Airliner tyre wear

[BrendAn]

Had enough of the sad events of late so thought I would change the subject.

Silly question but when big aircraft touch down the tyres squeal and smoke, I assume this is because the wheels are rotating slower than the aircraft speed. Why don't they have something like paddles on the rims to let the airflow spin up the wheels to a higher speed.

[kgwilson]

Adds weight and bulk plus the wheels not rotating assist in slowing the aircraft.

[BrendAn]

1 minute ago, kgwilson said:

Adds weight and bulk plus the wheels not rotating assist in slowing the aircraft.

Makes sense.  How long does a tyre last on a big Boeing or airbus.

[pmccarthy]

The energy absorbed helps the quick transition from flying to not flying.

[spacesailor]

How about a ' light ' aircraft appraisal. 

Seems a cheaper option, than a super sized jumbo tyre .

On a slower aircraft you may get away with a paper blade attached to your tyre .

Just have to put the park break on ( to stop bearing wear ) , and off when landing .

Another thing to remember! .

spacesailor

[skippydiesel]

I doubt that the inertia of a stationary aircraft wheel, touching down & accelerating to landing speed, contributes very much to landing role. A little yes but as a percentage to the total not much.😈

[onetrack]

But it's not just one wheel, Skippy, it's between 6 and 20 wheels. Ever tried to give a fast spin to a wheel on a hub, say a truck wheel (comparative size) and noted how much effort it took?

The amount of energy required to spin up a stationary set of wheels (and hubs - in total, a sizeable amount of weight) would be very substantial. You can notice the retarding effect in your passenger seat when you hit the runway.

[Deano747]

13 hours ago, BrendAn said:

 How long does a tyre last on a big Boeing or airbus.

On condition - the tread can retreaded a number (forget how many) of times.

Deep cuts through the tread and sidewall can be an issue and aquaplaning can get rid of a tread in 1 landing. 

 

[skippydiesel]

 

It's a long time since I flew by public transport - my recollection of touchdowns were little effect, until spoiler/reverse thrust & wheel breaking, which all occurred in quick succession immediately after landing.

 

The number of wheels, will be proportional to the Max TO/landing weight.  The inertia (retarding effect of a stationary wheel being accelerated) will be similar to any aircraft ie little (not none)

 

"You can notice the retarding effect in your passenger seat when you hit the runway." I imagine that it must be quite  terrifying 😁

 

FYI: a wheel is made up of a rim/hub & tyre combined.😈

 

[skippydiesel]

"..........aquaplaning can get rid of a tread in 1 landing"

 

Please expand?😈

[Deano747]

Happens to all tyres - cars as well.

If the wheel locks (ABS inoperative) (not a no-go item) on the top of a film of water, then the friction heats the water to boiling and melts the rubber.

Tyre not spinning so a localised melt.

Why pilots never aim for a 'greaser' on a wet runway. You want to get the tyres through the film of water onto the bitumen. Heavier the rain the more positive the touchdown.

Edited November 19 by Deano747

[spacesailor]

Lots of Negative talk  but one lightweight wheel,  will ( hopefully ) show a little difference in the wearing of a matched pair. 

Not much wear on the ' grass ' strip's,  with more wear on those ,

using hard strip landing .

So has anyone , looked at tyre wear . 

spacesailor

[facthunter]

Make "positive "touchdown on a measurable depth of water. Some runways are grooved in the touchdown zones When you really aquaplane you only have rudder to keep you in the centre of the runway. Nev

[facthunter]

On shorter runways with harder braking tyre wear will be faster. . Nev

[Deano747]

1 hour ago, facthunter said:

 When you really aquaplane you only have rudder to keep you in the centre of the runway. Nev

Had to use differential reverse thrust one stormy night in Bali to stop it going sideways.

 

Edited November 19 by Deano747

[facthunter]

Blankets the rudder on a B 727.  Nev

[facthunter]

Tyre wear has never been a problem if you are easy on the brakes and don't Use high speed exits at high speeds. Anti skid is mandatory.  Retread tyres are not that good. Usually the Max rated tyre speed is reduced with more retreading. Max speeds are rated  around 170 Knots. Shed  treads can enter rear mounted engines. Before you land you should have a good idea which taxiway you will turn off at. Not put everyone on the back of the seats in front of them to NOT make a taxiway and then have to add power to taxi to the NEXT one, with brakes so hot you risk a brake fire.  Nev

[BrendAn]

10 hours ago, Deano747 said:

Happens to all tyres - cars as well.

If the wheel locks (ABS inoperative) (not a no-go item) on the top of a film of water, then the friction heats the water to boiling and melts the rubber.

Tyre not spinning so a localised melt.

Why pilots never aim for a 'greaser' on a wet runway. You want to get the tyres through the film of water onto the bitumen. Heavier the rain the more positive the touchdown.

unreal, its natural to think water cools the tyres not the opposite

[BrendAn]

5 hours ago, facthunter said:

Tyre wear has never been a problem if you are easy on the brakes and don't Use high speed exits at high speeds. Anti skid is mandatory.  Retread tyres are not that good. Usually the Max rated tyre speed is reduced with more retreading. Max speeds are rated  around 170 Knots. Shed  treads can enter rear mounted engines. Before you land you should have a good idea which taxiway you will turn off at. Not put everyone on the back of the seats in front of them to NOT make a taxiway and then have to add power to taxi to the NEXT one, with brakes so hot you risk a brake fire.  Nev

retreads are bad news on trucks let alone a large jet. seems a bad way to save money.

[Deano747]

Airplane tyres don't do a lot of kilometres. 

Big airplane does maybe 2 from gate to runway, another 2-3 getting airborne and the same after landing.

1 flight per day gives maybe 3,000kms per year.

Private GA airplanes would be lucky to do half that.

Airplane retreads have been around a long time with a very low failure record.

 

Edited November 19 by Deano747

[Methusala]

Landed at Hamilton last week. 737 came in so hot we hit at about 2g then bounced. Full reverse thrust, lift dumped and brakes to avoid tumbling off the end into water. As Nev says, we had a close view of the tray tables. Landing pilot probably needs an eye check.

[BrendAn]

1 hour ago, Deano747 said:

Airplane tyres don't do a lot of kilometres. 

Big airplane does maybe 2 from gate to runway, another 2-3 getting airborne and the same after landing.

1 flight per day gives maybe 3,000kms per year.

Private GA airplanes would be lucky to do half that.

Airplane retreads have been around a long time with a very low failure record.

 

ok. i just thought the heat would effect them.  its funny i was just looking at facebook and an airbus video of testing tyres came on. i am sure facebook know what we are thinking.

[onetrack]

If you want to cut a piece of rubber with a knife more easily, you wet it down thoroughly.

[facthunter]

Tyres heat up with prolonged taxiing. Abort a take off at V1 and you will probably blow the thermal plugs or even have a brake fire. Some brakes are fitted with cooling fans  The Usual brake resembles a multiplate clutch. It all absorbs a large  amount of kinetic energy. Take a very hot brake into the air and you risk an ij flight fire in the wheel well.. Brake overheat is shown on the Panel usually associated with a "Ding". Nev

[Deano747]

Taxiing out to the reef runway in Honolulu would have the temps in the amber zone before takeoff on the old 747's with steel brakes.

An abort would deflate all the tyres.

Newer airplanes (744) with carbon brakes wasn't a problem. The hotter they got got the better they worked and less they wore.

Old airplanes use max reverse thrust and go easy on the brakes.

New airplanes use min reverse thrust and maybe less landing flap if that is an option, and go harder on the brakes.

Even after a max effort stop they were coolish by the time you had got to the gate.