Return-Path: Sender: "Marvin Kaye" To: lml@lancaironline.net Date: Thu, 21 Oct 2004 09:10:24 -0400 Message-ID: X-Original-Return-Path: Received: from rwcrmhc11.comcast.net ([204.127.198.35] verified) by logan.com (CommuniGate Pro SMTP 4.2.5) with ESMTP id 481355 for lml@lancaironline.net; Thu, 21 Oct 2004 06:38:46 -0400 Received-SPF: none receiver=logan.com; client-ip=204.127.198.35; envelope-from=mjrav@comcast.net Received: from MJR (h000094c615c2.ne.client2.attbi.com[65.96.140.242]) by comcast.net (rwcrmhc11) with SMTP id <20041021103806013009fh23e>; Thu, 21 Oct 2004 10:38:16 +0000 X-Original-Message-ID: <002201c4b75a$1cdcf980$f28c6041@ne2.client2.attbi.com> From: "Mark Ravinski" X-Original-To: "Lancair Mailing List" Subject: Another Plenum theory X-Original-Date: Thu, 21 Oct 2004 06:38:22 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_001F_01C4B738.8F585940" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1437 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1441 This is a multi-part message in MIME format. ------=_NextPart_000_001F_01C4B738.8F585940 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable As the prop rotates past the cooling air intakes I would suspect there = gets to be a pressure pulse of some magnitude in the system. I also = suspect that this pulse when acting on the cowling might contribute to = the stress cracking (or spider cracking) commonly seen on higher time = installations. This is a problem on Lancairs and a lot of other planes = using fiberglass cowling. Since I built a plennum about three years ago, my spider cracks have = stopped growing. Mark Ravinski N360KB 1307 hrs ------=_NextPart_000_001F_01C4B738.8F585940 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
As the prop rotates past the cooling = air intakes I=20 would suspect there gets to be a pressure pulse of some magnitude in the = system.  I also suspect that this pulse when acting on the cowling = might=20 contribute to the stress cracking (or spider cracking) commonly seen on = higher=20 time installations. This is a problem on Lancairs and a lot of = other=20 planes using fiberglass cowling.
 
Since I built a plennum about three = years ago, my=20 spider cracks have stopped growing.
 
Mark Ravinski
N360KB  1307 = hrs
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