duniho wrote:

I've always seen spoilers and flaps being deployed fully upon landing.
While the reason for spoilers is straightforward, I haven't yet figured
why flaps are deployed too. [...]

Flaps only improve lift to a point. Even on the little planes, past that
point they simply add drag. [...]

That only explains why one might prefer 40degrees over 30degrees of
flaps. There is still lift generated at both those settings.

This is why, on some small airplanes, the official short-field landing
procedure involves raising flaps on rollout. That way, lift is
reduced and maximum weight is applied to the main wheels where the
brakes are. People flying retractable-gear airplanes are sometimes
taught not to bother, in order to avoid playing with the gear selector
instead by mistake.


- FChE