[Jeroen]

Originally Posted by Sutripta

I thought fuel saving was because these were lighter.
.

If they are lighter they were certainly contribute to less fuel during flight as well.

Jeroen

[sukiwa]

Does anyone know usual tyre sizes for these aircrafts & if they also follow same notation pattern i.e. tyre width, aspect ratio et al.

[sgiitk]

One thing which most people are unaware of. Michelin were the first with Radials, specifically Steel Belted ones. Also, Michelin have a decent share in MRF. So Michelin are the pioneers and often the leaders.

[V.Narayan]

Who would have ever thought we'd discuss aircraft tyres on Team BHP. Is there anything we don't discuss.

Some fun facts about aircraft tyres [or tires if you are American].

Most jet airline tyres are designed for speeds of about 400 kmph.

Something most T-BHP readers must be knowing - that the tyres are inflated with nitrogen and not air. In the 1950s as Jets were becoming popular the landing speeds caused enough heat for the oxygen to combust with the tyre material. Hence nitrogen.

Airline tyres are retreaded 6 to 10 times before being discarded. A 747 tyre costs about US$ 2500 [INR 1.8 lakhs]

Something you may not know - Many airlines lease their tires with a fee paid per landing and rotate them out to the tyre lessor when time for retreading comes.

Airline tyres contain a fusible plug that is designed to melt at high temperatures. So if for any reason like an emergency braking the tyres [and brakes] overheat the plug melts and the nitrogen gradually deflates

Everytime your typical mid-sized airliner lands [say a A320 or B737] it leaves behind a smear of rubber on the runway of a few hundred grammes. In case of a B747 a lot more. The ground staf at the airport have to clean it out every so many weeks. Their expressions cannot be put down on T-BHP.

The tyres have a number on the wall which indicates how many times they have been re-treaded.


The largest aircraft tyres, to best of my knowledge [open to correction] were those of the first American strategic bomber the Convair B-36 pictured below. Diameter of ~110 inches I believe from what I read 35 years ago. For aircraft lovers note the pusher propeller. The B-36 had 6 of them plus 4 small turbojets!!! - ten engines must have created their own challenges of asymmetric trust; 6 turning 4 burning.



The aircraft with the lowest tyre life was the English Electric Lightning. It had exceptionally thin wheels - a design issue caused by the need to lie flat in a very thin wing. And its landing speed was around 300 kmph. Both together gave its tyres a life of around 25 landings. But I forgive the Lightning because it was the first production aircraft to demonstrate what today is termed super cruise ie the ability to fly supersonic without afterburners. This photo shows the thin wing and the thinner tyres. Judge the width of the tyre by the technicians palm- this for a 20-tonne machine.

[Sutripta]

^^^
Indian Airlines used to insist on bogie wheels. Leaving aside other considerations, any difference in tyre life/ life cycle cost of tyres?

Regards
Sutripta

PS - Missile with cockpit - Lightning or F104?

[V.Narayan]

Originally Posted by Sutripta

^^^
Indian Airlines used to insist on bogie wheels. Leaving aside other considerations, any difference in tyre life/ life cycle cost of tyres?

Regards
Sutripta

Very hard to say. An educated guess would be probably yes as the same weight [the A320- in this case] is being distributed over 8 main wheels instead of 4 [ignoring the nose wheel] while running or taxiing. However the maximum wear and tear caused by that searing touchdown will be roughly the same on the rear most pair on each strut. I do not have any data on Indian Airlines' A320s.

[Sutripta]

^^^
The tyres are smaller. Any ramifications?

Regards
Sutripta

[V.Narayan]

Originally Posted by Sutripta

^^^
The tyres are smaller. Any ramifications?

Aaahh, you got me LBW on that one. It is beyond my Peter's Principle of Incompetence. Never applied my mind to this one. Given that I have been losing 0.25% of my grey cells each year since age 30 or so I am not likely to catch up now.

In the case of the A320 the pressure on the tarmac of those 8 slightly smaller tyres was lower than of the 4 regular sized ones [this is a fact I know]; hence it could be assumed the rolling wear and tear was lesser on the 8.

[Motard_Blr]

Originally Posted by Sutripta

^^^
The tyres are smaller. Any ramifications?

Regards
Sutripta

Originally Posted by V.Narayan

...

In the case of the A320 the pressure on the tarmac of those 8 slightly smaller tyres was lower than of the 4 regular sized ones [this is a fact I know]; hence it could be assumed the rolling wear and tear was lesser on the 8.

8 narrower wheels would weigh more than 4 larger ones. So there is the additional fuel penalty.
However, the individual wheels would be lighter so there is less inertia and therefore less wear of the tyres upon touchdown.

I remember reading somewhere that runways in India were not built to the same standards as America or Europe and consequently had lower load capacity. That may explain Indian airlines' specification of 8 wheels to reduce ground pressure, as stated by Mr. Narayan. But the infrastructure has improved so the fewer wheels are required now.

[Sutripta]

^^^
The reason for the bogie wheels was the perceived need to operate from regional airports which leave something to be desired when it comes to quality of infrastructure. (Thiugh I wonder why Aeroflot never ordered bogie wheels on their Airbus. Afterall all their military aircraft are designed using a similar philosophy (deployment at forward airbases)).

When talking of bogie wheels, the major weight (and complexity) penalty will come from the undercarriage hardware. One of the reasons why IA found it difficult to both lease and lease out their aircraft.

Regards
Sutripta

[directinjection]

Originally Posted by TusharK

Michelin will be supplying Indigo Airlines with tyres for its Airbus and ATR aircrafts. These planes will be fitted with Michelin Air radial tyres that are claimed to reduce operation costs.

