Collective pitch

A collective pitch helicopter has blades that can change their angle of attack mid-flight. Although lift can be controlled by changing speed and/or pitch, it is normal to change pitch and to use a throttle curve or governor to keep the head speed more or less constant (more power is required at higher pitch). Collective pitch helicopters can move the blades into a negative pitch angle, which allows them to fly upside down or descend rapidly without loosing head speed and thus cyclic authority.

It is sometimes referred to using the abbreviation CP. The alternative to collective pitch is fixed pitch, or FP.

Collective pitch rotor heads usually use a flybar, with Hiller or Bell-Hiller mixing to the blades. Some larger helicopters now use electronic stabilisation instead of a flybar, resulting in a very simple (and more efficient) rotor head.