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National Advisory Committee for Aeronautics, Technical Notes - Wind Tunnel Tests of a Hall High Lift Wing

Wind-tunnel tests have been made to find the lift,
drag, and center-of—pressure characteristics of a Hall
high—lift wing model. The Hall wing is essentially a
split— flap airfoil with an internal air passage. Air en-
ters the passage through an Opening in the 1_ower surface
somewhat back of and parallel to the leading edge, and
flows out through an Opening made by deflecting the rear
portion of the under surface downward as a flap. For or—
dinary flight conditions the front Opening and the rear
flap can be closed, providing in effect a conventional air—
foil (the Clark Y in this case). The tests were made with
various flap settings and with the entrance to the passage
both Open and closed. The highest lift coefficient found,
CL = 2.08, was obtained with the passage closed.

The present Hall high—lift wing is the result of a de-
velopment which started with a study by Theodore P. Hall of
the poesibilities of converting the upper and lower sur—
faces Of the conventional wing into separate airfoils, form—
ing in effect a biplane combination with a small gap. (Ref-
erence l. ) The development was continued with the construcj
tion of an airplane incorporating the wing shown i_n Figure 5
1, which was entered in the Guggenheim safety competition. ‘
(Reference 2. ) The flaps on this airplane were later made
automatic in Operation. More recently, further wind—tuan‘w
-n§&rtests have been made on a small model of the Hall wing
in its latest form (similar to that in fig. 2). In both
the wind—tunnel and flight tests substantially higher lift
coefficients were obtained with the high—lift arrangements
than with conventional wings, but the approximate nature of
the flight tests and the low scale of the wind-tunnel tests
made further experiments desirable.

The present tests have been made as part of a series
on various high-lift devices in the N. A. C. A. 7 by 10 foot
wind tunnel. The latest form of Hall high-lift wing was
tested with the flap set at various angles, and the en—
trance to the internal pa.ssage both open and closed.