(c) Bow loading. The resultant limit load must be applied in the plane of symmetry of the .oat at a point one-fourth of the distance from the bow to the step and must be perpendicular to the tangent to the keel line at that point. The magnitude of the resultantloadisthat speci.edinparagraph(b) of this section.
(d) Unsymmetrical step loading. The resultant waterload consists of a component equal to0.75timestheload speci.edinparagraph(a) ofthis section and a side component equal to 0.25 tanβ times theload speci.edinparagraph(b) of this section.The sideload mustbeappliedperpendicularly totheplaneof symmetry of the .oatat a point midway between the keel and the chine.
(e) Unsymmetrical bow loading. The resultant water load consists of a component equal to0.75timestheload speci.edinparagraph(b) ofthis section and a side component equalto0.25tanβ times theload speci.edinparagraph(c) ofthis section.The side load must be applied perpendicularly to the lane of symmetry at a point midway between the keel and the chine.
(f) Immersed .oat condition. The resultant load must be applied at the centroid of the cross section of the .oat at a point one-third of the distance from the bow to the step. The limit load components are as follows :
vertical = ρgV
23
1
2
aft = Cx ρV (KVS0)
2
23
1
2
side = Cy ρV (KVS0)
2
where–
ρ : mass density of water [(slugs/ft.2)];
V : volume of .oat [(ft.2)];
Cx : coe.cient of drag force, equal to 0.133;
Cy : coe.cient of side force, equal to 0.106;
K =0.8,: exceptthatlowervaluesmaybeusedifitisshownthatthe .oats are incapable of submerging at a speed of 0.8VS0 in normal operations;
VS0 :seaplanestalling speed[(knots)] withlanding .apsexten-ded in the appropriate position and with no slipstream ef-fect; and
g : accelerationduetogravity(ft/sec).
(g) Float bottom pressures. The .oat bottom pressures must be established under Sec. 25.533[except that the value of K2 in the formulae maybe taken as1.0.]The angle of dead rise to be used in determining the .oat bottom pressures is set forth in paragraph(b) of this section.
Amdt. 25-23, E.. 5/8/70
FAR 25.537 : Seawing loads.
Seawing design loads must be based on applicable test data.
46.8 Emergency Landing Conditions
FAR 25.561 : General.
(a)
The airplane, although it may be damaged in emergency landing conditions on land or water, must be designed as prescribed in this section to protect each occupant under those conditions.
(b)
The structure must be designed to give each occupant every reasonable chance of escaping serious injury in a minor crash landing when–
(1)
Proper use is made of seats, belts, and all other safety design provisions;
(2)
The wheels are retracted(where applicable); and
(3)
The occupant experiences the following ultimate inertia forces relative to the surrounding structure :
(i)
Upward, 3.0g.
(ii)
Forward, 9.0g.
(iii) Sideward, 3.0g on the airframe; and 4.0g on the seats and their attach-ments.
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本文链接地址：FAA规章 美国联邦航空规章 Federal Aviation Regulations 3(65)
