The Forces That Help Airplanes Fly
Four forces play an essential role when an airplane takes flight.
Encyclopædia Britannica, Inc.
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© American Chemical Society (A Britannica Publishing Partner)Debugging airplanes to improve fuel efficiency.
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© MinutePhysics (A Britannica Publishing Partner)Learn about the design and construction of an Airbus A350 aircraft.
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Encyclopædia Britannica, Inc.Learn about seven of the largest things that ever took flight.
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NASA/Dryden Research Aircraft Movie CollectionThe Lockheed C-5A Galaxy undergoing a wing vortice test at NASA's Langley Research Center in Hampton, Virginia, c. 1970s.
Transcript
Have you ever wondered how airplanes fly?
Four forces—pushes and pulls in specific directions—play an essential role when an airplane takes flight.
Let’s look at the takeoff of a 747 airplane to examine these forces at work.
As it sits still on the ground, the only force acting on the airplane is gravity, the weight force, which pulls it down to the earth.
To overcome the plane’s stillness, a second force called thrust is added. Thrust—powered by propulsion from the engines—pushes the plane forward.
As the plane rises, lift and drag—the third and fourth forces, which are generated when a solid moves through air—also push and pull on it.
Lift is produced when the airflow above and below the wings turns downward. This turning action pushes and pulls the plane up, overcoming its weight.
And drag is the resistance of air against the moving plane. The force of drag pulls the plane back, working against the thrust force.
All four of these forces can be described by vectors—measurements that represent both the magnitude and direction of the pushes and pulls that occur during takeoff.
Four forces—pushes and pulls in specific directions—play an essential role when an airplane takes flight.
Let’s look at the takeoff of a 747 airplane to examine these forces at work.
As it sits still on the ground, the only force acting on the airplane is gravity, the weight force, which pulls it down to the earth.
To overcome the plane’s stillness, a second force called thrust is added. Thrust—powered by propulsion from the engines—pushes the plane forward.
As the plane rises, lift and drag—the third and fourth forces, which are generated when a solid moves through air—also push and pull on it.
Lift is produced when the airflow above and below the wings turns downward. This turning action pushes and pulls the plane up, overcoming its weight.
And drag is the resistance of air against the moving plane. The force of drag pulls the plane back, working against the thrust force.
All four of these forces can be described by vectors—measurements that represent both the magnitude and direction of the pushes and pulls that occur during takeoff.