The helicopter tail drive system was simplified

and it was presented that a helicopter tail drive system was a cascade system comprising shaft segments and disks.A bending dynamic analysis model in which the support stiffness of the bearing and coupling were included was established.Using transfer matrix method

the differential equations were solved.The results show that the effect of the angular stiffness and the radial stiffness of coupling on natural frequencies of the helicopter tail drive system is different

and the natural frequencies could be reduced with the increase of shaft segments or stiffness of the bearing.