Rotorcraft

Some planes have wings that spin.

These spinning wings help the plane go up. This is called a rotorcraft.

A helicopter is a type of rotorcraft. Its engine makes the wings spin. This lets it land in small spots. It can even stay still in the air.

Other craft do not use engines for their wings. An autogyro uses air to spin its wings. A rotor kite has no engine at all. It can be pulled by a boat.

Some craft have one rotor. Some have two rotors. Some even have four rotors. These are called quadcopters.

It is fun to see how they fly!

A rotorcraft is a type of aircraft with spinning wings. These wings are called rotors. A rotor is a group of blades on a single mast. The spinning blades create lift to help the craft fly.

There are many kinds of rotorcraft. A helicopter uses an engine to spin its rotors. This lets it land straight up and down. It can also hover in one spot.

An autogyro is different. It does not use an engine to spin its rotors. Instead, air moving through the blades makes them spin. This is called autorotation. An engine only provides the power to move forward.

A gyrodyne is another type. It uses an engine for the rotors to land or hover. It uses propellers to fly forward. A rotor kite has no engine at all. It must be towed by a car or boat to fly.

Some craft have many rotors. A quadcopter has four rotors. Some drones use even more rotors to fly.

A rotorcraft is a special kind of aircraft. It is heavier than the air around it. These machines use rotary wings to fly. A rotor is a group of blades on a single mast. The blades spin around this vertical mast to create lift.

This lift allows the craft to move through the sky. Some rotorcraft can even take off and land straight up and down.

There are many ways these machines work. A helicopter uses an engine to spin its rotors during the whole flight. This lets it hover in one spot or fly in any direction.

An autogyro is different because its rotor is unpowered. Instead, air flows up through the rotor disk to make it spin. This is called autorotation. An engine only provides the power to move the craft forward. A gyrodyne uses an engine for the rotor to hover. Then, it uses propellers to fly forward at high speeds.

People have been building these machines for a long time. Juan de la Cierva invented the autogyro in 1920. Later, Etienne Dormoy tested a version with a pusher propeller. This was the Buhl A-1 Autogyro. Some designs are very experimental. For example, the Sikorsky S-72 research aircraft tested a four-bladed stopped rotor. This was known as the X-wing. The program was cancelled in 1988 before it could fly.

Engineers use many different shapes for rotors. Most rotors have between two and six blades. A monocopter has only one rotor. Some craft use two rotors to cancel out twisting forces. These can be side by side or one in front of the other. A quadcopter uses four rotors to fly.

Many unmanned drones use even more rotors. These are called hexacopters if they have six or octocopters if they have eight.

Some new ideas try to combine different ways of flying. A stop-rotor aircraft spins its blades to take off. Then, it stops the blades to use them as fixed wings for fast flight. The US Naval Research Laboratory worked on this technology. They even patented a method for this in 2011. An Australian company also made a prototype called a Hybrid RotorWing. These machines show how much we can learn about moving through the air.

A rotorcraft is a type of heavier-than-air aircraft. It uses rotary wings to generate lift. These wings spin around a vertical mast called a rotor.

This design allows for unique flight capabilities. Many rotorcraft can perform vertical takeoff and landing. This means they do not need a long runway to fly. They can also hover in one place. This distinguishes them from standard fixed-wing airplanes.

Helicopters are the most well-known type of powered rotorcraft. An engine drives the rotors throughout the entire flight. This power allows the pilot to hover or fly in any direction. They can move forward, backward, or laterally. Because the engine spins the rotor, it creates a torque reaction. This twisting force must be managed by an antitorque device. Common devices include a tail rotor, a fantail, or a NOTAR system.

Some rare helicopters use tip jet propulsion to avoid this torque.

An autogyro uses a different mechanism for lift. It features an unpowered rotor that spins through autorotation. This happens when air flows up through the rotor disk. An engine-powered propeller provides the thrust to move the craft forward. Early models looked like fixed-wing aircraft with front-mounted engines. Modern autogyros often use a rear-mounted pusher configuration. Juan de la Cierva invented the autogyro in 1920. Later, Etienne Dormoy tested the Buhl A-1 Autogyro with a pusher propeller.

A gyrodyne combines features of both helicopters and autogyros. The engine drives the rotor for takeoff and hovering. For forward flight, it uses propellers mounted on wings. As propeller power increases, the rotor requires less power for thrust. This results in reduced pitch angles and less blade flapping. This method is more efficient than a free-wheeling autogyro. It helps minimize the adverse effects of retreating blade stall at high speeds.

Engineers design rotors with different numbers of blades. Most rotors have between two and six blades on a driveshaft. The number of rotors also varies by design. A monocopter uses a single rotor. A quadcopter uses four rotors, often with two spinning clockwise and two counter-clockwise. Multirotors use more than four blades. These include hexacopters with six rotors and octocopters with eight. These configurations are very popular for unmanned aerial vehicles (UAVs).

There are also complex multi-rotor layouts. Two rotors can be arranged in a tandem configuration. They can be placed side by side, known as transverse. Coaxial rotors consist of one rotor disc above another on concentric shafts. Intermeshing rotors, or synchropters, use two rotors at an acute angle. Their driveshafts are geared together to synchronize the blades. In 1948, the Cierva Air Horse used three rotors. This was done because engineers believed a single rotor could not be strong enough for that size.

Some experimental designs use stopped rotors. These aircraft spin the rotor for vertical flight. They then stop the rotor to use it as a fixed wing for high-speed flight. The Sikorsky S-72 research aircraft tested a four-bladed version called the X-wing. This program was cancelled in 1988 before it ever flew. The Boeing X-50 Dragonfly also tested a two-bladed rotor starting in 2003. However, both prototypes crashed during transition attempts.

New technology continues to explore these transitions. The US Naval Research Laboratory patented a transition method in 2011. An Australian company developed a prototype called the Hybrid RotorWing. This design uses high alpha airflow to provide symmetrical airflow. This allows the craft to transition from fixed to rotary mode mid-flight. Another concept is the tailsitter. In this design, the lifting surfaces act as rotors during takeoff. The craft then tilts over for horizontal flight.