"Jay Honeck" wrote

A clutch is one more thing to break -- but, wow, if it can eliminate that
violent twisting motion that our motor mounts and airframes must endure,
it might be a good thing?

Indeed, it is a good thing.

The problem is that the weight begins showing up as another problem, again.

A clutch for a 300 HP engine is going to be much more that 3 times heavier,
than a clutch for a 100 HP engine, I'll bet.

That clutch is yet another example of how Rotax can make their engines so
light. Spin them fast, to get more HP per cubic inch. Use a gearbox to
make the power useable by a prop. Make that gearbox as light as you can.
In order to make the gearbox light, (it is the weak link in all of this)
protect it from harmonic resonance loads, by using a clutch. Beautiful
engineering.

Problem is, I'm not buying the whole design philosophy. But you knew that,
already. g
--
Jim in NC