The Curtiss S was a water-cooled 6-cylinder in-line aero-engine built by the Curtiss Aeroplane and Motor Company in 1912.
The Model S was designed by Charles B. Kirkham, who went on to become Curtiss's chief engineer. The engine retained the same cylinder bore and stroke as the companyâÂÂs four-cylinder Model K but featured separate pushrods for the suction and exhaust valves. Production of the type was limited to six engines, five of which were acquired by the United States Navy.