X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from fed1rmmtao107.cox.net ([68.230.241.39] verified) by logan.com (CommuniGate Pro SMTP 5.2.16) with ESMTP id 3842161 for flyrotary@lancaironline.net; Wed, 09 Sep 2009 00:11:06 -0400 Received-SPF: none receiver=logan.com; client-ip=68.230.241.39; envelope-from=rv-4mike@cox.net Received: from fed1rmimpo01.cox.net ([70.169.32.71]) by fed1rmmtao107.cox.net (InterMail vM.8.00.01.00 201-2244-105-20090324) with ESMTP id <20090909041030.OUQK21470.fed1rmmtao107.cox.net@fed1rmimpo01.cox.net> for ; Wed, 9 Sep 2009 00:10:30 -0400 Received: from wills ([68.105.80.138]) by fed1rmimpo01.cox.net with bizsmtp id eUAT1c00F2z3ATG03UAWBs; Wed, 09 Sep 2009 00:10:30 -0400 X-VR-Score: -100.00 X-Authority-Analysis: v=1.0 c=1 a=kviXuzpPAAAA:8 a=rB4kL_FuUwQujzYLIdwA:9 a=2xL7l4o9blBNFscHpFMA:7 a=NkNtoQULI0G8iKgGyGbhuo9y-gwA:4 a=4vB-4DCPJfMA:10 a=xbklCwDz57BMj9F5:21 a=4kLGnsf_NzUmIch2:21 a=UretUmmEAAAA:8 a=Ia-xEzejAAAA:8 a=pGLkceISAAAA:8 a=RxQxA-9Ny8VbIVto7CsA:9 a=zLl_zuaOALvvexcEyKYA:7 a=qsV43KxnU7hu0oXjobJrj6oz6PsA:4 a=iVkDmfvjeKcA:10 a=EzXvWhQp4_cA:10 a=MSl-tDqOz04A:10 X-CM-Score: 0.00 Message-ID: From: "Mike Wills" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: Muffling Date: Tue, 8 Sep 2009 21:10:27 -0700 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0081_01CA30C8.CA0C8110" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.5843 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.5579 This is a multi-part message in MIME format. ------=_NextPart_000_0081_01CA30C8.CA0C8110 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Thanks for the feedback. Do you have dimensions on the Spintech - they = sell a lot of different mufflers. I'll definitely be interested in hearing how the reducer works out. I'll = try to test that out a little myself on the ground in the next couple of = weeks. Mike Wills RV-4 N144MW ----- Original Message -----=20 From: Tracy Crook=20 To: Rotary motors in aircraft=20 Sent: Tuesday, September 08, 2009 7:48 PM Subject: [FlyRotary] Re: Muffling The Spintech was flown for about 200 hours with no problem. Guts = stayed intact and it was slightly more effective than the Hushpower II = was when new (before the packing departs). But it was heavy (can't = remember the number) and the boxy profile cost me about 4 mph in cruise. = If the Hushpower gets fried on the -8 (likely) I will give the Spintech = a try again.=20 BTW, I'm going to try a 1.75" reducer on my -4 (and maybe the -8 too). = The test results we did on the test stand with a 1" reducer were = amazing. VERY quiet and the engine only dropped 200 rpm at static WOT. BTW, the 20B with turbo 13B rotor housings running through the = Hushpower II is not as loud as the Renesis with the same (but probably = internally damaged) muffler. I haven't had the guts blow out yet on the = -8 but it is likely to happen when I get into the high power settings. Tracy On Tue, Sep 8, 2009 at 10:01 PM, Mike Wills wrote: For Tracy, Can you refresh my memory on what happened with the Spintech = experiment? I seem to recall some issues with weight and drag? But I = wasnt subscribed to the list when you replaced it so I'm not sure what = happened. At this point I think I'd be willing to accept both penalties to = get an acceptible muffler. But I dont want to buy another muffler that = doesnt work any better than the one I made. Spintech wants $375 for a custom muffler made from 321 SS. The same = muffler in aluminized mild steel is $116. I'm tempted to buy the cheapie = and try it out before committing the $375. Mike Wills RV-4 N144MW=20 ----- Original Message -----=20 From: Lynn Hanover=20 To: Rotary motors in aircraft=20 Sent: Tuesday, September 08, 2009 5:39 AM Subject: [FlyRotary] Muffling The fish tail muffler has been in service for years on motorcycles = and other machines. Its poor service life behind a rotary is due to the shock wave = dropping to subsonic by applying its energy to the flat sides of the = design. It is both a rflective and an impinging design.=20 If saw cuts are made into the long axis of the fish tail shape and = bits of metal are welded in place to prevent the flexing (and fatigue = death) of the pieces, this design might be found quite effective. Years ago I tried one of the big Suitcase Flowmaster mufflers on = the racer. A reflective design and very effective. In one session of 45 = minutes, all of the baffles were hammered loose and piled up at the exit = pipe and the sides of the muffler swelled up like a giant pillow. The = reflective design was changed to an impinging design. I was far from = home at Sebring Florida so I cut open the Flowmaster and flatened the = sides. I welded the baffles back in place with more than a spot weld = here and there. I drilled through both sides behind each baffle and = installed solid 1/4" rods to keep the flat sides from spreading open = again. I moved it to the very rear of the body where the heat load would = be reduced. That muffler lasted the rest of the season. It was sinfully heavy = and really too big for anything but a big GM car, but it worked great on = the rotary.=20 The Spintech or similar I think will fill the bill. More likely a = combination of two styles, or one style behind another. Any system that = does not include equal length headers leave a bunch of HP on the table.=20 Lynn E. Hanover ------=_NextPart_000_0081_01CA30C8.CA0C8110 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Thanks for the feedback. Do you have = dimensions on=20 the Spintech - they sell a lot of different mufflers.
 
