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(Source: primeportal.net)

Has there ever been a fixed-wing aircraft whose propeller is in a scissor configuration? Like the Apache's tail-rotor seen here: What are the benefits of a non-orthogonal (scissor) tail-rotor?

This configuration improves the thrust and reduces the noise. If not, what are the drawbacks for such configuration when used for forward thrust?

The nearest match I could find was a stacked non-counter-rotating propeller. Not being coplanar is the only matching feature. It was on a modified Junkers W 34:

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    $\begingroup$ Without proof my answer is no. The distance between the wakes of the single propeller blades would be uneven, causing a loss in efficiency. Tractor aircraft propellers don't have to deal with rotor downwash and a bulky tail structure, and they enjoy the luxury of airflow which is pretty well aligned with their axis of rotation. Helicopter tail rotors suffer a pitiful existence in comparison. $\endgroup$ – Peter Kämpf Jan 28 '18 at 16:51
  • $\begingroup$ "Helicopter tail rotors suffer a pitiful existence in comparison" I wonder with they don't put the tail rotor above the main rotor to make its life easier. $\endgroup$ – mins Jan 28 '18 at 22:13
  • $\begingroup$ @mins is that a joke or a serious question? $\endgroup$ – KorvinStarmast Jan 30 '18 at 17:19

enter image description here
The tandem-engine Rumpler-Loutzkoy-Taube airplane.

Above is the closest thing to a scissor propeller I could find. As @PeterKämpf notes, unlike a tail-rotor, a tractor propeller is not in a rotor's downwash and its axis of rotation is aligned with the free stream.

The photo shows the world's first co-axial propeller. And it was non-contra-rotating, that is, both propellers rotated in the same direction, like the Apache's.

That, and not being co-planar, are the matching features. Each propeller was powered by a different engine, and they could run at different speeds. Long before variable pitch propellers, it was envisioned (and patented) that the second propeller could have a gearbox to reverse its direction for braking (aircraft at the time didn't have brakes).

Source: oldmachinepress.com


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