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Subject: RE: [FlyRotary] Re: Fuel System Design - Jet Pump
Date: Wed, 16 Feb 2005 16:16:57 -0600
Message-ID: <87DBA06C9A5CB84B80439BA09D86E69EC07F79@MAIL01.austin.utexas.edu>
Thread-Topic: [FlyRotary] Re: Fuel System Design - Jet Pump
Thread-Index: AcUUdGda2RnL/AP0S1C/CSJGNlHqTwAAEttQ
From: "Mark R Steitle" <mark.steitle@austin.utexas.edu>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>

Dale,
I thought so too.  I just don't know how to go about doing this with
capacitive fuel probes.  So, why stop with just an aural warning?  Why
not use this to switch tanks as needed.  You could take a little nap or
read a book.  ;-)

Mark S. =20

-----Original Message-----
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On
Behalf Of Dale Rogers
Sent: Wednesday, February 16, 2005 4:10 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Fuel System Design - Jet Pump

Ooh!  That suggests something actually useable on my=20
system.  A circuit that measures the differential between=20
the fuel level sensors in my two tanks, and when it exceeds=20
a certain value triggers an annunciator: "Dale, it's time=20
to switch tanks."

Dale R.
COZY MkIV #1254

=20
> From: "Mark R Steitle" <mark.steitle@austin.utexas.edu>
> Date: 2005/02/16 Wed AM 09:17:06 EST
> To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
> Subject: [FlyRotary] Re: Fuel System Design - Jet Pump
>=20
> Jim,
>=20
> What I was envisioning is a simple electrical solenoid controlling
fuel
> transfer.  Forget all the lines from bottom of A to top of B, etc.
Some
> sort of fuel level sensor could tell the solenoid when to open and
> close.  (Some of you electronic whizzes will have to step in here.)
> This would free up the pilot to do other things, like watch for
traffic.
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> =20
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> Mark S.
>=20
> =20
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> =20
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> =20
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> <... you'd want two lines.  One from the bottom of B to the jet pump.
> Another from the mid level of A to the top of B ... A full B empty...
B
> full A empty ... A & B half full ... A & B full ... parked on a hill
...
> >
> Sounds a lot like a ten-cent tail wagging a forty-dollar dog here.
> Didn't we set out to simplify something?  How about just ONE line from
B
> to A with a Facet pump.  To get fancy, you could have a momentary ON
for
> the pump that would cause it to pump for 2 or 3 min or something and
> then turn itself off. =20
>=20
> Just trying to stay on message ... Jim S.
>=20
> PS  Has anyone actually seen the two-line-jet-pump and watched it
> actually WORK ??
> (the devil made me say that )
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> Ernest Christley wrote:
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> Thoughts on the jet pump:=20
> <>=20
>=20
> Fuel tank levels needs to be controlled in order to eliminate a 'heavy
> wing' which is very fatiguing on a long cross country.  Aileron trim
can
> do it but that adds drag.  A valve can be used but that adds to the
> complexity again.=20
>=20
> Tracy=20
>=20
>=20
> Looking over the diagram in the PDF that Ed sent.  The jet pump works
> all the time, constantly pumping fuel from the bottom of B into A,
where
> the main pump can pick it up.  An important element to this is that
> there is a large return path for fuel to go from A to B.  If the tank
is
> half full or more, all the fuel moved by the jet pump just flows back
> over.=20
>=20
> In the airplane transfer, you'd want two lines.  One from the bottom
of
> B to the jet pump.  Another from the mid level of A to the top of B.
> The lines need to stay below the tanks.  At no point will the the
sides
> ever be more than 1/2 a tank different.  Consider:=20
>=20
> A is full, B is empty=20
>    Fuel will flow from A to B via the return line, until A is half
> empty.=20
> B is full, A is empty=20
>    Fuel will flow to A via the jet pump, until B is empty.=20
> A and B are both half full=20
>    Fuel will flow to A.  If A gets more than half full, fuel will flow
> back to B.=20
> A and B are both full, and you park sideways on a hill.=20
>    Fuel will flow to the ground until the high tank is empty. Doh!!=20
>=20
>=20
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> 	 Homepage:  http://www.flyrotary.com/=20
> 	 Archive:   http://lancaironline.net/lists/flyrotary/List.html=20
>=20
> =20
>=20
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>=20


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