X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Wed, 04 Dec 2013 09:59:52 -0500 Message-ID: X-Original-Return-Path: Received: from p3plex2out04.prod.phx3.secureserver.net ([184.168.131.18] verified) by logan.com (CommuniGate Pro SMTP 6.0.7) with ESMTP id 6624562 for lml@lancaironline.net; Tue, 03 Dec 2013 21:57:24 -0500 Received-SPF: none receiver=logan.com; client-ip=184.168.131.18; envelope-from=pete@leapfrogventures.com Received: from P3PW5EX1HT003.EX1.SECURESERVER.NET ([72.167.180.21]) by p3plex2out04.prod.phx3.secureserver.net with secureserver.net id xEwp1m0050U5vnL01EwpXQ; Tue, 03 Dec 2013 19:56:49 -0700 Received: from P3PW5EX1MB14.EX1.SECURESERVER.NET ([10.6.135.86]) by P3PW5EX1HT003.EX1.SECURESERVER.NET ([72.167.180.21]) with mapi; Tue, 3 Dec 2013 19:56:49 -0700 From: "pete@leapfrogventures.com" X-Original-To: Lancair Mailing List X-Original-Date: Tue, 3 Dec 2013 19:53:19 -0700 Subject: RE: [LML] Re: cabin pressure valve vs manifold pressure drop Thread-Topic: [LML] Re: cabin pressure valve vs manifold pressure drop Thread-Index: Ac7wbmerEDrgVp7OQ3KDRAujE553cAALSEwg X-Original-Message-ID: <2A14E6258A8534418F5498D73CCA51EF225AD035AE@P3PW5EX1MB14.EX1.SECURESERVER.NET> References: <4D9CE94A-E0DC-4355-A969-36D61C3EC665@earthlink.net> In-Reply-To: <4D9CE94A-E0DC-4355-A969-36D61C3EC665@earthlink.net> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: acceptlanguage: en-US Content-Type: multipart/alternative; boundary="_000_2A14E6258A8534418F5498D73CCA51EF225AD035AEP3PW5EX1MB14E_" MIME-Version: 1.0 --_000_2A14E6258A8534418F5498D73CCA51EF225AD035AEP3PW5EX1MB14E_ Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable I was told a few years ago that the intercoolers with the pressurized air t= akeoff ports ahead of the intercooler required that some air be bled out th= rough this port (or the "cold" air port we add downsteam of the intercooler= ) or a compressor stall can occur. Thus, just closing off the port is not = an option. On the Cirrus and Columbia installations of these same engines, max engine = HP is capped at 310 hp. I wonder if this has something to do with the comp= ressor stall issues, as neither of their intercoolers has the pressure take= off ports like ours do. Pete From: Colyn Case [mailto:colyncase@earthlink.net] Sent: Tuesday, December 03, 2013 9:09 AM To: Lancair Mailing List Subject: Re: [LML] Re: cabin pressure valve vs manifold pressure drop Bob, what would you expect to happen if your system had sonic nozzles on the hot= side and not on the cold, you had set the mixer to "cold" and then you shu= t off cabin air? It seems to me that would result in more MP loss than if= you had it on hot. ...which leads to an observation that Craig Berland made some while back, w= hich is that if the cold-side cabin air plumbing is compromised (e.g. a cla= mp lets loose) , you will suffer a loss of engine power. Colyn On Dec 3, 2013, at 11:54 AM, Robert R Pastusek wrote: 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_2A14E6258A8534418F5498D73CCA51EF225AD035AEP3PW5EX1MB14E_ Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

I was told a few years ago that the = intercoolers with the pressurized air takeoff ports ahead of the intercoole= r required that some air be bled out through this port (or the “cold&= #8221; air port we add downsteam of the intercooler) or a compressor stall = can occur.  Thus, just closing off the port is not an option.

