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National Advisory Committee for Aeronautics, Technical Notes - Wind Tunnel Investigation of the Effect of Vertical Position of the Wing on the Side Flow in the Region of the Vertical Tail

An investigation of the air flow at the tail of a
monoplane model was conducted in the NACA 7- by 10-foot
wind tunnel to determine the cause of-the change in ver-
tical— tail effectiveness with a change in the vertical
position of the wing on the fuselage_ and with flap de—
flection.

Surveys were made of the dynamic'pressure and the
air-stream angularity in the region of the tail for the
combination of a circular fuselage-with an NACA 23012
wing having a 3:1 taper ratio and a straight trailing
edge. The surveys were made with.the wing in high and
low positions on the fuselage anduwith a partial—Span ’
split flap deflected and neutral. Similar measurements
were made for the wing alone and the fuselage alone.
Force tests were also made of the complete model with the
vertical tail in place to determine the effect of wing
_poeition on the characteristics of the vertical tail at
large angles of vaw.

It was-found that the yawed wing—fuselage combina—
tion produced a side flow which increased the tail effec—
_tiveness by increasing the rate-of change of vertical-
tail angle of‘attack with a change'in the angle of yaw
when the wing was-in.the-low position-and'which tended to
decrease the tail effectivenessbe'decreasing this rate
of change yhen the.wing was-in the high position. Flap
deflection produced.a side flow that'increased the rate
of change Of the‘vertinaletail angle of attack with a
change in angle of yaw regardless of wing position. The
vertice.l- tail of the low—wing__ comhi_nation gave indications
of stall at- a smalls-r angle of yaw than the vertical tail
of the high-wing combination .

The National Advisory_Committee for Aeronautics is
undertaking an extensive investigation of the lateral-
stability characteristics of airplanes as affected by the
geometrical arrangement of the component parts. The re-
sults of a considerable amount of both theoretical and
experimental rese rch have been published on the deter—
mination of the 1 teral~stability characteristics of the
component parts of an airplane (references 1. 2. and 3)
and on the ap lication of_these characteristics to prac-
tical design reference 4). The interference effects on
the lateral-stability characteristics have been experi—
mentally determined-for certain types of models (refer-
ences 5 and 6).