading edge,
thus forming a simple split .flap with a chord 15 percent
of the airfoil chord.

A single row of pressure orifices was installed on
both upper and.lower surfaces of the airfoil and flap at a
section 15 inches inboard of the right wing tip.