X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Sun, 11 Nov 2012 12:09:13 -0500 Message-ID: X-Original-Return-Path: Received: from mail-wg0-f50.google.com ([74.125.82.50] verified) by logan.com (CommuniGate Pro SMTP 6.0c2) with ESMTPS id 5872917 for lml@lancaironline.net; Sun, 11 Nov 2012 01:26:10 -0500 Received-SPF: pass receiver=logan.com; client-ip=74.125.82.50; envelope-from=billhogarty@gmail.com Received: by mail-wg0-f50.google.com with SMTP id 16so2360265wgi.7 for ; Sat, 10 Nov 2012 22:25:34 -0800 (PST) MIME-Version: 1.0 Received: by 10.216.30.76 with SMTP id j54mr6147171wea.11.1352615134433; Sat, 10 Nov 2012 22:25:34 -0800 (PST) Received: by 10.194.169.73 with HTTP; Sat, 10 Nov 2012 22:25:34 -0800 (PST) In-Reply-To: References: X-Original-Date: Sun, 11 Nov 2012 01:25:34 -0500 X-Original-Message-ID: Subject: Re: [LML] Dukes pressurization controller From: "William A. Hogarty" X-Original-To: Lancair Mailing List Content-Type: multipart/alternative; boundary=0016e6db2fc99b116104ce32404d --0016e6db2fc99b116104ce32404d Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: quoted-printable Good discussion on the controller so I thought that I would add my 2 cents. The dump valve was added to the flow controller some time after 1994. I purchased the 1st pressurized kit that had the bulkheads and gearbox installed by the factory and the the flow controller I received did not have the dump valve. As I recalled it was added some months later after a lot of discussion following the fiirst inflight fire.. Also, there was a mod added to the flow controller a couple of years back. Cant recall the details but I could look it up is anyone is interested. Regards, Bill H. On Fri, Nov 9, 2012 at 8:45 AM, Jack Morgan wrote= : > Just a quick note on the controller. Bob's excellent description below is > all good. The Dukes controller is an "aneroid" controller which needs no > electric power to operate once the airport elevation is set. > The electrical control for altitude setting in the cabin controls an > electric motor in the controller which sets the aneroid so that it contro= ls > cabin pressure to just above the set airport altitude. This insures no > pressurization is present at landing. Once set, an electrical failure wil= l > not cause any problem for the cabin pressurization system. > > Jack Morgan > > On Nov 9, 2012, at 6:01 AM, Lancair Mailing List wrote: > > *From: *Robert R Pastusek > *Subject: **RE: [LML] IVP cabin heat* > *Date: *November 8, 2012 3:16:51 PM EST > *To: *lml@lancaironline.net > > > Dico,**** > ** ** > I=92ll answer via the LML as this may be of interest to other Lancair > owners/operators.**** > ** ** > First the disclaimer: The description below covers Lancair IV-Ps built > using the parts provided by Lancair, and following the building manual. I > have seen a couple of other configurations out there=85the product of > =93individualism,=94 and occasionally better ideas=85 So check to be sure= your > system is plumbed as described below before trying these things.**** > ** ** > The IV-P uses bleed air from the engine turbochargers to both pressurize > and heat the cockpit. The compressed air pipe exiting each turbocharger h= as > a port added to tap off some of the air for the cabin. (By the way, this > air has run through the turbochargers, but does not yet have any fuel > added, so is breathable.) This port should have a =93sonic nozzle=94 eith= er > welded to the port itself, or installed in the SCAT/SCEET line that=92s > attached. The sonic nozzle provides a relative constant flow of air to th= e > cabin heating/pressurization system over the typical range of pressure in > the turbocharger system (typically 25=94-38=94 MP at cruise power setting= s). > Depending on the power setting (MP), this compressed air is near ambient > temperature to quite hot (200+ degrees), and is the =93hot=94 feed for th= e > cabin heating/pressurization system. It is routed via SCAT/SCEET ducting = to > a flow controller (a gold-anodized round canister a bit smaller than a > coffee can) mounted to the top engine-side of the firewall.**** > ** ** > The cabin heating/pressurization system has a second =93cool=94 feed that > starts with an additional port welded to the engine inlet air ducting > downstream of the large intercoolers on each side of the engine. These > ports are connected with SCAT tubing to a third intercooler on the forwar= d > left chin of the engine, opposite the alternator. For the =93cool=94 feed= , > compressed air passes through the side intercoolers, then through this > third intercooler and then via a single SCAT tube to the flow controller. > Note that both hot and cool feeds are =93relative.=94 The hot side can yi= eld > luke-warm air if the engine power is low, and the cool side is, at best, > a few degrees above ambient; usually not cool at all in Florida in the > summertime.