X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Wed, 17 Dec 2008 07:42:50 -0500 Message-ID: X-Original-Return-Path: Received: from smtp-ext-05.mx.pitdc1.expedient.net ([206.210.69.145] verified) by logan.com (CommuniGate Pro SMTP 5.2.10) with ESMTPS id 3364472 for lml@lancaironline.net; Tue, 16 Dec 2008 15:36:58 -0500 Received-SPF: none receiver=logan.com; client-ip=206.210.69.145; envelope-from=rpastusek@htii.com Received: from dlhtpax009 (unknown [65.202.210.118]) by smtp-ext-05.mx.pitdc1.expedient.net (Postfix) with ESMTPA id BEDC6E5340 for ; Tue, 16 Dec 2008 15:36:20 -0500 (EST) Reply-To: From: "Robert Pastusek" X-Original-To: "'Lancair Mailing List'" References: In-Reply-To: Subject: RE: [LML] Re: Cabin heat LNC4 X-Original-Date: Tue, 16 Dec 2008 15:36:16 -0500 Organization: Holmes-Tucker International, Inc. X-Original-Message-ID: <01f101c95fbd$f2632010$d7296030$@com> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_01F2_01C95F94.098D1810" X-Mailer: Microsoft Office Outlook 12.0 Thread-Index: Aclfn2Lfk8XsJl2pQHiPHoWCFDSpOwAHlQjQ Content-Language: en-us This is a multipart message in MIME format. ------=_NextPart_000_01F2_01C95F94.098D1810 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit I think you'll see several advantages to turning them around. Keep us posted. BTW, do you have sonic nozzles in your "cold side" pressurization taps-the hoses leading to the third intercooler? BOB From: Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of zoelt@sio.midco.net Sent: Tuesday, December 16, 2008 11:57 AM To: lml@lancaironline.net Subject: [LML] Re: Cabin heat LNC4 Bob, I found my warm side sonics installed backwards (arrow towards intercooler not heat mixer). This probably led to blowing the warm air hose off at the mixer. Haven't flown to altitude and selected heat since turning them around. Thanks for the input. Tim _____ From: Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of Robert Pastusek Sent: Monday, December 15, 2008 6:52 PM To: lml@lancaironline.net Subject: [LML] Re: Cabin heat LNC4 Tim wrote: Are there Sonics in the Cold side of the intercooler? I don't think so.. Does the longer length of the hoses and the 3rd intercooler reduce flow/pressure ? You are correct on not using sonic nozzles on the cold side of the intercooler. The exit air is much cooler, and therefore under much less pressure (recall Boyle's Law), so full flow through the cold side tubes helps achieve a balanced flow between hot and cold temperature selection in the cockpit. Not the "scientific" way to achieve a flow balance, but it's very simple and works pretty well-over the flow rates and pressures we're using. And to answer your second question, the pressure and flow are not affected so much by the hose length and long flow path-which do contribute somewhat. The drop in temperature is responsible for the majority of reduced pressure/flow through the cold side. To answer another question posed by an LML contributor: the concept of a "sonic" nozzle is that when the air passing through the nozzle reaches supersonic flow, it sets up a shock wave in the throat that effectively "throttles" the flow. This causes the nozzle to flow a relatively constant volume of air over a wide range of input pressure-once the flow reaches supersonic in the throat. Without these, you'd see a very abrupt change in cabin in-flow and pressure every time you move the throttle of your turbocharged Continental while the cabin pressure controller-a rather slow-acting device, struggles to keep up with the changes. If you install the sonic nozzles backward, they won't work as intended, the flow will be closely proportional to the input pressure. Hope this helps. Bob Pastusek ------=_NextPart_000_01F2_01C95F94.098D1810 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

I think you’ll see several advantages to turning = them around.

 

Keep us posted…

 

BTW, do you have sonic nozzles in your “cold = side” pressurization taps—the hoses leading to the third = intercooler?


BOB

 

From: Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of = zoelt@sio.midco.net
Sent: Tuesday, December 16, 2008 11:57 AM
To: lml@lancaironline.net
Subject: [LML] Re: Cabin heat LNC4

 

Bob,

I found my warm side sonics installed backwards (arrow = towards intercooler not heat mixer).  This probably led to blowing the warm = air hose off at the mixer.  Haven’t flown to altitude and = selected heat since turning them around.

Thanks for the input.

Tim

 

From: Lancair Mailing List = [mailto:lml@lancaironline.net] On Behalf Of Robert Pastusek
Sent: Monday, December 15, 2008 6:52 PM
To: lml@lancaironline.net
Subject: [LML] Re: Cabin heat LNC4

 

Tim wrote:

 

Are there Sonics in the Cold side of the intercooler?  = I don’t think so..  Does the longer length of the hoses and the = 3rd intercooler reduce flow/pressure ?

 

You are correct on not using sonic nozzles on the cold side of the = intercooler. The exit air is much cooler, and therefore under much less pressure (recall Boyle’s Law), so full flow through the cold side tubes helps = achieve a balanced flow between hot and cold temperature selection in the cockpit. = Not the “scientific” way to achieve a flow balance, but = it’s very simple and works pretty well—over the flow rates and pressures we’re using. And to answer your second question, the pressure and = flow are not affected so much by the hose length and long flow = path—which do contribute somewhat. The drop in temperature is responsible for the = majority of reduced pressure/flow through the cold side.

To answer another question posed by an LML contributor: the concept of a “sonic” nozzle is that when the air passing through the = nozzle reaches supersonic flow, it sets up a shock wave in the throat that = effectively “throttles” the flow. This causes the nozzle to flow a = relatively constant volume of air over a wide range of input pressure-once the flow reaches supersonic in the throat. Without these, you’d see a very = abrupt change in cabin in-flow and pressure every time you move the throttle of = your turbocharged Continental while the cabin pressure controller—a = rather slow-acting device, struggles to keep up with the changes. If you = install the sonic nozzles backward, they won’t work as intended, the flow will = be closely proportional to the input pressure.

Hope this = helps.

Bob = Pastusek

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