Return-Path: Received: from [24.25.9.103] (HELO ms-smtp-04-eri0.southeast.rr.com) by logan.com (CommuniGate Pro SMTP 4.2b3) with ESMTP id 98999 for flyrotary@lancaironline.net; Tue, 01 Jun 2004 10:21:11 -0400 Received: from EDWARD (clt25-78-058.carolina.rr.com [24.25.78.58]) by ms-smtp-04-eri0.southeast.rr.com (8.12.10/8.12.7) with SMTP id i51EKbVw015058 for ; Tue, 1 Jun 2004 10:20:38 -0400 (EDT) Message-ID: <000c01c447e3$a0fb2b60$2402a8c0@EDWARD> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: Pop off Date: Tue, 1 Jun 2004 10:20:45 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0009_01C447C2.19B2C3F0" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1409 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1409 X-Virus-Scanned: Symantec AntiVirus Scan Engine This is a multi-part message in MIME format. ------=_NextPart_000_0009_01C447C2.19B2C3F0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MessageJohn, similar to a radiator cap, the POV capacity is rated = assuming differential pressure. In other words, the rating assumes = there is 14.7 psi "helping" the spring keep the lid on. Going up in = altitude will, of course, reduce that assist as the ambient pressure = decreases. This means that if will probably open at less boost than you = set it for on the ground which means it will likely "pop" open at less = boost pressure at altitude. And as Rusty indicated, if you set it so = you get your max boost at altitude, then it will likely not release = until even higher (harmful?) boost pressures at sea level. Ed Ed Anderson RV-6A N494BW Rotary Powered Matthews, NC ----- Original Message -----=20 From: John Slade=20 To: Rotary motors in aircraft=20 Sent: Tuesday, June 01, 2004 9:57 AM Subject: [FlyRotary] Re: Pop off I've been thinking about the POV, and wondering how it'll behave at = altitude. If the air is pushing against a spring, perhaps the ambient pressure = behind the spring wont make much difference. Has anyone tested the = behavior of a POV at altitude. Seems to me that it would hold back = pressure, even in a vacuum. John (popping off to the hangar to remove cowl and investigate the = last flight) ------=_NextPart_000_0009_01C447C2.19B2C3F0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Message
John, similar to a radiator cap, the = POV capacity=20 is rated assuming differential pressure.  In other words, the = rating=20 assumes there is 14.7 psi "helping" the spring keep the lid on.  = Going up=20 in altitude will, of course, reduce that assist as the ambient pressure=20 decreases.  This means that if will probably open at less boost = than you=20 set it for on the ground which  means it will likely "pop" open at = less=20 boost pressure at altitude.  And as Rusty indicated, if you set it = so you=20 get your max boost at altitude, then it will likely not release until = even=20 higher (harmful?) boost pressures at sea level.
 
Ed
 
Ed Anderson
RV-6A N494BW Rotary Powered
Matthews, NC
----- Original Message -----
From:=20 John=20 Slade
Sent: Tuesday, June 01, 2004 = 9:57=20 AM
Subject: [FlyRotary] Re: Pop = off

I've=20 been thinking about the POV, and wondering how it'll behave at=20 altitude.
If=20 the air is pushing against a spring, perhaps the ambient pressure = behind the=20 spring wont make much difference. Has anyone tested the behavior of a = POV at=20 altitude. Seems to me that it would hold back pressure, even in a=20 vacuum.
John=20 (popping off to the hangar to remove cowl and investigate the last=20 flight)
 
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