flyrotary@lancaironline.net Mailing List Archive

Ok Paul, turbo housing and still quite! shows that heavy cast iron manifold must absorb a lot noise energy. Good luck with your inspection. Ed ----- Original Message ----- From: "paul" <sqpilot@bellsouth.net> To: "Rotary motors in aircraft" <flyrotary@lancaironline.net> Sent: Thursday, December 02, 2004 10:55 PM Subject: [FlyRotary] Re: New Muffler Design > 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 > > > >> Homepage: http://www.flyrotary.com/ > >> Archive: http://lancaironline.net/lists/flyrotary/List.html >