On Tuesday, October 15, 2013 8:53:11 PM UTC-7, wrote:
Based on the replies, now I'm trying to understand why anyone bothers to make flapped
sailplanes if there is no measurable difference in having them...

In my experience owning various flapped and unflapped gliders, with flaps, you have a better view over the nose and can make a slower approach than is typical of equivalent unflapped gliders. If you always land at airports, it won''t make much difference, but I made my share of mistakes while learning cross-country flying, flaps saved my bacon more than once. I also found it advantageous to crank in full thermal flap (and sometimes more) when climbing full of water in the kind of small tight cores we sometimes need to deal with out here on the west coast. And, if you're cruising at 90+ knots with water, negative flaps do make a noticeable difference.

On the other hand, the work load in a flapped glider is noticeably higher than without flaps, for that reason alone I'll probably do without in my next glider...