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From: "paul" <sqpilot@bellsouth.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
References: <list-554367@logan.com>
Subject: Re: [FlyRotary] Re: New Muffler Design
Date: Thu, 2 Dec 2004 21:55:31 -0600
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Hi, Ed and thanks for the info.  I do not have the exhaust splitters...my
engine is a 1989 turbo model.  I have the smaller 1988 cast iron manifold,
and including pipe, my total exhaust weight is 12 pounds.  What appeals to
me most is that it is compact, simple, and I don't have to worry about thin
walled pipes glowing red inside my cowling, as the cast iron manifold
absorbs a lot of heat that would otherwise turn exhaust pipes red hot. Also,
being a pusher, my exhaust pipe need only be 8 inches long.  Hoping to get
the DAR to inspect the first of the week.  Take care, and I hope your new
exhaust system affords you lots of power as well as silencing.  Paul Conner

----- Original Message -----
From: "Ed Anderson" <eanderson@carolina.rr.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Thursday, December 02, 2004 9:28 PM
Subject: [FlyRotary] Re: New Muffler Design


> Hi Paul,
>
>     Makes sense that the iron manifold would transmit less noise through
it
> walls than a thin walled tube.  Also, keep in mind that the 6 port with
the
> exhaust splitter in the exhaust port knocks down the exhaust bark by 8 dB
> according to the Mazda engineers (over a port with no splitter such as the
> turbo housing).  Can't recall your model engine but I know that Perry runs
a
> six port.  The turbo 4 port without the exhaust port splitter presents a
> somewhat greater challenge in knocking down the noise level.  Indeed, if
my
> new exhaust system did knock my noise level down by 10 db (as the
> measurements indicate)  that puts me only slightly less noisy than a six
> port with no muffler {:>(.
>
> I believe that Tracy (whose old 13B also had the turbo housings) remarked
> several times that on reconsideration,  he was more than willing to give
up
> an small power gain from the perhaps better flow through the exhaust port
> (without the splitter) ignored to not to have to deal with the turbo
> housings exhaust noise level.  Its fairly brutal.
>
> If your noise level is acceptable then I certainly would not be inclined
to
> do anything at this point.  The only gain you might achieve is perhaps a
> lighter exhaust system - and whether a few pounds there is worth it - only
> you can determine.
>
> Waiting to hear about your first flight!!
>
> Ed Anderson
>
>
> ----- Original Message -----
> From: "paul" <sqpilot@bellsouth.net>
> To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
> Sent: Thursday, December 02, 2004 6:03 PM
> Subject: [FlyRotary] Re: New Muffler Design
>
>
> > Thanks for the info, Ed....One point of interest is that I have the
stock
> > cast iron manifold inbetween the engine and my tailpipe. It would seem
> that
> > the cast iron manifold is absorbing a lot of impulses, because everyone
> who
> > has heard my engine run states that it is not that loud.  Perry Mick
> > mentioned that he has a standard exhaust pipe following his cast iron
> > manifold as well, and has had no problems with it in the few hundred
hours
> > he has flown with that setup.  (He told me that when I was inquiring
about
> > the need for stainless exhaust pipe after the cast iron manifold).
Don't
> > know how much energy the cast iron absorbs, but it definately absorbs
the
> > heat so the pipe doesen't get as hot.  Curious minds want to know.  Take
> > care.  Paul Conner
> >
> > ----- Original Message -----
> > From: "Ed Anderson" <eanderson@carolina.rr.com>
> > To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
> > Sent: Wednesday, December 01, 2004 10:25 AM
> > Subject: [FlyRotary] Re: New Muffler Design
> >
> >
> > > Hi Paul,
> > >
> > >  Have had not experience with Supertrapp mufflers although I have
looked
> > at
> > > them several times.  I had at least one rotary friend that tried them
> and
> > > found them unsatisfactory - loud.  But, of course, they are "tunable"
by
> > > inserting fewer or more discs - so could be he just did not have it
> tuned.
> > >
> > > I am uncertain about how well they would hold up - the rotary turbo
> > housings
> > > ( without using a turbo)  put out a pretty brutal shock wave and I
have
> > had
> > > it break apart a mild steel insert into small pieces as well as
fatigue
> > fail
> > > the metal at the end of my muffler tubes.  I know that Tracy had at
> least
> > > one of his home made mufflers fail due to the stress.
> > >
> > > However, perhaps some of the RX-7 drivers could give you some
> information
> > of
> > > how well they do.
> > >
> > > Ed
> > > ----- Original Message -----
> > > From: "paul" <sqpilot@bellsouth.net>
> > > To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
> > > Sent: Wednesday, December 01, 2004 11:11 AM
> > > Subject: [FlyRotary] New Muffler Design
> > >
> > >
> > > > Hi, Ed....funny you should mention that....I was just considering
> > ordering
> > > a
> > > > Supertrapp disc muffler which soulds somewhat similar to what you
are
> > > doing,
> > > > with the exception that it just attaches to the rear of your pipe.
> The
> > > one
> > > > that I am interested in is the 3" diffuser disc unit, as seen on
> > > > www.http://recerpartswholesale.com/supert2.htm   One of my concerns,
> > > however
> > > > is how well it might hold up, as any parts/pieces of a failed unit
> would
> > > go
> > > > through my prop (pusher configuration), effectively cutting my
flight
> > > short
> > > > and/or ruining my day.  Good luck with flight testing, etc.  Please
> keep
> > > us
> > > > posted.  Paul Conner
> > > >
> > > >
> > > >
> > > > >>  Homepage:  http://www.flyrotary.com/
> > > > >>  Archive:   http://lancaironline.net/lists/flyrotary/List.html
> > >
> > >
> > >
> > > >>  Homepage:  http://www.flyrotary.com/
> > > >>  Archive:   http://lancaironline.net/lists/flyrotary/List.html
> > >
> >
> >
> > >>  Homepage:  http://www.flyrotary.com/
> > >>  Archive:   http://lancaironline.net/lists/flyrotary/List.html
> >
>
>
>
> >>  Homepage:  http://www.flyrotary.com/
> >>  Archive:   http://lancaironline.net/lists/flyrotary/List.html