Steve, Are you going to design and build
your own helicopter rotor head?

What do you think of this one?

Paul Lamar ...No rotor no motor.

I'm thinking about it.  It will have no hinges or bearings and it will not
depend on hydraulics.  That Kamov has the most complicated rotor head that
has ever been built.  I'm not a big fan of the co-axial types because they
are impossible to keep simple and they have problems with autorotation.
What I'm looking at is very low stressed, all mechanical with no power
assist and as inexpensive as possible.  That ball joint in place of a swash
plate only works on a rotor with very low control forces but I've seen it
used with an internal linkage.  The ball was under the transmission and the
control rods were inside the main rotor shaft.

The control system I'm looking at is nothing new.  I want to use servo tabs
like Kaman uses.  They've been successful on the Husky, KMax and the
Seasprite.  They also have an advantage in that since the angle of the blade
is not directly fixed, they can automatically respond to a gust with a pitch
change which makes the rotor more stable.  I've got my own ideas on
designing the linkage and rotor system, but I want to find info on the
Seasprite in particular because it's a relatively fast, medium sized,
tailrotor type.

I'm willing to trade some speed for superior autorotation characteristics
which means keeping the disk loading low and having more inertia in the
rotor.  This is why autorotation in the Osprey, even though it can
autorotate, is strongly not recommended--very high disk loading and low
inertia in the rotors.  I talked to one of the Air Force test pilots and he
told me the recommended procedure for total power failure is a forced
landing in airplane mode.  I think he said that it comes down at 5000 fpm in
autorotation and there isn't sufficient energy to flare.

Steve

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