Hi Frans,
> As far as I understand, Marcels intention is not to block the return
> line, but just not metering the return flow.
Indeed that was my initial plan, but I am now exploring to see if I can
come up with accurate flow measuring using a single sender (as per your
earlier recommendation).
> So there will be no static fuel in the lines, and the electric fuel
> pump will clear fuel fapor, just as with the original lay-out.
Have another look at the schema that I posted, and note that the return
line is T-ed off at an earlier stage than in the original layout: my
schema Tees it off between mechanical pump and both carbs, the original
layout tees it off 'beyond' the carbs.
In the original layout, there are only two short pieces of line where
vapor-locking can occur (the two short T-ed off appr. 25cms segments
directly to each carb). In the schema I posted there is an *additional*
segment of fuel line where vapor-locking can occur (the guestimated 40
cms segment connecting the two carbs together).
> 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
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