滑跑速度对直升机侧向模态频率的影响

Effect of Running Velocity on Helicopter Lateral Mode Frequency

建立了直升机滑跑时机体侧向模态频率的计算模型,用停机状态的试验数据对理论模型进行了验证,误差在10%以内。不大的总距操纵可建立起直升机的稳定滑跑,而起落架机轮侧向刚度随滑跑速度的增加而降低,这是导致机体侧向二阶模态频率随滑跑速度降低的主要原因。特别在低速滑跑阶段,机体侧向二阶模态频率随滑跑速度的提高而迅速下降,与停机状态相比,滑跑速度在35km/h时机体模态频率的降幅高达47.6%。

A calculation model is presented for predicting fuselage lateral mode frequency of helicopter during running on runway. The model is verified from shake test data at stayed condition, and the maximum theoretical error is less than 10%. Trim analysis shows that the helicopter steady running can be built up with only a small collective pitch pilot. Analytical results demonstrate that the decrement of lateral stiffness of tires is a primarily factor that leads the second lateral mode frequency decresing with the increase of running velocity. Especially in the low velocity margin, the second lateral mode frequency quickly drops as velocity increasing. Compared with the stayed condition, the mode frequency has 47.6%decrement at running velocity of 35 km/h.