Amdt. 25-91, E.. 7/29/97
FAR 25.337 : Limit maneuvering load factors.
(a)
Except wherelimitedby maximum(static) lift coe.cients,the airplaneis assumed to be subjected to symmetrical maneuvers resulting in the limit maneuvering load factorsprescribedinthis section.Pitching velocities appropriatetothe correspon-ding pull-up and steady turn maneuvers must be taken into account.
(b)
[The positive limit maneuveringload factor “nzcl ” for any speed up to VD may not
()
24000
be less than 2.1+except that “nzcl ” may not be less than 2.5 and need
W+10000
not be greater than 3.8–where “W” is the design maximum takeo. weight.]
(c)
The negative limit maneuvering load factor–
(1)
May not be less than -1.0 at speeds up to VC ; and
(2)
Must vary linearly with speed from the value at VC to zero at VD .
(d)
Maneuvering load factors lower than those speci.ed in this section may be used if the airplane has design features that make it impossible to exceed these values in .ight.
Amdt. 25-23, E.. 5/8/70
FAR25.341 :Gust[and turbulence] loads.
(a) [Discrete Gust Design Criteria. The airplane is assumed to be subjected to symme-trical vertical andlateralgustsinlevel .ight.Limitgustloadsmustbedetermined in accordance with the following provisions :
(1)
Loads on each part of the structure must be determined by dynamic analysis. The analysis must takeinto accountunsteady aerodynamic characteristics and all signi.cant structural degrees of freedom including rigid body motions.
(2)
The shape of the gust must be :
((π ))
Uds s
U =1.cosfor0 ≤ s ≤ 2H
2 H
where–
s : distance penetrated into the gust(feet);
Uds : the design gust velocity in equivalent airspeed speci.ed in para-graph(a)(4) of this section; and
H :thegustgradient whichis thedistance(feet) parallelto the air-plane’s .ight path for the gust to reach its peak velocity.
(3)
A su.cient number of gust gradient distances in the range 30 feet to 350 feet must be investigated to .nd the critical response for each load quantity.
(4)
The design gust velocity must be :
1/6
H
Uds = UREF Fg
350
where– UREF :the referencegust velocity in equivalent airspeedde.nedinpara-graph(a)(5) of this section. Fg :the .ightpro.lealleviationfactorde.nedinparagraph(a)(6) of this section.
′
Elodie Roux. Septembre 2003
Subpart C : Structure
(5)
The following reference gust velocities apply :
(i)
At the airplane design speed VC : Positive and negative gusts with refe-rencegust velocitiesof56.0feet/secEAS mustbe considered atsealevel. Thereferencegustvelocity maybe reducedlinearlyfrom56.0ft/secEAS at sea level to 44.0 ft/sec EAS at 15000 feet. The reference gust velocity may be further reduced linearly from 44.0 ft/sec EAS at 15000 feet to
26.0 ft/sec ES at 50000 feet.
(ii)
At the airplanedesign speed VD : The referencegust velocity must be 0.5 timesthe value obtained underSec.25.341(a)(5)(i).
(6)
The .ight pro.le alleviation factor, Fg, must be increased linearly from the sea level value to a value of 1.0 at the maximum operating altitude de.ned in Sec.25.1527.Atsealevel,the .ightpro.lealleviationfactorisdeterminedby
the following equation :
Fg = 0.5 (Fgz + Fgm)
where–
Fgz = 1. Zmo 250000
Fgm R1 = = R2 tan(π 4 R1)Maximum Landing Weight Maximum Take-O. Weight
R2 = Maximum Zero Fuel Weight
Maximum Take-O. Weight
Zmo = Maximum operating altitude de.ned in Sec. 25.1527.
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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(48)
