From: inc@tc.fluke.COM (Gary Benson)
Subject: Re: Tire burn-out during landings
X-Submission-Date: Wed, 23 Dec 1992 19:11:28 GMT
Organization: John Fluke Mfg. Co., Inc., Everett, WA
X-Submission-Message-ID: <1992Dec23.191128.13678@tc.fluke.COM>
Date: 27 Dec 92 17:34:54 CST

In article <airliners.1992.186@royko.Chicago.COM> megazone@obsidian.WPI.EDU (MegaZone23) writes:
>In article <airliners.1992.183@royko.Chicago.COM> todamhyp@unlv.edu (Brian M. Huey) writes:
>>the wheels come in contact from the ground due to friction. Couldn't
>>this cloud and the effect of friction be lessened by inducing a
>>angular velocity upon the wheels to match the airliners speed with
>
>Spinning the wheels would indeed cut down on the tire wear, and I believe that
>this has been tested. However, there are problems. When you spin a tire it acts
>as a gyroscope and will resists having it's course altered. This can make 
>handling tricky as you would have 10 or more wheels all spinning on most 
>airliners. Have you ever held a spinning bicycle tire in your hands and tried
>to move it? Same effect.
>
>You also need to weigh the advantages against the disadvantages. How much does
>the tire wear cost the airline? How much would mantenance on a system to spin
>the wheels cost?
>
>Plus you will have the initial cost for the system and the added weight. It is
>one more system to break down, etc...
>
>All in all it just doesn't appear to be worth it...
>
>###############################################################################
># I have one prejudice, and that is against stupidity.  Use your mind, think! #
>#Email megazone@wpi.wpi.edu  Moderator, WPI anime FTP site 130.215.24.1 /anime#
>###############################################################################
>

I'm glad this question was asked - I've often wondered the same thing! And I
think the answer was very thoughtful and all in all, probably states the
real reason spinnning the wheels is not done. However, if I may opine:

RE: Gyroscope effect

It seems that this could be used to advantage. After all, the wheels would
tend to make the bird retain its current course. If you didn't start
spinning till you were lined up with the runway, it seems that the spinning
wheels could conceivably even help counteract sheer forces.

RE: Maintenance

Maybe there would be NO cost, for example if the tires were designed so that
their tread caught the wind and got their spin from that. Or maybe the hubs
could be fitted with fans.

RE: Initial cost of system

I think this could be done for free, too; particularly if the tread- or hub-
induced spin just mentioned were employed. All you'd need to do is apply the
breaks to keep them from spinning until you were ready. For safety's sake,
you might want to have a "mini-brake" that would be enough to keep the
wheels from spinning but which would easily be overcome if you landed with
it applied. Seems cheap enough.

Does anyone have any estimates about the costs using the current "cloud of
smoke" and friction method of landing? How much does one of those tires
cost? What is the expected number of landings it can endure? How fast would
you have to spin the tire to get a 10% reduction in wear? 10% of the speed
of the aircraft?


-- 
Gary Benson   -_-_-_-_-_-_-_-_-_-inc@sisu.fluke.com_-_-_-_-_-_-_-_-_-_-_-_-_-_-

Stupidity cannot be cured with money, or through education, or by legislation. 
Stupidity is not a sin; the victim can't help being stupid. But stupidity
is the only universal capital crime; the sentence is death, there is no
appeal, and execution is carried out automatically and without pity.
                                                   -Lazarus Long
					   

Newsgroups: sci.aeronautics.airliners