The engines used by Ark Angel are electric motors driving counter-rotating propellers, mounted in pods below the hull.

方舟天使使用的引擎是反向旋转的螺旋桨驱动的电动马达，安装在船体下的分离舱中。

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One way to increase the efficiency of a high-bypass jet engine is to turn the fan into an open rotor, a bit like returning to propellers, but using two rings of stubby counter-rotating blades.

提高高旁通飞机引擎的方法之一就是把风扇变成开放式旋翼，有点回归于螺旋桨的味道，但要使用两圈粗短的反旋桨叶。

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"Most seals are very wary of propellers," she says. "But the seals may have been caught in the draft of a powerful current, and been dragged through a rotating blade."

“大多说海豹是会小心躲避螺旋桨的，”她说，“但他们可能会被强大的水流卷进螺旋桨中。”

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For nine months the ship Transocean Discoverer Spirit used 360-degree rotating propellers to hold itself steady in the 3, 500-foot-deep water as diamond-tipped bits cut the deepest oil well ever--6.5 miles down.

FORBES: Magazine Article

One way to increase the efficiency of a high-bypass jet engine is to turn the fan into an open rotor, a bit like returning to propellers, but using two rings of stubby counter-rotating blades.

ECONOMIST: A new way to build a greener jet engine