X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Mon, 11 Mar 2013 11:42:34 -0400 Message-ID: X-Original-Return-Path: Received: from hrndva-omtalb.mail.rr.com ([71.74.56.122] verified) by logan.com (CommuniGate Pro SMTP 6.0.2) with ESMTP id 6115521 for lml@lancaironline.net; Mon, 11 Mar 2013 11:12:51 -0400 Received-SPF: none receiver=logan.com; client-ip=71.74.56.122; envelope-from=Wolfgang@MiCom.net X-Original-Return-Path: X-Authority-Analysis: v=2.0 cv=adbjbGUt c=1 sm=0 a=MHZY6FYWMEQOp7S43i2QIw==:17 a=3Zlka_XeuxsA:10 a=ttCsPuSJ-FAA:10 a=rTjvlri0AAAA:8 a=OIb02pnn1wUA:10 a=Ia-xEzejAAAA:8 a=ayC55rCoAAAA:8 a=cV5C3Lt1AAAA:8 a=biznXsr5AAAA:8 a=RtSeQP2xbNkIHXxRiGQA:9 a=QEXdDO2ut3YA:10 a=b3O8e1rDz4sA:10 a=EzXvWhQp4_cA:10 a=EoWsjk9DV4PbOCT0:21 a=Dv-Fj13-YGG8Soba:21 a=pGLkceISAAAA:8 a=4PR2P7QzAAAA:8 a=YHU-mgiE9lh9NXvLE4gA:9 a=MSl-tDqOz04A:10 a=djSSOgbfo6cA:10 a=C9yDM4nu6D6X6TLC:21 a=6SaaS6e5Bp-5CWbL:21 a=1hyaeFFByRCJkey0:21 a=MHZY6FYWMEQOp7S43i2QIw==:117 X-Cloudmark-Score: 0 X-Authenticated-User: X-Originating-IP: 74.218.201.50 Received: from [74.218.201.50] ([74.218.201.50:1163] helo=lobo) by hrndva-oedge01.mail.rr.com (envelope-from ) (ecelerity 2.2.3.46 r()) with ESMTP id C2/83-27807-054FD315; Mon, 11 Mar 2013 15:12:16 +0000 X-Original-Message-ID: <9C3DD071A7F6449097E7378899CA1CE7@lobo> From: "Wolfgang" X-Original-To: References: Subject: Re: [LML] Re: Pressurization X-Original-Date: Mon, 11 Mar 2013 11:12:12 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0046_01CE1E49.47C60A10" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.5512 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.5512 This is a multi-part message in MIME format. ------=_NextPart_000_0046_01CE1E49.47C60A10 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable I'm not able to determine what you are trying to achieve. Do you want to keep an eye on the cabin pressure diferential ? . . . Then get a diferential pressure gage and plumb one side to static = and the other side to cabin interior. Do you want to read the cabin pressure in feet of altitude ? . . . Then get a small altimeter and keep it in the cabin with no = plumbing on it, ported to cabin interior. Wolfgang ----- Original Message -----=20 From: John Barrett=20 To: lml@lancaironline.net=20 Sent: Sunday, March 10, 2013 9:11 AM Subject: Re: [LML] Re: Pressurization Thanks to all for your input on this subject. Am sidetracked with = remounting the engine that got here a few days ago from Barrett's shop = in Tulsa. Will get back to pressurization in a few days. John Sent from my iPad On Mar 9, 2013, at 7:42 AM, Ted Noel wrote: John, Try = http://www.engineeringtoolbox.com/air-altitude-pressure-d_462.html Ted Noel On 3/8/2013 8:11 AM, John Barrett wrote:=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. I have a pocket altimeter I thought I=E2=80=99d use 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=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 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 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. Short of an altimeter that allows negative readings all the way to = something 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 couple hundred bucks to $450 or so. They all appeared to be = set up for plumbing into a pipe system and I don=E2=80=99t know if they = would read correctly if placed inside the cockpit.=20 How have you IVP builders out there gone about getting = measurements when sealing up the pressure vessel? Thanks, John Barrett, CEO Leading Edge Composites PO Box 428 Port Hadlock, WA 98339 www.carbinge.com ------=_NextPart_000_0046_01CE1E49.47C60A10 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable =EF=BB=BF
I'm not able to determine what you are = trying to=20 achieve.
Do you want to keep an eye on the cabin = pressure=20 diferential ?
. . . Then get a diferential pressure = gage and=20 plumb one side to static and the other side to cabin = interior.
Do you want to read the cabin pressure = in feet of=20 altitude ?
. . . Then get a small altimeter and = keep it in the=20 cabin with no plumbing on it, ported to cabin interior.
 
Wolfgang
 
----- Original Message -----
From:=20 John = Barrett=20
Sent: Sunday, March 10, 2013 = 9:11=20 AM
Subject: Re: [LML] Re:=20 Pressurization

Thanks to all for your input on this subject.  Am = sidetracked with=20 remounting the engine that got here a few days ago from Barrett's shop = in=20 Tulsa.  Will get back to pressurization in a few days.

John

Sent from my iPad


On Mar 9, 2013, at 7:42 AM, Ted Noel <tednoel@cfl.rr.com>=20 wrote:

John,

Try http://www.engineeringtoolbox.com/air-altitude-pressure-d_462.html=

Ted=20 Noel

On 3/8/2013 8:11 AM, John Barrett wrote:=20

I didn=E2=80=99t think I=E2=80=99d need help = with measurement issues,=20 but I=E2=80=99m hitting some stone walls.

I have a pocket altimeter I thought = I=E2=80=99d use but wonder=20 if it will have a stop on negative altitude.  Also I went = online to=20 see how to convert altitude differential to PSID.  Not much=20 luck.  The one site I found had conversion formulae that = don=E2=80=99t seem=20 correct.  It lists a correlation 1=E2=80=9D of mercury to = 1,000 feet of=20 altitude and that should be ok.  It then goes on to list a = .49=20 conversion factor to get from inches of mercury to psi. =20

My calculations show that at a service = ceiling of FL290=20 the altitude difference to 10,000 foot cabin alt is 19,000 = feet.  .49=20 times this difference is about 9.5 PSID.  That=E2=80=99s WAY = higher than the=20 5.0 PSI we=E2=80=99re supposed to be seeing in the LIVP at FL = 290.  I had=20 hoped to test to about 6 PSI.

Short of an altimeter that allows negative = readings all=20 the way to something over 19K and a formula that works, the only = other=20 instrument I can think of is a gauge that reads psi.  I found = some=20 online that sell for from a couple hundred bucks to $450 or = so.  They=20 all appeared to be set up for plumbing into a pipe system and I = don=E2=80=99t know=20 if they would read correctly if placed inside the cockpit. =

How have you IVP builders out there gone = about getting=20 measurements when sealing up the pressure vessel?

Thanks,

John Barrett, CEO

Leading Edge Composites

PO Box 428

Port Hadlock, WA 98339

www.carbinge.com

------=_NextPart_000_0046_01CE1E49.47C60A10--