Originally developed for use in a motorcycle by French inventor Felix Millet, the rotary engine was used sporadically for years until it was resurrected by brothers Louis and Laurent Seguin.

As the name may imply, the defining feature of the rotary engine is that the entire engine spins as it operates. The propeller is mounted to the front of the crankcase and the combination revolves around a fixed crankshaft. At the time of use, between 1909 and 1920, the rotary engine provided a favorable power to weight ratio, due largely to the nature of its operation. As an air-cooled engine, the weight of a radiator, liquid and all requisite pipes and hoses was eliminated. The rotating operation of the engine, coupled with a total loss lubrication system (where the oil flows through the engine and immediately lost through the exhaust valves) provided additional cooling benefits.

It was the oiling system that was largely responsible for the signature pilot’s outfit of World War I, the scarf and goggles. The goggles served their obvious purpose, keeping the wind and any debris out of the pilot’s eyes. The silk scarf served several purposes: one, to prevent the pilot’s neck from chafing as he scanned the skies for enemies; a second reason for the scarf was to clean the oil off the pilot’s goggles. Castor oil was used in rotary engines due to its outstanding lubricating qualities but caused some rather alarming intestinal difficulties. Wrapping a scarf around his face, a pilot avoided inhaling or absorbing the laxative oil.

Specifications: Model B; nine-cylinder air-cooled rotary; bore 120 mm., stroke 160 mm., displacement 16.3 liters, 130 hp at 1250 rpm.; weight 173 kg.

Accession no. 1992G51

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