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Rotating Gear Wheels While Landing.No Rubber Burn?  
User currently offlineJgore From Argentina, joined Feb 2002, 550 posts, RR: 2
Posted (11 years 10 months 3 weeks 6 hours ago) and read 3959 times:

Hi everyone.
I've always thought that by setting a kind of engine that can rotate the wheel to the same speed the aircraft is flying, would reduce the rubber-burn cost on each landing every plane makes.
The technique would be one engine for the left main gear, so with a chain or some mechanism it could move as many wheels the column would have, another one in the right main gear, and a last one in the nose gear.
In light that the average time a wheel can land, about 10 landings, this technique would improve the durability of each wheel on an aircraft.
I know everything is already thought, already invented, and already discussed, since i'm talking about an industry that every technical matter is involved.
Would it add more weight to the airplane ?, so might be there any chance of less passengers?, and in fact, less profit for the airline by setting those engines in the landing gear?
Is it just a matter of cost-benefit that is not necessary ? 'cause replacing a wheel each 10 landings, is cheaper than investing in a couple of engines to the landing gear ?
I don't know, hope you reply me with your ideas, or juist any reason to explainme why it doesnt exist in the Airline Industry.

jgore  Smile

28 replies: All unread, showing first 25:
 
User currently offlineVictech From United States of America, joined Jun 2000, 546 posts, RR: 2
Reply 1, posted (11 years 10 months 3 weeks 5 hours ago) and read 3935 times:

You know...I mentioned this to my father (a Mechanical Engineer) about a week ago and he didn't have an answer. I'd love to hear commentary on this...

User currently offlineMonocleman From United States of America, joined Apr 2001, 137 posts, RR: 0
Reply 2, posted (11 years 10 months 3 weeks 4 hours ago) and read 3915 times:

Seems to me a simple idea could be to use bleed air on a impeller on the wheels. That could probably get the wheels going significantly fast, without a chair or other complicated mechanical device. Just a thought.

-Will


User currently offlineAsgeirs From Iceland, joined May 2001, 516 posts, RR: 1
Reply 3, posted (11 years 10 months 3 weeks 4 hours ago) and read 3915 times:

I have wondered about this myself a couple of times...

I don't think it would be feasible to have some sort of a motor to turn the wheels, but maybe it would be possible to do it by leading pressurised air directly from the engines to drive an air turbine which would turn the wheels.
(in the same way a dentist's drill works).



Reykjavik Aviation Photography - Just bring the aircraft to us and we'll photograph them! :-)
User currently offlineCannibalZ3 From United States of America, joined May 2001, 392 posts, RR: 0
Reply 4, posted (11 years 10 months 3 weeks 4 hours ago) and read 3918 times:

I think the USAF is implementing a system on T-38s where the wheel or gear door is shaped so the wind starts turning the wheel when it comes down. Apparently it's very useful and cost-effective.
-Zach


User currently offlineAir2gxs From , joined Dec 1969, posts, RR:
Reply 5, posted (11 years 10 months 3 weeks 4 hours ago) and read 3910 times:

Pressurised air would be difficult to implement, also you don't want to bleed air un-necessarily from the engines during landing, it would impede engine spool up in case of go-around.

Motors are impractical: weight, maintenance and cost.

Tires are changed on condition, not on a time basis.


User currently offlineWilcharl From United States of America, joined Jun 2000, 1160 posts, RR: 3
Reply 6, posted (11 years 10 months 3 weeks 3 hours ago) and read 3898 times:

i remember this topic a year ago... the consensis was it was impractical for amount of rubber lost

User currently offlineCdfmxtech From United States of America, joined Jul 2000, 1338 posts, RR: 27
Reply 7, posted (11 years 10 months 3 weeks 2 hours ago) and read 3881 times:

Ummm...how about Ram Air??

User currently offlineApathoid From , joined Dec 1969, posts, RR:
Reply 8, posted (11 years 10 months 3 weeks 2 hours ago) and read 3876 times:

Some bizjets do use a system, notably early Citations. It sucks. Remember, the landing gear environment is not a pleasant one. Mud and gunk and heat all combine to add wear and tear and induce failures at an alarming rate. Also, it adds weight. Combined, the added weight and added cost (maintenance being a big one) make it impractical compared to tires which are relatively cheap.

