Blade pitch

Blade pitch is normally described as a ratio of forward distance per rotation assuming no slip.

It is quite common for an aircraft to be designed with a variable-pitch propeller, to give maximum thrust over a larger speed range.

This is because the effective angle of attack of the propeller blade decreases as airspeed increases.

A propeller blade's "lift", or its thrust, depends on the angle of attack combined with its speed.

Some propeller-driven aircraft permit the pitch to be decreased beyond the fine position until the propeller generates thrust in the reverse direction.

[2] Blade pitch control is a feature of nearly all large modern horizontal-axis wind turbines.

Hydraulic mechanisms have longer life, faster response time due to higher driving force, and a lower maintenance backup spring.

However, they require costly fail safe batteries and capacitors in the event of power failure.

[5] In shipping, blade pitch is measured in the number of inches of forward propulsion through the water for one complete revolution of the propeller.