From [Source ~ PHA p.72]

If the rotors are isolated [ie. Side-by-side) then m = 0 and P_i = P₁ + P₂ +(T₁^3/2+ T₂^3/2) / (√2ρA))

From [Source ~ PHA p.72]

The two rotor disks are in the same horizontal plane but are completely separate; in other words the horizontal distance (Stagger) between the centers of the 2 rotor disks is greater than the diameter of the disks. The calculations are based on each rotor disk carrying half the load.

When two rotors operate close together in hovering, without overlapping, the induced power loss is found to be less than the value indicated by simple momentum theory. [Helicopter Dynamics and Aerodynamics p.91]. This reduction in power is around 18%. For more information on this see [HT p.118]. Also see the last paragraph on page 9 and the next paragraph on page 10 of Study of Dual-Rotor Interference and .... This possible reduction is not included in the Access program.

Kamov RA-22 "Vintokryl"

Bell/Boeing - Vertol V-22 "Osprey"

Mi-12 Homer This is actually slightly interleaving.

A comparison between the Vintokryl configuration and that of the V-22 tiltrotor would be interesting. Particularly since the Vintokryl achieved 356km/h, plus the CarterCopter is striving for high speed. "Sadly, the fate of the Ka-22 was sealed by two tragic crashes." ~ Doesn't sound too different from the V-22.

>I'm curious what 3-4 reasons there might be for the Vint to be superior to the Step?<

These reasons are mine and are certainly open to debate. They are also based on both craft being of the same era (preferably current:).

1/ All other things being equal, the side-by-side configuration will give more vertical thrust than the intermeshing configuration. This is because;

a/ the side-by-side has a greater 'effective' disk area, since there is no overlap.

b/ some of the intermesher's angled thrust is wasted on its lateral component.

This means that the side-by-side can have smaller rotor disks, and therefore shorter blades.

2/ The vertical profile drag of the wings on the Vintokryl will probably be less than that of the fuselage, rotor hub, lower blades and horizontal stabilizer of the Steppy. This advantage may be even greater if the Vintokryl's wings were to have shortened chords when leading and trailing STOL type spoilers were extended down in high-lift mode. Again, resulting in smaller rotor disks.

3/ The wings on the Vintokryl allow for a partial off-loading of the rotors during high speed forward flight and this should result in a higher maximum speed. This has been demonstrated by the 356km/h it achieved, and this is the direction that the CarterCopter is attempting to go.

______________________

Superficially, it looks like a modern RA-22 could give the V-22 a run for its money.

1/ Cleaner transition between hover and forward flight.

2/ Can land in either mode.

3/ Probably not as susceptible to the vortex ring state.

4/ Propellers and rotors that are optimized for their own flight realm.

________________

Enough rambling for now. If you want me to try to find the reasons for 'the breast stroke' just say so.

The rotors of the Mi-12 Homer turn with the advancing side on the inside (breaststroke). It looks like the Interleaving - Landgraf ~ H-4 rotors also turn inside forward. The Focke Fw-61 rotors turn inside forward. The Kamov Ka-22 "Vintokryl" may have tried both directions of rotation.

Coaxial | Intermeshing | Interleaving | Side-by-Side | Tandem