Sender: <marv@lancaironline.net> (Marvin Kaye)
To: flyrotary
Date: Wed, 16 Apr 2003 22:45:28 -0400
Message-ID: <redirect-2131801@logan.com>
Reply-To: "David Carter" <dcarter@datarecall.net>
From: "David Carter" <dcarter@datarecall.net>
References: <list-2130934@logan.com>
Subject: Re: [FlyRotary] Re: fuel return
MIME-Version: 1.0
Content-Type: text/plain;
	charset="iso-8859-1"
Content-Transfer-Encoding: 7bit

Hmmm,  I don't understand something (actually, a lot of things), but, if
your engine sucks 16gph at full power at sea level on a cold day (worst case
for max flow), and your high pressure fuel injection pump puts out max
anticipated flow plus (what?  25%, 50%, like in the Canadian static fuel
flow drain checks?), then:
    -  If that pump output is 16 + 8 gph or 24 gph, then, does it put out 24
gph when you are at idle on the ground (or at idle decending from 10,000
feet) with the engine burning maybe 2 gph, so that 24-2 =22gph is being
bypassed by the fuel rail's regulator back to the header or tank being fed
from?

If so, then the return line could be about as big as the main feed line.
Except, so what if the return line is smaller?
    -  The bypass fuel will be restricted by the smaller return line and may
not allow 24gph.  That shouldn't cause any problem, unless the pump is
working harder/being loaded harder and maybe drawing more current.

David Carter

----- Original Message -----
From: "Marvin Kaye" <marv@lancaironline.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Wednesday, April 16, 2003 7:20 AM
Subject: [FlyRotary] Re: fuel return


> Posted for "Ed Anderson" <eanderson@carolina.rr.com>:
>
> Hi John,
>
>       I used 3/8" line simply because I had that size, however, since that
is
> also the size of the main fuel line a 3/8" line for return is clearly
> oversize and I would think a 1/4" dia line would do just fine.  I return
my
> line to the top of my sump tank. I have two plates in the sump with many
> small holes to prevent the fuel from splashing into the sump and creating
> bubbles (probably not needed).  Both of my fuel pumps draw from the bottom
> of the sump tank (each with its own fitting).
>
> Ed
>
> > Ed;  How large a fuel line does one need for the return line to the fuel
> > tank?  I'm  in the process of welding the fittings into the fuel tank.
> Also
> > where is the best place to return the fuel?, do you return it to the top
> or
> > bottom of the tank?   The fuel outlet on the Tailwind is in the center
> > bottom, with the tank located behind the control panel.
>
> >>  Homepage:  http://www.flyrotary.com/
>