X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from [207.46.163.187] (HELO na01-bn1-obe.outbound.protection.outlook.com) by logan.com (CommuniGate Pro SMTP 6.0.7) with ESMTPS id 6623899 for lml@lancaironline.net; Tue, 03 Dec 2013 11:55:20 -0500 Received-SPF: pass receiver=logan.com; client-ip=207.46.163.187; envelope-from=rpastusek@htii.com Received: from BY2PR07MB550.namprd07.prod.outlook.com (10.141.217.145) by BY2PR07MB551.namprd07.prod.outlook.com (10.141.217.150) with Microsoft SMTP Server (TLS) id 15.0.820.5; Tue, 3 Dec 2013 16:54:40 +0000 Received: from BY2PR07MB550.namprd07.prod.outlook.com ([10.141.217.145]) by BY2PR07MB550.namprd07.prod.outlook.com ([10.141.217.145]) with mapi id 15.00.0820.005; Tue, 3 Dec 2013 16:54:40 +0000 From: Robert R Pastusek To: Lancair Mailing List Subject: RE: [LML] cabin pressure valve vs manifold pressure drop Thread-Topic: [LML] cabin pressure valve vs manifold pressure drop Thread-Index: AQHO8B9gcBHsUB/JMkehnyRvIdgpi5pCmGeA Date: Tue, 3 Dec 2013 16:54:39 +0000 Message-ID: <3d64fcf5458d4d81ac3f8e5009bb2fcb@BY2PR07MB550.namprd07.prod.outlook.com> References: In-Reply-To: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [72.9.2.42] x-forefront-prvs: 0049B3F387 x-forefront-antispam-report: SFV:NSPM;SFS:(377454003)(199002)(189002)(65816001)(76576001)(2656002)(85306002)(19300405004)(56776001)(74706001)(54316002)(76482001)(79102001)(15202345003)(77982001)(59766001)(87936001)(74316001)(74876001)(83072001)(80022001)(66066001)(90146001)(56816005)(19580405001)(76796001)(19580395003)(4396001)(81686001)(76786001)(83322001)(81816001)(15975445006)(74662001)(81542001)(69226001)(54356001)(46102001)(51856001)(87266001)(47736001)(16236675002)(81342001)(80976001)(63696002)(49866001)(53806001)(31966008)(33646001)(47976001)(74366001)(50986001)(74502001)(47446002)(85852002)(24736002);DIR:OUT;SFP:;SCL:1;SRVR:BY2PR07MB551;H:BY2PR07MB550.namprd07.prod.outlook.com;CLIP:72.9.2.42;FPR:;RD:InfoNoRecords;A:1;MX:1;LANG:en; Content-Type: multipart/alternative; boundary="_000_3d64fcf5458d4d81ac3f8e5009bb2fcbBY2PR07MB550namprd07pro_" MIME-Version: 1.0 X-OriginatorOrg: htii.com --_000_3d64fcf5458d4d81ac3f8e5009bb2fcbBY2PR07MB550namprd07pro_ Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable CWFMD, I'd need more info to diagnose this completely, but write me directly and I= 'll try to help. rpastusek@htii.com Some basics on the pressurization system (applies to the IV-P with Continen= tal TSIO-550 engine ONLY--you didn't specify the aircraft/engine): The engine is designed to "vent" part of the turbocharger output overboard = during normal operation, through what are called "sonic nozzles" that basic= ally maintain a rather constant flow rate over a range of pressure differen= tials. The IV-P (and some other pressurized Lancairs with big bore Continen= tals) uses this bleed air to pressurize the cockpit. The air is routed thro= ugh a mixer/control box mounted near the top center of the firewall in the = engine compartment. This gold-colored aluminum can (about 2/3 the height of= a quart oil can) has a cockpit-controlled shuttle valve that allows select= ion of a mix of hot air directly from the turbochargers and cooler air that= has already passed through the intercoolers. It also has a separate valve= , with cockpit control, that shuts off airflow to the cabin and diverts it = out the bottom of the engine compartment when cockpit pressurization (and a= ssociated heat) is not needed. As to heat, at full throttle, the turbocharger output air temperature can b= e up to 300 degrees, and in the cabin heat on mode, flows pretty directly i= nto the cabin. With the heat control turned off, the turbocharger air passe= s through a pair of air-to-air intercoolers before heading to the cockpit f= or pressurization. The problem is that these intercoolers only lower the te= mperature; they don't deliver "cold" air out the backside. When the input i= s at 300, the output is warm, at best; hot in Texas in the summer. So, with= out air conditioning, there is not a good source of really cool air availab= le to pressurize the cockpit. As to the fixes: First check is to be sure the valves in the controller are= functioning as intended. Second check is to be sure you have sonic ports = installed in your turbocharger output lines that feed to this controller. T= he variation you report in MP would tend to indicate there are no sonic por= ts installed, and that you're getting "full flow" through the system, rathe= r than restricted flow as intended...but this is just a guess at this point= ... not enough data. Talk or write? Bob From: Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of cwfm= d@yahoo.com Sent: Tuesday, December 03, 2013 7:01 AM To: lml@lancaironline.net Subject: [LML] cabin pressure valve vs manifold pressure drop We put a new canopy seal in the IV-P. I fiddled with the cabin pressure val= ve to try to reduce or locate a squeal. (My Grainger smoke matches don't l= ight, with reduced partial pressure of Oxygen at altitude) I noticed that p= ulling the cabin pressure control partially out, reduced the cabin inflow, = as expected, but also dropped the manifold pressure by about 4 inches with = a loss of about 50 hp (estimated). This was at flight level 230. I had not = previously noticed this large effect on manifold pressure, but it could dem= ystify performance changes in previous data. Who knew the cabin pressure va= lve affected the "throttle" setting :) It makes sense because the previous = cabin pressure just dumps overboard at the firewall. Wondering why this is = set up this way.... Why not just close the valve to the cabin, when not nee= ded or wanted, and leave the manifold pressure in the manifold?? In general, I noticed others have similar issues with the cost of repair = of the Dukes valve. I would rather redesign the system, using the on-board = instrumentation and computers that already know the static pressure and the= cabin pressure. I hot climates I prefer to minimize the heat entering the = cabin, and maybe just use 4-5 psi relief valves to distribute air flow. I t= hink my system where all the inter-cooled air routes thru the firewall to u= nder the back seat was designed by Eskimos, who always need max heating. --_000_3d64fcf5458d4d81ac3f8e5009bb2fcbBY2PR07MB550namprd07pro_ Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

