Which type of engine is most efficient for high-speed and high-altitude flight?

The most efficient engine type for high-speed and high-altitude flight is the high bypass turbofan. This design is characterized by a large fan at the front of the engine, which moves a significant amount of air through the engine bypassing the turbine core. As a result, high bypass turbofans are capable of producing a larger thrust with improved fuel efficiency compared to other engine types.

At high altitudes, a high bypass turbofan operates more efficiently because the thin air allows for higher speed while maintaining lower drag. The bypass ratio, which is the ratio of the mass of air bypassing the engine core to the mass of air passing through the engine core, is high in these engines, which contributes to their better propulsive efficiency at cruise speeds. This combination of efficiency in thrust production and lower fuel consumption makes high bypass turbofans well-suited for commercial airliners and military aircraft designed for fast, high-altitude operations.

In contrast, turbojets, while efficient at very high speeds, are less fuel-efficient, particularly at lower speeds and altitudes. Turbochargers are used to increase the efficiency and power of internal combustion engines, but they are not types of aircraft engines designed for propulsion in high-speed jet applications. Low bypass turb