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Wind Tunnel Investigation of Perforated Split Flaps for Use as Dive Brakes on a Rectangular NACA 23012 Airfoil

Aerodznamic characteristics of a rectangular HAUL
23012 airfoil with single and double perforated split flaps
have been determined in the NAGA 7- by 10—foot wind tunnel.
A large range of flap spans and deflections and a'large
range of spanwise and chordwise locations of the flaps
iere investigated. Dynamic pressure surveys were made be-
hind the wing at the approximate location of the tail. in
order to determine the extent and location of the wake for
each flap arranbenent. Tests were also made with a full-
epan.plain flap to determine the effect of the various
split—flap arrangements on aileron control.

The results indicated that single or double perforated
split flaps may be used to obtain.satisfactory dive con:
trol without undue buffctinb effects, and that while lat-
eral control may be obtained with a plain aileron_behind
single split flaps. the aileron is effectively blanketed
and rendered useless behind double split flaps. Additional
tests are recommended to develop a satisfactory lateral-

control device for use with the perforated double‘split
flaps.

INTRODUCTION

The NADA has undertaken an extensive investigation
for the purpose of developing devices suitable for limit-
ing the diving speeds of airplanes. As a part of this in-
vestigationq a study has been made'of test results obtained
during the development of devices designed primarily for
other purposes. such as hibh lift or lateral control. but
which may also be used for dive control. The slot—lip ai-
leron combined with a full-span slotted flap is one of
N

these dual-purpose devices and data for its use have been
presented in reference 1. A study has also been made of a
large amount of uncorrehflnd data on various airfoil-flap
combinations from tests previously made for the Bureau of
Aeronautics. This study indicated that perforated double
split flaps would give the desired characteristics for use
as dive-control devices. The present investigation was
made to determine in more detail the aerodynamic character-
istics of various arrangements of single and double split
flaps on a rectangular NAGA 23012 airfoil. and to deter-
mine the wake characteristics of these devices in order
_ that designers may more closely evaluate their effects on
the performance of complete airplanes.