X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Fri, 09 Nov 2012 08:45:12 -0500 Message-ID: X-Original-Return-Path: Received: from qmta05.westchester.pa.mail.comcast.net ([76.96.62.48] verified) by logan.com (CommuniGate Pro SMTP 6.0c2) with ESMTP id 5870084 for lml@lancaironline.net; Fri, 09 Nov 2012 06:45:30 -0500 Received-SPF: pass receiver=logan.com; client-ip=76.96.62.48; envelope-from=jmorgan1023@comcast.net Received: from omta02.westchester.pa.mail.comcast.net ([76.96.62.19]) by qmta05.westchester.pa.mail.comcast.net with comcast id MP511k0010QuhwU55Pkv7J; Fri, 09 Nov 2012 11:44:55 +0000 Received: from [192.168.1.105] ([24.11.157.196]) by omta02.westchester.pa.mail.comcast.net with comcast id MPku1k00R4EXR5U3NPkuBl; Fri, 09 Nov 2012 11:44:55 +0000 From: Jack Morgan Mime-Version: 1.0 (Apple Message framework v1283) Content-Type: multipart/alternative; boundary="Apple-Mail=_1A510798-A14C-4060-B971-7AA1B08F8667" Subject: Dukes pressurization controller X-Original-Date: Fri, 9 Nov 2012 06:44:54 -0500 In-Reply-To: X-Original-To: "Lancair Mailing List" References: X-Original-Message-Id: <81AB8A28-B793-4A68-9046-2FE550250E6F@comcast.net> X-Mailer: Apple Mail (2.1283) --Apple-Mail=_1A510798-A14C-4060-B971-7AA1B08F8667 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=windows-1252 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 = controls cabin pressure to just above the set airport altitude. This = insures no pressurization is present at landing. Once set, an electrical = failure will 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 >=20 >=20 > Dico, > =20 > I=92ll answer via the LML as this may be of interest to other Lancair = owners/operators. > =20 > 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. > =20 > The IV-P uses bleed air from the engine turbochargers to both = pressurize and heat the cockpit. The compressed air pipe exiting each = turbocharger has 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 either 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 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 is 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 smaller than a coffee can) mounted to = the top engine-side of the firewall. > =20 > 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 = 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 side can yield 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. > =20 > The above compressed air is fed into the cabin directly 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 =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, 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 and closes the port into the cabin, dumping the = pressurized air overboard. This 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 at altitude. > =20 > 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. > =20 > 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 will 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 conditions 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 = the winter time just to keep Judy warm and happy. A good investment=85 = =20 > =20 > Just a last bit of information to =93polish off=94 the system: The = flow of high pressure air into the cockpit is =93unregulated=94 as long = as the dump control is closed, and although relatively constant, is = subject to changes 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 under 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 to =93get ahead=94 of = the pressurization system by rapidly changing the engine 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 happens = if you pull the engine back to below 25=94 MP or so while at altitude? = The air in the cabin actually back-flows through the engine and the = cabin altitude goes quickly to the outside pressure altitude. Solution: = Keep the MP above 25=94 until you=92re down out of the flight levels; = then slowly bring it back more if needed=85 > =20 > Hope this helps! > =20 > Bob >=20 --Apple-Mail=_1A510798-A14C-4060-B971-7AA1B08F8667 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=windows-1252 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 = controls cabin pressure to just above the set airport altitude. This = insures no pressurization is present at landing. Once set, an electrical = failure will 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
To: 
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 has = 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 = either 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 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 is 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 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 = 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 side can yield 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 = 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 =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, 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 and closes the port into the cabin, dumping the = pressurized air overboard. This 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 at = altitude.
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 will 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 conditions 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.
      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 the winter time = just to keep Judy warm and happy. A good investment=85 <grin>  Just = a last bit of information to =93polish off=94 the system: The flow of = high pressure air into the cockpit is =93unregulated=94 as long as the = dump control is closed, and although relatively constant, is subject to = changes 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 under 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 to =93get ahead=94 of the pressurization = system by rapidly changing the engine 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 happens if you pull the = engine back to below 25=94 MP or so while at altitude? The air in the = cabin actually back-flows through the engine and the cabin altitude goes = quickly to the outside pressure altitude. Solution: Keep the 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!

= --Apple-Mail=_1A510798-A14C-4060-B971-7AA1B08F8667--