Originally Posted by Quick61
If I may leave you all with something I had said long ago, and Dick, you have reminded of this.... It is not those that follow the text books that are remembered, it is those that the text books are written about. - Mark
While this might be true it would be sensible to thoroughly understand the content of those textbooks before coming to the conclusion they are incorrect. It also does not mean that it's a good idea to throw all the textbooks out of the window and 'just make stuff up
' without any supporting evidence. That is not how science works, it is much more like religious faith. The title of this thread does after all have the word 'science' in it so IMHO it's best we stick to a scientific, rather than a faith based, approach to the issue.
There appears among some to be a huge 'confirmation bias
' issue going on. Accepted scientific theory supported by expert peer review, years of testing, and countless real world applications are summarily dismissed as 'not applicable'. These same people are only too willing to unquestioningly accept half baked speculation which is unsupported by any factual data whatsoever. A case in point:- The 'vortex trapped behind the step'....I see this quoted often as if it were a 'cast in stone' factual statement, yet there is absolutely zero evidence that a KF step is capable of trapping a vortex. Quite the opposite is true in fact; the testing that has been done on 'trapped vortex' airfoils indicates that to maintain a stable vortex requires active vortex control ('suction' and 'blowing' of the vortex cavity): http://ltces.dem.ist.utl.pt/lxlaser/...ers/11.3_4.pdf
Passive TVC (Trapped Vortex Cavity) flow control is not able to control the flow separation. The vortex is not confined in the cavity and vortex shedding is present decreasing the aerodynamic characteristics of the original airfoil.
Please understand I'm not trying to 'do down' the KF airfoil.. For foamy models the KF has much going for it.. But this thread is supposed to be about science