Return-Path: Sender: (Marvin Kaye) To: lml@lancaironline.net Date: Fri, 28 May 2004 13:56:56 -0400 Message-ID: X-Original-Return-Path: Received: from mail.indian-creek.net ([209.176.40.9] verified) by logan.com (CommuniGate Pro SMTP 4.2b3) with ESMTP id 94714 for lml@lancaironline.net; Fri, 28 May 2004 13:54:37 -0400 Received: from pavilion (sl12.du.indian-creek.net [209.176.40.28] toucan@78055.com) by mail.indian-creek.net with SMTP (IOA-IPAD 4.02) id 76X9900 for ; Fri, 28 May 2004 12:54:31 -0500 X-Original-Message-ID: <002a01c444dd$1e527c80$1c28b0d1@pavilion> From: "Jim Cameron" X-Original-To: "Lancair Mailing List" Subject: Legacy exhaust X-Original-Date: Fri, 28 May 2004 12:56:29 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0022_01C444B3.318EE6A0" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 5.00.2615.200 X-MimeOLE: Produced By Microsoft MimeOLE V5.00.2615.200 This is a multi-part message in MIME format. ------=_NextPart_000_0022_01C444B3.318EE6A0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable After about 4 hrs on N121J, it's clear that it needs exhaust = modifications. The straight exhaust tubes supplied by Lancair come out = too close to the skin. The exhaust gas stream appears to be flowing = along the skin for about 3 or 4 feet before mixing with enough of the = airstream to cool it. If I keep flying with it as is, the paint will = start to blister and I'm afraid I might even see delamination. The factory suggested simply opening up the rear of the cowl exhaust = tunnels and deflecting the exhaust pipes downward. Bad idea, since the = ball joints won't accommodate that much bend without leaking. For some = reason, the ball joints were pointed straight back, more or less level, = instead of angling downward toward the exhaust tunnels. The short exhaust tube sections can't be bent -- they don't fit into = the usual benders for auto exhaust pipes, and in any case, the = thin-walled stainless they're made of would collapse unless a mandrel = bender is used. One solution would be to have an aircraft exhaust = company make new ones, which would undoubtedly take quite a while and be = expensive. What I've done instead is to order a U-bend piece from Borla = (www.borla.com) that consists of a 6-inch radius, 180-degree section, = with 8" legs, all in 2-1/2" diameter T-304 stainless (Borla part number = 19250). I'll bevel the ends of the legs, then cut so that I have a = 20-degree curve section on the other end. I've cut the exhaust pipes = off 10" from their ends, and found a gent locally who can weld the = thin-wall stainless. This ought to bring the open ends of the exhaust pipes several = inches lower and farther from the skin. Perhaps newer exhausts supplied = by Lancair are different, but if yours are like mine, think about = getting the exit ends well away from the belly of the airplane. With = any luck, the noise level inside might even be reduced a little. Jim Cameron Legacy N121J ------=_NextPart_000_0022_01C444B3.318EE6A0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

After about 4 hrs = on N121J,=20 it's clear that it needs exhaust modifications. The straight = exhaust tubes=20 supplied by Lancair come out too close to the skin. The exhaust = gas stream=20 appears to be flowing along the skin for about 3 or 4 feet before mixing = with=20 enough of the airstream to cool it. If I keep flying with it as = is, the=20 paint will start to blister and I'm afraid I might even see=20 delamination.

The factory = suggested=20 simply opening up the rear of the cowl exhaust tunnels and deflecting = the=20 exhaust pipes downward. Bad idea, since the ball joints won't = accommodate=20 that much bend without leaking. For some reason, the ball joints = were=20 pointed straight back, more or less level, instead of angling downward = toward=20 the exhaust tunnels.

The short exhaust = tube=20 sections can't be bent -- they don't fit into the usual benders for = auto=20 exhaust pipes, and in any case, the thin-walled stainless they're made = of would=20 collapse unless a mandrel bender is used. One solution would be to = have an=20 aircraft exhaust company make new ones, which would undoubtedly take = quite a=20 while and be expensive. What I've done instead is to order a = U-bend piece=20 from Borla (www.borla.com) = that consists=20 of a 6-inch radius, 180-degree section, with 8" legs, all in 2-1/2" = diameter=20 T-304 stainless (Borla part number 19250). I'll bevel the ends of = the=20 legs, then cut so that I have a 20-degree curve section on the other = end. =20 I've cut the exhaust pipes off 10" from their ends, and found a gent = locally who=20 can weld the thin-wall stainless.

This ought to = bring the=20 open ends of the exhaust pipes several inches lower and farther from the = skin. Perhaps newer exhausts supplied by Lancair are different, = but if=20 yours are like mine, think about getting the exit ends well away from = the belly=20 of the airplane. With any luck, the noise level inside might even = be=20 reduced a little.

Jim Cameron

Legacy N121J

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