X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from [24.25.9.103] (HELO ms-smtp-04-eri0.southeast.rr.com) by logan.com (CommuniGate Pro SMTP 5.0.8) with ESMTP id 999653 for flyrotary@lancaironline.net; Mon, 27 Feb 2006 07:35:45 -0500 Received-SPF: pass receiver=logan.com; client-ip=24.25.9.103; envelope-from=eanderson@carolina.rr.com Received: from edward2 (cpe-024-074-025-165.carolina.res.rr.com [24.74.25.165]) by ms-smtp-04-eri0.southeast.rr.com (8.13.4/8.13.4) with SMTP id k1RCYw3M025639 for ; Mon, 27 Feb 2006 07:34:59 -0500 (EST) Message-ID: <002101c63b99$f0093c50$2402a8c0@edward2> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Exhaust Blowout Date: Mon, 27 Feb 2006 07:32:56 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_001E_01C63B70.06EBCB10" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.2180 X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 X-Virus-Scanned: Symantec AntiVirus Scan Engine This is a multi-part message in MIME format. ------=_NextPart_000_001E_01C63B70.06EBCB10 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Joe, I have found that the strong exhaust pulses (not the heat) are very = detrimental to the life of Stainless Steel - especially if its a bit on = the thin side. The 200+ pulses per second appear to fatigue the metal = very quickly. I found that 0.048 thick SS tube would last approx 5 = minutes at full throttle. Heavier gauge metal and some inserts to break = up the shock wave seemed to help. Glad you caugth it on the ground (best place for any/every thing to go = wrong that's going to). Ed ----- Original Message -----=20 From: Joe Hull=20 To: Rotary motors in aircraft=20 Sent: Monday, February 27, 2006 2:09 AM Subject: [FlyRotary] Exhaust Blowout I'm still struggling with tuning my rotary/microtech. I spent an hour = or so running it yesterday and ended up a little closer on the tuning = front but also ended up with a blown out exhaust/muffler. It's come = apart at a bunch of places - not the welds but the Inconel itself next = to the welds. =20 The exhaust pipe coming out of the "tangential tube" is/was in the = profile of an "8" without the connection in the center. An engineer = friend of mine who looked it over said it makes sense - after the fact - = that the exhaust pulses were causing the tube to flex at the center = joint. It appears to have started at the outboard end and went all the = way to the center tube and then, perhaps from vibration, cracked out the = pipes except for about =BD" from the center connection. =20 The main manifold - runners and the tangential tube - are all sound = with no signs of stress. So, be careful out there! =20 Pics attached. =20 Thanx, Joe Hull Cozy Mk-IV #991 (Done Building! In Phase1 Flight Test - 0 hrs flown)=20 Redmond (Seattle), Washington -------------------------------------------------------------------------= ----- -- Homepage: http://www.flyrotary.com/ Archive and UnSub: http://mail.lancaironline.net/lists/flyrotary/ ------=_NextPart_000_001E_01C63B70.06EBCB10 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Joe, I have found that the strong exhaust pulses = (not the=20 heat) are very detrimental to the life of Stainless Steel - especially = if its a=20 bit on the thin side.   The 200+ pulses per second appear to = fatigue=20 the metal very quickly.  I found that 0.048 thick SS tube would = last approx=20 5 minutes at full throttle.  Heavier gauge metal and some inserts = to break=20 up the shock wave seemed to help.
 
Glad you caugth it on the ground (best place for = any/every=20 thing to go wrong that's going to).
 
Ed
----- Original Message -----
From:=20 Joe Hull=20
Sent: Monday, February 27, 2006 = 2:09=20 AM
Subject: [FlyRotary] Exhaust=20 Blowout

I=92m still struggling = with tuning=20 my rotary/microtech. I spent an hour or so running it yesterday and = ended up a=20 little closer on the tuning front but also ended up with a blown out=20 exhaust/muffler. It=92s come apart at a bunch of places =96 not the = welds but the=20 Inconel itself next to the welds.

 

The exhaust pipe coming = out of the=20 =93tangential tube=94 is/was in the profile of an =938=94 without the = connection in=20 the center. An engineer friend of mine who looked it over said it = makes sense=20 - after the fact - that the exhaust pulses were causing the tube to = flex at=20 the center joint.  It appears to have started at the outboard end = and=20 went all the way to the center tube and then, perhaps from vibration, = cracked=20 out the pipes except for about =BD=94 from the center=20 connection.

 

The main manifold =96 = runners and=20 the tangential tube =96 are all sound with no signs of=20 stress.

So, be careful out=20 there!

 

Pics=20 attached.

 

Thanx,

Joe=20 Hull

Cozy Mk-IV #991 (Done = Building! In=20 Phase1 Flight Test - 0 hrs flown)

Redmond (Seattle), Washington

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