Mailing List flyrotary@lancaironline.net Message #9310
From: <ronmilligan@cox.net>
Subject: Re: [FlyRotary] Re: Fuel System Question
Date: Tue, 29 Jun 2004 13:59:30 -0400
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
>     Let's look at this logically.  The only time you'll
> have fuel returning to the tank is when the engine is
> running (or a few seconds after shutdown).  The fuel pump
> is creating a negative pressure situation inside the tank
> by removing fuel.  The engine is burning some of the fuel
> being pumped out of the tank, so there will always be less
> fuel coming back than is being pumped out. Therefore, there
> should never be a head pressure against the return line -
> unless one positions the return outlet below the level of
> fuel.  Put the end of your return line near top center and
> you should never have a problem.
>
> Regards,
> Dale R.
> COZY MkIV-R13B #1254


The tank is vented and assuming it never gets blocked will always be at atmospheric pressure.  Everyone has a fuel pressure guage before their regulator.  I want to know what the pressure is in the line after the fuel regulator.  If it is greater than the pump output pressure of the transfer pump then I will never be able to transfer fuel.  If that is the case I will have to plumb two extra return lines to the tank.  One for the fuel returning from the engine and one for the fuel tranfer (I know this will work but don't want that complexity).  Anybody know what Tracy did?  I have Tracy's book, (not with me at the moment) does it give that level of detail (I can't remember).

Ron Milligan
RV7 QB Fuse
Aliso Viejo CA

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