(5)
W=seaplane design landing weight in pounds.

(6)
K1 = empirical hull station weighing factor, in accordance with .gure 2 of Appendix B.

(7)
rx = ratio ofdistance, measuredparallel tohull referenceaxis,fromthe center of gravity of the seaplane to the hull longitudinal station at which the load factorisbeing computed to the radius ofgyrationinpitch of the seaplane, the hull reference axis being a straight line, in the plane of symmetry, tangential to the keel at the main step.

(c) For a twin .oat seaplane, because of the e.ect of .exibility of the attachment of the .oats to the seaplane, the factor K1 may be reduced at the bow and stern to 0.8 of the value shown in .gure 2 of Appendix B. This reduction applies only to the design of the carry-through and seaplane structure.
Amdt. 25-23, E.. 5/8/70
FAR 25.529 : Hull and main .oat landing conditions.
(a)
Symmetrical step, bow, and stern landing. For symmetrical step, bow, and stern landings,thelimitwater reactionloadfactors arethose computed underSec.25.527. In addition–

(1)
For symmetrical step landings, the resultant waterload mustbe applied at the keel, through the center of gravity, and must be directed perpendicularly to the keel line;

(2)
For symmetricalbowlandings, the resultant waterload mustbe applied at the keel, one-.fth of the longitudinal distance from the bow to the step, and must bedirectedperpendicularly tothekeelline; and

(3)
For symmetrical stern landings, the resultant water load must be applied at the keel, at a point 85 percent of the longitudinal distance from the step to the stern post, and must be directed perpendicularly to the keel line.

(b)
Unsymmetrical landing for hull and single .oat seaplanes.Unsymmetrical step,bow, and stern landing conditions must be investigated. In addition–

(1)
The loading for each condition consists of an upward component and a side component equal, respectively, to 0.75 and 0.25 tan times the resultant load in the corresponding symmetrical landing condition; and

(2)
Thepoint of application anddirectionof the upward component of theloadis the same as that in the symmetrical condition, and the point of application of the side component is at the same longitudinal station as the upward com-ponent but is directed inward perpendicularly to the plane of symmetry at a point midway between the keel and chine lines.

(c)
Unsymmetricallanding; twin .oatseaplanes. The unsymmetrical loading consists of an upward load at the step of each .oat of 0.75 and a side load of 0.25 tanβ at one .oat times the step landing load reached under Sec. 25.527. The side load is directed inboard, perpendicularly to the plane of symmetry midway between the keel and chine lines of the .oat, at the same longitudinal station as the upward load.

FAR 25.531 : Hull and main .oat takeo. conditions.
For the wing and its attachment to the hull or main .oat–
′
Elodie Roux. Septembre 2003
Subpart C : Structure
(a)
The aerodynamic wing lift is assumed to be zero; and

(b)
Adownwardinertiaload, correspondingto aloadfactor computedfromthefollowing formula, must be applied :

2
CTC VS1
n =
(tanβ)
23

W
13

where–
n : inertia load factor; CTO : empirical seaplane operations factor equal to 0.004;
VS1 : seaplanestalling speed[(knots)] atthedesigntakeo. weight within the .aps extended in the appropriate takeo.position;
β : angle ofdead rise atthe main step(degrees); and
W :[design water takeo. weight in pounds.]
Amdt. 25-23, E.. 5/8/70
FAR 25.533 : Hull and main .oat bottom pressures.
(a)
General. The hull and main .oat structure, including frames and bulkheads, strin-gers, and bottom plating, must be designed under this section.
　
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