A dynamic model for helicopter rotor perturbation excited by impact of vertical landing is proposed, and a numerical simulation method is given to predict landing gear loading and the axial velocity amplitude of hydraulic lag damper in hard landing. Dynamic responses of helicopter fuselage, landing gears, rotor blades and lag dampers are numerical simulated in the vertical landing of an elastic globe-hinge rotor helicopter. The mechanical mechanism of lead-lag disturbance of the rotor blade due to the landing impact is analyzed. It is found that in the first period of oscillation after landing, each blade will undergo different amplitude of lead-lag displacement and result in response of regressive lag mode of rotor. Large disturbance of the rotor blade caused by landing impact will blow off the relieve valve of the damper, significantly decreasing the equivalent damping of the damper. As the sample helicopter undergoes a random vertical landing, the dynamic parameters such as impact velocities and overload factors of landing gears, the amplitude of blade flap and lead-lag displacement, and axial velocity of the damper are shown to be significantly scattered due to different attitudes and angular velocities of the airframe at landing, and the scatter depends on landing altitude.
HU Guocai
,
WU Jing
,
LIU Xiangyi
,
LIU Shuyan
. Dynamic behaviors of helicopter rotor in vertical landing[J]. ACTA AERONAUTICAET ASTRONAUTICA SINICA, 2018
, 39(6)
: 221355
-221355
.
DOI: 10.7527/S1000-6893.2018.21355
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