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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
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