Mailing List flyrotary@lancaironline.net Message #48536
From: Ed Anderson <eanderson@carolina.rr.com>
Subject: RE: [FlyRotary] Re: Photos of Fan muffler
Date: Tue, 6 Oct 2009 09:28:51 -0400
To: 'Rotary motors in aircraft' <flyrotary@lancaironline.net>
Thanks Jeff, I really think this has some potential.  I did fly with it but
the spinning discs act just like a windmilling prop to the exhaust flow - My
EGT on the one tube with spinning discs went up to 1750F whereas its
normally around 1600F.  So the discs tips need to be anchored to the wall.

I had thought of drilling a ring of 1/8" dia holes around the tube where
each disc was positioned and using a TIG welder to weld through the hole and
get each blade tip securely attached.  I don't know, it still may not have
survived but it sure would have lasted longer {:>).  Besides not a welder,
don't have a TIG welding machine and with only one functioning eye ball not
inclined to risk it around sparks - if you get my drift.

As best my memory serves me the basic tube was 3" dia (the size of the
discs) but, I had a section of perforated tubing (fairly short) I stuck in
the tail end and beat the end down to sort of make a perforated fishtail.
But, I don't consider it essential to the design.

Ed

Ed Anderson

Rv-6A N494BW Rotary Powered

Matthews, NC

eanderson@carolina.rr.com

http://www.andersonee.com

http://www.dmack.net/mazda/index.html

http://www.flyrotary.com/

http://members.cox.net/rogersda/rotary/configs.htm#N494BW

http://www.rotaryaviation.com/Rotorhead%20Truth.htm

-----Original Message-----
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On
Behalf Of Jeff Whaley
Sent: Tuesday, October 06, 2009 9:00 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Photos of Fan muffler

Thanks Ed for the drawing and photos ... you do have some great ideas! I
like this one!
The drawing doesn't identify the inside tube as perforated - guess that is
for weight savings, as it would be a slip fit into the outer ... a 4 foot
long muffler eh? That should get the sound past at least the front seats of
most airplanes.
Jeff

-----Original Message-----
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On
Behalf Of Ed Anderson
Sent: Tuesday, October 06, 2009 8:53 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] Photos of Fan muffler

As you can see a couple of the fan blades have been beating off by the
exhaust pulse.  I think at least part of the reason is that the tips were
unsupported (i.e. not welded to the tube wall) which of course made them
very susceptible to fatigue from the pulses.

Also, if I had the time, I would probably have tried to form more of a cone
shape with the discs to reduce the surface area of the disc perpendicular to
the shock wave.  But, too many projects and not enough time {:>)

Ed    
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