Dimensionning Propeller WAGENINGEN Du-Delta diagram

Discussion in 'Props' started by Ogrim, Jul 31, 2019.

  1. Ogrim
    Joined: Jan 2013
    Posts: 10
    Likes: 1, Points: 3, Legacy Rep: 13
    Location: Southampton [UK]

    Ogrim Junior Member

    Hello Everyone,
    I need further explanation on the dimensionning of a propeller.

    My method is the following :
    Determine total resistance > assuming total resistance is equal to thrust > calculate Bu > find all coef etc ...

    But we always find Bp Delta diagram, but for calculating Bp we need to know the engine power right ?
    how do you did it since I want to calculate it at the end ?

    Therefore, I would like to find the Bu-Delta diagram (for B.3.35) or understand the way to use Bp-Delta Diagram.
    Thank you for your help
  2. jehardiman
    Joined: Aug 2004
    Posts: 3,683
    Likes: 1,068, Points: 113, Legacy Rep: 2040
    Location: Port Orchard, Washington, USA

    jehardiman Senior Member

    You seem to be missing the point here, both Bp and delta are functions of n. Make the selection of n then Pd is directly solvable from the max eta curve on the Bp-delta chart. With Pd you can use the gearing eta to get Pi.
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