The internal housing shape is like a vane style hydraulic pump.
These pumps
have a tendency to develop chatter marks on the internal housing. The
engine would have to run at a higher RPM with heavier vanes than a
hydraulic pumps parts. I believe the engine will develop chatter
marks
quickly, requiring frequent overhauls with a need to replace the
housings
every time at a high cost to the owner. Re read Kenichi's
practical  rotary
engine requirements. It does make a rotating motion as (1)
describes but
the heavy vanes ruins the practicality.

Dale Davies