X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Tue, 21 Aug 2007 00:48:38 -0400 Message-ID: X-Original-Return-Path: Received: from mail34.syd.optusnet.com.au ([211.29.133.218] verified) by logan.com (CommuniGate Pro SMTP 5.1.11) with ESMTPS id 2275020 for lml@lancaironline.net; Mon, 20 Aug 2007 20:21:15 -0400 Received-SPF: none receiver=logan.com; client-ip=211.29.133.218; envelope-from=fredmoreno@optusnet.com.au Received: from fred (optussatellitebintb.22bjipb002.optus.net.au [59.154.24.148]) (authenticated sender fredmoreno) by mail34.syd.optusnet.com.au (8.13.1/8.13.1) with ESMTP id l7L0K30g008117 for ; Tue, 21 Aug 2007 10:20:20 +1000 From: "Fred Moreno" X-Original-To: "'Lancair Mailing List'" Subject: Oil Filler access door on Legacy X-Original-Date: Tue, 21 Aug 2007 08:24:19 +0800 X-Original-Message-ID: <00b301c7e389$a9370b10$c211140a@fred> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_00B4_01C7E3CC.B75A4B10" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.6822 X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2900.3138 Importance: Normal Thread-Index: AcfjEkXfqwAnAfm9Txakc7uNdHqzngAdiNSg This is a multi-part message in MIME format. ------=_NextPart_000_00B4_01C7E3CC.B75A4B10 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable "The cowl pressure is too great because the cowl air exit is not large enough or the inlets are too large." =20 BALDERDASH! (Whatever that is.) =20 You are being sandbagged by a colleague with a slower airplane. (It happens.) =20 If the engine cools OK, then there is no point in making inlets or = outlets larger. It will only increase cooling drag and overcool the engine. =20 The cowl pressure will be high at high cruise speeds, approaching the pressure measured by the pitot tube, that is, the ram pressure. At 200 = KIAS the ram pressure is about 1 psig. At 250 KIAS, it will be roughly 1.6 = psig. =20 Now consider your oil door. Imagine it is 4 by 5 inches, 20 square = inches. =20 Conduct the following mental experiment. Remove top cowl, invert, and = place on pillows to keep the oil door off the floor. Put 32 pounds of lead = shot bags on the oil door to push it out. Add some vibration. =20 =20 No wonder those two wimpy rivets failed. =20 =20 Reinforce door and go flying, snug in the fact that your cowl is = delivering good pressure recovery. =20 =20 And minimize cooling drag! =20 Fred =20 =20 =20 ------=_NextPart_000_00B4_01C7E3CC.B75A4B10 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

“The cowl = pressure is too great because the cowl air exit is not large enough or the inlets = are too large…”

 

BALDERDASH!  (Whatever that = is.)

 

You are being sandbagged by a = colleague with a slower airplane.  (It happens.)

 

If the engine cools OK, then there = is no point in making inlets or outlets larger.   It will only = increase cooling drag and overcool the engine.

 

The cowl pressure will be high at = high cruise speeds, approaching the pressure measured by the pitot tube, that = is, the ram pressure.  At 200 KIAS the ram pressure is about 1 = psig.  At 250 KIAS, it will be roughly 1.6 psig.

 

Now consider your oil door.  = Imagine it is 4 by 5 inches, 20 square inches. 

 

Conduct the following mental experiment.  Remove top cowl, invert, and place on pillows to keep = the oil door off the floor.  Put 32 pounds of lead shot bags on the oil = door to push it out.  Add some vibration. 

 

No wonder those two wimpy rivets failed. 

 

Reinforce door and go flying, snug = in the fact that your cowl is delivering good pressure recovery.  =

 

And minimize cooling = drag!

 

Fred

 

 

 

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