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How is an aircraft capable of flight? A key component in their ability to fly is the type of engine the plane houses and the parts that construct the engine. Aircraft engines are designed with the same core components across different planes, including fans, compressors, combustors, turbines, and nozzles. When these parts operate in unison, flight is possible. If any one of these parts was missing, then flight wouldn’t be achievable. The individual parts of the engine may be small be they contribute to a wholesome larger picture. Many aircraft today utilize gas powered turbine engines because of their efficacy, reliability, and performance. There are four main types of turbine engines in operation today: the turbojet, turboprop, turbofan, and turboshaft engine.
A turbojet engine produces thrust by ejecting a high energy gas stream from the engine exhaust nozzle. Air is directed into the engine through an inlet at the front of the plane, which is then heated by a compressor. Fuel is added in the combustion chamber and then ignited, expanding the air and adding energy to the exhaust stream. The turbine extracts energy from the exhaust stream in order to operate the compressor. The remainder of the exhaust energy is turned into thrust, aided by the exhaust nozzle. As gas passes through the exhaust nozzle it is accelerated into high speeds as it expands, resulting in propulsion. Turbojet engines are relatively simple in design, occupy little space, and are capable of very high speeds. On the other hand, this engine requires a considerable amount of fuel and tends to be louder than other engines.
A turboprop engine uses a gas turbine to turn a propeller. Propellers are efficient in flying and can be used with nearly any kind of engine. The core of a turboprop engine is relatively similar to a turbojet engine. A main difference is that instead of expanding all the hot exhaust through the nozzle to produce thrust, most of the energy is re-routed in a ducting system to power the turbine. Turboprop engines are mainly used for low speed aircraft such as cargo planes and general aviation aircraft.
Turbofan engines are most commonly found on commercial aircraft. They combine the best of both worlds between turbojet and turboprop engines. They work by attaching a ducted fan to the very front of a turbojet engine. This fan has many functions as it lowers the noise output of the engine, helps keep the engine cool, and creates additional thrust. As air enters the fan, it gets divided into two separate streams. One stream act as bypass air and flows around the engine, while the second stream passes through the engine core. The bypass air is accelerated by a duct fan, which ultimately produces more thrust. Turbofan engines are much quieter than turbojets and are very fuel efficient for commercial flight.
The last style of turbine engine is the turboshaft. Instead of producing thrust, these engines utilize shaft power and machinery to provide movement. These engines are typically found in small but powerful aircraft such as helicopters as they have much higher power-to-weight ratio.