CWFMD,

 

I’d need more info to diagnose this completel= y, but write me directly and I’ll try to help.  rpastusek@htii.com

 

Some basics on the pressurization system (applies t= o the IV-P with Continental TSIO-550 engine ONLY--you didn’t specify the aircraft/engine):

The engine is designed to “vent” part o= f the turbocharger output overboard during normal operation, through what a= re called “sonic nozzles” that basically maintain a rather consta= nt flow rate over a range of pressure differentials. The IV-P (and some oth= er pressurized Lancairs with big bore Continentals) uses thi= s bleed air to pressurize the cockpit. The air is routed through a mixer/co= ntrol box mounted near the top center of the firewall in the engine compart= ment. This gold-colored aluminum can (about 2/3 the height of a quart oil can) has a cockpit-controlled shuttle= valve that allows selection of a mix of hot air directly from the turbocha= rgers and cooler air that has already passed through the intercoolers.  It also has a separate valve,= with cockpit control, that shuts off airflow to the cabin and diverts it o= ut the bottom of the engine compartment when cockpit pressurization (and as= sociated heat) is not needed.

 

As to heat, at full throttle, the turbocharger outp= ut air temperature can be up to 300 degrees, and in the cabin heat on mode, flows pretty directly into the cabin. With the heat control turne= d off, the turbocharger air passes through a pair of air-to-air intercooler= s before heading to the cockpit for pressurization. The problem is that the= se intercoolers only lower the temperature; they don’t deliver “cold” air out the backside. When the= input is at 300, the output is warm, at best; hot in Texas in the summer. = So, without air conditioning, there is not a good source of really cool air= available to pressurize the cockpit.

 

As to the fixes: First check is to be sure the valv= es in the controller are functioning as intended.  Second check is to be sure yo= u have sonic ports installed in your turbocharger output lines that feed to= this controller. The variation you report in MP would tend to indicate the= re are no sonic ports installed, and that you’re getting “full flow” through the system, rather th= an restricted flow as intended…but this is just a guess at this point= … not enough data. Talk or write?

 

Bob

 

From: Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of cwfmd@yaho= o.com
Sent: Tuesday, December 03, 2013 7:01 AM
To: lml@lancaironline.net
Subject: [LML] cabin pressure valve vs manifold pressure drop

 

We = put a new canopy seal in the IV-P. I fiddled with the cabin pressure valve = to try to reduce or locate  a squeal. (My Grainger smoke matches don't light, with reduced partial pressure of Oxygen at alti= tude) I noticed that pulling the cabin pressure control partially out, redu= ced the cabin inflow, as expected, but also dropped the manifold pressure b= y about 4 inches with a loss of about 50 hp (estimated). This was at flight level 230. I had not previousl= y noticed this large effect on manifold pressure, but it could demystify pe= rformance changes in previous data. Who knew the cabin pressure valve affec= ted the "throttle" setting :) It makes sense because the previous cabin pressure just dumps overboard at th= e firewall. Wondering why this is set up this way.... Why not just close th= e valve to the cabin, when not needed or wanted, and leave the manifold pre= ssure in the manifold??

&nb= sp; In general, I noticed others have similar issues with the cost of repai= r of the Dukes valve. I would rather redesign the system, using the on-board instrumentation and computers that already know the sta= tic pressure and the cabin pressure. I hot climates I prefer to minimize th= e heat entering the cabin, and maybe just use 4-5 psi relief valves to dist= ribute air flow. I think my system where all the inter-cooled air routes thru the firewall to under the back = seat was designed by Eskimos, who always need max heating.

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