211
Federal Aviation Administration, DOT
§ 23.333
(b)
Maneuvering envelope. Except
where limited by maximum (static) lift
coefficients, the airplane is assumed to
be subjected to symmetrical maneu-
vers resulting in the following limit
load factors:
(1) The positive maneuvering load
factor specified in § 23.337 at speeds up
to
V
D
;
(2) The negative maneuvering load
factor specified in § 23.337 at
V
C
; and
(3) Factors varying linearly with
speed from the specified value at
V
C
to
0.0 at
V
D
for the normal and commuter
category, and ¥1.0 at
V
D
for the acro-
batic and utility categories.
(c)
Gust envelope. (1) The airplane is
assumed to be subjected to symmet-
rical vertical gusts in level flight. The
resulting limit load factors must cor-
respond to the conditions determined
as follows:
(i) Positive (up) and negative (down)
gusts of 50 f.p.s. at
V
C
must be consid-
ered at altitudes between sea level and
20,000 feet. The gust velocity may be
reduced linearly from 50 f.p.s. at 20,000
feet to 25 f.p.s. at 50,000 feet.
(ii) Positive and negative gusts of 25
f.p.s. at
V
D
must be considered at alti-
tudes between sea level and 20,000 feet.
The gust velocity may be reduced lin-
early from 25 f.p.s. at 20,000 feet to 12.5
f.p.s. at 50,000 feet.
(iii) In addition, for commuter cat-
egory airplanes, positive (up) and nega-
tive (down) rough air gusts of 66 f.p.s.
at V
B must be considered at altitudes
between sea level and 20,000 feet. The
gust velocity may be reduced linearly
from 66 f.p.s. at 20,000 feet to 38 f.p.s. at
50,000 feet.
(2) The following assumptions must
be made:
(i) The shape of the gust is—
U
U
s
C
de
=
−
⎛
⎝⎜
⎞
⎠⎟
2
1
2
25
COS
π
Where—
s=Distance penetrated into gust (ft.);
C=Mean geometric chord of wing (ft.); and
Ude=Derived gust velocity referred to in sub-
paragraph (1) of this section.
(ii) Gust load factors vary linearly
with speed between
V
C
and
V
D
.
(d)
Flight envelope.
[Doc. No. 4080, 29 FR 17955, Dec. 18, 1964, as amended by Amdt. 23–7, 34 FR 13087, Aug. 13, 1969;
Amdt. 23–34, 52 FR 1829, Jan. 15, 1987]
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