**** > ** ** > The above compressed air is fed into the cabin directly from the flow > controller on the firewall. With the cabin temperature control in the col= d > position, flow from the hot side (above) is completely blocked and all > pressurization air is being fed into the cockpit from the cool side. With > the temperature control in the hot position, the cool side feed is blocke= d > and the hot side feed is fully opened. As a side note, the flow controlle= r > has a second function that=92s important. The =93pressurization control= =94 in the > cockpit is connected to a flapper valve in the flow controller that > alternatively opens a port allowing pressurized air to flow into the > cockpit (normal operation) and closes a =93dump port=94 that feeds air, v= ia a > SCAT tube, down the forward side of the firewall to the engine exhaust > area. When in the dump position, this valve opens the dump port and close= s > the port into the cabin, dumping the pressurized air overboard. This migh= t > be useful in the case of an engine fire or other contamination of the inl= et > air=85not common, but could really ruin your day if it happened at altitu= de. > **** > ** ** > So why no heat? If you haven=92t done so, it would be very beneficial to > verify that the controls/components discussed work as described above. IF > there are leaks or the system is not connected/configured correctly, all > bets are off.**** > ** ** > The next task, assuming the system is plumbed and operating correctly, is > actually generating some heat=85especially up where Dico lives=85 At low = power > settings, the air coming directly off the turbochargers is not hot. Your > choices (via the cabin temperature control) of compressed air for > pressurization are cool and cold. 25=94 of MP is about the minimum that w= ill > maintain cabin pressurization, and the compressed air off the turbos is > just a bit above ambient temperature. Above 32=94 of MP, the exit air is > approaching 200 degrees and will keep the cockpit toasty in any condition= s > I=92ve seen to date=85but I don=92t like to run my engine at that high a = power > setting. So to answer your specific question, heat the cabin by:**** > 1) Ensuring the cabin pressure dump control is closed, and not > leaking air/heat out the dump vent.**** > 2) Set the cabin temperature control to full hot**** > 3) Increase engine power (MP), with care to the engine, to get the > needed heat.**** > Note: I=92ve actually taken to running the MP between 29-30=94 during th= e > winter time just to keep Judy warm and happy. A good investment=85 = * > *** > ** ** > Just a last bit of information to =93polish off=94 the system: The flow o= f > high pressure air into the cockpit is =93unregulated=94 as long as the du= mp > control is closed, and although relatively constant, is subject to change= s > in both pressure and flow rate depending on engine power setting. The > cockpit pressure is maintained by controlling the outflow (controlled > leakage) of air through the Dukes controller mounted in a =93bucket=94 un= der > the rear seat. This is an electrically-controlled exhaust valve and takes > some time to adjust to flow and pressure changes. It=92s therefore easy t= o > =93get ahead=94 of the pressurization system by rapidly changing the engi= ne > power setting. Most of us have learned to compensate for this, but if > you=92re getting a lot of ear-popping and complaints from your passengers= , > try changing the engine power more gradually, especially at level-off and > start of descent. =85And I=92m sure you=92ve all discovered by now what h= appens > if you pull the engine back to below 25=94 MP or so while at altitude? Th= e > air in the cabin actually back-flows through the engine and the cabin > altitude goes quickly to the outside pressure altitude. Solution: Keep th= e > MP above 25=94 until you=92re down out of the flight levels; then slowly = bring > it back more if needed=85**** > ** ** > Hope this helps!**** > ** ** > Bob**** > > > --0016e6db2fc99b116104ce32404d Content-Type: text/html; charset=windows-1252 Content-Transfer-Encoding: quoted-printable
Good discussion on the controller so I thought that I would add my 2 c= ents.
=A0
The dump valve was added to the flow controller some time after 1994.= =A0 I purchased the 1st pressurized kit that had the bulkheads and gearbox = installed by the factory and the the flow controller I received did not hav= e the dump valve.=A0 As I recalled it was added some months later after a l= ot of discussion following the fiirst inflight fire..
=A0
Also, there was a mod added to the flow=A0controller a couple of years= back.=A0Cant recall the details but I could look it up is anyone is intere= sted.=A0
Regards, Bill H.
=A0
=A0
=A0
=A0
On Fri, Nov 9, 2012 at 8:45 AM, Jack Morgan <jmorgan1023@comcas= t.net> wrote:
Just a quick note on the controller. Bo= b's excellent description below is all good. The Dukes controller is an= "aneroid" controller which needs no electric power to operate on= ce the airport elevation is set.=20
The electrical control for altitude setting in the cabin controls an e= lectric motor in the controller which sets the aneroid so that it controls = cabin pressure to just above the set airport altitude. This insures no pres= surization is present at landing. Once set, an electrical failure will not = cause any problem for the cabin pressurization system.=20

