Spinning tyres....

[Nishko]

People,

I heard a while ago that an ingenious engineer had developed the following idea:

If 'air vanes' were to be moulded onto the walls of aircraft tyres, in just the right shape, the airflow would spin up the tyres prior to touch down. The result of pre-spinning tyres would result in a dramatic reduction of tyre wear per landing. If true, this would seem to be a huge saving for what would be an extremely simple design incorporation.

Any comments?

Nish.

[Girt_bar]

I was suggesting that very idea to a mate at work not long ago. I hadn't realised that it had actually been attempted

[static]

just a few things that spring to mind:
-Noise. It seems that engine noise is only half of the noise created by an aircraft on approach. The rest is from the airframe, which might increase by 18 wheels whining round.
-Drag, the drag of the wheels will increase in flight with the gear down, probably negligible, but it might cause pitch-down momentum.
-Problems braking and stowing the wheels when retracting.

Otherwise, it sounds like a good idea.

[m&v]

It was actually done in World War 2,the wheels started to get too big for the initial touchdown spinup shock on the 'oleos'
Couldn't do it today as it would spinup the wheel in the air causing the spoilers to activate/auto braking to apply(15mph).wheel a lot 'smaller'now

[BOAC]

believe it was tried on a Lancaster during WW2 (with electric motors, I think) but whoever thought of it had not done any gyro theory as I understand the precession from the huge wheels caused significant fun and games!

[Lu Zuckerman]

It was tried in the USA about twenty or thirty years ago but the idea never went anywhere. I think your friend was a bit late.

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The Cat

[Smoketoomuch]

This idea keeps resurfacing. AIUI by far the most wear/damage is done prior to take-off as the plane is heavy. The patent office claims this is one of the most frequent submissions/searches by people thinking they've thought of it for the first time.

[The Boy Lard]

Interesting thread, my Father (Now retired) used to work for British Aerospace at Woodford and apparently they did some research into same idea many years ago, and the upshot was that the retarding effect of tyres going from virtually nil speed to landing speed at point of "impact" was such that the cost of replacing tyres was less than the cost of replacing brake parts.

I stand to be corrected.

TBL



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Flying is fun, not funny

[MasterBates]

When landing in standing water, we actually want stationary wheels "shocking" themself through the film of water. Noise is also a real factor.

-I'm a besserwisser-

[411A]

Both the Convair XC-99 (pax/cargo version of the B36 bomber) and the Lockheed Constitution had provisions for tire spinup prior to landing. Neither aircraft went into production, mainly because they were underpowered with the then largest piston engines available, the P&W 4360 Wasp Major.

[hopharrigan]

The DC3 had wheels that would slowly sag into the airflow, and we knew this was happening because we could hear them start to rumble as they turned. If they were to be left to turn they could get a reasonable speed prior to touchdown, but it had neglibible effect on the landing. I remember they were pretty big wheels too, for the size of the airplane at the time.

[SevenFiftySeven]

I may be wrong, but I seem to remember a similar thread a while ago (or maybe I read it in a trade mag), but isn't the greatest cause of aircraft tire wear the taxi and takeoff, rather than the landing?

As I say, I may be wrong - (so don't shout at me if I am!), but I'm sure that's what I heard!

[FLUFFY SHOES]

Tcas Climb,

The Citation 2 gravelkit is purely a bleed air spin up for the nosewheel to stop FOD into those 2 little Hoovers ie stops the gravel kicking upwards on nosewheel contact. Works well.
But from my understanding not initially designed to reduce nosewheel tyre wear.

[Boss Raptor]

Tyres are probably the least expensive factor in a landing...the brakes cost a fortune...

As an idea a brand new 727 main tyre costs about $700 and can be retreated about 7-10 times if taken off before it wears to the bead...break units last 2-3 months if you're lucky, two on each main wheel, $3K to overhaul and if you let them go beyond the limit throw 'em away, $8K to replace!

[Cyclic Hotline]

I read a story earlier this year about a retired minister from Orkney who had worked on this. He had donated his idea to the RAF, who were going to experiment with it!

He had patented an idea to modify tyres during the forming process, to include cups that were an integral part of the side wall. These cups would then cause the wheel to rotate whenever they were exposed to the airflow.

I'm almost certain I read the story in the Times, but can't find it in their search engine.

Sounded like a pretty good idea to me.

[Ultralights]

Speaking from an engineers point of view, 90% of the aircraft's tyre damage is a result of ground handling, during taxi, sharp turns during pushback and menouvering into hangars etc. Try turning your car with all 4 wheels locked in the same direction as they are in a bogie setup. The damage caused by touchdown is usually limited to a series of v shaped cuts in the surface of the rubber no bigger than 1/2 Inch at most, as i am sure many have noticed during a walkaround. this of course doesnt include excessive braking causing lockup, and lastly, there are many aircraft with tyres exposed to the airstream while in the stowed position, The B737 is an example! ( no undercarridge doors), dont forget , when the aircraft touches down, there is very little weight actually on the tyres until spoilers are deployed

[This message has been edited by Ultralights (edited 17 December 2000).]

[This message has been edited by Ultralights (edited 17 December 2000).]

[ORAC]

Discussed last August:

<A HREF="http://www.pprune.org/ubb/NonCGI/Forum46/HTML/000573.html" TARGET="_blank">http://www.pprune.org/ubb/NonCGI/Forum46/HTML/000573.html</A>

[buck-rogers]

As a side issue, I beleive you can 'crab' a big jet quite severely in high cross wind landings to keep the wings more level. Does this take off loads of rubber or is there some flexible 'give' in the bogeys on one axis to compensate?

Just wondering?

[before landing check list]

I actually thought of the vane think before but dismissed it due to the potential of vibration in flight if the balance was not very good. I am sure there are other reasons.......nice try though.
j

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Here's to cheating, stealing, fighting, and drinking.
If you cheat, may you cheat death.
If you steal, may you steal a woman's heart.
If you fight, may you fight for a brother.
And if you drink, may you drink with me.

[This message has been edited by before landing check list (edited 21 December 2000).]