Why has someone not designed a landing wheel with a fin or fins on it so that the air will start the wheels turning before the wheels touch the ground? Wouldn't that preserve the tires longer from wear? Or would it make the control of the aircraft more dangerous in some circumstances, such as rain or snow, to have the wheels already turning when landing? If so, perhaps the fins could be manually or computer controlled for various weather conditions.
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5You'd need to match speed exactly which is very hard. plus there is the weight issue, anything superfluous that is heavy will not get on board – ratchet freak May 03 '14 at 23:08
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62@ratchetfreak You wouldn't need to match it exactly at all! You'd just need to get closer to the actual ground speed than a stationary wheel is. Don't fall into the trap of failing to do anything just because a perfect solution isn't possible. (But I agree that the reason it's not been done will be that the advantages don't outweigh the costs.) – David Richerby May 04 '14 at 07:26
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How do you spin the wheels in a way that does not affect their friction upon contact? I mean, if you use any kind of clutched drive, how do you ensure the clutch does not still contact the axle upon landing; any contact of the clutch would cause it to potentially burn out. If you use fins and airflow, would there possibly be enough airflow to overcome the inertial weight of the total tire/hub/etc. – CGCampbell Oct 15 '14 at 12:47
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5This guy claims to have designed some hubcaps with fins in then that catch the wind and supposedly spin the wheels up after the landing gear is deployed – Matt Hill Mar 05 '15 at 14:44
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possible duplicate of How long do airliner tires last? Can this be improved? – Danny Beckett Apr 01 '15 at 05:48
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3I asked this exact question back in the old days when I was in the Civil Air Patrol. We were at an encampment at Chanute AFB in Illinois, and being given a tour of a B-58 they had on hand, whose tires were very badly worn. The instructor was telling us that the aircraft required new tires after about four landings. His response to my question was two parts: 1) anything that adds weight or complexity to a simple system is a bad thing, and 2) defense contractors don't make money by not selling you new tires. ^_^ – Robusto Sep 22 '15 at 16:36
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@MattHill IIRC Frank Capra (the movie director) claimed that he was involved in development of a similar hubcap back in the 1930s. – Carl Witthoft Nov 23 '21 at 14:35
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This has been researched over the years, but it seems that the solutions did not find wide application. The oldest I could find is from 1941 (see page 112 in the September 1941 issue of Popular Science), and there have been several attempts to implement a spin-up turbine. See “Wheels with wings” on NewScientist Blogs or “Spin Wheels Before Landing”, a discussion thread on Eng-Tips forums, for more. The biggest problem seems to be the inertia of the spinning wheel because it makes the aircraft react in funny ways if the pilot wants to correct his approach.
The rough field package on the Cessna Citation 500 uses this technique (for the nose wheel only) to protect the fuselage from debris which could be kicked up by the wheel spinup.
Peter Kämpf
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9So if gyroscopic precession is an issue, does it have the same effect during take off? – MK Yung May 05 '14 at 01:05
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7Also, after take-off you mind less when the aircraft rolls a little when you yaw and vice versa. This is quite different to trying to line up with the runway during an approach in gusty air. – Peter Kämpf May 05 '14 at 18:26
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7And that's why Concorde had a disk brake on the nose wheel that was activated during gear retraction. – Marco Sanfilippo Sep 04 '15 at 10:21
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2In the late 80s three German schoolboys invented “Aircraft tyres having an autorotation device” (rotation through airflow). They participated in “Schüler experimentieren” (which is “Jugend forscht” for kids under 15y). A picture is shown here (Engl. translation). AFAIK a major tyre manufacturer supported them but let it eventually disappear into a drawer. – PerlDuck Dec 26 '16 at 15:34
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1I've also read in once case that spinning up the wheels before landing significantly increased the stopping distance. Seems a little far-fetched but I definitely recall reading that. – quiet flyer Jun 26 '19 at 13:33
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It's just not cost-efficient. Any weight-add produces more fuel consumption, any systems produces more maintenance costs. It's just easier to change the tires if they're worn out. source: Aerospace engineering
Hubschr
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6could you expand your answer a bit? the content is fine, but expanding the reasoning would help. – Federico May 05 '14 at 09:03
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3I thing Hubschr is correct. In general the more things you add or make complex, the more things break and drive up the cost of maintenance. Also when a tire goes the mechanic knows how to change it. When some fancy electric motor or its controller, or it's power supply , or ... it's a much bigger deal to troubleshoot and fix. This can result in more down time. Planes only make money when they are working, so keep it simple and get back in the air making money. – JerryKur Oct 15 '14 at 20:24
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2Well, this is a generalization and in this case I do not agree. ^^ Progress is most of the time not the effect of simplification. Systems are getting more complicated.
(As an example: If you would build a special rim (when you have retractions wheels) which use the airflow for generating the spin it does not have to make the maintenance costs higher and it maybe also not produce more weight. And (maybe) the over-all cost is better, because fewer tires worn out.) Source: My two cents as an engineer
– TimK Mar 16 '19 at 18:16 -
A design based on the design of simple 3 cup anemometer would be lightweight, easy to understand and easy to maintain. – KDP Mar 26 '24 at 16:32