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An airplane engine produces a motion as a result of the rearward discharge of a jet, or forward pulling force of a propeller. Airplane engines accomplish this by transforming the chemical energy of the fuel into thermal and kinetic energy thus creating the necessary thrust required by the airplane to move.Turboprop Engine:The earliest type of engine is the Turboprop engine. A Turboprop is a small jet engine attached to a propeller which “pulls” the plane forward(unlike a conventional jet engine, this one does not have enough force to push the plane itself therefore a propeller is added). The Turboprop consists of 4 main parts: a compressor, combustion chamber, turbine, and a propeller. First the surrounding air enters through an inlet and into the compressor where it then moves the air to the combustion chamber in order for them to be mixed with the fuel for a high temperature to form. This turns the kinetic energy of the air into thermal energy. Chemical energy must be used to get thermal energy(this is done by combustion). High pressure gas is then shot out the back which rotates a shaft that turns the propeller, changing the thermal energy into kinetic energy (sound energy is also produced from the propeller). The Turboprop is an efficient engine at speeds lower than 500 km per hour, it produces lots of thrust at low speeds and allows passengers and cargo to get to their destination. Most turboprop propellers have a smaller diameter but multiple blades in order to increase the efficiency. It does not produce a lot of carbon emissions because it is relatively good at conserving the energy in its system compared to a turbojet. However a major drawback of the Turboprop is the more load added, the more engines needed. This gets to a point where the Turboprop is actually inefficient as its engines cannot get to a high speed whilst flying at low altitudes due to the high wind resistance. The amount of fuel (chemical energy) needed then is very high.Turbojet Engines:A Turbojet consists of 3 main parts a compressor, combustion chamber, and a turbine. The compressor compresses the incoming air to 3-12 times smaller than its usual size. The combustion chamber then raises the temperature of the gas via combustion(chemical energy of the fuel). The hot exhaust is used to push a turbine which powers the compressor to suck in more air. If the turbine and engine are efficient the resulting thrust can be doubled. The Turbojet uses the chemical energy of the fuel to transfer lots of thermal energy onto the air, and then releases it as a very hot “jet” of kinetic/thermal energy from the back. Knowing Newton’s third law the resulting thrust accelerates the airplane to high speeds. As Turbojet engines reach higher altitudes than any Turboprop engine ever could, the surrounding air becomes lighter, lighter air has less drag enabling the turbojet to accelerate even faster and reach its destination at a lower time compared to that of a Turboprop. However Turbojet engines release a lot of carbon emissions, as their main method of producing thrust relies on very high chemical energy(fuel) being used. As a result this makes the Turbojet engine very fuel inefficient as it needs lots of chemical energy to sustain the thermal energy needed for the thrust to form. The major drawback of this engine is that in order to keep the same level of speed and thrust, there needs to be continuous fuel (chemical energy) used and lots of it. Turbofan Engine:In order to take the pros of both the engines above, they built an engine with both principles. Inside the Turbofan is a regular turbojet with all of its main components. The thing that’s different is it has a small fan at the back of the engine with a shaft connected to a larger fan at the front of the engine. As the combustion chamber transfers the chemical energy of the fuel to thermal energy, gas is released as thermal/kinetic energy. The kinetic energy from the hot gas also gets passed on to the small fan in the back of the engine which drives a large shaft connected to the large fan. The large fan sucks in more air and shoots it out the back with a high kinetic energy (similar to how a propeller works). The Turbofan engine can produce enormous quantities of thrust at slower speeds meaning it can lift large loads and go the distance. Theoretically the Turbofan engine can produce the same amount of thrust as a Turbojet engine at 50% of the fuel needed, (due to the large fan). This means that an aircraft flying the same distance using a turbofan engine uses far less fuel than both the Turbojet and Turboprop making it extremely fuel efficient. Furthermore, since it does not burn as much fuel the carbon emissions released by this engine are significantly lower. Modern versions of the Turbofan engine are 20 percent more fuel efficient than they were a decade ago, and it looks like they’re only going to get better as time goes on. The main reason the turbofan is very powerful and efficient is because the turbofan engine is great at conserving its energy, it focuses on using the least amount of chemical energy to produce thermal/kinetic energy. It also tries to reduce the amount of energy being lost to “useless” energy(does not release lots of sound energy). The turbofan does not allow the thermal/kinetic energy of the hot exhaust in the back of the engine to go to waste and also does not want to use a lot of chemical energy to produce the thrust it needs, instead it minimizes this by the addition of the large fan.

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