I think Mark stated it very clearly. When the CG goes aft, the KR becomes less stable. Jim Faughn started really pressing this issue many years ago, and I believe that now all KR builders have adopted the standard envelop for the KR of 4" forward and 2" aft of CG.
I am doing a lot with that right now as I am testing my KR for passenger and gross weight. Also, when I put on my Corvair engine, I took out the header tank and added wing tanks. I did this to offset the added weight on the front, thinking it might be too much forward. My KR with header tank and 2276 VW on 2" spools, had the CG always in front, with any amount of fuel and me. It was very stable. In the new configuration, It is at 1.2" forward of center with 20 gallons and at 1.4" with 6 gallons. Tested to 80 pounds in the right seat and 14 gallons, it is .6" aft of center. As soon as it goes aft of center, I can really tell the difference. I now wish I had made my wing tanks to keep the fuel, no more than 10" aft of the front spar, like Larry F. did. I know that some builders with wing tanks were making them full span and it was more convenient for me to build them that way. But, I would much rather have less fuel and more stability. Remember, this is a KR2 with a Corvair engine and I am concerned about aft CG, which is just the opposite of what I thought I would have to deal with. I do not think that the issue is as prominent with the 2S, but that is not from experience as I have only been a passenger in 2 different 2S, and never flown one. Here is the bottom line as far as my experience tells me and what Jim Faughn was telling us, CG forward, stable, CG aft, not so stable. Just get your CG right and all this talk about re-designing the controls becomes mute. One more time.... Get the CG forward!!!!!!!!!!!!!! See N64KR at http://KRBuilder.org - Then click on the pics See you at the 2012 - KR Gathering in Mt. Vernon, Il MVN 40th Anniversary There is a time for building and it is over. Daniel R. Heath - Lexington, SC http://www.krbuilder.org/MyUSA/ -----Original Message----- From: krnet-boun...@mylist.net [mailto:krnet-boun...@mylist.net] On Behalf Of rdrace...@aol.com Sent: Friday, May 04, 2012 12:22 AM To: kr...@mylist.net Subject: Re: KR> VG's ? or stabilator ? Isn't the definition of an unstable aircraft basically that if momentarily disrupted from it's flight path it will not attempt to return to it's original state, but instead continue to diverge from that state. I don't recall anyone (other than Mark L. when his aircraft was flown completely outside the design CG range) ever saying they had this kind of problem with a KR-2/KR-2S. Seems to me everyone who is of the opinion the KR-2s are too responsive for average pilots wants to keep bringing up a mythical stability problem. For those of you building, if you think the control response it too "touchy" for you, you can certainly try to design the responsiveness out of it. You're the builder. However, in my opinion, nothing is gained for the KR community by perpetuating stories of some mythical instability inherent in the KR design. Again, just my opinion. Todd Thelin Spanaway, WA In a message dated 5/3/2012 2:13:34 P.M. Pacific Daylight Time, gyrowo...@yahoo.com writes: I wondered if using a full flying tail (sometimes referred to as a "stabilator") would cure the stability problems ? _______________________________________ Search the KRnet Archives at http://mylist.net/private/krnet/ to UNsubscribe from KRnet, send a message to krnet-le...@mylist.net please see other KRnet info at http://www.krnet.org/info.html
