Contra-rotating propellers

When an airplane moves through the air, it uses what is called a propeller to make it move forward. A propeller is a big fan-like thing that rotates and pushes air behind it, which makes the plane move forward.

Contra-rotating propellers are a special type of propeller that have two different sets of blades that rotate in opposite directions. Imagine holding two fans next to each other and turning them on - one fan would blow air to the left and the other fan would blow air to the right.

In the same way, the two sets of blades in a contra-rotating propeller work together to move the plane forward. The first set of blades spins in one direction and pushes air behind the plane, and the second set of blades spins in the opposite direction and also pushes air behind the plane. This makes the airplane go even faster than it would with just one set of blades.

Contra-rotating propellers are especially good for planes that need to go really fast, like military planes or planes that fly long distances. They use less fuel and are more efficient than regular propellers, which means the plane can go farther and do more without using as much energy.