X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from imr-da01.mx.aol.com ([205.188.105.143] verified) by logan.com (CommuniGate Pro SMTP 6.0.2) with ESMTP id 6114449 for lml@lancaironline.net; Sun, 10 Mar 2013 14:05:15 -0400 Received-SPF: pass receiver=logan.com; client-ip=205.188.105.143; envelope-from=vtailjeff@aol.com Received: from mtaomg-ma01.r1000.mx.aol.com (mtaomg-ma01.r1000.mx.aol.com [172.29.41.8]) by imr-da01.mx.aol.com (Outbound Mail Relay) with ESMTP id 2F4AA1C000063 for ; Sun, 10 Mar 2013 14:04:43 -0400 (EDT) Received: from core-mnb003b.r1000.mail.aol.com (core-mnb003.r1000.mail.aol.com [172.29.106.137]) by mtaomg-ma01.r1000.mx.aol.com (OMAG/Core Interface) with ESMTP id E248CE00008B for ; Sun, 10 Mar 2013 14:04:42 -0400 (EDT) References: To: lml@lancaironline.net Subject: Re: [LML] Re: Pressurization In-Reply-To: X-MB-Message-Source: WebUI MIME-Version: 1.0 From: vtailjeff@aol.com X-MB-Message-Type: User Content-Type: multipart/alternative; boundary="--------MB_8CFEBD0DFF93B45_1EF8_70719_webmailstg-m05.sysops.aol.com" X-Mailer: AOL Webmail 37547-STANDARD Received: from 24.107.65.42 by webmailstg-m05.sysops.aol.com (64.12.225.56) with HTTP (WebMailUI); Sun, 10 Mar 2013 14:04:42 -0400 Message-Id: <8CFEBD0DFED54BF-1EF8-234D4@webmailstg-m05.sysops.aol.com> X-Originating-IP: [24.107.65.42] Date: Sun, 10 Mar 2013 14:04:42 -0400 (EDT) x-aol-global-disposition: G DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mx.aol.com; s=20121107; t=1362938683; bh=g9gc7bxxHKBY9LI5MoS7uJa0rrImj5sQuzkQDeVSNSU=; h=From:To:Subject:Message-Id:Date:MIME-Version:Content-Type; b=Ht7GWUI5gLW8kCvkBOraXph56DNamaCAP/A1iysZ+mpNivrWxVmmgmPkDJh/fTY0m Ocr8BoYnESu6Ptx/c+wul8rb3K5La9RI68vXWAyEWMIyNdz9iInzAsPQiI15TrK/c7 hv7VSQG6nDZ6xfWbTJvhuOUbSca2D2GUyoOpxqgE= X-AOL-SCOLL-SCORE: 0:2:492942624:93952408 X-AOL-SCOLL-URL_COUNT: 0 x-aol-sid: 3039ac1d2908513ccb3a0c32 This is a multi-part message in MIME format. ----------MB_8CFEBD0DFF93B45_1EF8_70719_webmailstg-m05.sysops.aol.com Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" John, How do you set the desired cabin altitude and control the pressure? Jeff -----Original Message----- From: Colyn Case To: Lancair Mailing List Sent: Sun, Mar 10, 2013 12:50 pm Subject: [LML] Re: Pressurization In addition to all the reasons Pete mentioned, I would add that there will = be lots of times where you will want to be able to monitor how your pressur= ization system is doing. having delta psi + cabin altitude are both reall= y useful. After you reseal that main gear (seat bottom) inspection plate;= develop a pinhole leak in your door seal; adjust your mixer valve etc. I don't know the chelton or VP systems but it's hard to believe they don't = have configurable aux ports into which you could plug a pressure transducer= if you absolutely don't have room for the analog instruments. On Mar 10, 2013, at 10:11 AM, John Barrett wrote: Pete, Thanks for the info. I do not have a cabin altimeter inst on my panel and = I'm pretty sure neither Cheltons nor the VP 200 can be configured for this = data. Yes, I would appreciate borrowing the tools you have. I would be happy to = pay shipping and a rental fee to help defray your acquisition costs for any= thing that helps. John Barrett 243 Old Oak Bay Rd Port Hadlock, WA 98339 3603011066 Sent from my iPad On Mar 9, 2013, at 9:18 AM, "pete@leapfrogventures.com" wrote: John, =20 I assume you are adding a cabin altimeter to your instrument panel? It