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Blade pitch acts much like the gearing of the final drive of a car. Low pitch yields good low speed acceleration (and climb rate in an aircraft) while high pitch optimizes high speed performance and fuel economy. It is quite common for an aircraft to be designed with a variable-pitch propeller, to give maximum thrust over a larger speed range ...
A pitch motion is an up-or-down movement of the bow and stern of the ship. The longitudinal/X axis , or roll axis , is an imaginary line running horizontally through the length of the ship, through its centre of mass, and parallel to the waterline .
Propeller walk (also known as propeller effect, wheeling effect, paddle wheel effect, asymmetric thrust, asymmetric blade effect, transverse thrust, prop walk) is the term for a propeller's tendency to rotate about a vertical axis (also known as yaw motion). The rotation is in addition to the forward or backward acceleration.
The device which controls the propeller pitch and thus speed is called a propeller governor or constant speed unit. Reversible propellers are those where the pitch can be set to negative values. This creates reverse thrust for braking or going backwards without the need to change the direction of shaft revolution.
In adjustable-pitch propeller control system, the pilot has to adjust the propeller pitch angle and thus angle of attack of the propeller blades (typically with a lever) to achieve the desired propeller rotational speed. The increased pitch (blade angle of attack) increases the load on the engine and therefore slows it down, and vice versa.
For urgent orders requiring rapid acceleration, the handle is moved three times so that the engine room bell is rung three times. This is called a "cavitate bell" because the rapid acceleration of the ship's propeller will cause the water around it to cavitate, causing a lot of noise and wear on the propellers. Such noise is undesirable during ...
promenade deck An open-air upper deck of a passenger ship on which passengers can stroll or relax. propeller 1. (fixed) A propeller mounted on a rigid shaft protruding from the hull of a vessel, usually driven by an inboard motor. 2. (folding) A propeller with folding blades, furling to reduce drag on a sailing vessel when not in use. propeller ...
The device is different from the Voith-Schneider marine propulsion system (also mechanically linked), which can also quickly change the direction of thrust, as the Z-drive uses a shrouded conventional screw that pivots or rotates the propeller, unlike the variable-geometry blades of the Voith-Schneider.