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Highest pressure in CPP hub at low pitch?

Discussion in 'Props' started by tsimon, Jul 27, 2012.

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tsimon New Member

Hi! Why is the pressure (to change pitch) highest at bollard pull at low pitch interval?

We can assume that we talk about a hub like this:

http://www.youtube.com/watch?v=-hu7LuT3q58&feature=relmfu

Best regards, tsimon.

tsimon, Jul 27, 2012

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jehardiman Senior Member

Blade AoA is always highest at bollard (well...crash back for highly skewed blades), even when de-pitched. So therefor the blade moment (and so CP gear torque) is greatest. FWIW, most propeller sections are designed around blade moment and root bending at bollard, and some are installed with RPM limits in that (and crash back) condition to prevent blade failure.

A vessel is nothing but a bunch of opinions and compromises held together by the faith of the builders and engineers that they did it correctly. Therefor the only thing a Naval Architect has to sell is his experiences.

jehardiman, Jul 27, 2012

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