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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. -----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 system. A circuit that measures the differential between the fuel level sensors in my two tanks, and when it exceeds a certain value triggers an annunciator: "Dale, it's time to switch tanks."
Dale R.
COZY MkIV #1254
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
Jim,
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.
Mark S.
<... 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. Just trying to stay on message ... Jim S.
PS Has anyone actually seen the two-line-jet-pump and watched it
actually WORK ??
(the devil made me say that )
Ernest Christley wrote:
Thoughts on the jet pump: <> 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. Tracy 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. 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: A is full, B is empty Fuel will flow from A to B via the return line, until A is half
empty. B is full, A is empty Fuel will flow to A via the jet pump, until B is empty. A and B are both half full Fuel will flow to A. If A gets more than half full, fuel will flow
back to B. A and B are both full, and you park sideways on a hill. Fuel will flow to the ground until the high tank is empty. Doh!! Homepage: http://www.flyrotary.com/ Archive: http://lancaironline.net/lists/flyrotary/List.html
Homepage: http://www.flyrotary.com/
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