EJC made a 6-cylinder bi-rotary engine giving 60 HP. The outer propeller rotates with the crankshaft and the inner one with the crankcase that carries the cylinders. There is one at the Paris Air and Space Museum.

"EJC"

-The maximum rotation is 1200 rpm for the propeller with the crankshaft and 800 rpm for the propeller with the cylinders.

From Appendix 9: A photo of the Bi-rotary EJC with the two propellers well visible.

“EJC on a test bench”

"EJC cross-section"

From Appendix 10: The engine rotates in solidarity with the rear propeller, while the front propeller rotates in the opposite direction.

-It is another attempt to minimize the gyroscopic effect of the motor mass.