On Aug 17, 8:47*am, wrote:
On Aug 16, 10:26*pm, toad wrote:

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.

I kind of disagree.
From my experience, the benefit of "real" landing flaps is very high
drag such that speed increases only slightly when approach is
steepened and drops off quickly during round out and landing.
They also have the very positive effect of reducing the angle of
attack at the tip, giving much better roll response. Look at a '20 in
full "crow" mode and the tips almost look like they are bending down
relative to inboard part of the wing.
My View FWIW.
*UH
(Don't try what I've done at home)

I actually kind of agree with you. The purpose of the initial
deflection is lift increase/stall speed decrease. By increasing the
flap deflection available to the "real landing flap" range, the
designer got the high drag/glide-slope control feature without adding
a second system. Obviously some designers have chosen having 2
systems instead.

If all the designer wanted was the drag, he would have used a drag
device. IMHO.

Todd