- Jul 29, 2005
- Orange County, California
The qualifier was "modern" laminar-flow airfoils. Newer than the NACA 64-66 series. What's "modern"? Roncz made the comment in his 1991 series of articles in Sport Aviation, entitled "Designing Your Homebuilt." So "modern" means: Harry Riblett's laminar-flow sections, the NASA NLF series, and any sailplane airfoil designed after about 1985 or so. Roncz's own airfoils post-1985 or so also qualify, but those tend to be proprietary, and coordinates aren't often readily available.As someone else said -- it is too broad. And usually not correct. Especially not usually correct if looking at stall speed, but it does depend on the airfoil design. You can have airfoils that have laminar flow at cruise, and at the same time handle Clmax nearly same dirty vs clean, and thus get the same stall speed. So back to ... the statement is too broad. I wonder in what context Roncz said this? I'm guessing that some qualifiers were included. He has designed airfoils that are vastly different (not desirable) when 'turbulent' (dirty).
Older (NACA in particular) laminar-flow sections tend to have lower Clmax when "dirty." One of the great improvements in airfoils in the last 40 years is that the newer ones generally do not.