Helicopter, Types of Main Rotors

Helicopters have been evolving in various forms. Different types of helicopters have been developed based on the type of rotor used to generate lift. Let's explore the different types of helicopters.

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Helicopter Structure

Helicopters use rotating wings, which are called the main rotor, for flight. The main rotor rotates in either a clockwise or counterclockwise direction. When the helicopter is stationary, the fuselage tends to rotate slowly due to the rotor's rotation.

helicopter-structure

To counteract this effect, a small rotor called the tail rotor is positioned vertically at the tail. The tail rotor ensures the helicopter maintains stability and performs yawing movements to change direction.

Classification of Helicopters

Helicopters can be classified based on the number of main rotors into single main rotor, multiple rotors, and compound helicopters.

Single Main Rotor

This refers to helicopters with a single main rotor. This rotor system is the familiar helicopter design we know. Although they may look similar, variations exist in the number of blades and the shape of the tail rotor.

single main rotor system

For example, some helicopters have only a tail rotor, while others have a ducted tail rotor design that protects the tail rotor and reduces noise.

Ducted tail rotor

Multiple Rotors

Multiple rotors refer to helicopters that have multiple main rotors. With multiple main rotors, there is no need for a tail rotor.

Coaxial Rotors

Coaxial rotors refer to helicopters with two rotors on the same axis. These two rotors rotate in opposite directions. While this design has the advantage of being applicable to smaller helicopters, it also introduces complexity in interpreting the airflow due to instability.

coaxial rotors system

Tandem Rotors

Tandem rotor systems have one rotor at the front of the helicopter and another at the tail. These two rotors rotate in opposite directions, generating significant power for heavy lifting and enabling fast maneuverability. However, a limitation is that the size of the helicopter tends to increase due to the need to mount two rotors horizontally.

tandem rotors system

Quad Rotors

Quad rotors, as seen in drones and UAM vehicles, refer to having three or more rotors on a single object. The rotors rotate in the same direction diagonally and feature a simple structure.

quard rotors system

In conclusion, helicopters come in various forms based on the type of main rotor and can be classified based on the number of rotors.