From: "Marvin Kaye" <marv@lancaironline.net>
Subject: Re: [LML] Summary - when to turn on the fuel boost pump
To: lml
Date: Wed, 07 Feb 2007 18:35:03 -0500
Message-ID: <web-1822468@logan.com>
In-Reply-To: <170857.67327.qm@web34901.mail.mud.yahoo.com>
References: <170857.67327.qm@web34901.mail.mud.yahoo.com>
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Posted for bob mackey <n103md@yahoo.com>:

Dr Andre Katz <bu131@swbell.net> wrote:
  
> you forgot one more factor in the myriad of answers, the duke's 
   > fuel pump is located inside the cockpit, therefore is
   > pressurized, pressurization in a IV-P has a factor in the fuel
   > flow, in my IV-P I believe its the reason for the acute engine
   > power loss when shifting tanks, the only way to avoid it is to
   > go high in the boost prior to switching, if you get a leak in
   > the fuel pump like it occurred to me you lose pressure. This
   > event never happens at low altitude, therefor my small brain
   > tells me it pressure related. One more thing to consider.
   >   andres

   The above doesn't quite make sense to me, but maybe it
   is because I haven't built a IV-P and don't understand how
   it's fuel and pressurization systems interact.

   What I would expect is that even though fuel lines pass
   through the pressure vessel, the fuel system is vented
   outside. The Dukes pump presumably pumps from the tanks
   and towards the engine, which are both outside the pressure
   vessel. The fact that the pump is located inside the cockpit
   shouldn't matter. The volume pressurized does not include the
   volume inside the fuel lines or pump.

   I don't understand why cockpit pressurization would be a
   factor in fuel flow.

   Thanks to John for the summary.