I have 2 projects that both have the phenolic triangle engine mounts. I see no mention of them in the plans or the plans changes. The plans call for a .250" aluminum plate.
The reason I ask is one projects has had a history of vibration. We balanced the prop (with concerns about the manufacturers quality) as best we could. The engine ran somewhat smooth until I reached 40MPH indicated at about 3,000 RPM, then a new and major vibration occurred. I closed the throttle and it immediately subsided. We are suspect of a harmonic resonance of the phenolic mount, instead of the aluminum spec. in the plans.
I went to the Q type fly-in last weekend and learned a LOT! The answer to the question I posted was "Kevlar". Terry Crouch, answered this and many other questions I had. The Kevlar fiber engine mount would not have a cycle failure as the aluminum mount would have an eventual crack/fail. The additional flexibility of the Kevlar would no doubt, also dampen vibration. THANK YOU TERRY for that answer!
We continued to adjust the carb and engine controls to get a relatively smooth and reliable range of operation. I did a couple of more runs down the runway and I feel the vibration is in the wheels/tires not the engine/prop. With the runway speed getting close to flying speed, and good engine RPM's I feel it is time to get the Quickie fully ready to fly prior to anymore tests.