Mart,
Vortex theory is really neat and interesting, but it is too complex a theory to use at this level of evaluation, particularly when trying to apply it to twin main-rotors. Blade element theory and common logic will do.
the reason behind your recent migration to interleavers.
I strongly believe, until proven wrong, that the Intermeshing configuration is the best configuration for small rotorcraft, where speed and agility are important.
I think, until proven wrong, that the Interleaving configuration may be the best for large transport rotorcraft, where lift and speed are important but high maneuverability is not.
Must admit to still wondering what advantages this head would give over say the Sikorsky/Schweizer 300 articulating lead (rigid with lead-lag).
It might offer two advantages. One, that its
undersling may eliminated the need for lead/lag hinges. And two, that its large flapping hinge offset will allow for a smaller
obliquity when used in an Intermeshing configuration.
Reguarding the 3-blade and 4-blade Lockheed, the Sikorsky S-69 (XH-59) ABC coaxial had quite rigid 3-blade rotors. It was intended to fly at 250 kts, however it only got up to 220 kts due to the high vibrations. This would appear to be the reason that the sketch of their new X2 coaxial series shows 4-blade rotors.
Dave