The high tech swimwear that folks are using these days is far from smooth. One I saw had little triangular projections all over it – felt as rough as a pinecone.
Dirty aircraft are not the same as surfaces with CFD designed “rough” surfaces. Dirty planes will always be slower, it just may not be material in a particular airframe.
Only laminar airfoils can be affected by normal dirt or insects
Only laminar airfoils can be affected by normal dirt or insects
Do you expect us to just accept this statement? Any proof?
No proof, but one of my best friends is a Professor of Aerodynamics. Among other things he was one of the scientists who developed the “shark skin” foil that was tested on an A320 wing. He has told me this several times, and I simply chose to believe him.
There is equally no obvious proof that
Dirty planes will always be slower
It must depend on the kind of “dirt”.
Oh, come on. It’s simply logical to believe a professor of aerodynamics rather than a pilot. I have no personal interest in proving this, my plane is fast enough even with bugs.
In the same way that tips to Speed up your PC or How to speed up a Slow Windows never work, neither does cleaning a plane make it measurably faster.
However upgrading to a newer, more powerful PC does work, and so will upgrading to a more powerful aeroplane.
JasonC wrote:
Only laminar airfoils can be affected by normal dirt or insects
Do you expect us to just accept this statement? Any proof?
I can show you proof.
My hot-rod; true laminar flow wing profiled Lancair Columbia would demonstrate this.
The variable is just how dirty do we make the benchmark run ? 
