Hirth F-40The Hirth F-40 is a German aircraft engine, that was designed and produced by Hirth of Benningen for use in ultralight aircraft.By March 2018, the engine was no longer advertised on the company website and seems to be out of production.Design and developmentThe Hirth F-40 is a four-cylinder, two-stroke, displacement, liquid-cooled, petrol engine design, with a helical gear mechanical gearbox reduction drive. It produces at 4800 rpm.