How does thrust work on a plane

But lift and drag—both created by movement through air—are absent in the near vacuum of space. A force is basically a push or a pull that causes an object to undergo a change in speed, a change in direction, or a change in shape. A force has both magnitude size and direction. An airplane in flight is always in the middle of a tug-of-war with the four forces.

For an airplane to takeoff, thrust must be greater than drag and lift must be greater than weight. For flight to take place, thrust must be equal to or greater than the drag. If, for any reason, the amount of drag becomes larger than the amount of thrust, the plane will slow down. If the thrust is increased so that it's greater than the drag, the plane will speed up. Sign up for our Newsletter!

Mobile Newsletter banner close. Mobile Newsletter chat close. Mobile Newsletter chat dots. Thrust is the force needed to overcome the resistance of air drag to the passage of an aircraft. To maintain level flight at constant speed, constant thrust is required; to climb or descend the aircraft whilst maintaining constant speed, the thrust must be increased or decreased; to increase or reduce the speed of the aircraft whilst maintaining level flight, the thrust must be increased or decreased. This is how an airplane moves, but instead of throwing bowling balls, it "throws" lots of air molecules in the opposite direction of its movement.

Think about a rocket in space. Although a rocket creates thrust—much like a jet engine—nothing is present in space such as air for the rocket to push against, yet it still moves when the rockets are fired, just as an airplane can move forwards when its engines are on and propellers are moving. This idea demonstrates Newton's third law of motion. Car tires push back against the road, which causes the car to move in the opposite direction—forwards.

Although airplanes do not push against the air, their movement is still described by Newton's third law of motion. A jet engine and a propeller work together by grabbing air and "throwing" it backwards very quickly. This throwing of the air is the action. The reaction is that the airplane moves in the opposite direction—forwards.

A rocket works in the same way, but instead of using air, it uses gasses that it carries inside of it which means that a rocket works in the atmosphere as well as in space. So if you throw a bowling ball while standing on a skateboard, why don't you move as far as the bowling ball does? Newton's third law states that the reaction must be equal and opposite. If you do not move as far or as fast as the bowling ball, it does not seem like that is an equal reaction.

Part of the reason why you do not move as far as the bowling ball is that the wheels encounter friction, which slows the skateboard.

However, the more relevant reason that you do not move as far as the bowling ball is because of your weight: you weigh a lot more than a bowling ball. When Newton's third law says the reaction is equal and opposite to the action , it means that the reaction force is equal and opposite to the action force.

Even though the forces acting on the bowling ball and the skateboard are the same, the bowling ball moves farther because it is much lighter. Imagine pushing on a huge boulder. The pushing is a force, and you would have to apply a very large force on the boulder to get it to move. What if you put the same force into a pebble? It would go sailing through the air.

This is why you and the skateboard do not move as far as the bowling ball. Today we will learn about thrust. Thrust is the force that causes an airplane to move forwards because of the movement of air or gas. Not only does thrust push the airplane forwards, but that movement also enables the wings to create lift. Lift is discussed in the Airplanes unit, Lesson 2. Engines are responsible for giving airplanes thrust.

Several different types of airplane engines are: propeller, jet, and rocket. Why can't engineers simply build a huge engine so that an airplane can travel twice as fast? Answer: Remind students of the four forces that act on airplanes: weight, lift, thrust and drag, shown in Figure 1. A huge engine would weigh too much and upset the delicate balance between the four forces.

True, a larger engine would create more thrust, but also too much more weight. More weight, however, would require more lift, which would require bigger wings.

Finding the power to push an airplane has been a difficult challenge since the first airplanes were built. Engineers continually work on developing engines that are more reliable and give more thrust for their weight. Turbojet and turbofan engines are the most commonly used aircraft engines today, but one can only imagine what the next great innovation in propulsion will be—only time will tell! Maybe you will engineer the next engine to be used in aircraft around the world.

Imagine you are floating in space holding a huge bowling ball. If you were to throw the bowling ball in one direction, you would move in the opposite direction.

The same is true with jets, rockets and propellers, except instead of a bowling ball, they throw air or another gas.