Marcel Zwakenberg wrote:
>
> 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.
Did you sent an attachment? I did not receive it.
If it is your plan to block the return line, I agree with Brian that
this would be a bad idea. Especially at idle the fuel consumption is
low, and the fuel will remain quite some time in an environment with
temperatures above its boiling point. You would well risk to make a not
so pleasant discovery at the subsequent take-off run, just above the
treshold at rwy 28 of EHHO. ;-)
Note that this is not about the additional fuel line where vaporization
can occur, but about the fact that blocking the return flow will cause
the fuel to heat up much more than original, and making vapor lock much
more likely.
> 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).
If I understand correctly from earlier conversations, you already bought
the second fuel flow sensor. So why not fit it temporarily in the return
line, measure what the return flow is, and then take it away again and
implement a correction factor to the single flow sensor?
--
Frans Veldman
|