Pre-rotating of aircraft wheels before landing?

Pre-rotating of aircraft wheels before landing?

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Discussion

onyx39

Original Poster:

11,109 posts

149 months

Friday 5th December 2014
quotequote all
Here's a question.
Every time an aircraft lands, the tyres hit the runway at over 100 mph, which obviously takes a large amount of the tyre was, as evidenced by the tyre smoke.
Would it not be possible (and presumably not too expensive) to have the tyres "pre-rotating" at the ground speed of landing?
You would obviously lose a very small amount of retardation that you get currently, and there is a cost involved, but presumably there would be a net gain over the life time of the aircraft in terms of tyre costs?

alangla

4,723 posts

180 months

Friday 5th December 2014
quotequote all
I always wondered why the tyre manufacturers didn't mould fins on to the sidewalls - that would let the tyre spin up using the airflow as the plane came into land. The only downside I can see is that it would put a bit more load on the brakes when they stop the wheels before the undercarriage retracts after takeoff. I guess it would also mean that aircraft tyres would become rotational rather than being fitted anywhere (assuming they're not rotational already, obviously!)

Marcellus

7,111 posts

218 months

Friday 5th December 2014
quotequote all
Surely its a free part of the braking process?

blueg33

35,586 posts

223 months

Friday 5th December 2014
quotequote all
If I was a tyre maker for aircraft, I think I would be happy not to do something that would reduce the wear rate.......

onyx39

Original Poster:

11,109 posts

149 months

Friday 5th December 2014
quotequote all
blueg33 said:
If I was a tyre maker for aircraft, I think I would be happy not to do something that would reduce the wear rate.......
I can see why there would be no benefit for the tyre manufacturer, but not so with the aircraft manufacturer / airline.

onyx39

Original Poster:

11,109 posts

149 months

Friday 5th December 2014
quotequote all
Marcellus said:
Surely its a free part of the braking process?
Free, but negligible, surely?

Abagnale

366 posts

113 months

Friday 5th December 2014
quotequote all
As I understand it, the cost & fuel penalties involved in adding something to spin the wheels far outweighs the benefits in savings to tyre costs. As ever, brighter & better people have thought of this before & reached the conclusion you see on aircraft today.

otolith

55,899 posts

203 months

Friday 5th December 2014
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Cost of tyre wear vs cost in fuel of lugging tyre rotating machinery round with the plane?

ianrb

1,529 posts

139 months

Friday 5th December 2014
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Now if the plane landed on a conveyor belt...


dr_gn

16,140 posts

183 months

Friday 5th December 2014
quotequote all
Driven mainwheels for taxying are currently being investigated (to save fuel), and these would also allow pre-rotation and regenerative braking for landing.

dr_gn

16,140 posts

183 months

Friday 5th December 2014
quotequote all
alangla said:
I always wondered why the tyre manufacturers didn't mould fins on to the sidewalls - that would let the tyre spin up using the airflow as the plane came into land. The only downside I can see is that it would put a bit more load on the brakes when they stop the wheels before the undercarriage retracts after takeoff. I guess it would also mean that aircraft tyres would become rotational rather than being fitted anywhere (assuming they're not rotational already, obviously!)
What would the fins look like to allow rotation?

Marcellus

7,111 posts

218 months

Friday 5th December 2014
quotequote all
dr_gn said:
What would the fins look like to allow rotation?
All wrong? getmecoat (sorry wrong topic)

blueg33

35,586 posts

223 months

Friday 5th December 2014
quotequote all
ianrb said:
Now if the plane landed on a conveyor belt...
..... your baggage would get to reclaim faster

anonymous-user

53 months

Friday 5th December 2014
quotequote all
For large passenger airframes, i believe the tyre life limitations are primarily load/fatigue based, rather than "tread wear" in most normal cases (when operating from long, well surfaced 1st world r/w). Each time you land or take off, those tyres are supporting hundreds of tonnes of airframe traveling at nearly 200mph, and those stresses lead to a slow degradation in the tyre integrity. And whilst you could make a tyre strong enough to last indefinitely, it would be so heavy and bulky it would cost you more in terms of payload & drag!

