Paul Visk wrote: >> With Sid's landing gear being 17" aft of datum (leading edge) and the >> problem with the tail falling down. What would be a good position for the >> landing gear if you haven't drilled your legs yet? I know you wouldn't >> wanna make the nose to heavy because you would have problems rotating. <<
The Diehl gear installation instructions read "The taildragger conversion mounts the main gear on the forward side of the main spar with castings bolted on just outside the fuselage sides. The gear legs angle forward. The tri-gear mounts the gear legs on the aft side of the main spar with legs angled back." So with the Diehl gear, it's simply assembled and it works out close enough to have served people well over the years. If you aren't using Diehl (nvAero) gear legs, you'll have to get the angle from somebody who has them and cut yours to match. Along the same line, the plans call for a CG centered exactly on the 25% chord line, 10% each way (15%-35%). That's an impressively large CG range for a plane that is short-coupled and has no flaps, and is a departure from the more average range of about 15% from forward to aft CG limit. For many years, conventional wisdom in the KR community is to NOT use the aft 2" of the CG range, as the aircraft is likely to be unstable there.(likely gained from actual flight experience, rather than choosing nice round numbers). This is mentioned in various newsletters as well. In the 90's Dr. Richard Mole did a very methodical stability analysis on the KR2S (which shares the same CG range, and should have an even larger range than the plain KR2 due to the longer fuselage and larger tail volume). Below is what I wrote about it in my "KR Opinions" piece at http://www.n56ml.com/kopinion.html : "An analysis of the KR2S by PhD aeronautical engineer Dr. Richard Mole has revealed that using the aft two inches of the published CG range results in a fundamentally "unstable" airplane! Don't go there! I've done it (accidently) and I can tell you that I'm lucky to survive to tell the story (which is also on my webpage somewhere). And if you'll ditch the header tank and go with wing tanks (and maybe a SMALL header tank) the CG will not migrate nearly as far during a flight, allowing you to set up the plane towards the front end of the CG range, where you'll enjoy a nicely controllable airplane." So smart builders will use the range of 8"-14" aft of the leading edge of the stub wing, and gravitate toward the front end of it, rather than the aft end, or at least start out flying it there... Mark Langford ML at N56ML.com website at http://www.N56ML.com --------------------------------------------------------
