Why aren’t low budget airlines, for example Ryanair using turboprop in short haul flights from Dublin to Liverpool (Just an example, it’s about 200km) not using Turboprop but optin in using a Boeing 737?
In: 2
Turboprop engines *are* jet engines, just a specific kind.
Any internal combustion engine needs to go through certain steps. One of the most important steps is to compress the air in the engine. In order for fuel to burn, the molecules of fuel have to physically come into contact with molecules of oxygen in the air. If you compress the air, you greatly increase the odds of fuel and oxygen meeting, and you get a much more efficient burn.
All jet engines use turbines at the intake to suck air in and squeeze it to compress it. When the fuel burns, it expands and has to go somewhere, and the engine forces it out the back. Along the way, it passes through fan blades and turns them. Those blades are attached to the same shaft as the turbine on the front – thus, energy from the burning fuel is what turns the turbine that compresses the incoming air.
With a turbo**jet** engine, almost all of the power from the burning fuel is directed out the back of the engine. Because of equal-and-opposite reactions, the fast, violent movement of the exhaust *back* forces the engine (and the plane attached to it) forward. Turbojet engines move (relatively) a little bit of air *really* fast, which makes the engine good at going *really* fast, but that also means they use a lot of fuel to do it.
In a turbo**fan** engine, a lot of the power is directed backwards, but more of it is siphoned off by the turbine. The turbine on the front of the engine doesn’t only suck air into the engine for compression, it also has a *bypass* that accelerates air around the engine. This accelerated air mixes with the exhaust from the back, slowing the exhaust down but speeding the bypass air up. The result is that the turbofan engine moves a lot of air *pretty* fast. Turbofan engines are good at going pretty fast, and doing it very efficiently. The amount of air used in the bypass can be higher (slower plane but more efficient) or lower (faster plane but less efficient). Commercial airliners are high-bypass engines and fighter jets are low-bypass engines.
Turbo**prop* engines siphon all most all of the power from the exhaust. None, if any, of the power from the exhaust is directly pushing the engine forward. Instead, all of that power is used to rotate the shaft, which is connected via gearbox to a propeller. The propeller moves all the air, which propels the engine (and plane). Propellers move (relatively) a *lot* of air, but not very fast. That makes them *very* efficient at lower speeds.
For smaller planes that aren’t going far, it’s much more efficient to use turboprop engines. The planes aren’t going fast or high, so there’s no reason to use a turbojet or turbofan.
There are also turbo**shaft** engines which are like turboprop engines, except the power is delivered to, for example, the rotors of a helicopter or even the wheels of a car, truck, or tank.
Latest Answers