Went to an airshow up at Ramona Airport, and while I was there I found the Classic Rotors museum located on the field. It's a pretty small museum but they have an amazing selection of helicopters there. Amazingly, quite a few of them are airworthy or could be with an annual. Apparently Goodyear (the tire company) built a single seat helo in the 50's!
Anyways, I'd recommend checking it out sometime. The guy who showed us around said the museum's goal is to have a display of all of the different types of rotor systems out there. I don't know if they have them all but they definitely have a pretty wide selection. The most interesting to me was looking at a Russian Ka-26 with the counter rotating rotors on the same shaft.
http://www.rotors.org/
Anyways, I'd recommend checking it out sometime. The guy who showed us around said the museum's goal is to have a display of all of the different types of rotor systems out there. I don't know if they have them all but they definitely have a pretty wide selection. The most interesting to me was looking at a Russian Ka-26 with the counter rotating rotors on the same shaft.
http://www.rotors.org/