I was changing the parameters in the DesignFoil demo. And got interesting positive change for the NLF-115 airfoil: increasing the thickness to 20%, it does not effect the laminar bucket low Cl area, but it increases the laminar bucket towards higher Cl area. On other airfoils, this change usually moves the low drag bucket upwards to higher Cl, but on this airfoil, the low drag bucket seems to rather extend than move. I was trying it out with Reynolds numbers 2000000, 3000000 and 5000000.
The higher thickness (if the simulation is at all correct) would be favorable for structural reasons. The Burt Rutan's canards also use thick airfoils in the canard wing, the thickness of the original GU25 is 20%. I don't know the exact thickness of Roncz R1145MS and haven't measured (I have the Cozy MKIV plans which have the Roncz airfoil included, so I could measure it if I had time to look at it).
The larger thickness contributes to the strength achieved (only those little glass fiber spar caps are needed instead of very heavy big wing spar or alternatively a wing spar made of carbon fiber).
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