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Do faired wheels rotate in flight ?
I have been told that out of balance faired wheels can induce vibrations in the plane during the flight. This implies that faired wheels do rotate during the flight. Is is this the case? |
Simple, non-retractable faired wheels (e.g. C172, Grumman Cheetah) can rotate in flight. That doesn't mean they always do.
The bottom of the wheel sticks out of the fairing into the slipstream, and thus can be spun by the passing air, like a stream waterwheel. https://en.wikipedia.org/wiki/Water_wheel#/media/File:Stream_waterwheel_simple.svg Mass of the wheel, axle lubrication, roughness of the tire tread, and aircraft speed will all affect whether the force is enough to spin the wheel. I've never felt vibrations, myself. Complex wheels that are faired into the fuselage once retracted (e.g. 737) won't have the same asymmetrical force, and usually are braked to a standstill during the retraction process. |
Originally Posted by pattern_is_full
(Post 10388872)
Simple, non-retractable faired wheels (e.g. C172, Grumman Cheetah) can rotate in flight. That doesn't mean they always do.
The bottom of the wheel sticks out of the fairing into the slipstream, and thus can be spun by the passing air, like a stream waterwheel. https://en.wikipedia.org/wiki/Water_wheel#/media/File:Stream_waterwheel_simple.svg Mass of the wheel, axle lubrication, roughness of the tire tread, and aircraft speed will all affect whether the force is enough to spin the wheel. I've never felt vibrations, myself. Complex wheels that are faired into the fuselage once retracted (e.g. 737) won't have the same asymmetrical force, and usually are braked to a standstill during the retraction process. https://cimg5.ibsrv.net/gimg/pprune....2c05117b90.jpg That may have been a result of snubbers in the bay, it's been a long time ... |
Makes for a much smoother gear-up landing too! Didn’t the Anson, C-47 and B-17 have a similar design? |
Some British WW2 era types had cups mouded into the tyres to make them rotate after gear extension, with the intention of saving tyre wear.
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Originally Posted by eckhard
(Post 10389159)
Makes for a much smoother gear-up landing too! Didn’t the Anson, C-47 and B-17 have a similar design? |
The A-10 (Warthog) gear has a similar design as well.
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On light aircraft brakes always drag a little. I’ve never seen or felt wheels turn in flight. Difficult to draw but it’s not that hard to visualize that faired wheels barely have any air pressure on them because of the air being deflected by the wheel pants. https://cimg4.ibsrv.net/gimg/pprune....4d1598ea5.jpeg |
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