There has not been a big demand for helicopter UAVs, despite the growing number of models available for sale.

对无人直升机没有大的需求，尽管可用于销售型号的数量在增长。

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For the current helicopter of single main rotor with tail rotor, the effect of inflow models with different characteristics on helicopter trim and digital simulation was discussed.

以常规单旋翼带尾桨直升机为对象，讨论均匀与非均匀入流模型对直升机飞行数值仿真的影响。

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For the classical helicopter of single main rotor with tail rotor, the effect of inflow models with different characteristics on helicopter trim and digital simulation were discussed in this paper.

针对常规单旋翼带尾桨直升机，讨论不同特性的入流模型在直升机数值仿真中的作用。

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Super Puma EC 225 models have been grounded since a helicopter put down in the sea on 22 October.

BBC: Super Puma grounding hits Aberdeen air traffic

Investigators say they plan to fly around the disaster site in a helicopter equipped with a high-resolution camera, and they're using sophisticated computer models to recreate the bridge collapse, which may reveal clues about how it happened.

NPR: Cleanup Begins at Minneapolis' Collapsed Bridge