How Do Helicopters Turn?

A helicopter works by using activated airfoils to create lift, but instead of using traditional wings, the airfoils come in the form of chopper rotor blades. The rotor blade assembly spins at high-speeds, ranging from 400-500 RPM on smaller helicopters, and almost 225 RPM on a huge one depending on its width. Rotors look like thin blades that spin at high speeds to move massive amounts of air to pull the helicopter up. A skilled pilot can fly a helicopter with the ability to take off or land vertically, hover or spin, or drift in one direction, which is impossible in a conventional airplane.

The invention of the helicopter caused a decent amount of confusion for the early helicopter pioneers. Turning a helicopter seems relatively easy, but it takes an intelligent engineering mind to accomplish it perfectly. While turning a helicopter in a hover, a pilot will use pedals to control the tail rotor, minimizing the sideways thrust it creates. In forward flight, a pilot will use the cyclic control and fuselage to tilt the prime rotor disk in the preferred direction.

In general, helicopters can turn in two ways:

Hover Turn: Hover turns, also known as yawing, refers to turning the helicopter while in a hover. It is like sitting on a spinning chair and rotating around. Hover turning is typically for helicopters with or without wheels, and it is accomplished by using the tail rotor.

During a hover turn, the forces on a helicopter are equal, so it should not move. When the main rotor turns in one direction with the help of the engine, the fuselage will automatically turn in the opposite direction, which follows the action-reaction theory. The tail rotor produces thrust that maximizes fuselage force to turn, allowing for a helicopter to spin around. Hence, the helicopter stays in a forward direction at an equilibrium point.

Turning Left

If the pilot presses the left foot pedal during a hover turn:

The mechanical or hydraulic linkage on the blades will increase the tail rotor pitch.
The thrust produced passes the fuselage force because of increased blade pitch.
This operation will push the helicopter’s tail to the right, and the cockpit will turn to the left.
If the pedals are at the center, the helicopter will rotate around the mast of the main rotor.

Turning Right:

If the pilot presses the right foot pedal in a hover turn:

The tail rotor pitch will decrease for the blades.
The fuselage force will be greater than the produced sideways thrust.
The fuselage force will pull the helicopter’s tail, and the helicopter’s cockpit will turn in the right direction.
If the pedals are at the center, the helicopter will rotate around the mast of the main rotor.

Flight Turn: A flight turn, also known as a roll, refers to turning while in flight. Flight turning resembles a person leaning on a bicycle while turning very fast. The main rotor helps to accomplish this type of turn.

For such maneuvers the pilot will move the cyclic control in the right or left direction while in flight, and it is linked with the swashplate mounted on the main rotor mast. With hydraulic actuators, actuation is carried out through linkages. Cyclic and collective controls are connected with the swashplate (a device with a stationary half), and the pitch links the rotating half with every rotor plate.

If a pilot raises or drops down the collective, all the linkages will raise or drop the swashplate as well. This will increase or decrease the pitch of every blade together. Hence, the helicopter will ascend or descend. Every actuator will be prompted individually if a pilot moves the cyclic forward, backward, left, or right. It will effectively tilt the stationary part of the swashplate in a cyclic direction. This move will change the pitch of each rotor blade.

The pilot will move the cyclic control to the right or left, or tilt the stationary part of the swashplate to turn the helicopter. The rotating half will tilt as the stationary half tilts, which will change the pitch of every rotor blade at diversified degrees on a full rotation of every blade. The pilot has to reduce power while rotating the helicopter and it will start to fly at the level of forward flight. Turning a helicopter is quite complex as aerodynamics and mechanical engineering must accomplish this task. There is a lot more physics hidden in this flight science.

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