 

On the Cirrus and = Columbia installations of these same engines, max engine HP is capped at 31= 0 hp.  I wonder if this has something to do with the compressor stall = issues, as neither of their intercoolers has the pressure takeoff ports lik= e ours do.

 

=

<= span style=3D'font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F= 497D'>Pete

 

From: Colyn Case [mailto:coly= ncase@earthlink.net]
Sent: Tuesday, December 03, 2013 9:09 AM
To: Lancair Mailing List
Subject: Re: [LML] Re: cabin pressure valve vs manifold pressu= re drop

&nb= sp;

Bob,=

 

<= p class=3DMsoNormal>what would you expect to happen if your system had sonic = nozzles on the hot side and not on the cold, you had set the mixer to "= ;cold" and then you shut off cabin air?   It seems to me that wou= ld result in more MP loss than if you had it on hot.

 

...which leads to an observation that Craig Berla= nd made some while back, which is that if the cold-side cabin air plumbing = is compromised (e.g. a clamp lets loose) , you will suffer a loss of engine= power.

&nbs= p;

Colyn

 

On Dec 3, 2013, at 11:54 AM, Robert R Pastusek wrot= e:



CWFMD,

&= nbsp;

I’d need more info to d= iagnose this completely, but write me directly and I’ll try to help.&= nbsp; rpastusek@htii.com

<= div>

 

Some basics on the pres= surization system (applies to the IV-P with Continental TSIO-550 engine ONL= Y--you didn’t specify the aircraft/engine):<= /p>

The engine is designed to “vent” part of the tur= bocharger output overboard during normal operation, through what are called= “sonic nozzles” that basically maintain a rather constant flow= rate over a range of pressure differentials. The IV-P (and some other pres= surized Lancairs with big = bore Continentals) uses this bleed air to pressurize the cockpit. The air i= s routed through a mixer/control box mounted near the top center of the fir= ewall 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 selection of a mix of hot air directly from the turbochargers and co= oler air that has already passed through the intercoolers.  It also has a separate valve, with co= ckpit control, that shuts off airflow to the cabin and diverts it out the b= ottom of the engine compartment when cockpit pressurization (and associated= heat) is not needed.

 =

As to heat, at full throttle, the turboc= harger output air temperature can be up to 300 degrees, and in the cabin he= at on mode, flows pretty directly into the cabin. With the heat control tur= ned off, the turbocharger air passes through a pair of air-to-air intercool= ers before heading to the cockpit for pressurization. The problem is that t= hese intercoolers only lower the temperature; they don’t deliver R= 20;cold” air out the backside. When the input is at 300, the output i= s 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 c= ockpit.

 

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

 

Bob=

 

From:<= /b> Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf O= f cwfmd@yahoo.com
Sent: Tuesd= ay, December 03, 2013 7:01 AM
To: lml@lancaironline.net
Subject: <= /span>[LML] cabin pressure valve vs manifold pressure drop

 

We put a new canopy seal in the IV-P. I f= iddled with the cabin pressure valve to try to reduce or locate  a squ= eal. (My Grainger smoke matches don't light, with reduced partial pressure = of Oxygen at altitude) I noticed that pulling the cabin pressure control pa= rtially out, reduced the cabin inflow, as expected, but also dropped the ma= nifold pressure by about 4 inches with a loss of about 50 hp (estimated). T= his was at flight level 230. I had not previously noticed this large effect= on manifold pressure, but it could demystify performance changes in previo= us data. Who knew the cabin pressure valve 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 no= t just close the valve to the cabin, when not needed or wanted, and leave t= he 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, usi= ng the on-board instrumentation and computers that already know the static = pressure and the cabin pressure. I hot climates I prefer to minimize the he= at entering the cabin, and maybe just use 4-5 psi relief valves to distribu= te air flow. I think my system where all the inter-cooled air routes thru t= he firewall to under the back seat was designed by Eskimos, who always need= max heating.

 

= --_000_2A14E6258A8534418F5498D73CCA51EF225AD035AEP3PW5EX1MB14E_--