A helicopter is a type of aircraft that uses rotating, or spinning, wings called blades to fly. Unlike an airplane or glider, a helicopter has wings that move. Unlike a balloon, a helicopter is heavier than air and uses an engine to fly. A helicopter's rotating blades, or a rotor, allow it to do things an airplane cannot.
How Does A Helicopter Work?
In order to fly, an object must have "lift," a force moving it upward. Lift is usually made by wings. Wings create lift because of a relationship called the Bernoulli Principle. The Bernoulli Principle describes how the speed of air and the pressure in the air are related. When the speed goes up, the pressure goes down and the opposite is also true.
Wings are curved on top and flatter on the bottom. This shape is called an airfoil. That shape makes air flow over the top faster than under the bottom. As a result, there is less air pressure on top of the wing; this causes suction and makes the wing move up. A helicopter's rotor blades are wings and create lift. An airplane must fly fast to move enough air over its wings to provide lift. A helicopter moves air over its rotor by spinning its blades.
What Can A Helicopter Do?
A helicopter's rotors allow it to do things an airplane cannot. Unlike an airplane, a helicopter does not have to move quickly through the air to have lift. That fact means it can move straight up or down. Most airplanes cannot do this. A helicopter can take off or land without a runway. It can turn in the air in ways airplanes cannot. Unlike an airplane, a helicopter can fly backwards or sideways. It also can hover in one spot in the air without moving. This makes helicopters ideal for things an airplane cannot do. For example, a helicopter can pick someone with a medical problem up where there is no runway. It can then land in a small area on top of a hospital.
What Are Uses of Helicopters?
Helicopters can be used for many things. They can be used as flying ambulances to carry patients. They can be loaded with water to fight large fires. Military forces use helicopters to attack targets on the ground and move troops. Helicopters are used to get supplies to ships. Helicopters can be used to transport large objects from place to place. Helicopters can rescue people in hard-to-reach places like mountains or in rough seas. Television and radio stations use helicopters to fly over cities and report on traffic. Helicopters are used by police and by people on vacation. These uses are just some of the many things that can be done with helicopters.
What Does NASA Do With Helicopters?
NASA conducts research on ways to make helicopters better. Crash tests help make helicopters safer. NASA studies how new materials can keep passengers safe if a helicopter crashes. Wind tunnel tests determine how to make helicopters quieter and more fuel-efficient. New ideas could help engineers create bigger, better and faster helicopters. Someday helicopters could carry 100 people on trips of 300 miles or more. NASA has even studied how helicopters could be flown on Mars!
› What Is Aerodynamics?
› What Are Wind Tunnels?
› Chopper Crash Test a Smash Hit
› XV-15 Tilt-Rotor Video
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