jgore
Posts: 518
Joined: Sun Feb 17, 2002 2:41 am

Rotating Gear Wheels While Landing.No Rubber Burn?

Tue Jun 04, 2002 9:17 am

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
 
victech
Posts: 541
Joined: Sun Jun 11, 2000 9:46 am

RE: Rotating Gear Wheels While Landing.No Rubber Burn?

Tue Jun 04, 2002 9:34 am

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...
 
Monocleman
Posts: 133
Joined: Fri Apr 27, 2001 10:21 am

RE: Rotating Gear Wheels While Landing.No Rubber Burn?

Tue Jun 04, 2002 10:34 am

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
 
asgeirs
Posts: 508
Joined: Sat May 05, 2001 7:34 am

RE: Rotating Gear Wheels While Landing.No Rubber Burn?

Tue Jun 04, 2002 10:40 am

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! :-)
 
cannibalz3
Posts: 382
Joined: Mon May 21, 2001 2:10 pm

RE: Rotating Gear Wheels While Landing.No Rubber Burn?

Tue Jun 04, 2002 10:45 am

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
 
air2gxs
Posts: 1443
Joined: Mon Jun 18, 2001 1:29 pm

RE: Rotating Gear Wheels While Landing.No Rubber Burn?

Tue Jun 04, 2002 11:11 am

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.
 
wilcharl
Posts: 1153
Joined: Sun Jun 25, 2000 11:19 am

RE: Rotating Gear Wheels While Landing.No Rubber Burn?

Tue Jun 04, 2002 11:44 am

i remember this topic a year ago... the consensis was it was impractical for amount of rubber lost
 
cdfmxtech
Posts: 1319
Joined: Wed Jul 05, 2000 11:37 am

RE: Rotating Gear Wheels While Landing.No Rubber Burn?

Tue Jun 04, 2002 12:41 pm

Ummm...how about Ram Air??
 
apathoid
Posts: 887
Joined: Fri Sep 28, 2001 3:19 pm

RE: Rotating Gear Wheels While Landing.No Rubber Burn?

Tue Jun 04, 2002 1:05 pm

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.
 
SJC-Alien
Posts: 870
Joined: Wed Jul 14, 1999 1:15 pm

RE: Rotating Gear Wheels While Landing.No Rubber Burn?

Tue Jun 04, 2002 1:18 pm

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


Alien
 
Metwrench
Posts: 715
Joined: Fri Aug 17, 2001 11:25 am

RE: Rotating Gear Wheels While Landing.No Rubber Burn?

Tue Jun 04, 2002 2:25 pm

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.
 
apathoid
Posts: 887
Joined: Fri Sep 28, 2001 3:19 pm

RE: Rotating Gear Wheels While Landing.No Rubber Burn?

Tue Jun 04, 2002 4:31 pm

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.
 
VC-10
Posts: 3546
Joined: Tue Oct 26, 1999 11:34 am

RE: Rotating Gear Wheels While Landing.No Rubber Burn?

Tue Jun 04, 2002 6:09 pm

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 ?
 
duff
Posts: 107
Joined: Thu Oct 11, 2001 10:29 am

RE: Rotating Gear Wheels While Landing.No Rubber Burn?

Tue Jun 04, 2002 8:49 pm

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.
 
FDXmech
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Joined: Sun Mar 19, 2000 9:48 pm

RE: Rotating Gear Wheels While Landing.No Rubber Burn?

Tue Jun 04, 2002 11:58 pm

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.
 
Beefmoney
Posts: 1065
Joined: Tue Oct 10, 2000 2:16 am

RE: Rotating Gear Wheels While Landing.No Rubber Burn?

Wed Jun 05, 2002 1:55 pm

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
Posts: 439
Joined: Thu Mar 14, 2002 4:10 pm

RE: Rotating Gear Wheels While Landing.No Rubber Burn?

Wed Jun 05, 2002 4:02 pm

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
Posts: 518
Joined: Sun Feb 17, 2002 2:41 am

RE: Rotating Gear Wheels While Landing.No Rubber Burn?

Thu Jun 06, 2002 12:52 am

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

 
barney captain
Posts: 1410
Joined: Tue Nov 06, 2001 5:47 pm

RE: Rotating Gear Wheels While Landing.No Rubber Burn?

Thu Jun 06, 2002 3:23 am

What about the increased stopping distance on touchdown? Those tires being stationary create friction on contact. Friction = drag = decreased roll out.
Southeast Of Disorder
 
jgore
Posts: 518
Joined: Sun Feb 17, 2002 2:41 am

RE: Rotating Gear Wheels While Landing.No Rubber Burn?

Thu Jun 06, 2002 4:48 am

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
 
barney captain
Posts: 1410
Joined: Tue Nov 06, 2001 5:47 pm

RE: Rotating Gear Wheels While Landing.No Rubber Burn?

Thu Jun 06, 2002 5:45 am

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.
Southeast Of Disorder
 
jgore
Posts: 518
Joined: Sun Feb 17, 2002 2:41 am

RE: Rotating Gear Wheels While Landing.No Rubber Burn?

Thu Jun 06, 2002 10:48 am

oooo i got it

jgore  Smile
 
Guest

RE: Rotating Gear Wheels While Landing.No Rubber Burn?

Thu Jun 06, 2002 12:50 pm

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!
 
Guest

RE: Rotating Gear Wheels While Landing.No Rubber Burn?

Thu Jun 06, 2002 2:14 pm

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
 
barney captain
Posts: 1410
Joined: Tue Nov 06, 2001 5:47 pm

RE: Rotating Gear Wheels While Landing.No Rubber Burn?

Thu Jun 06, 2002 3:43 pm

No worries amigo. I was really only theorising more then stating fact.
Southeast Of Disorder
 
L-188
Posts: 29881
Joined: Wed Jul 07, 1999 11:27 am

RE: Rotating Gear Wheels While Landing.No Rubber Burn?

Thu Jun 06, 2002 5:56 pm

In theory Barney captain is right, however since tires are designed to rotate anyway any increased drag from the "spin up" is negligible.

Besides unless you can get the wheels to spin at the exact speed the aircraft is covering the ground at, you are going to grind down some rubber regardless.

OBAMA-WORST PRESIDENT EVER....Even SKOORB would be better.
 
duff
Posts: 107
Joined: Thu Oct 11, 2001 10:29 am

RE: Rotating Gear Wheels While Landing.No Rubber Burn?

Thu Jun 06, 2002 11:53 pm

I was reading somewhere that tight turns on the ground (during pushback, taxi) are actually more damaging to the wheels than landings. Remember that when flaps are deployed the weight on the landing gear is fairly minimal (in relative terms). This fact is not forgotten when landing light aircraft on wet runways. The procedure is to retract flap after touchdown which puts more weight on the main landing gear and improves brake performance.
 
L-188
Posts: 29881
Joined: Wed Jul 07, 1999 11:27 am

RE: Rotating Gear Wheels While Landing.No Rubber Burn?

Thu Jun 06, 2002 11:56 pm

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. Since turning left or right will make the tire stress in opposite directions, I would believe that that would wear it down faster.
OBAMA-WORST PRESIDENT EVER....Even SKOORB would be better.
 
airmech
Posts: 75
Joined: Fri Oct 12, 2001 4:47 am

RE: Rotating Gear Wheels While Landing.No Rubber Burn?

Fri Jun 07, 2002 1:01 am

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.desser.com/retreadingp2.html

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