Having flown aft-cg most of the time in my bush work, especially in Africa, I'm not as sensitive to the issue qs Colin. It does make the elevator more sensitive and the plane less "stable" which requires one to stay on top of the elevator with more attention and to give a few extra knots to approach and landing but aft-cg to start with empty is not something to build into the basic structure. You need to have an even starting point before loading it with stuff.
More important than the vert stab which is fine as per plans is the rudder, which I've always found to also be fine as per plans. A little more wouldn't hurt but the standard has always been sufficient for stiff crosswinds. I've never found it to be lacking in authority for takeoff either. It's strong crosswinds that can be the problem although as I've mentioned, it's fine as is. Re takeoffs, Ken Rand was taking off at FlaBob in the early days and got blown into the airport boundary fence on takeoff so perhaps he enlarged it in further designs or perhaps he was just careless that day. FlaBob gets strong winds coming in from the desert and can be turbulent. Just noticed the subject of this post is "Horizontal stabilizer KR-2". My response has been as if the subject was "Vertical Stabilizer & Rudder". Sorry. Mike StirewaltKSEE On Wednesday, March 1, 2023 at 06:12:56 PM PST, colin hales via KRnet <krnet@list.krnet.org> wrote: Hi Jamie, With regards to solid proven advice, I can solidly say, I didn't extend the fin forward. I don't have any stability issues so my advice is that there is no need to extend the fin. But if you want to extend forward the fin an inch or two, I can't see any harm. But I am blue in the face because I say this until I am blue in the face, stability is all to do with centre of gravity. The standard KR2 might be pitch sensitive to those who fly jumbo's but there are no yaw issues with the plane. Far more of an issue is engine torque. Depending on how much power you will have will depend on how much corrective rudder you need to counteract engine torque, adding to the fin isn't going to help that one bit. Since there is no offset built into the fin, as there is on many other aircraft, size is not really an issue. For clarification, some aircraft have the fin offset to counteract permanently engine torque, so you don't need a rudder trim tab or to keep so much rudder in when taking off or climbing with full power. The KR2 fin is set in line with the fuselage centre line for simplicity. Also, VW engines you need to offset the fin to the right, Continetal or lycoming, off to the left, because they rotate in opposite directions. So to save confusion, on such a plane where engine choice is open, the fin is set down the middle with no offset. I came across a Midget Mustang where the owner cursed it because he could never keep it straight on take off. I was asked to look into it and quickly discovered that the original builder of many previous owners had put the fin offset bracket on the wrong way. Swapping it around made the pilot a lot happier. So my personal advice is to build it light and keep a forward C of G and keep to the plans. One less issue for your inspector to study. Where I live, that type of deviation from the plans would require lots of paperwork. I know this hasn't answered your question perfectly, but the advice is sound. CH.-- KRnet mailing list KRnet@list.krnet.org https://list.krnet.org/mailman/listinfo/krnet
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