A320 performance Question for Air India

[Gilles Hudicourt]

I hope someone at Air India is reading this.

Air India Operates A320s with both 2 wheel MLG bogies and 4 wheel MLG bogies.

I would like to know what Accelerate-Stop advantage, if any, the 4 wheeled version has over the 2 wheeled version.

I imagine that the 4 wheeled version was not ordered just for Pavement Classification Reasons but for performance reasons as well, since the better braking should theoretically allow the 4 wheeled version to take off from shorter runways, especially in hot conditions.

Does anyone have actual figures ?

[underfire]

Dont have the technical data, but it was still only 2 brakes out of the 4. As the weight is virtually the same, weight on wheels would seem to diminish braking with skidding.

[Gilles Hudicourt]

Thank you for the reply but I think you are incorrect. There seems to be brakes on all four wheels.
There is an incident report on line which contains a picture of one of those bogies which clearly shows the presence of brakes on all 4 wheels.

https://www.mot.gov.sg/uploadedFiles...Nov%202005.pdf

The picture is on page 4.

[underfire]

Gilles, you are correct, I was mistaken with the brakebar only shown on one side...

More braking, but still much less weight on each wheel...must be a challenge with anti-skid.

Good luck!

[Goldenrivett]

Hi Gilles Hudicourt,

I would like to know what Accelerate-Stop advantage, if any, the 4 wheeled version has over the 2 wheeled version.

There is no advantage. This link has no reference to the number of tyres / wheels.
Engineering Inspiration - Brake System Design Calculations

The maximum braking effort on any wheel depends on the weight exerted on the tyre and the coefficient of friction between the tyre and runway.

If you have more wheels - there is less load per wheel - hence less braking effort per wheel - but the total braking effort is unchanged.

[Amadis of Gaul]

I had understood that aircraft with 4-wheel bogies were ordered by Indian Airlines because they had planned for some operations from less-than-perfect runways rather than for any sort of a performance advantage.

[SADDLER]

Interesting posts
Thanks all.

[Piltdown Man]

?..because they had planned for some operations from less-than-perfect runways...

Were they planning to operate into LBA then?

[iflytb20]

They were ordered as a direct replacement for the B 737-200s. As the govt wanted IC (the pre merger entity) to keep operating to the airfields serviced by the 732s, they went for the bogie to have a lower ACN. Once the airfields were improved and their PCNs increased, the bogies became dead weights. As per my friends who flew them, there was not much of a performance increase except the higher payload capacity.

Disclaimer: As this is mainly second hand information, please feel free to correct me.

Regards

[bucks_raj]

I have seen AI operate the 4 MLG wheels to VELP . Thats on place where I have laways seen them

[underfire]

A350 options...lots o brakes!



Just curious why Boeing didnt simply make an extendable support for the 737 to get it off the ground more for larger engines

Wouldnt that simplify the cert process?

[Gilles Hudicourt]

What brought this question to my mind is the soon to be A321LR with a 97 tonne MTOW.
How much runway will it need at MTOW in hot conditions.
For example, our airline used to fly from Newcastle to Toronto with both the B757 (228 pax) and the A310 (240 pax), a westbound 3000 NM segment.
Newcastle just has a 7640 foot runway with obstacles in the climb-out path. Both aircraft could do it but were taxed when the winds were blowing the wrong way or if it was raining. It's never really hot there, but these were summer flights.

The A321LR claims ranges from 3000 to 4000 NM but can it do it from such a short runway like the B757 and A310 could ?

This is why I was wondering if a 4 wheel bogie would help the accelerate-stop performance.