X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from [216.211.128.10] (HELO mail-in03.adhost.com) by logan.com (CommuniGate Pro SMTP 5.1c.2) with ESMTP id 1317248 for flyrotary@lancaironline.net; Wed, 26 Jul 2006 15:44:34 -0400 Received-SPF: none receiver=logan.com; client-ip=216.211.128.10; envelope-from=joeh@pilgrimtech.com Received: from Pilgrim10 (tide534.microsoft.com [131.107.0.104]) by mail-in03.adhost.com (Postfix) with ESMTP id 3963F2A7DDA for ; Wed, 26 Jul 2006 12:43:10 -0700 (PDT) (envelope-from joeh@pilgrimtech.com) From: "Joe Hull" To: "'Rotary motors in aircraft'" Subject: RE: [FlyRotary] Re: Joe Hull's OSH Trip - Part 2 Date: Wed, 26 Jul 2006 12:42:47 -0700 Message-ID: <00c101c6b0eb$b980b1a0$bc40379d@redmond.corp.microsoft.com> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_00C2_01C6B0B1.0D21D9A0" X-Mailer: Microsoft Office Outlook 11 In-Reply-To: X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2869 Thread-Index: Acaw6QhQ8PnXMumTRrmvphVmePUpOAAAPj4Q This is a multi-part message in MIME format. ------=_NextPart_000_00C2_01C6B0B1.0D21D9A0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit The crack min February was along the length of the seam of the figure-8 exit tube and where it attached to the end plate of the 5" tube. I say it is brittle because it has failed twice and both times quite spectacularly. Not only did the inconel fail in the area adjacent to the welds but spider cracks formed flowing out of the main cracks and into the surrounding area. It looked like glass might look if you punch a hole in it (i.e. not tempered glass!). The gasket is something that came from Dave - it is metal with dimples - not sure if that is stock or not. Thanx, Joe Hull Cozy Mk-IV N31CZ (65 hrs - Rotary 13B NA) Redmond (Seattle), Washington _____ From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Al Gietzen Sent: Wednesday, July 26, 2006 12:23 PM To: Rotary motors in aircraft Subject: [FlyRotary] Re: Joe Hull's OSH Trip - Part 2 Now tell me more about the muffler, since I probably have something very similar on my 3-rotor. You got this from Atkins? Inconel headers (2") tangentially into 5" inconel tube? Was this welded by Atkins buddy, Mark Sadikas? OK - it is similar to Dave Atkins - Racing Beat flange, 2"D x 4"-5" stubs out into the top of a 5" tube (I bought from Dave). Out the end of the 5" tube is a 13" long exit tube. All out of Inconel and all welded by a master welder with Inconel welding rod. The attached picture shows the finished muffler - except after the crack that occurred last Joe; Thanks for info. When the crack occurred last Feb, where was that - also at the header to muffler tube weld? I expect that to be the worst stress point because of the axial expansion of the muffler being greater than that of the engine between the ports. BTW; do you have the stock exhaust gaskets on there? My setup is similar, and potentially worse because it looks like the headers are shorter, and the dimensional change from rotor 1 to rotor 3 will be greater due to the longer length (photo). I have a SS baffle over the exhaust in a similar manner as yours (photo). My engine/exhaust has about 12-14 hours on it; dyno runs plus on the plane testing, and no cracks at this point. Lots of full power cycles on the dyno, some up to 7000 rpm. I think the design has too many welds/joints subject to thermal and mechanical stress which Inconel, being brittle, cannot handle I don't know that inconel can be considered brittle, it bends and stretches. It is very strong, has good high temp strength, is very corrosion resistant; and considered to have good fatigue resistance, which increases as temperature is increased. Its behavior is dependant on heat treatment (and of course which alloy - 600, 718 or 800). Unfortunately we don't know what we have, nor what sort of post weld treatment it received. I'm very interested in seeing your new design when you're ready to show us that. I'm guessing the probability is quite high that I will be doing something else at some point. Al ------=_NextPart_000_00C2_01C6B0B1.0D21D9A0 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

The crack min February was along = the length of the seam of the figure-8 exit tube and where it attached to the end = plate of the 5” tube.

 

I say it is brittle because it has = failed twice and both times quite spectacularly. Not only did the inconel fail = in the area adjacent to the welds but spider cracks formed flowing out of the = main cracks and into the surrounding area. It looked like glass might look if = you punch a hole in it (i.e. not tempered = glass!).

 

The gasket is something that came = from Dave – it is metal with dimples – not sure if that is stock = or not.

 

Thanx,

Joe = Hull

Cozy Mk-IV N31CZ (65 hrs - Rotary = 13B NA)

Redmond (Seattle), Washington

 

From: = Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Al Gietzen
Sent: Wednesday, July 26, = 2006 12:23 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: = Joe Hull's OSH Trip - Part 2

 

 

Now tell me more about the muffler, since I probably have something very = similar on my 3-rotor.  You got this from Atkins?  Inconel headers = (2”) tangentially into 5” inconel tube?  Was this welded by Atkins = buddy, Mark Sadikas? 

 

OK – it is = similar to Dave Atkins – Racing Beat flange, 2”D x 4”-5” = stubs out into the top of a 5” tube (I bought from Dave). Out the end of the 5” tube is a 13” long exit tube. All out of Inconel and all = welded by a master welder with Inconel welding rod. The attached picture shows = the finished muffler – except after the crack that occurred last =

 

Joe;

 

Thanks for = info.  When the crack occurred last Feb, where was that – also at the = header to muffler tube weld?  I expect that to be the worst stress point = because of the axial expansion of the muffler being greater than that of the engine between the ports.  BTW; do you have the stock exhaust gaskets on = there?

 

My setup is = similar, and potentially worse because it looks like the headers are shorter, and = the dimensional change from rotor 1 to rotor 3 will be greater due to the = longer length (photo).  I have a SS baffle over the exhaust in a similar = manner as yours (photo).

 

My = engine/exhaust has about 12-14 hours on it; dyno runs plus on the plane testing, and no = cracks at this point.  Lots of full power cycles on the dyno, some up to 7000 rpm. 

 

I think the design has too many welds/joints subject to thermal and mechanical = stress which Inconel, being brittle,  cannot = handle

I don’t = know that inconel can be considered brittle, it bends and stretches.  It is = very strong, has good high temp strength, is very corrosion resistant; and considered to have good fatigue resistance, which increases as = temperature is increased.  Its behavior is dependant on heat treatment (and of = course which alloy – 600, 718 or 800).  Unfortunately we don’t = know what we have, nor what sort of post weld treatment it = received.

 

I’m very interested in seeing your new design when you’re ready to show us that.  I’m guessing the probability is quite high that I will = be doing something else at some point.

 

Al

------=_NextPart_000_00C2_01C6B0B1.0D21D9A0--