In reply to Pierre Terrail: I left the project soon after the stage shown in the photograph when Mr. Shapiro wanted me to join his office (Servotec) in an unsatisfactory position rather than work as a consultant from my own firm of Technical Investigations Ltd. I should also point out that the MK 2 version had its engines in the rear rather than the previous front location. As far as the rotor system is concerned it was very close coupled and the rotors were (theoretically) held apart by a rigid conta-rotating structure patented by Mr. Shapiro. If thay are far apart, as per the Russians, it is not very efficient. My analysis of the system concluded that it would not work safely unless there was a very sophisticated higher harmonic blade pitch control system though something could be done with an appropriate delta 3 hinge. I think that the Sikorsky high speed helicopter under development, which has close coupled contra-rotating rotors, has individual blade pitch control.

Dear Dr. Opatowski, may we have an evaluation of this coax helo: vibrations? performances? why there is no follow up? Why this is not a success? Why aren't we seeing more coax in the sky???
Thanks.

I carried out some of the early development work on this aircraft at Redhill (on a consultancy basis) and have a photograph of the engineer Mr. Tony Higgins and myself running the bare platform with blades on one of the two co-axial rotors only.