Ah, thanks guys! I guess they tune the stiffness to keep blade 3/4 wavelength mode below 3P then, while keeping good cyclic control for reduced g manouvres. Nice reliable design, although i wonder about the control forces.
I've dealt with Lord, Trelleborg and Silentblock for spherelastic bearings, and have always been impressed at what they were capable of withstanding. The only problem i've ever come across is that they are difficult to life, especially if you cannot define the exact duty cycle. Failure is easy to spot though from rubber splitting, and the failure mode is nice and progressive.
Dave did you ever get anywhere with your compliant hub design? I always thought this was one of your best ideas.
That fenestron looks interesting in a small helicopter too. How does it handle foward flight, without teetering and delta3? Does the advancing side end up producing most of the thrust, or is that a cyclic servo i see?
