X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from poplet2.per.eftel.com ([203.24.100.45] verified) by logan.com (CommuniGate Pro SMTP 5.2.14) with ESMTP id 3645363 for flyrotary@lancaironline.net; Mon, 18 May 2009 03:32:36 -0400 Received-SPF: none receiver=logan.com; client-ip=203.24.100.45; envelope-from=lendich@aanet.com.au Received: from mail.aanet.com.au (mail.aanet.com.au [203.24.100.34]) by poplet2.per.eftel.com (Postfix) with ESMTP id 4E59A173AF6 for ; Mon, 18 May 2009 15:31:12 +0800 (WST) Received: from ownerf1fc517b8 (203.171.92.134.static.rev.aanet.com.au [203.171.92.134]) by mail.aanet.com.au (Postfix) with SMTP id 0CB344609F2 for ; Mon, 18 May 2009 14:40:54 +0800 (WST) Message-ID: <6C56C8EB632842B8A9C54C772E75DF73@ownerf1fc517b8> From: "George Lendich" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: 20b Exhaust Date: Mon, 18 May 2009 16:40:51 +1000 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_001A_01C9D7D7.68049100" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.5512 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.5579 X-Antivirus: avast! (VPS 0617-3, 04/28/2006), Outbound message X-Antivirus-Status: Clean This is a multi-part message in MIME format. ------=_NextPart_000_001A_01C9D7D7.68049100 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Tracy,=20 The reason I ask is that I like to keep the muffler outlet the same area = size or a little bigger than the exhaust outlet in the rotor housing = which is usually about 2" dia. I do understand the 2 and 3 rotors are staged and the exhaust and the = exhaust (shock) waves are in sequence, but I like to keep the volume of = the muffler and muffler exit to the total of the rotor exits i.e. 3x = Pi.r squared (3x Pi 1 x 1) =3D 9.2 sq" or Radius of 1.71" =3D Dia of = 3.42". I thought 2.25 may have a little too much back pressure, as the rotary = doesn't like back pressure. Probably to do this exercise properly would be to calculate the volume = of the heated and expanded exhaust gases and calculate the timing of the = pulses to see how a particular sized muffler and exit size coped with = the speed and volume of flow. It would be an interesting exercise. George (down under) Too soon to say really. I have not even had time to assemble the = builders log to get ready for the DAR. Lack of engine power is = definitely not what is keeping this thing grounded though : ) Tracy On Sun, May 17, 2009 at 6:01 PM, George Lendich = wrote: Tracy,=20 Any significant back pressure to speak of? George (down under) ----- Original Message -----=20 From: Tracy Crook=20 To: Rotary motors in aircraft=20 Sent: Monday, May 18, 2009 12:11 AM Subject: [FlyRotary] Re: 20b Exhaust In general, the bigger the exit pipe, the louder the exhaust will = be. I used 2.25" which I think is about the minimum for a 20B. Tracy On Sat, May 16, 2009 at 9:28 AM, wrote: I have fabricated my exhaust manifold/tangential muffler for my = 20b. All I have left is to fit and weld the exhaust pipe. I would like = opinions on the size the exhaust pipe should be. This is in a pusher = application (Velocity) with a relatively short run from the muffler to = the exit point. Similar installation to Al G. Thanks, Joe -- Homepage: http://www.flyrotary.com/ Archive and UnSub: = http://mail.lancaironline.net:81/lists/flyrotary/List.html ------=_NextPart_000_001A_01C9D7D7.68049100 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

Tracy,

The reason I ask is that I like to keep = the muffler=20 outlet the same area size or a little bigger than the exhaust outlet in = the=20 rotor housing which is usually about 2" dia.

I do understand the 2 and 3 rotors are = staged and=20 the exhaust and the exhaust (shock) waves are in sequence, but = I like=20 to keep the volume of the muffler and muffler exit to the total of the = rotor=20 exits i.e. 3x Pi.r squared (3x Pi 1 x 1) =3D 9.2 sq" or Radius of 1.71" = =3D Dia of=20 3.42".

I thought 2.25 may have a little too = much back=20 pressure, as the rotary doesn't like back pressure.

Probably to do this exercise properly = would be to=20 calculate the volume of the heated and expanded exhaust gases and = calculate the=20 timing of the pulses to see how a particular sized muffler and exit size = coped=20 with the speed and volume of flow. It would be an interesting=20 exercise.

George (down under)

Too=20 soon to say really. I have not even had time to assemble the = builders=20 log to get ready for the DAR. Lack of engine power is definitely not = what is=20 keeping this thing grounded though : )

Tracy

On Sun, May 17, 2009 at 6:01 PM, George = Lendich <lendich@aanet.com.au> = wrote:

Tracy,

Any significant back pressure to = speak=20 of?

George (down under)
-----=20 Original Message -----
From:=20 Tracy Crook

To:=20 Rotary = motors in=20 aircraft Sent:=20 Monday, May 18, 2009 12:11 AM Subject:=20 [FlyRotary] Re: 20b Exhaust

In general, the bigger the exit pipe, the louder = the=20 exhaust will be. I used 2.25" which I think is about the = minimum for=20 a 20B.

Tracy

On Sat, May 16, 2009 at 9:28 AM, <jewen@comporium.net> wrote:

I=20 have fabricated my exhaust manifold/tangential muffler for my = 20b.=20 All I have left is to fit and weld the exhaust pipe. = I would=20 like opinions on the size the exhaust pipe should be. This = is in a=20 pusher application (Velocity) with a relatively short run from = the=20 muffler to the exit point. Similar installation to Al=20 G.

Thanks,
Joe

--
Homepage:=20 http://www.flyrotary.com/
Archive and = UnSub: =20 http://mail.lancaironline.net:81/lists/flyrotary/List.htm= l

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