alangla

4,723 posts

180 months

Friday 5th December 2014
quotequote all
dr_gn said:
alangla said:
I always wondered why the tyre manufacturers didn't mould fins on to the sidewalls - that would let the tyre spin up using the airflow as the plane came into land. The only downside I can see is that it would put a bit more load on the brakes when they stop the wheels before the undercarriage retracts after takeoff. I guess it would also mean that aircraft tyres would become rotational rather than being fitted anywhere (assuming they're not rotational already, obviously!)
What would the fins look like to allow rotation?
Probably something like the cups on an anemometer I'd have thought

blueg33

35,586 posts

223 months

Friday 5th December 2014
quotequote all
This was posted in a similar discussion elsewhere and seems plausible

internet said:
The articulated main landing gear of most "heavy" type aircraft (747, A320, MD-11, etc.) already serves to minimize touchdown tire wear, and reduce blowouts, by providing some articulated initial "soft" loading of the tire clusters at touchdown. You can see this working as the rear most tires, "hanging" lowest immediately prior to touchdown, first contact the runway, and the landing gear then is quickly compressed/rotated slightly to bring additional tires, farther forward, into ground contact.
There is also this summary of a technical document that costs $70

aircraft industry said:
Standard: AIR5800

Issued: 2009-10-29

Issuing:

A-5c Aircraft Tires Committee
Committee Information

Scope:

This SAE Aerospace Information Report (AIR) applies to landing gear tires and airframe structure for all types and models of civil and military aircraft having tires as part of the landing gear. This report describes the advantages and disadvantages of prerotating tires prior to landing, and explains why this practice is not generally adopted. Two potential benefits of this practice are considered: 1) Tire wear and 2) Spin-up loads on the landing gear and aircraft structure.

Rationale:

The idea of tire prerotation at landing to reduce tire wear and spin-up loads has been proposed many times in the past, and continues to be proposed for new airplane projects. Yet, this practice has not been adopted in the aircraft industry. This report explains why this is generally not a feasible idea, and also discusses situations where it may be beneficial. This report is a compilation of all of the information available to SAE A-5, and comprises the general consensus from the aircraft and landing gear industry on this subject.

C0ffin D0dger

3,440 posts

144 months

Friday 5th December 2014
quotequote all
dr_gn said:
Driven mainwheels for taxying are currently being investigated (to save fuel), and these would also allow pre-rotation and regenerative braking for landing.
Was going to mention that. The large aerospace company I work for has such a product. Don't know too much about it other than the electric taxiing to save fuel but I don't see no reason why the wheels could not be spun up on landing with such as system if it is safe to do so.

Blaster72

10,772 posts

196 months

Friday 5th December 2014
quotequote all
Why take something that works well, lasts a long time and doesn't cause safety issues and lumber it with extra complication.

The cost savings would be minimal, extra weight carried just for one phase of flight burdensome on fuel consumption and the extra equipment an added maintenance burden.

Thats without even considering that dangling 20 huge gyroscopes under the aircraft may have some small effect on handling during this critical phase of flight (20 in the case of an A380 main wheels)

I personally think its a non starter as all airlines are looking to strip out any unnecessary weight to save fuel rather than add more weight in. In the grand scheme of things tyre wear due to touchdown speeds isn't a huge cost, more damage is done braking on grooved runways and taking high speed exits from the runways. A lot of tyre wear also occurs when turning tight intersections and during pushback.

Eric Mc

121,779 posts

264 months

Friday 5th December 2014
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Who needs wheels -


Fishtigua

9,786 posts

194 months

Friday 5th December 2014
quotequote all
blueg33 said:
If I was a tyre maker for aircraft, I think I would be happy not to do something that would reduce the wear rate.......
The company next door to us does very nicely out of doing remoulds for aircraft. Imagine how much cheaper a set of remoulds are for a 747?

http://www.monaflex.com/products/