Jack Morgan

On Nov 9, 2012, at 6:01 AM, Lancair Mailing List wrote:

From:=A0Robert R Pastusek <rpastusek@htii.com>
Subject:=A0RE: [LML] IVP cabin heat<= /b>
Date:=A0November 8, 2012 3:16:51 PM EST=


Dico,
=A0
I=92ll answer via the LML as this may be of inter= est to other Lancair owners/operators.
=A0
First the disclaimer: The description below cover= s Lancair IV-Ps built using the parts provided by Lancair, and following th= e building manual. I have seen a couple of other configurations out there= =85the product of =93individualism,=94 and occasionally better ideas=85 So = check to be sure your system is plumbed as described below before trying th= ese things.
=A0
The IV-P uses bleed air from the engine turbochar= gers to both pressurize and heat the cockpit. The compressed air pipe exiti= ng each turbocharger has a port added to tap off some of the air for the ca= bin. (By the way, this air has run through the turbochargers, but does not = yet have any fuel added, so is breathable.) This port should have a =93soni= c nozzle=94 either welded to the port itself, or installed in the SCAT/SCEE= T line that=92s attached. The sonic nozzle provides a relative constant flo= w of air to the cabin heating/pressurization system over the typical range = of pressure in the turbocharger system (typically 25=94-38=94 MP at cruise = power settings). Depending on the power setting (MP), this compressed air i= s near ambient temperature to quite hot (200+ degrees), and is the =93hot= =94 feed for the cabin heating/pressurization system. It is routed via SCAT= /SCEET ducting to a flow controller (a gold-anodized round canister a bit s= maller than a coffee can) mounted to the top engine-side of the firewall.
=A0
The cabin heating/pressurization system has a sec= ond =93cool=94 feed that starts with an additional port welded to the engin= e inlet air ducting downstream of the large intercoolers on each side of th= e engine. These ports are connected with SCAT tubing to a third intercooler= on the forward left chin of the engine, opposite the alternator. For the = =93cool=94 feed, compressed air passes through the side intercoolers, then = through this third intercooler and then via a single SCAT tube to the flow = controller. Note that both hot and cool feeds are =93relative.=94 The hot s= ide can yield=A0luke-warm air if the engine power= is low, and the cool side is, at best, a few degrees above ambient; usuall= y not cool at all in Florida in the summertime.
=A0
The above compressed air is fed into the cabin di= rectly from the flow controller on the firewall. With the cabin temperature= control in the cold position, flow from the hot side (above) is completely= blocked and all pressurization air is being fed into the cockpit from the = cool side. With the temperature control in the hot position, the cool side = feed is blocked and the hot side feed is fully opened. As a side note, the = flow controller has a second function that=92s important. The =93pressuriza= tion control=94 in the cockpit is connected to a flapper valve in the flow = controller that alternatively opens a port allowing pressurized air to flow= into the cockpit (normal operation) and closes a =93dump port=94 that feed= s air, via a SCAT tube, down the forward side of the firewall to the engine= exhaust area. When in the dump position, this valve opens the dump port an= d closes the port into the cabin, dumping the pressurized air overboard. Th= is might be useful in the case of an engine fire or other contamination of = the inlet air=85not common, but could really ruin your day if it happened a= t altitude.
=A0
So why no heat?=A0=A0If= you haven=92t done so, it would be very beneficial to verify that the cont= rols/components discussed work as described above. IF there are leaks or th= e system is not connected/configured correctly, all bets are off.=
=A0
The next task, assuming the system is plumbed and= operating correctly, is actually generating some heat=85especially up wher= e Dico lives=85 At low power settings, the air coming directly off the turb= ochargers is not hot. Your choices (via the cabin temperature control) of c= ompressed air for pressurization are cool and cold. 25=94 of MP is about th= e minimum that will maintain cabin pressurization, and the compressed air o= ff the=A0turbos=A0is just a bit abov= e ambient temperature. Above 32=94 of MP, the exit air is approaching 200 d= egrees and will keep the cockpit toasty in any conditions I=92ve seen to da= te=85but I don=92t like to run my engine at that high a power setting. So t= o answer your specific question, heat the cabin by:
1)=A0=A0=A0=A0=A0=A0Ensuring the cabin pressure dump control is closed, and not leaking air/he= at out the dump vent.
2)=A0=A0=A0=A0=A0=A0Set the cabin temperature control to full hot
3)=A0=A0=A0=A0=A0=A0Increase engine power (MP), with care to the engine, to get the needed hea= t.
Note:=A0=A0I=92ve actua= lly taken to running the MP between 29-30=94 during the winter time just to= keep Judy warm and happy. A good investment=85 <grin>=A0=A0
=A0
Just a last bit of information to =93polish off= =94 the system: The flow of high pressure air into the cockpit is =93unregu= lated=94 as long as the dump control is closed, and although relatively con= stant, is subject to changes in both pressure and flow rate depending on en= gine power setting. The cockpit pressure is maintained by controlling the o= utflow (controlled leakage) of air through the Dukes controller mounted in = a =93bucket=94 under the rear seat. This is an electrically-controlled exha= ust valve and takes some time to adjust to flow and pressure changes. It=92= s therefore easy to =93get ahead=94 of the pressurization system by rapidly= changing the engine power setting. Most of us have learned to compensate f= or this, but if you=92re getting a lot of ear-popping and complaints from y= our passengers, try changing the engine power more gradually, especially at= level-off and start of descent. =85And I=92m sure you=92ve all discovered = by now what happens if you pull the engine back to below 25=94 MP or so whi= le at altitude? The air in the cabin actually back-flows through the engine= and the cabin altitude goes quickly to the outside pressure altitude. Solu= tion: Keep the MP above 25=94 until you=92re down out of the flight levels;= then slowly bring it back more if needed=85
=A0
Hope this helps!
=A0
Bob



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