Originally Posted by
Goldenrivett
Hi vilas,
I hope this link explains tyre friction
https://suspensionsecrets.co.uk/tyre...a-deeper-look/ and how once
F= uN is maximum, you can't increase it further by applying more brake pressure.
The "Friction Circle" helps explain why steering is improved with brakes released.
Thanks Goldenrivett
I think this is an example of this concept which is in The Boeing training manuals.
Drifting off the side of the runway
A tyre can apply a force to runway laterally and longitudinally, and normally does both, but when you reach max autobrake or full anti skid, you are using all the available friction fore and aft to try and stop. None left for lateral forces. And in a cross wind you can drift downwind and off the side.
To regain traction you have to do the almost unthinkable and release the brakes, cancel reverse which by now is vectoring you downwind too, and point the ship towards the wind using rudder and yes, maybe diff braking.
Once back on C/L or even a bit upwind of it, back to full reverse and max braking. This is from memory but it is in the manual which I am trying to find.
A 747 did this at LHR a few years back and I think still blocked 27R for a while but no damage. Anyone got a pic?
Cheers
R Guy