• Version
• 187 Downloads
• 2.44 MB File Size
• 1 File Count
• November 2, 2016 Create Date
• November 2, 2016 Last Updated

National Advisory Committee for Aeronautics, Report - Wind Tunnel Investigation at Low Speed of the Effects of Chordwise Wing Fences and Horizontal Tail Position on the Static Longitudinal Stability

Low-speed tests of a model with a wing swept baclc 35° at the
0.33-chord line and a horizontal tail located well above the ec—
tended wing—chord plane indicated static longitudinal instability
at moderate angles of attack for all configurations tested. An
investigation therefore was made to determine whether the longi-
tudinal stability could be improved by the use of chordwise wing
fences, by lowering the horizontal tail, or by a combination of
both. Experience with fences on other models has indicated
that fence efi'ectiveness in improving static longitudinal stability
can be modified by variations in Mach number and Reynolds
number; hence, the low Mach number and Reynolds number of
the present investigation should be kept in mind in conszklering
the data obtained in this study.

The results of the investigation showed that the longitudinal
stability characteristics of the model with slats retracted could be
improved at moderate angles of attack by placing chordurise
wing fences at a spanwise station of about 73 percent of the wing
semispan from the plane of symmetry provided the nose of the
fence extended slightly beyond or around the wing leading edge.
The static longitudinal stability characteristics of the model with
slats extended could be appreciably improved by placing chord—
wise fences at a spanwise position of approximately 36‘ percent
of the wing semispan from the plane of symmetry. This con-
clusion confirmed the results of an earlier unpublished investi-
gation made by Douglas Aircraft 00., Inc. No single fence
position was found which would cause an appreciable improve-
ment of the model longitudinal stability characteristics for all
model configurations; however, use offences at both 36' percent
and ’73 percent of the wing semispan from the plane of symmetry
caused a large improvement in the longitudinal stability char-
acteristics for all model configurations investigated. Lowering
the horizonml tail from the high position to the fuselage center
line improved the longitudinal stability characteristics of all
model configurations tested, so that all configurations tested
were longitudinally stable in the angle-of-attaclc range from 0°
to about 20°.