On Sunday, February 28, 2016 at 7:54:18 AM UTC-7, Paul Villinski wrote:
Could any of you shed some light on use of flaps while dolphin flying? I.e., in my DG-400, cruising at 70 - 75 knots with -4 degrees flaps, if I fly under a cloud and want to maximize the climb without thermalling, what is the best approach in terms of shifting gears with the flaps? I assume this is dependent on many different factors, but is there a general consensus about whether or not to down-shift to 0 degrees or positive (thermalling settings) flaps when flying straight?

My answer to this flap question will not agree with the intuition of some flyers -- here is the truth on the matter according to GW:

Flap optimization is not about airspeed; it is about angle of attack. If you are going to slow down, the time to lower the flaps is when you make that decision and start pulling the stick back increasing AOA. Conversely, when you speed up, best to raise the flaps as you begin to push.

However, there is an important caveat to this. Most gliders have a structural speed limit for positive flaps. Despite what may be performance optimal, one must never overspeed the flaps.

Should someone express a counter opinion (likely), please do not misinterpret a lack of further reply on my part.