>> At 155 indicated my KR, standard wing built to plans, appears to fly >> with the nose down at a -2 degrees.
>>> I did a quick check yesterday and found that my trim tab is "down" >>> (for nose up trim) at 155mph >>> My C.G. on that flight was probably about midpoint of the range >>> I tried to set my H.S. to zero degrees with the fuselage level and >>> that required a small shim under the forward spar Great stuff here, thanks Larry. I assume your KR is rigged with the standard +3.5 positive wing incidence at the root. We know the HS is zero (with a 24" longer moment) and you still need some of "up" trim in the cruise with a relatively neutral CG - I am really surprised and pleased to know this before I finalize anything. Assuming also that you used the typical 2 to 2.5 degrees washout that appears to be normal amongst builders - it looks like the relationship between the wing root and HS of +3.5 is about right (if not a little shy) - say 4 degrees decaulage should be pretty close. (For an RAF48) I would have expected this to be less - 2 to 2.5 degrees (with -2 washout). Maybe there is an influence from the other dimension - thrust line. I would imagine that your thrust line is pretty close to zero and thus effectively 2 degrees down thrust in the cruise. This may tell us why your bird is looking for a bit extra "up" in the cruise - to compensate for the engine pulling down. Interesting test would be to get the bird trimmed out in the cruise - let her settle down (everything balanced), then remove the thrust component by throttling back for a few seconds - my guess is that she will nose-up briefly before settling into a slower than expected glide. Your KR flies 2 degrees nose-down, so maybe the root should be at +1.5 for the best drag profile of the fuselage - and the stab <4 degrees. I wonder how this will change with: a) The newer Ashok wing sections b) A more deliberate airfoil section on the HS - 007) I think an airplane looks really cool in a nose down attitude - like the older Bonanza's - so mine will be rigged 1 degree up from whatever finally comes out here. Take care and enjoy. Steve J
