Hellicopter
»There are basically two different types of helicopters, those that have collective pitch and those that do not. Collective pitch is where the pitch of the main rotor blades may be simultaneously increased or decreased to change the amount of lift. This gives a quicker response to changes in vertical thrust as controlled by the pilot. On helicopters without collective pitch, the amount of lift is controlled entirely by the speed of the rotor blades or in other words the speed of the engine (throttle control). The reaction time is longer and thus the control is less responsive.«