Thanks Haf and Wil.
Wil, with regard to the patch-tests which you carried out, may I know the thickest patch that was installed? Also, what is the length of the duct that you tested and what was the max thrust of the engine?
I have a similar query with regards to effect of surface waviness on surface flow. This time, my problem pertains to flow into the engine intake.
I read in aviation books that engine intake ducts are painted, possibly with a polyurethane paint coating. However, friends have warned about erosion...
