Dave,
"...what has this got to do with ... hub spring ...? You keep moving the goalpost."
You were proposing a 2-blade teetering design with hub compliance. Nick commented that the only real advatage of teetering is it's low mass. In response i commented that you could apply teetering to an interleaver, allowing low mass with fast roll rate. I also commented that such a machine would be ungainly, unless you pushed up the diskloading which then undoes the mass advantage.
The practical upshot is that for fast roll rate a "rigid" rotor is the best solution. This is why i have being trying to understand the Comanche head...
"Stepniewski was required to use 'an extended' coaxial and tandem Momentum Theory ... in his final publication."
Where can i get hold of this? I've read "Rotary-Wing Aerodynamics", but no mention was made of this publication. It sounds pretty good.
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Nick,
"Comanche was similar to the EC-135, the brown cylinders on the lower and upper side shown here:"
Ah, this is starting to make a lot more sense to me now. Having the hydromount lead/lag damper buried definately had me puzzled. I'll have another look at that Comanche footage, to put it all into place.
Out of interest has anyone tried the concept of actively moving mass inboard/outboard along the spar? The control system would be:
Blade lead error ---> move mass outboard : Coriolis applies lag force.
Blade lag error -----> move mass inboard : Coriolis applies lead force.
Conceptually at least, fairly simple...
Mart