Jgore From Argentina, joined Feb 2002, 550 posts, RR: 2 Posted (13 years 4 months 1 week 2 days 12 hours ago) and read 5217 times:
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.
Monocleman From United States of America, joined Apr 2001, 137 posts, RR: 0
Reply 2, posted (13 years 4 months 1 week 2 days 10 hours ago) and read 5173 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.
Asgeirs From Iceland, joined May 2001, 518 posts, RR: 1
Reply 3, posted (13 years 4 months 1 week 2 days 10 hours ago) and read 5173 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! :-)
Apathoid From , joined Dec 1969, posts, RR:
Reply 8, posted (13 years 4 months 1 week 2 days 8 hours ago) and read 5134 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.
Metwrench From United States of America, joined Aug 2001, 750 posts, RR: 2
Reply 10, posted (13 years 4 months 1 week 2 days 6 hours ago) and read 5109 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.
Apathoid From , joined Dec 1969, posts, RR:
Reply 11, posted (13 years 4 months 1 week 2 days 4 hours ago) and read 5091 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.
Duff From New Zealand, joined Oct 2001, 119 posts, RR: 1
Reply 13, posted (13 years 4 months 1 week 2 days ago) and read 5070 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.
Beefmoney From United States of America, joined Oct 2000, 1124 posts, RR: 3
Reply 15, posted (13 years 4 months 1 week 1 day 7 hours ago) and read 4967 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.
Shaun3000 From United States of America, joined Mar 2002, 445 posts, RR: 0
Reply 16, posted (13 years 4 months 1 week 1 day 5 hours ago) and read 4944 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.
Jgore From Argentina, joined Feb 2002, 550 posts, RR: 2
Reply 17, posted (13 years 4 months 1 week 20 hours ago) and read 4891 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.
Barney captain From United States of America, joined Nov 2001, 1247 posts, RR: 12
Reply 20, posted (13 years 4 months 1 week 15 hours ago) and read 4850 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.
Jetguy From , joined Dec 1969, posts, RR:
Reply 22, posted (13 years 4 months 1 week 8 hours ago) and read 4810 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!