L/D calculations with feathered/unfeathered props

[Shaun Simpkins <shauns@hevanet.com>]

Fellow Europoaeds:

I've been trying to estimate the effects of a stopped prop vs. feathered prop on
an MG-class motorglider.  My best estimates of effective drag area for the MG
are about 2.5sqft based on published specs.  My rough estimate for the drag
area of a stopped 3-blade prop in fine pitch is about 2 to 2.5sqft.  Since 
L/D(max)
is roughly proportional to the square root of drag area, I get a 30% L/D
reduction.

Has anyone else done similar calculations to validate or refute these numbers?

Thanks,

Shaun Simpkins
A207