rea= ds out both the cabin differential in psi and the cabin altitude. It is a = must have IMHO to monitor and prevent cabin over-pressurization. It is the= only test instrument needed for calibrating the Dukes and sealing the cabi= n. =20 I know that there is an overpressure valve that mounts next to the Dukes. = However, my Dukes head was not working properly during testing and was not = opening. The overpressure valve was no match for the amount of pressurized= air coming in the cabin, and the pressure quickly went over 6.5 psi before= I was able to do a manual dump. If you look at the teeny size of the over= pressure valve and compare that to the volume of pressurized air coming int= o the cabin on climb-out, you will quickly come to the conclusion that it p= rovides inadequate over pressurization protection. =20 I think you are using a G900 like me. It has an annunciator input called C= ABIN ALTITUDE. I connected that annunciator to a pressure switch set to 6 = psi that compares the pressure in the cabin to the pressure under the floor= in the baggage compartment (where the switch is mounted). In case the Duk= es valve fails and the cabin pressure rises too high, at least I will get s= ome notice (see note above about not depending on the manual vent valve). =20 I do have a digital differential manometer that measures PSI you are welcom= e to borrow. I used it to calibrate the overpressure valve that mounts nex= t to the Dukes (I set it to 6psi). I built a plenum from a large plastic f= ood container that you can pressurize with a compressor (carefully) that yo= u can borrow as well. =20 Pete =20 From: John Barrett [mailto:jbarrett@carbinge.com]=20 Sent: Friday, March 08, 2013 5:11 AM To: lml@lancaironline.net Subject: Pressurization =20 I didn=E2=80=99t think I=E2=80=99d need help with measurement issues, but I= =E2=80=99m hitting some stone walls. =20 I have a pocket altimeter I thought I=E2=80=99d use but wonder if it will h= ave a stop on negative altitude. Also I went online to see how to convert = altitude differential to PSID. Not much luck. The one site I found had co= nversion formulae that don=E2=80=99t seem correct. It lists a correlation = 1=E2=80=9D of mercury to 1,000 feet of altitude and that should be ok. It = then goes on to list a .49 conversion factor to get from inches of mercury = to psi. =20 =20 My calculations show that at a service ceiling of FL290 the altitude differ= ence to 10,000 foot cabin alt is 19,000 feet. .49 times this difference is= about 9.5 PSID. That=E2=80=99s WAY higher than the 5.0 PSI we=E2=80=99re = supposed to be seeing in the LIVP at FL 290. I had hoped to test to about = 6 PSI. =20 Short of an altimeter that allows negative readings all the way to somethin= g over 19K and a formula that works, the only other instrument I can think = of is a gauge that reads psi. I found some online that sell for from a cou= ple hundred bucks to $450 or so. They all appeared to be set up for plumbi= ng into a pipe system and I don=E2=80=99t know if they would read correctly= if placed inside the cockpit.=20 =20 How have you IVP builders out there gone about getting measurements when se= aling up the pressure vessel? =20 Thanks, =20 John Barrett, CEO Leading Edge Composites PO Box 428 Port Hadlock, WA 98339 =20 www.carbinge.com =20 =20 ----------MB_8CFEBD0DFF93B45_1EF8_70719_webmailstg-m05.sysops.aol.com Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset="utf-8"
John,
 
