a/c tyres

[dazdaz1]

After reading on R&N "A321 Aeroflot from Moscow overrun in Kaliningrad" Why are a/c flying in these winter conditions not fitted with winter tyres with a deeper and cross sectioned (rally tread) as cars in cold/snowy countries?

Before anyone suggests as to the cost, a/c winter tyres could also be used in warmer climates without the need for two sets summer/winter.

Aside, I've seen some a/c tyres that if scaled down and fitted to a car would result in a ticket from the traffic Taliban.

[turbroprop]

Aircraft do not drive the wheels like a car is one reason. Also an aircraft can operate from a hot airport to a very cold airport.

Aircraft tyre design has many factors to take into account, that do not apply to vehicles. For example shock loading on landing. Heat transfer as there is quite a bit of heat generated to stop most airliners.

Water dispersal to prevent aquaplanning is a major factor in modern tyre design / thread pattern. Plus keeping the tread layout simple makes it easier to assess if a tyre is fit for service etc.

[dazdaz1]

Turboprob........"Aircraft do not drive the wheels like a car is one reason" I think most people understand that, but they need to grip the runway when landing, do they not?

[WindSheer]

Who said the aerofoil incident has anything to do with tyres?

If the conditions are so bad that the only defence is a slightly thicker set of tyres then we have problems. Surely taxiing technique is a more appropriate mitigation??

[Council Van]

I am sure the engineers at Boeing and Airbus and Dunlop etc give a great deal of thought to the design of aircraft tyres. At least I hope so.

I trust that they have given the design and performance a great deal of thought and know exactly how they are going to perform in specific conditions.

As an example when we performed out take of calculation yesterday the most limiting factor was the brakes. The performance of the breaks is directly connected with the ability of the tyres to grip the runway if we were to stop at V1.

[NudgingSteel]

A deeper section with cross-cut tread pattern would add quite a bit of weight. Also, the individual tread 'blocks', when subject to the huge forces during take-off and landing, would flex and eventually disintegrate, risking catastrophic tyre failure / loss of directional or braking control / runway debris and so on.

Under normal (dry) conditions, the cut tread pattern in any tyre reduces the contact area with the surface. Car tyres are a massive compromise to cover a huge range of road conditions, as well as vehicle weight (load), ambient temperature and even driving style. When you can knock out loads of those variables and need a specific, very high performance, you can design the tyre accordingly, e.g. Formula 1 dry or wet tyres.

Aircraft tyre manufacturers are doing likewise with a very narrow and demanding specification - any compromise to weight, braking performance, durability etc would be unacceptable.

[pax britanica]

Better yet use the steel studded winter tyres the Scandis use on their cars (by law from Mid Nov to Mid march) ,

trouble with those and the big treads on the 'softer' model winter tyres as has been pointed out what do you do if the plane is flying into Stockholm but out again to say Tenerife .

And the incredible force the tyre has to withstand as it spins up on landing would surely rip the trad off every time -which i gues is why aircraft tyres are always pretty much slicks with a few circumferential grooves to help counter hydroplaning. Trouble is that why they very occasionally slip off taxiways but thats the lesser fo two evils compared to them having a life of about four landings. (years ago did a short summer job at Dunlop at LHR , just a bit of clerical between school and Uni but it was very interesting listening to what the fitters and tech guys said and indeed learning that changing plane tyres is a risky business and needs a great deal of care just when the pressue is on to get the job done quickly. No place for amateurs there

[dazdaz1]

Pax......"trouble with those and the big treads on the 'softer' model winter tyres as has been pointed out what do you do if the plane is flying into Stockholm but out again to say Tenerife ."

In my original post my thoughts were as to local regional airlines flying purely in sectors where icing/runway conditions are a known concern in the winter months. Come spring/summer maybe a change to normal tread patterns.

If one needed a good tyre grip on an icy surface, who in their right mind would be happy with a slick tread over a tyre designed for 'grip'? That aside, I'm presuming regional airports in Russian states are not 'up to speed' de-icing runways as maybe Heathrow.

[Hotel Tango]

dazdaz1, the A321 in this incident was most probably flying on the entire AFL European/Asian/Middle East (A321) network. That's a lot of varying climates, even within Russia.

[kenparry]

That aside, I'm presuming regional airports in Russian states are not 'up to speed' de-icing runways as maybe Heathrow.

Very cold countries don't normally de-ice runways. For example, in Norway it is common practice to apply sand to the snow/ice. It works well. The problem in the UK is that it does not get very cold. If you are say -5 degC, the weight of the wheels on the ice will melt the top layer, so you will be in literally a very slippery situation.

[pax britanica]

But would it really be worth making and more importantly certificating special tyres for a/c that only operate in certain conditions.

Alsoas Ken parry says when its very cold -ice is seldom a problem as all the moisture goes from the air , and places like UK Holland Denmark where temp wobbles about either side of zero C where it gets slippiest.

I suspect many Russian regional airports are in the 'too cold'category and as for the others wellc ontries who know it is going to snow can afford to invest in the gear whereas LHR can really struggle ebcause it needs a snow clearing fleet twice or three times what its got but it only needs it every 7-8 years.

Anyway you make an interesting point about specialised landing gear because I am sure I have seen a pic somehwere of an aircraft with tracked landing gear for use on snow and a Herc (C130) on Skis must surely be a handful if not ultra precise

[Mad (Flt) Scientist]

I seem to recall that deHavilland Canada looked at equipping one of their types (a DHC-7 probably) with some kind of air cushion/hovercraft type arrangement to facilitate operations of various "dodgy" surfaces. I think I read that a big problem was the lack of any kind of resistance to lateral forces, compared to tyres etc.

[Hotel Tango]

The subject is drifting. Yes, there are aircraft equipped with special wheels/skis etc. These are for local operations in particular extreme environments. However, the OP was suggesting there should be special Winter tyres for airliners such as the Aeroflot A321. Now if this a/c was operating exclusively in a severe Winter environment, there might be merit to that idea. But, the point is that it doesn't and, as such, it would be futile to equip it with anything other than tyres which can sustain operations in all climates.

[ShyTorque]

Better yet use the steel studded winter tyres the Scandis use on their cars (by law from Mid Nov to Mid march) ,Bearing in mind the relatively very high speeds at which jet aircraft touch down and lift off, not really a good idea to risk a metal stud coming out and going through a turbine engine.

[pax britanica]

Iwas being ironic with my suggestion of metal studded winter tyres.

Quite what they would do to the TDZ ona runway based on what they do to Swedish roads i cannot imagine. (If you havent been to that part of the world the winter tyres dig a groove where the wheel tracks run meaning a lot of resurfacing and a speed limit

[turbroprop]

Wet sand is used on runways in Northern Sweden. Gives a very effective braking action on ice / snow covered runways. Thus no need for special tyres.

Non standard or special tyres can lead to safety issues, due to mixing types of wheels. It does happen, for example B737 Classic there are two sizes of tyre 40 or 44 inch. Murphy says......