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Subject: RE: [FlyRotary] Re: fuel pump mounting ( fuel system architecture)
Date: Wed, 15 Jun 2005 07:12:04 -0500
Message-ID: <87DBA06C9A5CB84B80439BA09D86E69E016C1A20@MAIL01.austin.utexas.edu>
Thread-Topic: [FlyRotary] Re: fuel pump mounting ( fuel system architecture)
Thread-Index: AcVxRTvrDQbiNTKZQVCO10nBZ3TPGgAXG6+Q
From: "Mark R Steitle" <mark.steitle@austin.utexas.edu>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>

Bernie,
I tried to follow Lancair's fuel system design as close as possible.
Also, the kit included the Andair 6-way valve.  It may not be very clear
in the diagram, but the return fuel goes through the Andair valve and is
routed to whichever tank you are drawing from at the time.  So, it
always returns fuel to the appropriate tank. =20

Where are your pumps located?  I think that makes a big difference in
whether or not a bleed circuit is needed.  The closer to the tanks, the
less the need for it.  I had discovered a potentially fatal design flaw
and found a simple remedy.  With air in the lines, the efi pumps simply
could not overcome the back pressure from the pressure regulator until
they were well primed.  The bleed circuit allows air to bleed off
rapidly, then the pumps can build up pressure so the system operates
normally.  The .020 orifice doesn't pass enough fuel to even notice.

Mark S. =20

-----Original Message-----
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On
Behalf Of WALTER B KERR
Sent: Tuesday, June 14, 2005 7:54 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: fuel pump mounting ( fuel system architecture)


On Tue, 14 Jun 2005 16:23:22 -0500 "Mark R Steitle"
<mark.steitle@austin.utexas.edu> writes:
> Jerry,
> You forced me to do a sketch.  So, here it is. =20
>=20
> Mark=20
>---------------------------------------
Mark, why do you choose not to return fuel to the tank instead of to the
selector valve? I have been to 17000 feet in Fla on auto gas and when I
landed the tanks feel very cool to hand and this is the fuel that the
pump sees rather than the elevated temps coming back from the engine
bay.
I have run tanks dry above 10000 and the engine quickly fired off as
soon
as I switched tanks so returning fuel to the tank has passed any test I
can think of. The fact that the system apparently boils someplace along
the way during ground shutdown but quickly clears when the pump is
turned
on says that if I had a small orifice that it probably would take longer
to bleed the vapor rather than returning it to a cooler tank.

Bernie

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