Junkers L1

The Junkers L1 was the first engine made by Junkers to fly. It was an air-cooled, upright six-cylinder inline four-stroke petrol engine, produced only in small numbers and used largely for research, but it led to the successful L5 and to its V12 development, the L55. Hugo Junkers had earlier worked on stationary opposed-piston two-stroke diesels, so the L1 was the firm's first petrol-fuelled aero engine, and the letter L became Junkers' notation for petrol engines from the L1 to the L10. It first ran in 1921, and a small production line was set up in 1925. It had four large valves per cylinder and double ignition with twin magnetos, and it flew in aircraft such as the Junkers T 19.