How do you set the desired cabin altitude and control the pressure?
 
Jeff
-----Original Message-----
From: Colyn Case <colyncase@earthlink.net>
To: Lancair Mailing List <lml@lancaironline.net>
Sent: Sun, Mar 10, 2013 12:50 pm
Subject: [LML] Re: Pressurization

In addition to all the reasons Pete mentioned, I would add that there will = be lots of times where you will want to be able to monitor how your pressur= ization system is doing.   having delta psi + cabin altitude are both = really useful.   After you reseal that main gear (seat bottom) inspect= ion plate; develop a pinhole leak in your door seal; adjust your mixer valv= e etc.

I don't know the chelton or VP systems but it's hard to believe they d= on't have configurable aux ports into which you could plug a pressure trans= ducer if you absolutely don't have room for the analog instruments.

On Mar 10, 2013, at 10:11 AM, John Barrett wrote:

Pete,

Thanks for the info.  I do not have a cabin altimeter inst on my = panel and I'm pretty sure neither Cheltons nor the VP 200 can be configured= for this data.

Yes, I would appreciate borrowing the tools you have.  I would be= happy to pay shipping and a rental fee to help defray your acquisition cos= ts for anything that helps.

John Barrett
243 Old Oak Bay Rd
Port Hadlock, WA 98339
3603011066

Sent from my iPad


On Mar 9, 2013, at 9:18 AM, "p= ete@leapfrogventures.com" <pete@leapfrogventures.com> wrote:

John,
 
I assume = you are adding a cabin altimeter to your instrument panel?  It reads o= ut both the cabin differential in psi and the cabin altitude.  It is a= must have IMHO to monitor and prevent cabin over-pressurization.  It = is the only test instrument needed for calibrating the Dukes and sealing th= e cabin.
 
I know th= at there is an overpressure valve that mounts next to the Dukes.  Howe= ver, my Dukes head was not working properly during testing and was not open= ing.  The overpressure valve was no match for the amount of pressurize= d air coming in the cabin, and the pressure quickly went over 6.5 psi befor= e I was able to do a manual dump.  If you look at the teeny size of th= e overpressure valve and compare that to the volume of pressurized air comi= ng into the cabin on climb-out, you will quickly come to the conclusion tha= t it provides inadequate over pressurization protection.
 
I think y= ou are using a G900 like me.  It has an annunciator input called CABIN= ALTITUDE.  I connected that annunciator to a pressure switch set to 6= psi that compares the pressure in the cabin to the pressure under the floo= r in the baggage compartment (where the switch is mounted).  In case t= he Dukes valve fails and the cabin pressure rises too high, at least I will= get some notice (see note above about not depending on the manual vent val= ve).
 
I do have= a digital differential manometer that measures PSI you are welcome to borr= ow.  I used it to calibrate the overpressure valve that mounts next to= the Dukes (I set it to 6psi).  I built a plenum from a large plastic = food container that you can pressurize with a compressor (carefully) that y= ou can borrow as well.
 
Pete
 
 
I didn=E2=80=99t think I=E2=80=99d need help with = measurement issues, but I=E2=80=99m hitting some stone walls.
 
I have a pocket altimeter I thought I=E2=80=99d us= e but wonder if it will have a stop on negative altitude.  Also I went= online to see how to convert altitude differential to PSID.  Not much= luck.  The one site I found had conversion formulae that don=E2=80=99= t seem correct.  It lists a correlation 1=E2=80=9D of mercury to 1,000= feet of altitude and that should be ok.  It then goes on to list a .4= 9 conversion factor to get from inches of mercury to psi. 
 
My calculations show that at a service ceiling of = FL290 the altitude difference to 10,000 foot cabin alt is 19,000 feet. = ; .49 times this difference is about 9.5 PSID.  That=E2=80=99s WAY hig= her than the 5.0 PSI we=E2=80=99re supposed to be seeing in the LIVP at FL = 290.  I had hoped to test to about 6 PSI.
 
Short of an altimeter that allows negative reading= s all the way to something over 19K and a formula that works, the only othe= r instrument I can think of is a gauge that reads psi.  I found some o= nline that sell for from a couple hundred bucks to $450 or so.  They a= ll appeared to be set up for plumbing into a pipe system and I don=E2=80=99= t know if they would read correctly if placed inside the cockpit.
 
How have you IVP builders out there gone about get= ting measurements when sealing up the pressure vessel?
 
Thanks,
 
John Barrett, CEO
Leading Edge Composites
PO Box 428
Port Hadlock, WA 98339
 
www.carbinge.com
 

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