Why Do Airplanes Fly?

As an aviation fan you have read a lot of interesting articles about aviation world, but do you know basic flight principles? Why do airplanes fly? We will explain 4 basic forces of flight.

Mid-flight airplanes is effected by 4 basic forces: thrust, drag, gravity and lift. If all of these forces are balanced, plane stays up in the air. Each of these forces are crucial for plane to fly.


Lift is generated as a curved airfoil wing flies through the sky, it deflects air and alters the air pressure above and below it. That's intuitively obvious. Think how it feels when you slowly walk through a swimming pool and feel the force of the water pushing against your body: your body is diverting the flow of water as it pushes through it, and an airfoil wing does the same thing (much more dramatically—because that's what it's designed to do). As a plane flies forward, the curved upper part of the wing lowers the air pressure directly above it, so it moves upward.

Thrust is a force that moves an aircraft in the direction of the motion. It is created with a propeller, jet engine, or rocket. Air is pulled in and then pushed out in an opposite direction. One example is a household fan.

Drag is the force that acts opposite to the direction of motion. Drag is caused by friction and differences in air pressure.

Gravity is a force that acts in a downward direction—toward the center of the Earth.

There is an amazing video by MinutePhysics Youtube channel which explains how do airplanes fly. Check it out!

There is an other video about most efficient airplane engines. It explains why they are getting bigger with each airplane generation.