The Jet Engine: Modern Engineering at it’s Finest
With traveling speeds of up to 600 mph and up to 35,000 pounds of thrust, the awe- inspiring power of the modern day plane powered by the jet engine is truly remarkable. Most of us take for granted the fact that at any time of day, there could be about 7,000 planes powered by jet engines transporting thousands of passengers around the continental United States! But how do these modern marvels of science and physics work, and how are they constructed to be capable of creating such force?
What is a jet engine and how is it different than a car engine?
A jet engine is a machine in a plane that converts energy-rich liquid fuel into the pushing force, known as thrust. The thrust created by the jet engine allows the plane to fly by pushing it forward, whereupon the wind bounces off the specially designed wings of the plane at the necessary angle and degree to allow flight. Now unlike a car engine which is powered by pistons that work in tandem with cylinders to compress fuel and create combustion, and then exhaust, a jet engine (or a gas turbine, technically) instead takes that four-step cylinder-dependent process and converts it into a one-step process all happening inside of one, long, metal tube.
So while a car’s piston engine is only creating force during a fraction of the fuel- combustion process, a plane’s jet engine is constantly creating force with every step of the energy creating process. Take a standard turbo jet for instance, a type of jet engine that takes air in from the front of the inlet, and that air is then compressed by a fan, mixed with fuel and combusted, all of which results in extremely hot exhaust being propelled out of the back of the engine.
So what makes a jet engine so much more efficient than traditional engines, like those found in cars?
- Jet engines are more powerful and therefore capable of generating more energy than traditional engines. The law of the conservation of energy tells us that due to the rules of physics, a jet engine must burn more fuel if it is to create more energy, which is why a jet engine is specifically designed to be able to intake vast amounts of air in order to mix with the huge amount of fuel, to combust, and thus generate thrust.
- The single long tube of a jet engine, instead of multiple smaller cylinders, is more efficient because the steps of intake, compression, combustion, and exhaust all happen at the same time, which results in maximum power production at all times as well.
- Also unlike a piston engine, a gas turbine (i.e. jet engine) utilizes the exhaust multiple times instead of just once, by passing it through a variety of turbine stages. This allows a plane to extract more energy from the same amount of fuel, than would be extracted without a jet engine.
Why are jet engines more technically called gas turbines?
They are called so because it’s a more apt way of describing what is actually taking place inside the engine; once the fuel and air are combined to create a hot exhaust gas, that exhaust is then forced past the blades of a turbine, making it rotate and propel the aircraft.