User currently offlineSJC-Alien From United States of America, joined Jul 1999, 919 posts, RR: 1
Reply 9, posted (11 years 10 months 3 weeks 2 hours ago) and read 3870 times:

....I need something 'fun' when I photograph airliners........don't take away the fun things......(just teasing.........)  Big thumbs up


Alien


User currently offlineMetwrench From United States of America, joined Aug 2001, 750 posts, RR: 2
Reply 10, posted (11 years 10 months 3 weeks ago) and read 3851 times:

Apathoid is right, Cessna did it on at least one aircraft that I know of. The Citation II. They extracted bleed air to run a turbine on the nose wheel to "spin" it up prior to touch down. This was a measure to "approve" the aircraft to land on "un-approved" runways. The theory being that it would reduce FOD ingestion into the engines. The belly, wing leading edges, and wing lower suffices still take a beating though.

The theory of spin up works on nose gear because they tend to be able to rotate freely. Main gear are already inhibited to rotate due to brake drag. It would likely take a considerable amount of monkey motion to overcome that.

Not to mention that many aircraft incorporate automatic brake application of the main wheels upon retraction and bumpers in the nose gear well to stop nose wheel rotation after wheels up.

The trade off on worn rubber probably isn't worth the engineering.

Just some rambling thoughts from an old mechanic that would rather change a tire than overhaul a wheel spin up system.

P.S. The CEO is likely behind me on this one.


User currently offlineApathoid From , joined Dec 1969, posts, RR:
Reply 11, posted (11 years 10 months 2 weeks 6 days 22 hours ago) and read 3833 times:

The truly annoying thing about the Citation system is that if it were inoperative, the aircraft was not dispatchable, even if you were going pavement to pavement. Anyone want to take a guess on how often it broke? Those of you who know my love for Fairchild products (take that tongue in cheek) will understand when I say that this is probably one system that was sooooooo bad that even Fairchild engineers could have improved it.

User currently offlineVC-10 From United Kingdom, joined Oct 1999, 3695 posts, RR: 35
Reply 12, posted (11 years 10 months 2 weeks 6 days 21 hours ago) and read 3825 times:
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Which do you think would cost more, the rubber lost in spinning up the wheel on ground contact as at present, or the maint costs and fuel burned in carrying the extra weight of a spin up system ?

User currently offlineDuff From New Zealand, joined Oct 2001, 116 posts, RR: 1
Reply 13, posted (11 years 10 months 2 weeks 6 days 18 hours ago) and read 3812 times:

The following is cut and pasted from the duplicate thread that was on the other forum...

It has already been thought of. However, it was quashed because the wheels were unable to penetrate water or any other runway contamitants. The wheels were prone to aquaplaning. That is one reason. I am sure there are others.


User currently offlineFDXmech From United States of America, joined Mar 2000, 3251 posts, RR: 35
Reply 14, posted (11 years 10 months 2 weeks 6 days 15 hours ago) and read 3783 times:

The transition from stationary wheels to touchdown wheelspinup is a critical parameter in many aircraft systems.

For instance the ground spoilers utilize wheel spinup as a primary input to allow the spoilers to pop up (there are back up modes should the wheels hydroplane).

Wheel spin up is also a major input to the antiskid system and the autopilot system (during autoland) during the critical transition from airborne to on-ground.

Deleting this mode to save some rubber would entail major reengineering of many peripheral systems.





You're only as good as your last departure.
User currently offlineBeefmoney From United States of America, joined Oct 2000, 1111 posts, RR: 4
Reply 15, posted (11 years 10 months 2 weeks 6 days 1 hour ago) and read 3709 times:

Also, what if one motor failed while the other sides motor spun up the wheels only on that side? You would get some wild yawing action after touchdown, it would be like applying brakes to one side of the aircraft right on touchdown.

User currently offlineShaun3000 From United States of America, joined Mar 2002, 445 posts, RR: 0
Reply 16, posted (11 years 10 months 2 weeks 5 days 23 hours ago) and read 3686 times:

I would imagine the friction of the tire hitting the pavement vs. the tire already spinning would be next to nil, especially on a large jet traveling at 200 MPH. If the friction were high enough to yaw the plane any signigicant amount, then we'd all be thrown foward in our seats at touchdown.

