I have a Wild Hare Edge 540 on the way. 28% - 1390 square inches of wing -- 19 lbs. ZDZ 60cc gas. Futaba 1024 PCM receiver operating on 6 volts. Will a HiTec 645MG servo (100 oz. torque) be enough if I put one on each elevator -- one on each aileron ? How about one on the rudder? I'm new to 3D. Would appreciate advice from experienced flyers. Thanks

I think that they would be sufficient although the 6** series hitecs have a centering problem. The dont center well. they are usually a degree or so off from center. Not much. I had 615MG on my Hangar 9 edge and they were great with 110 oz. or torque. If you are not worried about precision, then dont worry about the centering problem. the ariflow over the control suface helps them center out a little. But as far a strength they should be fine. The only exception might be the rudder. You might want to on it for any high g stuff, but they should be sufficient for knife edge or high alpha knife edge. Hope this helps.

A rule of thumb that I use for servo selection is Weight of the plane per control function = minimum servo selection. What I mean by that is if the plane weighs 12.5 lbs including engine and radio gear and has one servo for each elevator, aileron and rudder, then I use servo's that are a minumum 100 oz per control surface, double that for the rudder. ie: 100 oz for each elevator half, 100 oz for each aileron and as close to 200 oz on the rudder as I can get.
I also prefer metal gears for 3d planes although I am trying the new Hitec "karbonite" as they say it is 4 times stronger then nylon and no slop. The verdict is still out on that one though.
One last thing. You should really look at the digital servo's that Hitec makes. For 3D, the response time and holding power plus the return to center advantage of the digitals is definitely noticable when performing 3D manuvers.

'Course thats just my opinion.