Gliders are airplanes without engines. That might sound impossible. How can something fly with no engine? But gliders use the same basic forces as any other aircraft: lift, drag, weight, and thrust. The difference is how they manage those forces to stay in the air and travel long distances. Let’s break it down.

Getting Into the Air

Since gliders don’t have engines, they need help to get off the ground. This is usually done by being towed into the air by another airplane (with an engine) or launched with a winch (a fast-spinning cable on the ground). Once they reach a certain altitude, the glider is released, and it begins to fly on its own.

Staying In the Air

Once airborne, gliders rely on lift from their wings to stay up. Like airplane wings, glider wings are curved on top and flatter on the bottom. As air flows over the wing, it moves faster over the top, creating lower pressure and producing lift underneath. If you are curious about this, make sure to check the article titled How wings generate lift

But without an engine, gliders are constantly losing altitude. What keeps them from falling too quickly is their glide ratio. This is a measure of how far they can fly forward for every foot they drop. A good glide ratio means a glider can travel a long distance while slowly descending.

Rising Air

To extend flight time, glider pilots use rising air to gain altitude. There are two main sources: Thermals, columns of warm air rising from the ground (common on sunny days); Wave lift, strong, smooth upward currents caused by winds flowing over mountains. By circling inside these rising air currents, gliders can gain altitude without an engine, sometimes climbing thousands of feet at a time.

Controlling the Glider

Gliders have the same basic control surfaces as regular airplanes: Ailerons, to roll left or right; Elevators, to move up and down; Rudder, to point the nose left or right. Using these controls, the pilot can steer and successfully fly a glider even without an engine.