Michael Selig made this airfoil with a slightly different philosophy than the others. While the others have been designed with a bubble ramp – an integrated turbulator, this airfoil has both a bubble ramp and is designed with a turbulator in mind. How does this work? The turbulator shall be about 0,5-0,8mm high at 57,5% of the chord and it is behind the bubble ramp. At slow flight and high angle of attack, the bubble ramp works and the turbulator is hidden in turbulated air. At faster flight and lower angle of attack, the Renoylds numbers rises, the air can now overcome the bubble ramp, and instead it meets the turbulator and trips here instead. At low speed the turbulator is in already turbulated air and does no harm while the bubble ramp does all the turbulating work. When the speed increases the bubble ramp sits down exhausted, and the turbulator is now ready to do its part of the work. This way it was easier to determine where the bubble ramp should be. If you compare S 7075 with SD 7037, it should be just as good at higher speeds and maybe better at lower speeds and in launch (=high CL). Besides this S 7075 should have a fairly low critical Renoylds number and is therefore also suited for HLG’s or just plain narrow wings. Don’t even think of making an open wing covered with iron-on-film with this airfoil if you want any of the above stated advantages.