Here is a little refinement on George's idea for an automatic
fuel return system. I could not find any balls that would
float so these are 1/2 inch nylon balls from Stock Drive Products
or W.M. Berg. The float part is welded out of thin wall
aluminum tubing. Durable and will never leak. 

The float lengths are adjusted or weighted so the ball
floats even with the top of the fuel If you somehow 
made the cylinders out of transparent material such as Plexiglas
tubing  these devices could do double duty as fuel level 
indictors.

The major difference between this one and the last one is it 
fails safe. The return pressure can force the balls off their
seats if necessary as the fuel now comes in from the top.

Never the less if one tank is full and the ball is seated
the return flow will automatically  go to the other tank.
No need to worry about a solenoid or manual valve to switch
return flow to the tanks. These look complicated but they are
easy to make. They are outside the tanks for maintenance
purposes. they also can be made high enough to accommodate 
any dihedral in the wings. In a slip the down side ball
will come off its seat and return fuel will go there.

Paul Lamar
 
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