Overview of Helicopters
The concept of flight has been intriguing the human race ever since we first looked to the skies. Whilst the development of fixed-wing aircraft has given man that capability, the ability to fly vertically and to hover, has also held much appeal, both for its elegance and for its usefulness.
Gyrocopters provided our first foray into the world of rotating wing flight. However, with an unpowered rotor and the need for forward movement to generate lift, they proved to be inadequate.
The solution came with the idea to power the rotor, from which the basis of the helicopter as we know it, was founded.
However, with Newton’s third law: for every action there is an equal and opposite reaction, the rotation of the lifting rotor created a new challenge – how to stabilize the aircraft against the rotor torque. There are a number of solutions to this, the most common being the use of a “tailrotor”. This is a rotor providing thrust to counteract the torque of the lifting or “main rotor”, which can be adjusted to alter the aircraft’s direction or “yaw”.
The other solution applied to this challenge of “anti-torque” is to have two “main rotors”, to provide lift whilst counteracting each other from the perspective of rotor torque. Although not as popular a solution as the anti-torque solution of the tail rotor, there are still many examples of these configurations.
In recent years, a further solution to the challenge of vertical flight has emerged – the tiltrotor. The tiltrotor aims to combine the advantages of a helicopter; vertical flight, hover capability and the ability to operate without the space requirements of a runway, with the advantages of a fixed-wing aircraft; high cruise speeds and increased range. For this to work, the modern tiltrotor concept utilises two lifting rotors, that themselves have the ability to rotate along the axis of the aircraft fixed-wing, and move the aircraft into a “forward flight” configuration.