• Version
• 174 Downloads
• 1.64 MB File Size
• 1 File Count
• April 2, 2017 Create Date
• April 2, 2017 Last Updated

Wind Tunnel Investigation of Control Surface Characteristics - XII - Various Cover Plate Alinements on the NACA 0015 Airfoil with a 30% Chord Flap and Large Sealed Internal Balance

By H. Page Hoggard, Jr.
SUMMARY

Force—test measurements in two—dimensional flow have
been made in the FAOA 4— by 6—foot vertical tunnel to dew
termine the aerodynamic effects of changing the alinement
of the cover plates on a sealed internally balanced flap.
An NACA 0015 airfoil was utilized for the tests. The
chord of the straight—contour flap was 30 percent of the
airfoil chord and the balance was 50 percent of the flap
chord.

Manufacturing imperfections in the alinement of the
cover plates with tl-e airfoil contour, if large, may have
serious effects on resultant hinge moment of a flap with
a sealed internal balance. With the cover plates bent out
from the airfoil contour a rudder would show a tendency to
look in a sideslip, and an elevator to overbalance when
used in the landing attitude. In general, bending the
cover plates in or out increased the negative slope of the
curves of flap hinge moment against angle of. attack and
agai nst flap deflection.

The slope of the lift curve for the airfoil remained
practically unchanged w. an the cover plates were bent in
or out. The lift effectiveness of the flap was decreased
by bending the plates out only through the range where
flap deflection and angle of attack were of like sign.
Bending the plates in did not affect the lift effective— "
ness but reduced the lift obtainable for the arrangements
tested.

The increment of minimum profile drag caused by bend—
ing the plates out Was appreciable and wee larger when the
bend location was near the trailing edge of the cover plate.
Bending the cover plates in appeared to have no appreci—
able effect on the minimum profile drag coefficient.

INTRODUCTION

The NASA has instituted an extensive investigation Of
the aerodynamic characteristics of various flap arrange“
ments in an effort to determine the types best suited for
control surfaces and to supply experimental data for de—
sign purposes. The results of this investigation that re-~
late to the present report are given in references 1 and

'.J

Difficulties have been experienced by manufacturers
in making cover plates for flaps conform exactly to the
airfoil contour. The tests reported herein were made to
determine the effect, particularly on the flap hinge mo—
ments, of various misnlinenents of the cover plates. The
model used was an NASA 0015 airfoil with a 0.30c straight—
contour flap having a 0.50cf sealed internal balance. The
wide cover plates, discussed in reference 1, were used.
The plates were bent for misalinement at two chordwise bend
locations to find the effect on the aerodynamic character—
istics for different chordwise lengths of misalined cover
plates.