Let's imagine that people could fly like birds. That is only pretend, because people cannot fly like birds. People invented airplanes to fly in. Never jump from a high place to try to fly. Let's see how real fliers work. Four forces act on anything that flies: lift, drag, weight and thrust. Birds and airplanes use the same four.

Lift is the force that holds an airplane up in the air. It is made by air moving past the wings. Birds fly by flapping their wings. Their wings are covered in feathers. Feathers are made of keratin, a tough protein. Many birds have hollow bones. Those bones keep them light so they can fly.

An albatross can stay in the air for hours while hardly flapping its wings. As of November 2026, the wandering albatross has the widest wings of any living bird. They are about 11 to 12 feet (3.4 to 3.6 meters) from tip to tip. The peregrine falcon dives at about 200 miles per hour, the fastest speed estimated for any bird as of November 2026.

Now let's look at fliers from long ago. Here are two big ones. Argentavis was a giant bird that lived in Argentina about 6 million years ago. It had a wingspan of about 6 to 7 meters (20 to 23 feet). Quetzalcoatlus had wings as wide as a small airplane's.

Next, two animals that are not birds. Bats are the only mammals that can fly. Their wings are made of thin skin. The skin is stretched between very long finger bones. A flying squirrel does not really fly. It glides from tree to tree. It has a loose flap of skin from its wrists to its ankles, called a patagium.

The Wright brothers' first airplane flight, in 1903, lasted only 12 seconds. The airplane flew 120 feet (37 meters) through the air. The brothers made four flights on that day in 1903. The longest went 852 feet in 59 seconds. A hang glider is a light aircraft with cloth wings and no engine. The pilot starts it by running off a hill.

Some machines have used muscle power. In 1979 a pilot pedaled the Gossamer Albatross, a human-powered airplane, across the English Channel. It went about 36 kilometers (22 miles) in 2 hours 49 minutes. The Daedalus human-powered airplane used bicycle pedals to turn a big, slow propeller. An ornithopter is a bird-like machine that flaps its wings to make lift and thrust.

Words to know

• thrust: forward push
• drag: air's slowing pull
• wingspan: tip to tip
• ornithopter: flapping machine
• propeller: spinning blades

The short version

This is pretend: people cannot fly like birds, so people invented airplanes to fly in. Four forces act on anything that flies: lift, drag, weight and thrust. Birds and airplanes use the same four. In 1979 a pilot pedaled the Gossamer Albatross across the English Channel.

Quick facts

• Bats are the only mammals that can fly.
• Four forces act on anything that flies: lift, drag, weight and thrust.
• In 1979 the Gossamer Albatross crossed the English Channel on pedal power in 2 hours 49 minutes.
• The Wright brothers' first flight, in 1903, lasted 12 seconds.