Nick,
Interesting analysis - thanks.
Would it be fair for me to comment that a more holistic design would be required with this approach? With your well informed example, the tail rotor power goes down from 55HP (5.5% of 1000HP) to 38.5HP. This increases main rotor available power from 945HP to 961.5HP, allowing a total lift of 10,175 lbs. Subtract the 33 lbs, you neatly worked out, still gives a net gain of 142 lbs.
I realise that exact figures require several iterations, since increased lift means more torque. The tail aerofoil is also operating in the whirl component of downwash, so that the drag vector will be rotated to reduce download further. The practical upshot is that either helo weight can go up or power required goes down. I suspect that the rearward shifted downforce, along with the adverse torque reaction in autorotation, was the real reason Igor Sikorsky dropped it (bearing in mind the control problems overcome).
Could a conclusion be that Sikorsky should reconsider the merit of tail boom aerofoil torque reaction? Clearly the camber (or AOA depending on design) would need to be linked in with the collective.
Mart
[Edit: 'cos hot choc and typing don't mix...]
Last edited by Graviman; 12th Jun 2005 at 13:36.