Expert: Paul Soderman - 2/3/2011

Question
Will the wings of an aircraft which employ the Coandă effect like the C 17 III)wear out faster??

Answer
Muktesh
Every aircraft wing has some Coanda effect which allows the air to follow the wing surface as far as possible.  The C-17 has a blown flap, which is what I think you are referring to.  That is - the jet exhaust impacts the flap and blows through slots as well as getting deflected downward for extra lift compared to non-blown flaps.  Yes, I imagine the hot, high velocity jet causes extra stress on the flap surfaces and structure and can result in fatigue damage at a faster rate than non-blown flaps.  I don't have any data on that, but if you do a google search on C-17 flap fatigue you can find technical papers that deal with that subject.  I doubt that the rest of the wing has much of a problem with the exhaust system except for some vibration from scrubbing and jet noise.
Paul