fuselage integrity is the least of your problems +++++++++++++++++++++++++++++++++++
Hey Doug - thanks for the input. As I said before - flutter has been a big issue for a long time, but this phobia got worse after I actually experienced it in a mundane old C206. I did a great deal of experimenting via my other interest, giant scale radio control models. A typical test bed would be 25 to 40 lbs, of similar wood/composite structure as a KR and around 8 to 10' span. I considered this big enough to be representative (and a great deal less painful to crash). Believe me when I tell you that the fuselage takes a beating - I have had a model survive aileron flutter (other then stripped servo gears) but the fuselage had to be rebuilt - more than half of the glue joints let go. You are no doubt right - I am leaning toward overkill - we have seen all sorts of anomalies on home built birds and very few reports of flutter - I have not heard of any on a KR. The matter is mostly academic - with what I have learnt from my experimenting and from this (and other) discussion groups - I seriously doubt that I will come up against this beast. I have evolved a set of rules for myself and I don't mind if they are over-kill. At the risk of being boring: = Go to every effort to keep the moving surface light and rigid (without compromising strength). = At least balance statically - preferably static and aerodynamic - even for the 120 mph birds. = Counter-weights evenly spread (or divided evenly between tip and control horn). = Consider likely G loads when designing counterweight attachments. (There was some input from Oz requiring something like 30G capability. I don't know about that - I would make sure the attachments could handle the same G as the wing spars. It was good for me to read about this - with all the other trouble I was going to, I never considered this important aspect. = Zero slop in the hinges and linkages (rather have them a tad tight). = The moving surface must never be thinner (at the hinge line) than the fixed surface - I will always make the elevator / aileron / rudder a tad thicker than the mating bit just to be sure. = Test results passed on to me via KRnet indicated NO drag penalty even with the control surface 10% thicker. I am referring to wind tunnel tests by a US university. I forget who gave me the info - maybe he will pick up on the post and fill us in. Give all the same consideration to trim tabs - they can set off the whole party. Steve J Zambia
