They are the initials of Gadoux & Crouse, and the main designer was Maurice Gadoux.

-It is an engine with a double shaft for contra-rotating propellers, with hollow shafts to be used with a cannon.

“GC”

As we saw in the main chapter of Gadoux & Crouse, the engine has double cylinders placed around the axles as if it were a "barrel" or "revolver" type engine by which these engines are known with cylinders around the central axis and axially arranged.

-In this lateral section we see that the cylinder groups drives by means of conical gears -fixed to each small crankshaft- two other conical gears, one for each propeller shaft, causing them to turn in the opposite direction.

-It was supercharged and gave 900 CV increasing to 1,300 CV, with minimal frontal area.