Max,
The basic idea is to have two independent streamtubes for lift get combined into one streamtube for propulsion.
Your
second sentence is correct.
However. it appears that your idea is not changing the 'effective' disk area from when the rotors are facing up (lift) to when they are facing forward (propulsion).
Is this a one rotor version of your idea?
http://patft.uspto.gov/netacgi/nph-P...S=PN/6,382,556
or ~ if the above does not work
This patent number 6,382,556 to go in this page
http://patft.uspto.gov/netahtml/PTO/srchnum.htm
Dave