Hi Al

Just a note. The header tank is about 24” above the main wing tank.
The wing tank is vented at both wing tips.
Both main wing tank and header tank have drains.
As far as the return:
That was for overflow should the transfer pump remain on after filling the header tank.
If this happened and there was a vent then it would pump fuel overboard. If there was no vent then it would pressurize the header tank to Facet pressure minus any pressure reduction caused by the sum of the outgoing  and returning fuel from the main rail. I thought even a few psi would be dangerous for the tank.

Steve Izett


On 7/10/09 12:24 AM, "Al Gietzen" <ALVentures@cox.net> wrote:

Steve;
 
Basically looks OK to me with the following comments:
Although not shown, I assume you have a vent system for the main tanks and sump.
I’d hesitate to have anything but a relatively course screen filter anywhere ahead of pumps.  Restriction on the suction side of a pump is a vapor lock issue.
I assume you have sump drains on main tanks and sump tank.
Take the exit from the sump tank from somewhere above the bottom.  Leave a quart or so of volume at the bottom to collect any water or debris which will then drain out the sump drain.  You can then eliminate the filters ahead of the high pressure pumps.
What is the purpose of the return line from sump to main tank? With an 8 ga sump tank there should be no real concern about recirc to the sump.
Locate the HP pumps below the level of the sump exit so there is gravity feed to the pumps.
 
My return from the fuel rail goes to a sump tank of about 2 ¾ ga (cabin side of firewall, behind a ‘vanity’ bulkhead).  During flight test phase I would occasionally check the temp of the sump.  Never noted anything more than slightly warm to the touch.
 
Al G (Velocity 20B, 155 hours)
 
 
-----Original Message-----
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of stevei@carey.asn.au
Sent: Monday, October 05, 2009 3:35 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Fuel System

Hi All

We are trying to make a decision re: fuel system.
I’ve attached a PDF with design and questions etc.
Could you please pull it to pieces, make recommendations?
Steve Thomas can you comment also from the GSIIRG perspective?

Thanks

Steve Izett
Perth Western Australia
Building Glasair SIIRG Renesis 4 Port RD1C EC2 EM3

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