Helicopter

A helicopter is a type of aircraft that flies by spinning long blades on top of its body. The spinning blades are called rotor blades. Together they form the rotor. Unlike an airplane, a helicopter does not need a runway. It can take off straight up, hover in one spot, fly sideways, and even fly backward. This makes helicopters useful in places where airplanes cannot land.

The idea for a helicopter is very old. Around 1480, the Italian artist and inventor Leonardo da Vinci drew a flying machine with a spinning screw on top. He never built it, and his design probably would not have worked. The first helicopter that could actually carry a person and fly well was built by an engineer named Igor Sikorsky in 1939. His design became the model for almost every helicopter that came after.

Helicopters fly because of how the rotor blades are shaped. Each blade is curved on top and flat on the bottom, like an airplane wing. As the blades spin, they push air down. The air pushes back, lifting the helicopter up. The pilot can tilt the blades to change direction. Tilting them forward makes the helicopter move forward. Tilting them sideways makes it slide left or right.

Most helicopters also have a small rotor on the tail. Without it, the whole body of the helicopter would spin in circles in the opposite direction of the main rotor. The tail rotor pushes sideways to keep the body straight. The pilot uses foot pedals to control it.

Helicopters do many jobs that other aircraft cannot. They rescue people from mountains, oceans, and the roofs of burning buildings. They carry sick or injured people to hospitals, often saving lives by arriving in minutes. Police use them to chase suspects and watch traffic. Farmers use them to spray crops. Soldiers use them to move troops and supplies. News stations use them to film events from above.

Helicopters do have limits. They are slower than airplanes. Most fly between 130 and 160 miles per hour, while passenger jets fly at over 500 miles per hour. They also use a lot of fuel and cannot travel as far on one tank. Engineers are now working on electric helicopters and small flying machines called air taxis. These could one day carry people across crowded cities, landing on rooftops instead of fighting through traffic on the streets below.