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Are there examples of propellers tilted in a controlled way to help in attitude control for pitch and yaw, adding a torque component?

enter image description here
Tilted propeller assumption

This would be similar to thrust vectoring in jets. enter image description here
Vectored thrust principle

Alternatively could a swashplate similar to the one used in helicopter main rotor be used to generate asymmetric thrust?

(I think this excludes convertiplanes where the propellers are converted into rotors to take-off, land or move vertically.)

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    $\begingroup$ I don't know of any full scale planes that do this but it's quite common in RC. $\endgroup$ – slebetman Jan 23 '16 at 13:26
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    $\begingroup$ Here's one I built several years ago: youtube.com/watch?v=TDFUr_UDVTE $\endgroup$ – slebetman Jan 23 '16 at 13:28
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    $\begingroup$ Note that gyroscopic precession would cause the sum total of torque forces to be different than the simple addition of the new thrust angle. $\endgroup$ – J Walters Jan 23 '16 at 14:49
  • $\begingroup$ @JonathanWalters: A point I had forgotten. Would the gyroscopic torque stop when the propeller stops swiveling? $\endgroup$ – mins Jan 23 '16 at 18:46
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    $\begingroup$ The force moment of the gyroscopic precession is a result of the change in rotation plane of the propeller, so as the swivel stops so does the force moment, so yes, sort of. In actual practice the result of the gyroscopic precession usually results in some oscillations, depending on the level of dampening, which extend beyond the initial change in rotational plane. $\endgroup$ – J Walters Jan 23 '16 at 19:53
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Yes, on airships.

The Zeppelin NT can rotate its two forward and one rear propellers to create lift instead of thrust, a capability of particular value when the airship descends in an atmosphere with a strong temperature gradient. From this page about the Zeppelin NT:

The two forward propellors swivel to 120° and the aft one to 90°, and a fixed aft lateral propeller give a high level of manoeuverability, and enable smooth, quiet flight and impressive fuel economy. Some of the unique flight characteristics come from the swivelling propellers, like vertical take offs, precise landings, hovering over exact locations, turns on its axis and flying backwards.

Zeppelin-NT-Airship-Tail-Propellers

Tail propellers of the Zeppelin NT Airship. While the sideways mounted propeller is fixed, the rear propeller can swivel through 90° (picture source)

Front view of the Zeppelin NT with the forward propellers tilted up

Front view of the Zeppelin NT with the forward propellers tilted up (picture source)

Another example would be the V-22 Osprey, obviously, but you might prefer to call those whirly things rotors, not propellers.

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    $\begingroup$ Correct, V-22 Osprey is not in my scope, Zeppelin NT is. I've added a note in the question. Thanks. $\endgroup$ – mins Jan 23 '16 at 19:19
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While in case most VTOL aircraft, the rotors are tilted, one unique case is the Curtis Wright X-19, which had what the company called tilt-propellers. Curtis Wright at that point was a propeller manufacturer and its designers made the aircraft around the propeller.

X-19

Image from warbirdinformationexchange.org

This in turn, was developed from the X-100

X-100

Image from airandspace.si.edu

The designers used a property of the propeller called the radial lift force:

... as a propeller is inclined towards the vertical from the horizontal, the resultant of the propeller's thrust and the pressure of the relative wind acting on the rotating disk is a force with an additional lift component in the vertical axis. ... short propellers with wide blades magnified the radial force effect by increasing the surface area of the propeller disk without the compressibility issues of longer rotor blades. This offered a potential advantage over other tilt-rotor models, such as the Bell XV-3, with longer and narrower blades that did not have sufficient surface area to take advantage of the phenomenon. The added lift generated from the radial force permitted an aircraft built with the specially constructed lifting propellers to have smaller wings, which decreased weight and high-speed drag. This resulted in the most aerodynamically efficient of all of the VTOL designs.

In hover, the roll control was provided by differential pitch of the propellers. The aircraft basically behaved like a high-disc loading helicopter and was statically unstable in hover and in pitch and roll at low speed. The aircraft crashed during its first transition flight in 1965, with the progra ending soon.


This method is also used in a number of small UAVs.

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  • $\begingroup$ This is really helpful! I'm getting a 404 page not found from the called the radial lift force link though. $\endgroup$ – uhoh Sep 24 '16 at 5:06
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Yes, this is possible because many helicopters use this method to some of their control. There are also some aircraft like the V-22 Osprey which use some variation on this control method.

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    $\begingroup$ This does not provide an answer to the question. To critique or request clarification from an author, leave a comment below their post. - From Review $\endgroup$ – fooot Jan 23 '16 at 22:08
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    $\begingroup$ @fooot I think this answer does address the question; it's not a critique, and it isn't requesting clarification. $\endgroup$ – Jules Jan 23 '16 at 23:12

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