One of the ancient kings of the flywheel (said in 1910), Mr. Henry Rougier, built a 4-cylinder vertical in-line, water-cooled aviation engine.

-It had 150 mm bore and 160 mm stroke.

-It had red copper (cuivre rouge) wrapped around the cylinders giving it a monobloc shape.

-It could be conditioned to operate by thermosiphon towards the radiator. The start was by crank and with a decompressor. It gave 70/75 HP at 1,150 rpm. It weighed 130 kg and consumed 22 to 23 liters per hour and its price then was 10,000 francs.