Section 25.349
14 CFR Ch. I (1-1-19 Edition)
taking into account, as separate conditions, the effects of -
(1)
Propeller
slipstream
corresponding to maximum continuous
power at the design flap speeds VF, and
with takeoff power at not less than 1.4
times the stalling speed for the particular flap position and associated
maximum weight; and
(2) A head-on gust of 25 feet per second velocity (EAS).
(c) If flaps or other high lift devices
are to be used in en route conditions,
and with flaps in the appropriate position at speeds up to the flap design
speed chosen for these conditions, the
airplane is assumed to be subjected to
symmetrical maneuvers and gusts
within the range determined by -
(1) Maneuvering to a positive limit
load factor as prescribed in Section 25.337(b);
and
(2) The vertical gust and turbulence
conditions prescribed in Section 25.341(a) and
(b).
(d) The airplane must be designed for
a maneuvering load factor of 1.5 g at
the maximum take-off weight with the
wing-flaps and similar high lift devices
in the landing configurations.
[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as
amended by Amdt. 25-46, 43 FR 50595, Oct. 30,
1978; Amdt. 25-72, 55 FR 37607, Sept. 17, 1990;
Amdt. 25-86, 61 FR 5221, Feb. 9, 1996; Amdt.
25-91, 62 FR 40704, July 29, 1997; Amdt. 25-141,
79 FR 73468, Dec. 11, 2014]
spaschal on DSK3GDR082PROD with CFR
Section 25.349
Rolling conditions.
The airplane must be designed for
loads resulting from the rolling conditions specified in paragraphs (a) and (b)
of this section. Unbalanced aerodynamic moments about the center of
gravity must be reacted in a rational
or conservative manner, considering
the principal masses furnishing the reacting inertia forces.
(a) Maneuvering. The following conditions, speeds, and aileron deflections
(except as the deflections may be limited by pilot effort) must be considered
in combination with an airplane load
factor of zero and of two-thirds of the
positive maneuvering factor used in design. In determining the required aileron deflections, the torsional flexibility of the wing must be considered
in accordance with Section 25.301(b):
(1) Conditions corresponding to
steady rolling velocities must be investigated. In addition, conditions corresponding to maximum angular acceleration must be investigated for airplanes with engines or other weight
concentrations outboard of the fuselage. For the angular acceleration conditions, zero rolling velocity may be
assumed in the absence of a rational
time history investigation of the maneuver.
(2) At VA, a sudden deflection of the
aileron to the stop is assumed.
(3) At VC, the aileron deflection must
be that required to produce a rate of
roll not less than that obtained in
paragraph (a)(2) of this section.
(4) At VD, the aileron deflection must
be that required to produce a rate of
roll not less than one-third of that in
paragraph (a)(2) of this section.
(b) Unsymmetrical gusts. The airplane
is assumed to be subjected to unsymmetrical vertical gusts in level flight.
The resulting limit loads must be determined from either the wing maximum airload derived directly from
Section 25.341(a), or the wing maximum airload derived indirectly from the
vertical load factor calculated from
Section 25.341(a). It must be assumed that 100
percent of the wing air load acts on one
side of the airplane and 80 percent of
the wing air load acts on the other
side.
[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as
amended by Amdt. 25-23, 35 FR 5672, Apr. 8,
1970; Amdt. 25-86, 61 FR 5222, Feb. 9, 1996;
Amdt. 25-94, 63 FR 8848, Feb. 23, 1998]
Section 25.351
Yaw maneuver conditions.
The airplane must be designed for
loads resulting from the yaw maneuver
conditions specified in paragraphs (a)
through (d) of this section at speeds
from VMC to VD. Unbalanced aerodynamic moments about the center of
gravity must be reacted in a rational
or conservative manner considering the
airplane inertia forces. In computing
the tail loads the yawing velocity may
be assumed to be zero.
(a) With the airplane in unaccelerated flight at zero yaw, it is assumed
that the cockpit rudder control is suddenly displaced to achieve the resulting rudder deflection, as limited by:
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