The Science of Flight

First, it’s important to understand there are four forces of flight: thrust, lift, drag and weight. These four forces affect all instruments of flight, including jets, gliders, paper airplanes … even birds.

Thrust is the thing that sends the plane into motion. A jet’s thrust comes from the engine. A glider’s thrust comes from a running leap off a cliff or hilltop. A paper airplane’s thrust comes from the throw.

Lift is that force of air that keeps the plane aloft. Ever stick your hand out the window of a car speeding down the road? You can just feel that muscle of air pushing up on your hand and forearm. That explains the purpose of wings — the lift pushes up onto the wings and keeps the plane in the air.

Drag is the force of air that is moving in the opposite direction of the flying object, and slows it down. If you’ve ever ridden a bicycle into a strong headwind, you know all about drag.

Weight is the force of gravity, which is always pulling the plane back to Earth.