No Karl, you have not missed anything. If you install the fuel system as
recommended by the factory on a Rotax 921, you need two transducers so that
the return flow is subtracted from the total flow- leaving you with fuel
consumption. If you change the fuel supply configuration so that the return
line starts before the fuel gets to the carbs, you can then have a single
feed to the carbs. The fuel flow in this single feed is the fuel
consumption of the engine.
Hope that helps.
Brian Davies
_____
From: owner-europa-list-server@matronics.com
[mailto:owner-europa-list-server@matronics.com] On Behalf Of Karl Heindl
Sent: 22 April 2009 18:22
Subject: RE: Europa-List: Fuel return line attachment point with 912UL
Hi,
I am also very confused about what has been said so far. I will be
installing a FS450 fuel flow gadget, and it calls for transducers in the
flow and return lines. I am not interested in how much fuel is flowing to
the engine, I am interested in the fuel consumption. And that consumption is
the difference between flow and return. Have I missed something ?
BTW, I am looking for another Floscan 201 A6 with a matching K-factor.
Karl
> From: roberthatton1@googlemail.com
> To: europa-list@matronics.com
> Subject: RE: Europa-List: Fuel return line attachment point with 912UL
> Date: Wed, 22 Apr 2009 18:00:53 +0100
>
<roberthatton1@googlemail.com>
>
> Hello Graham,
>
> I am following this thread for I shall also be looking at fitting a fuel
> flow meter. Could I ask you to elaborate on your comment about ignoring
the
> return flow for you are only measuring the fuel to the engine. I think I
> understand that with the placement of the Flowscan (from Marcel's the
> schematic) no problem in measuring the fuel going to the engine. But with
> the fuel coming back via the return line will that not eventually (after
> going through the system) go back to the engine again via the Flowscan?
The
> question being, are the amounts so small not to worry about it and does
this
> just build in a safety margin? Sorry to sound thick on this, I am just
> trying to get my head around what has been said so far and the schematic.
>
>
> Robert
>
> Robert Hatton
> email: roberthatton1@googlemail.com
> US Cell: +01 303 906 9395
> UK Mobile: +44 79 66 184171
>
>
> -----Original Message-----
> From: owner-europa-list-server@matronics.com
> [mailto:owner-europa-list-server@matronics.com] On Behalf Of Graham
> Singleton
> Sent: Wednesday, April 22, 2009 1:12 PM
> To: europa-list@matronics.com
> Subject: Re: Europa-List: Fuel return line attachment point with 912UL
>
> <grahamsingleton@btinternet.com>
>
> The question is, how does ignoring the return flow affect the accuracy
> >> of the fuel flow instrument? It depends on the quantity of the return
> >> flow of course. Is there any data about this? Maybe in the rotax
> >> maintenance manuals?
> >>
> >
> > That's indeed the question I so far have not found an answer to. The
> > only thing I was told by different people is that return flow varies
> > with RPM, but no hard numbers on return flow have made it my way. So
> > basically I *know* there will be an inaccuracy when ignoring return
> > flow, but *do not know* just how large this inaccuracy is (hence my
> > attempt to come up with something better for a single sender setup).
> >
> > Marcel
> >
> Marcel
> The return flow does not affect your fuel flow to the engine and that is
> what you are measuring. So you can forget about it with this configuration
> Graham
>
>
>
>
>
>======================
&g======
>
>
>
16:48:00
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