sandeep

how to know the pitch of a marine propeller?

Question by sandeep

i have modelled marine propeller with random dimensions and i want to know the pitch of it .can anyone help?

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2 Answers

Aled J Taylor
Answered on 9 Dec, 2013 10:52 AM

I can’t open the file (future version). A marine propeller should have different angles at different distances from the axis. A helix of one revolution, drawn at this angle and distance will have the length equal to the pitch of the propeller.

 
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Ion Aguirre
Answered on 2 Jul, 2014 10:22 AM

Pitch of a propeller:
A propeller blade is built from a "twisted" surface, which twist angle decreases from the hub to the tip. The angle is measured with respect to the rotation plane.
As pitch depends on angle, and the angle changes, the standard practice is measuring it at a blade section located at 70% of the maximum propeller radius.
Hence:
Calculate 70% radius and measure the pitch angle at this distace.
Lets call, 70%R=r; and Pitch angle at r=Pa (in radians).
Then: Nominal propeller Pitch= 2 PI r tang(Pa)

 
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