I know you and maybe others are interested in single developments, so I spread the information.  

Hi George,

Thanks, always interested in hearing about this stuff.  I noticed that Atkins has single rotors listed for marine applications, but no mention that I can find of any aircraft usage  His belt drive is nowhere to be found either, but the web site is pretty darn disorganized, so it's hard to be sure.  

I only just recently discovered they were looking at the single and I offered to help, but their well down the track as they have done a couple before for people, but they had none of the problems you are seeing - I still feel it's fundamentally a problem with balancing of the rotating components, but it could be a need for a heaver flywheel and I suggested that to GURU. As they build for all manual applications it's something they may not see. 

Well, I'm quite certain that the balancing is just fine.  The problem seems to be due to the torque reversals, and the lack of any significant flywheel weight, or dampener.   The flywheel weight would work, but it's the brute force way to solve the problem.  There really needs to be a dampener that can smooth out the pulses, before they get a chance to excite the natural frequency of the prop assembly. 

I've spent almost no time looking at this, since it's not my current priority, but eventually, I plan to look at what sort of dampener is used on the single cylinder two stroke engines.  It looks like they would have nearly the same problem with torque reversals, and there have been plenty of single cylinder 2 stroke engines flown.