X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml Date: Mon, 27 Nov 2006 11:55:53 -0500 Message-ID: X-Original-Return-Path: Received: from imo-m26.mx.aol.com ([64.12.137.7] verified) by logan.com (CommuniGate Pro SMTP 5.1.3) with ESMTP id 1610200 for lml@lancaironline.net; Sun, 26 Nov 2006 22:18:49 -0500 Received-SPF: pass receiver=logan.com; client-ip=64.12.137.7; envelope-from=Sky2high@aol.com Received: from Sky2high@aol.com by imo-m26.mx.aol.com (mail_out_v38_r7.6.) id q.bf8.9e54be0 (41811) for ; Sun, 26 Nov 2006 22:18:16 -0500 (EST) From: Sky2high@aol.com X-Original-Message-ID: X-Original-Date: Sun, 26 Nov 2006 22:18:16 EST Subject: Re: [LML] Re: Electrical /Hydraulic system questionslancair235/320 X-Original-To: lml@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="-----------------------------1164597496" X-Mailer: 9.0 Security Edition for Windows sub 5330 X-Spam-Flag: NO -------------------------------1164597496 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit In a message dated 11/26/2006 8:42:25 P.M. Central Standard Time, marv@lancaironline.net writes: Last week's discussion of hydraulics prompted me to fire up the test stand I use for trouble shooting and testing to record some scenarios discussed. One topic that comes up every so often is the loss of pressure while climbing and the gain in pressure while descending. If you don't have pressure gauges you may take the pump blip during a climb to 18k as a leak. With a gauge you can watch pressure follow temperature. Of course, in our planes we have the nose gear hydraulics warming from engine heat and the main gear hydraulics being influenced by ambient temperatures so the relationship between ambient and pressure gets a little distorted. Trapping hydraulic fluid and heating it can build enormous pressure and it should be respected. The embedded photos show a time history of a single cylinder being warmed and than cooled. After the first pump blip during the cooling cycle, I turned the pump off so pressure could continue to fall. Heating is from a hobby heat gun and cooling is done with a hand full of ice. Chris, What a super experiment! It certainly helps as a basis for understanding some of the exotic lock-ups that have been described here. Thanks. Scott -------------------------------1164597496 Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable

In a message dated 11/26/2006 8:42:25 P.M. Central Standard Time,=20 marv@lancaironline.net writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>Last=20 week's discussion of hydraulics prompted me to fire up the test stand Iuse=20 for trouble shooting and testing to record some scenarios discussed. = =20 One
topic that comes up every so often is the loss of pressure while=20 climbing and
the gain in pressure while descending. If you don't=20= have=20 pressure gauges you
may take the pump blip during a climb to 18k as a l= eak.=20 With a gauge you can
watch pressure follow temperature. Of course= , in=20 our planes we have the nose
gear hydraulics warming from engine heat an= d=20 the main gear hydraulics being
influenced by ambient temperatures so th= e=20 relationship between ambient and
pressure gets a little distorted. = ;=20 Trapping hydraulic fluid and heating it can
build enormous pressure and= it=20 should be respected. The embedded photos show
a time history of a= =20 single cylinder being warmed and than cooled. After the
first pum= p=20 blip during the cooling cycle, I turned the pump off so pressure
could=20 continue to fall. Heating is from a hobby heat gun and cooling is=20 done
with a hand full of ice.

Chris,

What a super experiment! It certainly helps as a basis for=20 understanding some of the exotic lock-ups that have been described here.

Thanks.

Scott

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