The aerodynamic characteristics of a slotted Clark y wing as affected by the auxiliary airfoil position Page: 1 of 16
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REPORT No. 400
THE AERODYNAMIC CHARACTERISTICS OF A SLOTTED CLARK Y WING AS
AFFECTED BY THE AUXILIARY AIRFOIL POSITION
By CARL J. WENZINGER and JOSEPH A. SHORTALSUMMARY
Aerodynamic force tests on a slotted Clark Y wing
were conducted in the vertical wind tunnel of the National
Advisory Committee for Aeronautics to determine the
best position for a given auxiliary airfoil with respect to
the main wing. A systematic series of 100 changes in
location of the auxiliary airfoil were made to cover all the
probable useful ranges of slot gap, slot width, and slot
depth. The results of the investigation may be applied
to the design of automatic or controlled slots on wings
with geometric characteristics similar to the wing tested.
An increase of 41.5 per cent in the maximum lfit above
that of the plain wing was obtained for the slotted Clark Y
wing. At the same time, the angle of attack for maximum
ifit was increased 183. It was found that a maximum
increase of about 800 was possible in the highest stalling
angle, but at a maximum lift coefficient slightly less than
that of the plain wing. However, with one slot position,
an increase of 65, together with an increase in the maxi-
mum lift coeficient of 23.8 per cent, was obtained. The
best positions of the auxiliary airfoil were covered by the
range of the tests, and the position for desired aerody-
namic characteristics may easily be obtained from charts
prepared especially for the purpose.
INTRODUCTION
Lateral stability and control up to large angles of
attack form an important part in the program of re-
search relating to safety in flight now being conducted
by the National Advisory Committee for Aeronautics.
A series of tests, comparing a large number of devices
for obtaining lateral control and stability, has been
started in the atmospheric wind tunnels. A wing with
slots and ailerons (one of the standard forms in com-
mon use) will be tested among the first, to serve as a
basis of comparison for special devices.
By the use of slots, a large increase in the maximum
lift coefficient is obtained and the angle of attack is I
raised considerably above that at which the plain wing
would ordinarily stall. The slots prevent the air flow
over the wing from breaking away at the usual stalling. I
speed, and so cause the wing to retain its lift and the
controls to function normally.A study was made of the available data on slotted
wings, the development of which has been due largely
to G. Lachmann and Handley Page. The study showed
that the total ranges in geometric characteristics of the
auxiliary airfoil had been about as follows (references I
to 12, inclusive):
Average
Maximnm, Mhimum, of best
Item per cent per cent results,
chord chord per cent
ohord
Arli alrfo - chord.-..--.---.--------2-. 8.34 14.70
C-of- . -------------------- 2too (11 L8
Maimum thickness--------- 0 (
-O- :-- ::::- ---------:- ---: &3 s 208 2.50
lOtwitL-----------------------------17.-.- -- 50 O s 13.00
Slaot depth---------- too 1&3. 1 3.00JThin plate.
'Below "C."
Above "C."
The geometric variables of the auxiliary airfoil and
main wing are defined in Figure 1. All dimensionsa 'dth
Cut-ori e a-
FmuRaz I.--Variable geometrffact-sIotted Clark Y wingare given as percentages of the main wing chord with
the slot closed.
The total ranges covered were large, but individual
tests each included only a small portion of the total,
and as a result the information obtained was inade-
quate to definitely determine the best slot for a given
wing. However, from a consideration of the effects of
the geometric variables on the highest maximum lift
obtainable it was concluded that the shape and size
707.-- . ,
...I.
.. _,.=_L
I_ __
YL - - --
--
~YT
--
- -C~
u' -- )
I -~ LC~
--
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Wenzinger, Carl J. & Shortal, Joseph A. The aerodynamic characteristics of a slotted Clark y wing as affected by the auxiliary airfoil position, report, 1932~; (https://digital.library.unt.edu/ark:/67531/metadc66057/m1/1/: accessed April 24, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.