I've rattled the rudder and elevator of almost every KR that's been parked at a Gathering in the last 20 years, and some of the high-timers have as much as 3/16" of slop back there. Probably the worst is a high-time KR2 that's famous for pulling high-G maneuvers while flying with a passenger above the gross weight design limits. Having seen him do this and get away with it makes me think that the stock hinges are probably sufficient, however.
I am a fan of the oil impregnated bushings though. They are cheap, will definitely last longer than steel-on-aluminum, and are easy to install. I'm not sure if my website says this, but I used a piece of 1/4" Nylaflow tubing as a spacer on the inside to ensure the sleeved (non-flanged) bushings didn't slide out of the inside aluminum angle, even though they were also locked in place with Loctite sleeve retainer. As for the extra hinges, I did that because I made my horizontal stabilizer and rudder are longer, and later heard that the Aussie government was requiring the same for KR builders down under. Of course if they're anything like the Brits, it could be overkill! I do suspect that 3/16" bolts are overkill, perhaps chosen in an effort to keep all the nuts and bolts in the same "family", like 5/8" x 5/8" spruce that is also ubiquitous in the KRs. #8's could probably be used, but then the bearing area on the aluminum would be smaller and the hinges would wear even faster. You could then add bushings, but then you'd be almost as heavy as with #10 bolts anyway. Bottom line is that if money is a big factor, aluminum seems to work. A look at some of the old tube and fabric airplanes will amaze you at what works for a hinge back there. I don't remember anybody fluttering a KR elevator. Speaking of that, Troy Petteway "un"-balanced his elevator when he rebuilt his tail with longer surfaces, yet continued to burn up the sky at well over 200 mph with impunity. So there's some more weight in the tail that can probably go away... Mark Langford ML at N56ML.com website at http://www.N56ML.com --------------------------------------------------------
