This model is a very naive attempt at creating a helicopter rotor without me really knowing how a helicopter works. One thing going for this design is that it is very strong.
This view shows the rotor slightly tilted. You can see the top of the small pnuematic actuator in the left center.
Here you can start to see some of the structure of the assembly. The lever that is pushed by the pneumatic actuator is mounted with two small grey pieces keeping it in place.
I removed the tubes for the photo since they really would have obscured the inside.
Here you can see a little more how the pneumatic actuator and switch are mounted.
The universal joint that allows the rotational energy to be transfered around the tilt can be seen in this view. You can also see the small grey gear that is the external drive for the rotor.
The gear work to transfer power from the small gear through to the rotor.
I admit that the photos are not great: the black Lego doesn't photograph well. However, I think that it should be possible to re-create the rotor from these photos.