Hello! For my project (15 m racing class glider with electric propulsion) I will use the AH93K131 airfoil. Like all recent flapped glider airfoils, it was specifically designed so that : - The bottom surface is continuous with flap slightly up for optimal transition performance. Airfoil coordinates are given with the flap in this position (considered 0°). - The top surface is continuous with flap slightly down for optimal thermal performance. Flap position is 12° down compared to the above reference position. My performance estimations are the following for my project : - With flap at 0°, best L/D is 39 at 126 km/h - With flap at +12°, lowest sink rate is 0,54 m/s at 80 km/h. But overall best L/D is obtained with +6° flaps and is 45 at 97 km/h (consistent with other gliders of the same class). I must now design (and build on the almost completed fuselage) the shape of the wing root fairing but I can’t decide what is the best “neutral” flap position that will be “frozen” in this wing root! Is it 0°? Is it +6°, or something between? On older flapped airfoils, 0° flap setting gave already the best L/D and you used the airfoil as it was, but it not the case with the new ones.... What are the other big sailplane manufacturers doing? (pictures on internet are never zoomed properly at the interesting spots!). Opinions of soaring specialists and others are welcomed!