On Aug 15, 10:55*pm, BobW wrote:

The 'purpose of flaps' - Is this where philosophy enters the aerodynamic world
definable by flaps' effect on a glider's polar?
....
Where I'm headed with this is, one can reasonably conclude the 'purpose of
flaps' is whatever JGP decides, within their aerodynamic capabilities. ....

Joe Pilot didn't put the flaps there, Bob the designer did. He had a
"purpose", which was probably to lower the stall speed and thus the
approach speed and all the other good things that come from that.