On Jul 10, 11:49 am, "Ken Kochanski (KK)"
wrote:
I understand, a wing will perform optimally when the flap is set at
the proper angle for the airspeed ... any mismatch of flap to airspeed
will result in some performance losses vs. the correct setting. Of
course, we have a couple of compromises here ... the flaps are set at
fixed increments and the airspeed varies continuously ... so by
design, you will rarely have the flap and airspeed matched up
perfectly.

I remember seeing a story where one of the German schools modified an
LS-3 with springs, etc. so it automatically put in the correct amount
of flap for the airspeed ... did this result in a measurable
improvement?

Along the same lines, I have heard some pilots say they put the flap
in a position where they feel no pressure ... does this work?

I myself tend to go negative quicker or maintain a negative setting
longer ... then pulling in positive flap ... thinking being too
positive is more costly then too negative ... is this valid?

KK

Hi Ken - It depends very much on the glider. The Antares manual
specifically says "do not let the flap handle move to the position
of no force, as you will have the wrong flap setting" (I'm on the
road so that's an approximate quote). In other gliders I've flown
this is sort-of the correct flap setting (but far from exactly right).

Factors include the mechanics of the flap system, any trim
spring interconnect to flap, airfoil, etc...

To your second question, correct flap setting depends on CL
not airspeed. Again, the Antares manual specifically warns
against pulling the flap down during a pull-up. Because of the
flat polar and consequent high cruise speed, you would end
up with the flaps down way too soon and incur much extra
drag during the pull-up - more so than older designs.

Hope that helps,
Best Regards, Dave "YO"