What is the difference between turbojet and turbofan?
Whereas all the air taken in by a turbojet passes through the combustion chamber and turbines, in a turbofan some of the air entering the nacelle bypasses these components. A turbofan can be thought of as a turbojet being used to drive a ducted fan, with both of these contributing to the thrust. Many aircraft use a form of the gas turbine engine to produce power for thrust. These engines are normally the turboprop, turboshaft, turbofan, and a few turbojet engines. Turbojet” is the former term for any turbine engine.
Why are turbojets not used anymore?
Turbojets have poor efficiency at low vehicle speeds, which limits their usefulness in vehicles other than aircraft. Many modern fighter planes actually use low bypass ratio turbofans equipped with afterburners. They can then cruise efficiently but still have high thrust when dogfighting.Fighter jets need to be able to fly at high speeds and altitudes. High bypass turbofans are more efficient at low speeds and altitudes, but they are not as efficient at high speeds and altitudes.