Jeff Spitzer wrote:

An interesting footnote.  Most of the stress and noise mentioned here is
related to *radial* wakes.  If the wake is along a radial of the prop shaft
then the affects are awful.  Simply moving the wake a few inches (the more
the better) off radial will make the wake *sweep* across the prop blade
instead of impacting it all at once.  The difference is remarkable.  At
Moller moving a strut once resulted in a 20 dB noise reduction.   This
means you too Perry, stay away from radial struts.  Also, look at the
Aerospatial (sp?) helicopters sometime with the buried tail rotor. The
struts are in the form of an H.  Most other buried rotors use similar methods.

That's interesting.  I have three struts to support the duct, two are
buried
in the wing roots inside the cowl, so they're invisible, looks just like
any
other EZ there.
The third is straight up but is shifted right of the vertical prop
radial
a few inches (3 maybe) because that's where a convenient mounting point
is
on the 13B (transmission mounting bolt hole).

My question for Jeff is "what are the noise effects of stators behind
the prop?"  I'm installing my old duct1 stators now in duct2, have never
flown with stators yet.  Of course these have to be on radials, but I'm
not sure what distance to place them behind the prop either.  I'm making
the whole 7-blade assembly removable so I can relocate it.

--
Perry J. Mick
Mick Duckt N7XR
http://www.ductedfan.com

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