I like two high pressure pumps in the left tank and two low
pressure pumps to transfer fuel from right to left.
You just have to make sure that the low pressure pumps can pump more
than you burn. I think it is the simplest plumbing.  One return line,
one delivery line, two lines from right to left.
    Tracy has something similar. You could have a device that would
sense unequal tank levels and pump fuel
from right to left.
     The problem with the fuel valves is the plumbing is more
complicated and you need four expensive pumps to get redundancy.
Blake

On Fri, Nov 7, 2008 at 5:54 AM,  <neilak@sympatico.ca> wrote:
> Brooks,
>
>           Returning to a single tank is not a great idea.  One day, flying
> along, fat, dumb and happy, you'll forget you're draining from one tank and
> filling the other till it over-flows and you send your liquid gold
> overboard, out the vent  (Ask me how I know…)  Best case, you'll have gas
> stains all along the fuselage.  Medium case, you'll smell gas in the cockpit
> and suck up a seat cushion wondering what broke.  Worst case, you won't have
> fuel to make you destination.
>
>           Andair make the perfect solution with their FS20-20 Duplex Fuel
> Selector.  Send the fuel back to the tank that it came from.  (You need to
> keep it simple for the stupid pilot.)  No check valves to hang up.  Then
> like all other RVs flying, you run an hour on one tank, switch, run an hour
> on the other and back and forth.
>
> Neil
>
>
>
> ________________________________
>
> From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On
> Behalf Of Brooks Wolfe
> Sent: Thursday, November 06, 2008 11:42 PM
> To: Rotary motors in aircraft
> Subject: [FlyRotary] Fuel considerations
>
>
>
> The airplane I fly in my day job gave me an idea for my RV-7 rotary
> project.  This airplane requires the center tank to be burned first, then
> the wing tanks may be used.  To accomplish this, there are no sophisticated
> electronics nor any active logic at work; there are simply check valves in
> the system that allow the higher-pressure center pumps to push fuel ahead of
> the wing tank's pumps.  When the center tanks run dry, the check valves
> close from reduced fuel pressure, allowing fuel from the wings to flow.
>
>
>
> Soo, if it works for Boeing, it should work for a rotary, right?  I figure
> in this case, fuel lines would join together at some point with check valves
> to prevent back-pressurizing the tank that's not being used.  Switching
> tanks would be a simple matter of turning one pump on, and the other pump
> off.  For simplicity, I'm only planning on return fuel to one tank.
>
>
>
> Any thoughts?
>
>
>
> Brooks
>
> RV-7 -- Wiring up the EC2 for the engine's first run!
>
>
>
> Rent our "Sky's Landing" Beach House direct from us and save!
>
> Need a vacation? see http://vrbo.com/210620
>
>
>
>
>
>



--
Blake C. Lewis