The number of takeoffs should equal the number of landings

December 5, 2006 at 5:48 am Leave a comment

So sayeth the sage of flying. Today’s airline passengers are insulated by the airbridge loading from the realisation that their plane lands and take off on 10 to 18 rubber tyred wheels. That is up to 360 tonne of aircraft spread over 18 wheels, which is a lot of mass on each wheel.Yet, the tread pattern used is very basic. Just a few grooves running circumferentially around the tyre. This is because the job that an aircraft tyre has to do is very simple. Just run in a straight line on takeoff and particularly on landing, on tarmac, in wet or dry. With 20 tonne load on each tyre, water gets squeezed out from under the tyre rather quickly. If it doesn’t, it boils, becomes superheated steam, and if the wheel locks under braking, cooks a hot and very sticky flat spot on the tyre, requiring a wheel change. If this happens to all main wheels, the plane continues on its merry way down the runway until the speed drops, or it runs out of runway- very embarrassing.

An airplane tyre can’t have grooves cut into the pattern running sideways to the direction of rotation to improve the drainage. When landing, the tyre accelerates from zero to 150 knots or so almost instantaneously. If blocks were present, they would get torn off by this treatment.

So next time, look out your window as the plane turns at the end of the runway to take off. You will see that for around 400 metres or so, the “tread pattern” has been cut into the tarmac surface. A series of closely spaced narrow slots are cut across the runway to permit sideways displacement of water. Clever, eh?

Entry filed under: Tyre Technology. Tags: , , .

Benefits of larger diameter rims Why Pay More? They’re all fat and black BUT Tyres can be different.

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