Message-Id: <5.2.0.9.0.20040525194611.027a4b90@mail.teleport.com>
Date: Tue, 25 May 2004 19:49:38 -0700
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
From: Michael McGee <jmpcrftr@teleport.com>
Subject: Re: [FlyRotary] Re: Fuel Pump Design
In-Reply-To: <list-90081@logan.com>
Mime-Version: 1.0
Content-Type: text/plain; charset="us-ascii"; format=flowed

At 19:17 2004-05-25, you wrote:
>Mark Steitle <msteitle@mail.utexas.edu> wrote:
>
>  > > > >
>Bill,
>Yes, the regulator is mounted on the firewall and is located between the 
>pumps/filters and fuel rail.  Also, there is a fuel return line off the 
>regulator.
>  < < < <
>
>Wouldn't it make more sense to make the regulator the last thing in the 
>circuit?  This seems to be typical on just about all automotive EFI 
>installations, and millions of installations can't be wrong.  I think the 
>logic here is that regulator failures aren't sudden, and when they fail 
>they bypass more fuel than they should (ie, lowering pressure).  In this 
>setup there is no way that you can get an airlock, at least I don't see 
>how one would be possible.  Proven systems all seem to have the fuel pumps 
>as close to the tank as possible (inside the tank on most auto 
>installations), then the filter, followed by a direct line to the fuel 
>rail and injectors, then to the regulator, then the return.  On the 
>Eagle540 we put the fuel filters between the tanks and pumps, and they are 
>located just aft of the main spar, just inches away from the tanks (the 
>filter outlet screws directly into the pump inlet)... out of the pumps to 
>the selector, on through the flow transducers, then to the rails.  The 
>regulator is at the end of the circuit and returns through the (horribly 
>expensive) fuel selector as well to direct the return fuel back to the 
>tank from which we're pumping.  Everything has worked extremely well in 
>ground runs, and we are weeks away from first flight.  Just my 2c.
>
>  <Marv>

Yes, and heat soak of the fuel is eliminated with the regulator on the out 
going end of the fuel rail so as to not make a dead end.  After a hot 
shutdown and heat soak of the fuel rail, the system can be cooled down by 
just turning on a boost pump and letting the fuel circulate for a few seconds.


Mike McGee, RV-4 N996RV, O320-E2G, Hillsboro, OR
13B in gestation mode, RD-1C, EC-2