wrote:
Eric, a small three blade CPP design isn't that hard to make up if you
have a mill or access to a shop.

Basically you have three blades, these get connected to the hub with a
rotating collar. The collar transmits the thrust to the hub. Inside the
hub you have what amounts to eccentric levers. These connect to the
collar and by simply pushing/pulling the rod you control the angle of
the blades.

The one I had used a 1 1/2" shaft diameter with a 1/2" rod inside it.
The shaft was turned with a simple twin sprocket on the outside. The
adjuster stuck out the front of the shaft with a lever attached.
Steve,
Got any pictures or drawings? I thought about something like that and
looked at buying a used one. Very pricey. But maybe really fun to
build. And I have the tools to make one. But making the blades would
be tough to program.
Eric


The blades are actually easy. Because you can adjust the pitch on the
fly they don't have to be real complex.

Some good info.

http://www.boatdesign.net/forums/pro...ary-30695.html

Controllable pitch propeller on you tube shows a bunch of animated rough
ideas.

The interior of the one I had was nothing more than three eccentrics
with pins that engaged the collar.
The collar was round and made of hardened steel.

Basically it looks like a helicopter collective but internal.

If you want to see one up close there are some made for model aircraft
and model boats.
http://www.youtube.com/watch?v=FT8gz...eature=related
http://aircraft-world.com/prod_datas...0-ESP-BLUE.htm

simple version
http://www.youtube.com/user/juicepop.../2/uTOJEP8jIGA


--
Steve W.