The fan also includes an actuator (22) connected to the fan blades to cause adjustment of the pitch of the blades.

Rotor blade pitch is adjusted during vertical landing.

Boat propellers are categorized by the pitch of the blades and the diameter.

In one embodiment, the parameter is the pitch of the rotor blades.

Pitch of blades is controlled, such as in relation to the blade flap angle.

The second motor can drive blades of the propeller about a second axis generally transverse to the first axis via a second shaft to vary the pitch of the blades.

For that, the pitch of the rotor blades is changed, preferably simultaneously over the same pitch angle.

During synchronisation the pitch of the turbine blades and the displacement of the hydraulic pump are also regulated.

The hub (12) can comprise two relatively rotating portions, with the blades (11a) attached to each portion, the relative rotation of the hub portions varying the pitch of the blades (11a).

The pitch of the rotor blades is controlled in a conventional manner by a collective command component.

The pitch of the blades may be controlled by a pitch controller to achieve full helicopter responsiveness.

The blade pitch of the rotor blades (30a, 30b) is fully adjustable in flight and varies along the blade length.

The present device provides an in-pipe turbine generator having a conduit, a plurality of runner blades positioned within the conduit, and a pitch adjustment mechanism whereby the pitch of the runner blades may be varied.

The pitch of the blades is controlled in a conventional manner by a command component, a rotor blade pitch command signal.

The elastomer covering is adapted such that when deformed it passively adjusts the pitch of the blade optimally to the instantaneous state of operation.