It was an unmanned biplane with player-piano bellows to power its gyroscope and a cash-register mechanism that calculated distance flown by counting the rotations of a propeller-like rotor.

这是一个无人驾驶的双翼飞机，它有着自动钢琴的风箱来为回旋装置提供动力，以及一个收银机的机械装置——通过记录类似螺旋推进器的转子的旋转次数来计算飞行的距离。

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This means it can hover like a helicopter, but when flying forward can reduce the speed of the main rotor because the wings provide part of the lift.

这意味着它能像一架直升机那样作空中悬停，而在向前飞行时，又能降低主旋翼的速度，因为它的一对短翼提供了部分升力。

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This means it can hover like a helicopter, but when flying forwards can reduce the speed of the main rotor and let the wings provide part of the lift.

这意味着它能像直升机一样悬停，但向前飞时可能减少主旋翼的速度并让这两个短翼提供部分提升力。

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Friend vibrates a lead zirconate titanate crystal, and those vibrations twist a spring-like element attached to a rotor.

FORBES: Breakthroughs

The company created an automatic movement with the use of contemporary materials like silicon and a hand engraved rotor on the reverse side of the timepiece.

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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.

ECONOMIST: A new way to build a greener jet engine