Jim,

I went back to the article (http://www.autoshop101.com/forms/h42.pdf) and looked at the drawing on pg. 5.  I noticed two things I had missed at first, the pressure regulator is in the tank with the pump and filter, which seems to go against the advice to put the pressure regulator at the end of the system.   And the jet pump appears to be connected to the return line of the pressure regulator.  Tracy stated that adding such a device to the return would mess up the fuel pressure readings.  He should know.  I would still like to experiment with this gizmo at a future date… once I get caught up on all the other stuff around the house.  Interesting mental exercise none the less.

 

Mark S.

 

 

Got no problem with that.  It really sounded good at first blush.  It just sounded to me that things kind of got out of hand when we looked a little deeper into the plumbing and mechanisms that we have to add to compensate for the fact that we can't turn the transfer pump off.  Sounds to me like a really nice looking concept is going to get us INTO more trouble than it gets us OUT of.

Haven't heard much around the effect back pressure will have on regulator ... Jim S.

Mark R Steitle wrote:

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!!

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