Thanks for all the hard work, Rusty.  Good info for the group.  Though you are right.  Not much help in identifying my unidentified rear counter weight.  Since I finally decided on the S5 rotors I can use the S5 front CW that I know I have.  My "unknown" rear cw is currently running with my other s5 rotors and the engine is not falling apart, though the vibration level is higher than I expected from a rotary (even noted on the computer analysis when I had my prop balanced).

 

Who thinks it might be a good idea to randomly shave off a little bit of my counter weight and see if that makes anything better?  :-)


--
Dave Leonard
Turbo Rotary RV-6 N4VY

Dave and Group,

 I think you are getting too "pistoned" up about the counterweights. If you use the counterweights from the same series engine the balance will be better than that achieved on ANY piston engine, The best they can hope for is decent primary balance. Then there will always be rocking couples at some rpm, greater or lesser depending on how well the engine is tuned/timed/balanced for a certain RPM. The Rotary engine is capable of nearly perfect balance. Paul Lamar has posted the balance tables listed in "The Rotary Engine" which if accurately measured will balance exactly. The only really tough variable is the weight of the oil in the rotor. Dynamic balancing can compensate for the oil and could even be done on the running engine for those of us with nothing to do! The rotary can be improved with dynamic balancing but unless you have mismatched rotors or something it doesn't shake much to begin with.

Bill Jepson