Then the outside surface of the 'swashwheel' (special cam follower) has a spherical profile. The 'swashring ' has a constant vertical distance between the upper and lower rings, which contain the 'swashwheels'. Whatever orientation of the 'swashwheel' has, the vertical distance never varies.

The design should be such that the 'swashwheels' are always in contact with just one surface otherwise the wheels will want to change their direction of rotation twice per RRPM. This may be easy to achieve since an asymmetrical airfoil may want to cause a negative pitch and a 'bungecord' arrangement on the other side of the swash-ring may provide a one side contact.

The use of a swash-ring may have an advantage over a conventional swashplate. This is because the swash-ring could have one or more 'humps' in it. These humps would give a short duration pitch change to the blade as it passes through the downwash and/or downdraft of a blade of the other rotor.

This swash-ring could be rotated about the mast axis so that the azimuth of the 'humps' can be moved as changes in forward velocity relocate the location of blade to blade interactions. The swash-ring will probably have to be rotateable because otherwise at certain forward speed the 'hump(s)' will compound the problem. Perhaps the swash-ring could initially be incorporated without 'hump(s)'.