User currently offlineJgore From Argentina, joined Feb 2002, 550 posts, RR: 2
Reply 17, posted (11 years 10 months 2 weeks 5 days 14 hours ago) and read 3633 times:

Well guys, there are many replys and opinions. Something interesting that has been said by FDXmech, is that i didn't know the wheels are used to help in the spoiler mechanism wheen deploying. Some others said what if a motor failed. Well, i think that in light of the aircraft's weight, there shouldn't be any trouble, 'cause the aicraft's own weight is much greather than the resistence a steady-wheel could do.
The truth, i think, is that i cannot give any reasonable answer to that, since i'm not a mechanic, engineer or a pilot.
There still will be many other questions about airline industry, many of them like "Why fuel on wings?, insted of locating it along the fuselage in order to raise the survival chances in a accident ?", and so on.
Maybe when we all be pilots, someones already are, we can get some answers to those questions.
Hope you still have any ideas or answers to the first question of this thread:

"Rotating Gear Wheels While Landing. No Rubber Burn?"

Thanks everyone in this wonderfoul site. I'm very proud being part of it.

Jgore  Smile



User currently offlineBarney captain From United States of America, joined Nov 2001, 887 posts, RR: 13
Reply 18, posted (11 years 10 months 2 weeks 5 days 11 hours ago) and read 3616 times:

What about the increased stopping distance on touchdown? Those tires being stationary create friction on contact. Friction = drag = decreased roll out.


...from the Banana Republic....
User currently offlineJgore From Argentina, joined Feb 2002, 550 posts, RR: 2
Reply 19, posted (11 years 10 months 2 weeks 5 days 10 hours ago) and read 3607 times:

What was that Barney Captain ?, i didn't understand. You said Frition=drag=decreased roll out is equal to decreased runway lenght need ? ,in other words, decreased slowdown time at landing ?.

thanks

jgore  Smile


User currently offlineBarney captain From United States of America, joined Nov 2001, 887 posts, RR: 13
Reply 20, posted (11 years 10 months 2 weeks 5 days 9 hours ago) and read 3592 times:

Sorry if I wasn't clear. I was trying to indicate that having the wheels stationary at touchdown (no pre-spinning) helps the a/c slow more effectively. I.e., rubber loss is a good thing when it comes to gettin' her stopped.


...from the Banana Republic....
User currently offlineJgore From Argentina, joined Feb 2002, 550 posts, RR: 2
Reply 21, posted (11 years 10 months 2 weeks 5 days 4 hours ago) and read 3564 times:

oooo i got it

jgore  Smile


User currently offlineJetguy From , joined Dec 1969, posts, RR:
Reply 22, posted (11 years 10 months 2 weeks 5 days 2 hours ago) and read 3552 times:

Dear Barney Captain...
Not to question you, but what the heck are you talking about? Just how much more effectivness is gained by the wheels being stationary? It couldn't possibly be much and how would one measure it? Also, I'm curious about the comment about rubber loss being a good thing when it comes to braking. I don't think so. Taken to an extreme, reverted rubber hydroplaning ought to be just the ticket, then, to getting your airplane stopped. Not!


User currently offlineJetguy From , joined Dec 1969, posts, RR:
Reply 23, posted (11 years 10 months 2 weeks 5 days 1 hour ago) and read 3542 times:

Barney Captain and Other Forum Members,

I'd like to apologise to Barney Captain for coming across so "harsh" in my last post. It's been a long day and I've received some bad news. He was just a convenient target. I'm sorry.

Jetguy


User currently offlineBarney captain From United States of America, joined Nov 2001, 887 posts, RR: 13
Reply 24, posted (11 years 10 months 2 weeks 4 days 23 hours ago) and read 3531 times:

No worries amigo. I was really only theorising more then stating fact.


...from the Banana Republic....
25 L-188 : In theory Barney captain is right, however since tires are designed to rotate anyway any increased drag from the "spin up" is negligible. Besides unle
26 Duff : I was reading somewhere that tight turns on the ground (during pushback, taxi) are actually more damaging to the wheels than landings. Remember that w
27 L-188 : Your probably right Duff. With my car, when I rotate the tires I don't want to change the direction of rotation, because of the way the rubber wears.
28 Post contains links Airmech : Here are a couple of articles that discuss spinning up the tires prior to touchdown. http://www.sensorsmag.com/articles/0200/14/main.shtml http://www.
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