Nick and Dave,
I have been following your exchanges concerning helicopters for a long time and I appreciate the knowledge gained.
Nick, I also am interested in alternative helicopter designs. My motivation is ease of control. I have a friend with a R-22 and he has let me take the controls many times. I also have flown many fixed wing aircraft. Except for getting your descent and landing timing correct, the fixed wing aircraft are no more difficult to control than a car. The R-22 is unstable and difficult to control and it definately has my attention when I am trying to fly it. If anyone ever made a fixed wing aircraft with the stability of a R-22 they would never sell a single one. I know all helicopter pilots find the control of a helicopter as natural as driving a car, but that is a skill aquirred through many hours of carefull study. I feel if you could eliminate all the torque compensation issues that would be a step forward in the creation af an easy to fly helicopter. Therfore I am not very concerned about small differences in efficiency (5%) since a helicopter is already a very inefficient flying machine. Also concerning drag, if speed is limited by issues such as retreating blade stall or supersonic tips does it really matter if the second rotor has more drag than a smaller tail rotor?
So, Nick I would be interested in any insight you can provide into the potential for a tailrotorless design being easier to fly. Was the ABC easy to fly? Is a K-Max easy to fly? Also, can you comment on the pros and cons of servo flap control as on a K-Max or H-43? That is another area I am quite interested in as it seems to be an easy way to eliminate some critical highly loaded hardware in the rotor head.
If any of you reading this follow the Discovery Wings channel as I do you may have seen the recent Choppers episodes where they interview Charles Kaman. These episodes show early footage of synchropters flying around doing amazing things for their time. This was while the tailrotor design was in its infancy. The narrator specifically states that the intermeshing rotor helicopters performed extremely well. But then the intermeshing rotor helicopters just dissappear. There is no mention in the program as to why seemingly overnight the were replaced with helicopters that at that time had inferior capabilities. One guess I have is the reason was political since the best intermeshing designs were German. I would be interested in any comments anyone has as to why, other than Kaman's apparantly successfull designs intermeshing helicopters have disappeared.
I know I may sound biased in Dave's favor but I am really just looking for a helicopter design that approaches the design goals of the new Cirrus aircraft which are safe, easy to fly and accessible.
Thanks,
Rene