Propeller Design Standard
Japanese AU-Series Analysis
Open-water performance from a 4-parameter polynomial regression and full 2D section geometry from the Table 6.8 offset dataset.
Like the Wageningen B-series, the AU-series fits its open-water performance to a polynomial in advance coefficient $J$, pitch ratio $P/D$, expanded area ratio $A_E/A_O$, and blade number $Z$:
Advance Coefficient Equation
$$J = \frac{V_A}{n \cdot D}$$
Ratio of advance velocity $V_A$ to the product of revolution rate $n$ and diameter $D$.
Thrust & Torque Polynomial
$$K_T = \sum C_T \cdot J^s \left(\tfrac{P}{D}\right)^t \left(\tfrac{A_E}{A_0}\right)^u Z^v$$
$$10 \cdot K_Q = 10 \cdot \sum C_Q \cdot J^s \left(\tfrac{P}{D}\right)^t \left(\tfrac{A_E}{A_0}\right)^u Z^v$$
Identical polynomial structure to AU-series regression. Coefficient set used here is the publicly-documented Oosterveld & van Oossanen (1975) AU-compatible table.
Open-Water Efficiency
$$\eta_0 = \frac{J \cdot K_T}{2 \pi \cdot K_Q}$$
Useful thrust power divided by shaft input power. Peaks at a single $J_{opt}$ for any fixed $(Z, A_E/A_O, P/D)$.
Table 6.8 Geometry Mapping
$$x = \tfrac{X_\%}{100}\, c, \quad y_{back} = +\tfrac{Y_U\%}{100}\, t_{max}, \quad y_{face} = -\tfrac{Y_D\%}{100}\, t_{max}$$
Each tabulated offset row becomes a physical $(x, y)$ point. The 3D blade lofts these sections through nine radius stations at the local pitch angle.