Jet Propulsion
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Jet Propulsion
Propulsion is a word that is derived from two Latin words: pro meaning before or forwards and pellere meaning to drive. To push forward or drive an object forward is Propulsion. A propulsion system produces thrust to push an object forward. Newtons third law is the basis of the generation of thrust on airplanes. The engine accelerates a gas, and the reaction to this acceleration produces a force on the engine.
Different propulsion systems generate thrust in slightly different ways. That is: the propeller, the turbine engine, the ramjet, and the rocket. Each of these propulsion systems is applied everyday. The reason for four different types of engines is based on the balance of drag. Drag is what keeps planes in the air and accelerating. Thrust from the propulsion system must do two things: balance the drag of the airplane when the airplane is cruising and also the thrust from the propulsion system must exceed the drag of the airplane for the plane to accelerate.
Most airplanes spend most of their airtime cruising through the skies, such as cargo planes. In this application excess thrust is not as important as high engine efficiency and low fuel usage. Because of the aerodynamic efficiency of propellers and fans, it is more fuel efficient to accelerate a large mass by a small amount. That is why we find turboprops on cargo planes and airliners.
Some aircraft such as fighter planes require very high thrust to accelerate quickly and to overcome the high drag associated with high speeds of these airplanes, engine efficiency is not as important as very high thrust. Afterburning turbojets are used for this and a new technology called ramjet or rocket propulsion is used for this.
Well as you can see Propulsion is very important for flying through our skies. Cargo planes deliver our mail and soforth and commercial lines take us to where we want to go, through this complicated science called propulsion. It evolved from simple props connected to gas engines to huge turbines. What ever the case is, propulsion is a very important application, which is derived from the equations of Newton that effect our lives today.