Originally posted by Voss:
When I land an airplane it isn't lifting anymore. I never brake while taking off.
Voss 13th T.A.S.
If air is moving over the wing it is creating lift unless it's stalled or you have the nose pointed down (which is kind of hard to do with the gear on the ground without crashing).
Just because there is insufficent lift to overcome the action gravity of the mass of the aircraft and create a positive vertical velocity doesn't mean it's gone completely... =)
What this does is reduce the force acting down on the undercarriage. The amount of grip available from a pneumatic tire in roughtly proportional to the force acting to push it against a surface (within a 'normal'
range). So as a result it is easier to lock the wheels while the wing is still creating signicant lift and less retardation is possible as a result.
This is one of the reasons why you'll see large aircraft, like airliners, deploy large spoilers along most of the wing on touchdown. To 'dump' the lift generated by the wing and allow more control during braking, as well as acting as an extra airbrake.
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Graywolfe <tim@flibble.org>
