By applying this gear system It eliminates the need for a piston or a complicated mechanism,
and can develop a twice high efficiency engine with the same combustion chamber volume.
It is lightweight and compact, so the number of parts is small, so development cost is low.
A reciprocating engine usually has one explosion each time it rotates twice.
The Fan rotary engine has two explosions each time it rotates two turns.
Use two fans instead of a piston.
Pistons, connecting rods, crankshaft, etc. become unnecessary.