Turbofan

A turbofan is an airbreathing jet engine that combines a gas turbine core with a ducted fan, so that part of the intake air bypasses the combustion core entirely while still being accelerated rearward by the fan, the ratio between bypassed and core-routed air called the bypass ratio. The British engineer Frank Whittle described the underlying principle in a 1936 UK patent, but the first turbofan actually built and run, the German Daimler-Benz DB 670, only reached a test bed, first running on May 27, 1943; the Rolls-Royce Conway became the first turbofan placed into production, entering service in the 1950s. High-bypass turbofans now power nearly every commercial jet airliner for their fuel efficiency, while low-bypass turbofans remain typical of modern fighter aircraft.