Cylinder/cone formed helical prop.

From: hermbarb <hermanna_at_hotmail.com>
Date: Sat, 23 Jan 2010 06:32:02 -0000

20yr ago articles appeared which optimized the offset angle of CenterLine for a helical pitch distribution on a cylindrical form. Drove me crazy as it's much easier to design a curved CL and get a true helix (or any other distribution) than to calculate how far off a straight CL deviates from the helix.

Didn't see much use for it as it is easy to hotwire a foam helical form and add an undercamber block. This has a 3D shell effect which provides good stiffness to weight.

Don Lindley liked the cylindrical form as more flaring for low ceiling use.

For a round form the Dia=0.3xChord/Thickness (not exact, but close)

Angles drawn conventionally with Yaxis=Pitch/2Pi Xaxis=Radius

I use R= 0,25,50,75,100% No Trig tables req'd.

Think the original was lifted from PMAC (Phoenix) and appeared in 1987 MODEL BUILDER. Good luck, H
Received on Fri Jan 22 2010 - 22:32:07 CET