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┣━┻━━━━━━━━━━━╋━━━┻━━━╋━┻━━━━━━╋━┻━━━━╋━┻━━━━╋━┻━━━━╋━━━┻━━━┫
┃ L ┃ . .f ┃ 1, ┃.2 1. ┃6 2. ┃.0 2 ┃4 2: ┃
┗━━━━━━━━━━━━━┻━━━━━━━┻━━━━━━━━┻━━━━━━┻━━━━━━┻━━━━━━┻━━━━━━━┛
Effective ratio of body diameter ro root chord, ./,U,
a) With afterbody
┏━━┳━━━┳━━┳━━━━┳━┳━━━━━━━━┳━━━━┳━━┳━━━━┳━┳━┳━┳━━━┳━┓
┃ ┃ ┃ ┃ ┃ ┃ ┃ ┃ ┃ ┃ ┃ ┃ ┃ ┃ ┃
┃ ┣━━━┻━━╋━━━━╋━╋━━━━━━━━╋━━━━╋━━╋━━━━╋━╋━╋━╋━━━╋━┫
┃pl ┃-OT r \- ┃ - ┃ ┃ ┃ ┃ ┃ ┃ ┃ ┃ ┃ ┃ ┃
┣━━╋━━━┳━━╋━━━━╋━╋━━━━━━━━╋━━━━╋━━╋━━━━╋━╋━╋━╋━━━╋━┫
┃ ┃~Ul I\LE7 ┃ ┃ ┃ ┃ ┃ ┃ tl -l ┃ ┃ ┃ ┃. r\ ┃ ┃
┃h ┃/ ┃ ┃ ┃ ┃pA* (l + Ae) (i﹢ Effective ratio of body diamctcr ro root chord, g
b) No afterbody
Fig.3.22 Aerodynamic centerlocation for wing-lift carryover body}
2) Supersonic:
For
pAt(l+Ae)(l+~B,.,lA, ) > 4.0 (3.40)
use the data given in Fig. 3.22a or Fig. 3.22b depending on whether the fuselage
has an afterbody or not.
Fojr
pAe(l+Ae)(l+p~A )_4.0 (3.41)
use the method ofinterpolation as described above for the subsonic case.
It may be noted that a positive value of Xac.WB indicates that the aerodynamic
center of the wing-body combination is aft of the leading edge of the exposed
wing root chord and vice versa.
(-. ),(w;67
PERFORMANCE, STABILITY, DYNAMICS, AND CONTROL
a) Vortex sheet behind the wing
b) Local flow directions at wing and tail
Fig 3.23 Flow directions at wing and horuontal tail.
The local angle of attack of the horizontal tail is affected by the wing downwash
as shown in Fig. 3.23. Let /w and it be the incidences of wing and horizontal tail
surfaces with respect to the zero-lift line (reference line) of the aircraft. The tail
angle of attack is given by
ctt - arn - iw + /r - f
(3.42)
where 6 is the downwash angle at the horizontal tail aerodynamic center. The
downwash is induced mainly because of wing-trailing vortices, and the magnitude
of downwash depends on wing planform, aspect ratio, and the distance between
the aerodynamic centers of wing and horizontal tail. The downwash caused by the
fuselage is generally small in comparison with that caused by the wing and can be
ignored.
Analytical deternunation of downwashis quite complex and is beyond the scope
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