Jon, It occurred to me that although the KR wing planform may not be perfect, there's certainly nothing badly wrong with it or it's stall characteristics that should keep anybody from forging ahead and getting a KR built and in the air. It might be past the point of diminishing returns to try to improve on it a lot. The "new" KR airfoil (the AS504x series) created by graduate student PhD Ashok Gopalarathnam was thoroughly evaluated for stall characteristics during the redesign. This airfoil was specifically designed for this airplane, and not many homebuilders have this luxury. His charter was that lift coefficient and pitching moment not be degraded, and that stall characteristics didn't suffer. Past experience by a LOT of KR pilots have not revealed a real problem with either the stock airfoil or the new one.
That's not to say that the wing planform can't be improved on, just that it might not be worth the trouble to "fix it". I fully understand if you enjoy a good challenge and view it as an opportunity to get the cobwebs out and review some aero knowledge, make another incremental improvement to the breed, and are not in a hurry to get in the air. But for those builders in their 60's, 70's, and 80's, they have no reason to slow down and wait for developments. As William Wynne says, "every day you find something to do other than building your airplane is another day closer to losing your medical"! Having said that, I've certainly done my share of that stuff. While I'm on my soapbox, anyone building a new KR should go straight to the AS504x series, rather than using the RAF48 provided with the plans. This new airfoil has been thoroughly tested with good results, and the only real difference is the shape of the airfoil, not the wing structure or anything else. There are no "gotchas" hiding in this airfoil. It's the elusive free lunch. See http://www.krnet.org/as504x/ for details and free airfoil template downloads. It's a no-brainer, and I have no personal monetary gain to make from "selling" this airfoil as opposed to the RAF48.... Mark Langford ML at N56ML.com website at http://www.N56ML.com --------------------------------------------------------