Are these tyres being made in India? If not, how is this news? Indigo is a big airline and will obviously buy tyres from one manufacturer or the other.

Originally Posted by Sutripta

IIRC, Dunlop used to manufacture aircraft tyres in India.

True. It made aircraft tyres in India from 1942 onwards but the company became sick in the 1990s. It got registered with BIFR in 1997 and came out of its purview in 2007. Today it no longer makes aircraft tyres.

http://www.dunlop.co.in/products/products.php

Originally Posted by anandpadhye

- Aircraft tyres are high tech stuff as they have to withstand high load, high acceleration and high braking. Offroad and truck/bus tyres have to withstand only high load and performance car tyres have to withstand only high acceleration and braking. Aricraft tyres have to face all 3!

True, they are built unusually strong. I remember in the old days some roadside shoe repairers used to keep pieces of worn out aircraft tyres and would offer them as shoe soles at a price higher than that of normal soles! People happily paid extra to get long lasting soles!

Originally Posted by anandpadhye

- Only the big 3 have the technology (Michelin, Bridgestone and Goodyear) and they won't share it with anyone

Don't see any Russian name. Where do they get their tyres from?

Originally Posted by anandpadhye

- Indian tyre manufacturers haven't been able break through except MRF who started manufacturing Sukhoi main wheel tyres in India in 2014 after what they claim as 6 years of in house research

- Recently they started manufacturing Sukhoi nose wheel tyre:

Hats off to MRF for this initiative! They developed the technology right here in India without any foreign help which is quite creditable. They also make tyres for Chetak/Alouette helicopters. They are now developing tyres for a number of other IAF planes but I don't know which ones - the info is classified.

[greenhorn]

Originally Posted by Sutripta

^^^
Indian Airlines used to insist on bogie wheels.

Newbie question - what are bogie wheels?

[V.Narayan]

Originally Posted by Sutripta

^^^
The reason for the bogie wheels was the perceived need to operate from regional airports which leave something to be desired when it comes to quality of infrastructure.

True. In c.1985 when Rajiv Gandhi took a decision to go for the A320 Cochin airport was the main reason for this two-axle bogie arrangement.

Though I wonder why Aeroflot never ordered bogie wheels on their Airbus. After all all their military aircraft are designed using a similar philosophy (deployment at forward airbases).

Actually the Soviets had both - strong & long runways as well as airliners with multi-bogie landing gears. Photo below of the landing gear of a Tupolev Tu-154M with its 3-axle bogie and 12 wheels on the main landing gear. The closest comparison amongst western airliners, in size, weight and engines is the Boeing 727 with only 4 wheels on the main landing gear. The Tu-154M for example regularly operated from air strips of packed mud and gravel in remote Siberian areas.

One of the reasons why IA found it difficult to both lease and lease out their aircraft.

Very true. Being a Govt. owned entity they never considered the commercial consequences of insisting on a customized landing gear. Later as those machines reached [are reaching] the end of their passenger carrying lives AI have had difficulty selling them too.

Originally Posted by directinjection

Are these tyres being made in India? If not, how is this news? Indigo is a big airline and will obviously buy tyres from one manufacturer or the other.

Well said. My thoughts exactly.

Don't see any Russian name. Where do they get their tyres from?

They make their own. Do not know the names.

Hats off to MRF for this initiative! They developed the technology right here in India without any foreign help which is quite creditable. They also make tyres for Chetak/Alouette helicopters. They are now developing tyres for a number of other IAF planes but I don't know which ones - the info is classified.

+1 to that.

Originally Posted by greenhorn

Newbie question - what are bogie wheels?

Layman language and technical words have got all wrapped on here. At the risk of boring you to tears let me elaborate as I am unemployed this Sunday morning.

In its airframe maintenance handbook, the Federal Aviation Authority defines a bogie as:
"When more than two wheels are attached to a landing gear strut, the attaching mechanism is known as a bogie." However to confuse us they then go on to describe a Boeing 777's three-axle landing gear as a "triple bogie main landing gear assembly."

In layman's terms [to the extent we are talking of aviation]bogie wheels means two or more axles on a single landing gear strut. In more correct parlance (I believe) each axle [holding 2 wheels] is a bogie as shown below.


So what you see in the photo immediately below is a two-axle bogie and in the photo further down a three-axle bogie.



But in everyday language we just say bogie wheels. Not to be confused with bogeyman. I hope I have confused you enough.

After engines and flying surfaces I would put the good old landing gear as the most vital piece to get you back home.

There are many landing gear arrangements and hybrids.

[Sutripta]

Originally Posted by greenhorn

Newbie question - what are bogie wheels?

As Mr. Narayan has ably explained. Though I don't think anyone considers the nosewheel in the picture to be a bogie arrangement!

Originally Posted by V.Narayan

Actually the Soviets had both - strong & long runways as well as airliners with multi-bogie landing gears. Photo below of the landing gear of a Tupolev Tu-154M with its 3-axle bogie and 12 wheels on the main landing gear.

No, my question was regarding the A320, which forms a major part of Aeroflots fleet now. Do they have A320's with bogie wheels? Their operational requirements were similar.

Regards
Sutripta

[AirbusCapt]

Originally Posted by Sutripta

^^^
Indian Airlines used to insist on bogie wheels. Leaving aside other considerations, any difference in tyre life/ life cycle cost of tyres?

Regards
Sutripta

PS - Missile with cockpit - Lightning or F104?

It was because at that time a lot of IA flights landed on rough fields or under prepared tarmac. Not all airports had pavement classification number (PCN), big enough to support the 320, especially the shorter remote, airfields.
A bogie gear would distribute the weight between more tyres, thereby reducing the weight on each wheel, helping the 320 land on softer pcn Fields as well.