The Hirth HM 60 was a four-cylinder inverted air-cooled inline aircraft engine designed in 1923 and first sold in 1924. The engine was of very high quality, and its sales success contributed to Hirth's rapid pre-war expansion. It was a popular engine for light aircraft delivering 80 hp (60 kW) at 2,300 rpm. Later Hirth engines built upon the HM 60's success and provided greater power with many of the same design features.[1]