Dave, blade vortex interaction is a fact of life. At the very least it means that the tip cannot be profiled to use as high a Cl/Cd as in a free stream. Even X2 designers have recognised this by using that neat tip profile (the tip vortex is thus a larger diam, so reducing its rotational velocity). An intermesher in hover puts the BVI further away from the tip, so would need to limit lift produced at this radius (ie max lift radius would move inboard).
My original question remains: how much power is lost in the Kmax from blade vortex interaction through lower blade tip? There must be some estimates somewhere?
Regarding powertrain: i have always agreed that the FL-282 has a very well thought out gearbox. I sent you some photos from Coventry air museum at one point. But you seem to be championing the interleaver over the intermesher, which from your layouts will need a more complicated drivetrain - perhaps it is you that is changing the goalposts.
But the general point remains. The conventional has very well understood dynamics up to 165Ktas. Since each new project is a risk you will have some convincing to do that the intermesher should be the config and not conventional.
For example R22 handles well enough, once you learn the quirks (mostly a cyclic response lag). If you don't wish the pilot to learn the quirks then SCAS is the way to go. If you don't like the sometimes messy development of hydraulics then electric actuators are becoming more powerful each year. This makes it hard to justify moving away from the positive yaw response provided by a tail rotor for some purist aerodynamic handling advantage.
Above 200Ktas it is a different story. The benefit of lateral symmetry (at least projected to plan view) is that the retreating side no longer needs to balance the advancing. Agreed S-69 has set the standard for X2 to beat.
Regarding your last post: it is unlikely that rotor aerodynamics will ever be as efficient as a wing, because as rotor technology moves on so does fixed wing technology...
Last edited by Graviman; 26th Jan 2008 at 11:33.
Reason: Reread tidy-up only.