It seems the vast majority - if not all - successful laminar flow airfoil and fuselage surfaces are of rigid construction. But is it possible to achieve significant laminar flow with flexible materials? I'm thinking of stretched laminated sailcloth, doped fabric, thin composite sheets without supporting foam core underneath, etc. Let's assume the roughness and contour accuracy of the flexible skin is adequate for laminar flow .. how much vibration and rippling induced by the passing airflow will cause a turbulent transition? Higher tension should reduce displacement amplitude, but also increase frequency .. where's the critical transition point? I have been searching for data on this topic, but to no avail .. this now closed old HBA thread came about the closest: https://www.homebuiltairplanes.com/...ng-trikes-hangliders-homebuilt.html#post89664 In that thread, Mr. Skeates talked of laminar wind surfer and sailboat sails.. is that true, or marketing hype?