Re: Hey Tom
We looked at a variety of concepts using rotors, including some where the rotors came out the top of a horizontally-landing vehicle and it flew like a regular helicopter. We never really arrived at a satisfactory method for deploying the blades in the atmosphere at high speed, and there were problems with heating deploying the blades in orbit on a large vehicle.
On reflection, if we were doing it over, I think we would go some direction other than rotors if we were specifying a large vehicle.
I still have some hopes for a smaller vehicle, as seen below.
Had to pull this off some obscure site, since I have no way to put my own pictures up. This is a picture I rendered, though.