动力机械和机身手册2(101)

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

For simplicity, we ignore thrust variations during the disturbance. Suppose the air-
craftis disturbed in forward speed. We have U  - Uo + AU, so that au ='aAU.
Then,
aAF,   aFi    aAD   aD
aAU - aAU = -aAU = -au              (4.428)
_ a(;:pU2scD)
   au
= -pUSCD - gpU2Saacju
(4.429)
(4.430)
With U ~ Uo, we have
                            a Fx                                           D
                                  u a~U~ = -p Uo SCD - 2p Uo2S U(., :. )                  (4.431)
With u = AU/Uo and Cx = Fx/~:pUo2S,Eq. (4.431) simplifies to
                                    Cxu - -2CD - CDu                          (4.432)
Next, let us suppose that the aircraft is disturbed in pitch angle O. Then, from Eq.
(4-427),
                                      a AFx     aF
                          dAO - ~d2 =-W,os0o                 (4.433)
or
                                                 Cx0 - -CL cos0o                                   (4.434)
     Next, consider the forces in the Oz direction, we have
                                              Fzo - W cos 0o - Lo = O                               (4.435)
382              PERFORMANCE, STABILITY, DYNAMICS, AND CONTROL
                            Fz = Fzo + AFz
                                               -  W cos(8o + AO) - L
                                               = w cos(0o + AO) - (Lo + AL)
Proceeding in a similar fashion as before, we can show that
                                    Czu = -2CL - CLu
                                                                 Czo  -. -CL siri 0o
　
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