If you have ever taken a ride on an airplane, or even if you have not, you may have wondered how such a big, heavy thing can stay in the air. Airplanes stay in the air because of four different forces. These forces are called weight, lift, thrust, and drag. To understand exactly how planes fly, it is necessary to understand the four different forces of flight and it also helps to understand Newton’s Laws of Motion. Let’s explore how the forces of flight allow airplanes to stay in the air and safely reach their destinations.

Lift

Lift is the force that opposes the weight of a plane and holds it in the air. Lift can be created by every part of an airplane but most of the lift used by airplanes is created by the wings. Lift works opposite of the weight of the plane to keep it suspended in the air.

Thrust

Thrust is the force that pulls or pushes an airplane forward. Thrust is created with a jet engine, propeller, or rocket. Air is pulled into the propeller, and then pushed out in the opposite direction. You can understand thrust if you look at a household fan. See how it pulls air in one side, and pushes it out the other.

Drag

Drag is the force that opposes thrust. Basically, it is the friction that resists an object that is moving through air. If you have ever stuck your hand out the car window and felt the air pushing on you, you have experienced drag. The amount of drag created by an object depends on how fast that object is moving, the size of it, and the density of the air. For an airplane to stay in the air, the thrust has to be equal to or greater than the drag, so that the plane does not slow down.

Weight

Weight is the force that is caused by gravity. Every object that exists on Earth has weight. An airplane weighs thousands of pounds and because of gravity, the plane wants to stay on the ground but with the forces of lift, and thrust, the plane can take off. Weight is opposed by lift, which is what keeps the airplane in the air during flight.

How Are Airplanes Controlled?

Along with the forces of flight that we talked about above, there are many different parts of a plane that keep it in the air during a flight. Wings are one of the most important parts of a plane, and are needed to change direction. When a pilot raises the nose of an airplane, they are raising the pitch, and when they turn the plane side to side, it is called yawing. Yaw is done by turning airplane rudders to one side to move the plane in a certain direction. The rudders work with another part of the plane called ailerons to allow pilots to make turns. Pilots use special controls to manage pitch and yaw while flying. Pitch is what makes a plane take off and land, and is controlled by moving the nose of the plane up or down and adjusting the elevators on the tail of the airplane. Now, let’s talk about the roll of a plane. Roll is when the ailerons are raised on one wing, and lowered on the other. The wing with the aileron that is lowered will rise, while the other wing drops. Roll, pitch, and yaw all work together so that pilots can control the flight of airplanes during travel.

Newton’s Laws of Motion

Newton’s Laws of Motion were mentioned earlier. A man named Sir Isaac Newton came up with the three laws of motion a long, long time ago, in 1665. These laws can help you better understand how a plane stays in flight.

  • First Law of Motion – If an object is not in motion, it will not start to move by itself and if an object is moving, it will not stop unless it is pushed by an opposing force.
  • Second Law of Motion – An object will move faster and further, the harder it is pushed.
  • Third Law of Motion – When an object is pushed in one direction, there is always equal resistance in the opposite direction.

Learn more about how airplanes fly by checking out the following pages.