Greetings,

 

Made the first attempt to crank the engine today.  This turned out to be a good news/ bad news event.  The good news is that it fired up instantly, and everything seems to work.  The bad news is that it’s rough as a cob :-0

 

It would appear that my worst fears about the torque reversals with the RD-1C drive have come true.  I didn’t notice the rpm, but the engine barely made it over the speed the starter turns it.  In fact, the starter stayed engaged a couple times, because the engine didn’t accelerate enough to push the gear back.  Did I mention that’s it’s rough :-)  It shook the living crap out of the plane, but the engine mounts work well. The main gear of the plane was actually jumping slightly off the ground.  Good thing I was sitting in the plane, or it really might have been interesting.  

 

While the engine was running, no amount of throttle changes anything.  It’s simply impossible for the engine to accelerate out of this mode.   BTW, this is EXACTLY how the 912S used to behave on this plane.  If you didn’t crank the engine with enough throttle opening, it would get stuck in the gearbox shaking mode, and the best thing you could do was shut it down, and try again.  Rotax came out with a  “slipper clutch” to eliminate the problem on the 912S.    

 

Next step will be to remove the prop, and try it that way.  Eliminating the rotational mass of the prop should make it better, if not eliminate the problem altogether.   If that works OK, then I may have to try a different hardness of rubber dampeners on the redrive thrust plate.  Mainly, I just want to get the engine to the point where I can run it routinely, to keep it happy while I'm building the RV-8.

 

Happy New Years. The down under boys should have a nice hangover about now :-)

 

Rusty