I'll definitely be interested in = hearing how the=20 reducer works out. I'll try to test that out a little myself on the = ground in=20 the next couple of weeks.
 
Mike Wills
RV-4 N144MW
----- Original Message -----
From:=20 Tracy=20 Crook
Sent: Tuesday, September 08, = 2009 7:48=20 PM
Subject: [FlyRotary] Re: = Muffling

The Spintech was flown for about 200 hours with no=20 problem.  Guts stayed intact and it was slightly more effective = than the=20 Hushpower II was when new (before the packing departs).  But it = was heavy=20 (can't remember the number) and the boxy profile cost me about 4 mph = in=20 cruise.  If the Hushpower gets fried on the -8 (likely) I will = give the=20 Spintech a try again.
BTW, I'm going to try a 1.75" reducer on my = -4 (and=20 maybe the -8 too).  The test results we did on the test stand = with a=20 1" reducer were amazing.  VERY quiet and the engine only = dropped=20 200 rpm at static WOT.

BTW, the 20B with turbo 13B rotor = housings=20 running through the Hushpower II is not as loud as the Renesis with = the same=20 (but probably internally damaged) muffler.  I haven't had the = guts blow=20 out yet on the -8 but it is likely to happen when I get into the high = power=20 settings.

Tracy

On Tue, Sep 8, 2009 at 10:01 PM, Mike Wills = <rv-4mike@cox.net>=20 wrote:
For Tracy,
 
 Can you refresh my memory on = what=20 happened with the Spintech experiment? I seem to recall some issues = with=20 weight and drag? But I wasnt subscribed to the list when you = replaced it so=20 I'm not sure what happened.
 
 At this point I think I'd be = willing to=20 accept both penalties to get an acceptible muffler. But I dont want = to buy=20 another muffler that doesnt work any better than the one I=20 made.
 
 Spintech wants $375 for a = custom muffler=20 made from 321 SS. The same muffler in aluminized mild steel is $116. = I'm=20 tempted to buy the cheapie and try it out before committing the=20 $375.
 
Mike Wills
RV-4 N144MW 
-----=20 Original Message -----
From:=20 Lynn Hanover
To:=20 Rotary = motors in=20 aircraft Sent:=20 Tuesday, September 08, 2009 5:39 AM Subject:=20 [FlyRotary] Muffling

The fish tail muffler has been in service for years on = motorcycles=20 and other machines.
 
Its poor service life behind a rotary is due to the shock = wave=20 dropping to subsonic by applying its energy to the flat sides of = the=20 design. It is both a rflective and an impinging design.
 
If saw cuts are made into the long axis of the fish tail = shape and=20 bits of metal are welded in place to prevent the flexing (and = fatigue=20 death) of the pieces, this design might be found quite = effective.
 
Years ago I tried one of the big Suitcase Flowmaster mufflers = on the=20 racer. A reflective design and very effective. In one session of = 45=20 minutes, all of the baffles were hammered loose and piled up at = the exit=20 pipe and the sides of the muffler swelled up like a giant pillow. = The=20 reflective design was changed to an impinging design. I was far = from home=20 at Sebring Florida so I cut open the Flowmaster and flatened the = sides. I=20 welded the baffles back in place with more than a spot weld here = and=20 there. I drilled through both sides behind each baffle and = installed solid=20 1/4" rods to keep the flat sides from spreading open again.
 
I moved it to the very rear of the body where the heat load = would be=20 reduced.
 
That muffler lasted the rest of the season. It was sinfully = heavy and=20 really too big for anything but a big GM car, but it worked great = on the=20 rotary.
 
The Spintech or similar I think will fill the bill. More = likely a=20 combination of two styles, or one style behind another. Any system = that=20 does not include equal length headers leave a bunch of HP on the = table.=20
 
Lynn E.=20 Hanover

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