曝光台 注意防骗
网曝天猫店富美金盛家居专营店坑蒙拐骗欺诈消费者
The above Eqs. (7.113-7.115) can be written as
L+Li - O
M + M, - 0
N+Nt -0
(7.113)
(7.114)
(7.115)
(7.116)
(7.117)
(7.118)
where Lr is the inertia-rolling moment, Mi is the inertia-pitching moment, and N,
is the inertia-yawing moment as given by
Li = qr(ly - Iz)
~2
= 22 sin2asinX(Iz -Iy)
. Mt -rp(lz - Ix)
Q2
= Q2 sy12a- cos X(Iz - Ix)
N, = pq(L - ry)
Q2
= ~ ,os2 a- sin 2X(ly - Ix)
Ba/ance of pitching moments. We have
Mi = (Iz - Ix) r p .
Q2
= l:;- sin 2cr cos X(Iz - Ix)
(7.119)
(7.120)
(7.121)
(7.122)
(7.123)
(7.124)
(7.125)
(7.126)
To have a physical understanding of how the inertia-pitching moment arises,let us
assume that the masses Mi and M2 located at the fuselage extremities represent
inertia in yaw Iz ancl masses M3 and M4 located at the wingtips represent the
inertia in roll Ix as shown in Fig. 7.17. In a right spin, the inertia-induced pitching
couple due to Mi and M2 is nose up so as to fiattert the spin attitude, whereas that
due to M3 and M4 is nose down so as to steepen the spin attitude. The netinertial
pitching couple is the difference between these two opposing contributions.
An altemative way of understanding the inertia-induced pitching moment is to
use the gyroscopic analogy. Let us imagine that the inertias in pitch, roll, and yaw
are represented by three gyroscopes located at the airplane's center of gravity as
shown in Fig. 7.18. The gyroscope with inertia Ix is aligned along the x-body axis
and is assumed to be rotating with an angular velocity p. Similarly, the other two
INERTIA COUPLING AND SPIN
Fig. 7.17 Schematicillustration ofinertia-pitching moment.
657
gyroscopes with Iy and Iz are aligned along y- and z-body axes and are assumed
to be rotating with angular velocities of q and r, respectively.
Now if the gyroscope in Fig. 7.18c is disturbed because of an extemal torque
that imparts it a rolling velocity p, then, according to the gyroscopic principles,
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