[quote=Edchris177]Thanks, never thought about permanent ink bleeding through, I won't do it.
You are correct, I mixed my luffs with my leech, that green is the only one.
I may not be an experienced sailor, but I know a bit about airfoils, did a few courses in aeronautical engineering early in my career. I don't know why all blow boats DON"T come with trailing edge tell tales. We had access to a supersonic wind tunnel,(very small working area) as well as a low speed tunnel. While experimenting with various angles of attack, & their effect on the lift/drag curve the yarn tufts were enlightening to say the least. We had them glued every 3 sq inches to a wing, & it was surprising how/when some of them would burble, showing breakdown of the laminar flow of the boundary layer. Wings also have washout, similar to twist in a sail, though not as pronounced.
Many people assume that you want smooth flow over the ENTIRE wing, but that may not generate the greatest lift. In fact some turbulence can help to re energize the boundary layer, & keep it attached longer. Other wings utilize vortex generators for the same purpose. A wing with leading edge slats, drooping ailerons, & slotted flaps might have many areas of boundary separation, but they pull like a mule. Once you get away from the ground, thing cam be cleaned up for better efficiency. The clean wing performs best at only a certain speed, I'm sure sails are much the same, & therein lies the art of trimming. It would be wonderful to put a sail in a wind tunnel & derive true scientific empirical data about what tweaks result in the most pull. I think many would be surprised that some tell tales will be luffing at this point[/quote]
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