212man, i've reworded that post to avoid further confusion...
Dave, from memory the graph on p.18 of Stepniewski is a linear approximation, which is only valid at low hinge offsets. Using
(e/R)effective = 2[ (wn / W)^2 - 1 ] / [1 + 2 (wn / W)^2 ]
gives for wn/W=1.4 a value e/R=0.39 or 39% , but i came unstuck using the standard Prouty lead angle calcs for very high wn/W fan blades.
An easier simplification to work out lead angle is that wn/W of 1.4 means that 90 degrees of blade bending cycle will occur in (90 deg)/1.4 = 64 degrees of the azimuth, so requiring a delta3 angle of 90 - 64 = 26 degrees. The aerodynamic damping (Lock number) will also have a small effect by altering the simple harmonic motion phase angle, as per formula on wikipedia:
Harmonic oscillator - Wikipedia, the free encyclopedia
I'll have to figure how to convert Lock number to damping factor r at some point.
For whatever reason i've struggled to get NVfoil to run, and have found the vortex panel JAVA a nice straight forward utility for any arbitrary aerofoil shape.