229
Federal Aviation Administration, DOT
§ 23.533
side load is directed inboard, per-
pendicularly to the plane of symmetry
midway between the keel and chine
lines of the float, at the same longitu-
dinal station as the upward load.
[Doc. No. 26269, 58 FR 42161, Aug. 6, 1993]
§ 23.531
Hull and main float takeoff
condition.
For the wing and its attachment to
the hull or main float—
(a) The aerodynamic wing lift is as-
sumed to be zero; and
(b) A downward inertia load, cor-
responding to a load factor computed
from the following formula, must be
applied:
n
C
V
Tan
W
TO
S1
2
3
1
3
=
⎛
⎝
⎞
⎠
2
β
Where—
n=inertia load factor;
C
TO
=empirical seaplane operations factor
equal to 0.004;
V
S1
=seaplane stalling speed (knots) at the de-
sign takeoff weight with the flaps ex-
tended in the appropriate takeoff posi-
tion;
b=angle of dead rise at the main step (de-
grees); and
W=design water takeoff weight in pounds.
[Doc. No. 26269, 58 FR 42161, Aug. 6, 1993]
§ 23.533
Hull and main float bottom
pressures.
(a)
General. The hull and main float
structure, including frames and bulk-
heads, stringers, and bottom plating,
must be designed under this section.
(b)
Local pressures. For the design of
the bottom plating and stringers and
their attachments to the supporting
structure, the following pressure dis-
tributions must be applied:
(1) For an unflared bottom, the pres-
sure at the chine is 0.75 times the pres-
sure at the keel, and the pressures be-
tween the keel and chine vary linearly,
in accordance with figure 3 of appendix
I of this part. The pressure at the keel
(p.s.i.) is computed as follows:
P
C K V
Tan
K
2
2
S1
k
=
2
β
where—
P
k
=pressure (p.s.i.) at the keel;
C
2
=0.00213;
K
2
=hull station weighing factor, in accord-
ance with figure 2 of appendix I of this
part;
V
S1
=seaplane stalling speed (knots) at the de-
sign water takeoff weight with flaps ex-
tended in the appropriate takeoff posi-
tion; and
b
K
=angle of dead rise at keel, in accordance
with figure 1 of appendix I of this part.
(2) For a flared bottom, the pressure
at the beginning of the flare is the
same as that for an unflared bottom,
and the pressure between the chine and
the beginning of the flare varies lin-
early, in accordance with figure 3 of ap-
pendix I of this part. The pressure dis-
tribution is the same as that prescribed
in paragraph (b)(1) of this section for
an unflared bottom except that the
pressure at the chine is computed as
follows:
P
C K V
Tan
ch
3
2
S1
=
2
β
where—
P
ch
=pressure (p.s.i.) at the chine;
C
3
=0.0016;
K
2
=hull station weighing factor, in accord-
ance with figure 2 of appendix I of this
part;
V
S1
=seaplane stalling speed (knots) at the de-
sign water takeoff weight with flaps ex-
tended in the appropriate takeoff posi-
tion; and
b=angle of dead rise at appropriate station.
The area over which these pressures
are applied must simulate pressures oc-
curring during high localized impacts
on the hull or float, but need not ex-
tend over an area that would induce
critical stresses in the frames or in the
overall structure.
(c)
Distributed pressures. For the de-
sign of the frames, keel, and chine
structure, the following pressure dis-
tributions apply:
(1) Symmetrical pressures are com-
puted as follows:
P
C K V
Tan
4
2
SO
=
2
β
where—
P=pressure (p.s.i.);
C
4
=0.078 C
1
(with C
1
computed under § 23.527);
K
2
=hull station weighing factor, determined
in accordance with figure 2 of appendix I
of this part;
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