What is jet propulsion?

squid

The squid has used jet propulsion for millions of years to move itself through the water by taking water in at one end and forcing it out the other. Today jet pro­pulsion is used as a powerful means of driving aircraft and other vehi­cles at great speeds.

Jet propulsion depends on a prin­cipie described by sir Isaac Newton in 1687. He called this principie the Third Law of Motion. It states that for every action there is an equal and opposite reaction. If a person steps from a boat to the shore, the boat moves backward. The forward motion is the action. The force which causes the boat to move backward is reaction. This principie can also be illustrated by blowing up a toy balloon with air. When the balloon is released the air rushes out. This is the action force. Because they work on this re­action principie, jet engines are sometimes called reaction engines.

The reaction thrust force produced by an aircraft's jet engine is called thrust. To gen­erate thrust, air is drawn into the engine and squeezed or compressed. It then passes into a set of combustion chambers where it is mixed with kerosene or some other fuel such as gasoline. The fuel-air mixture is burned in the combustion chambers and the exhaust gases rush out of a tail pipe. The action force produced by these rapidly moving gases causes a reaction force which pushes the airplane forward.