Remi=0AI think it makes more sense for the return to go to the top of the t
ank, at the bottom warm fuel can be taken straight back to the engine.=0ATh
at's how I always did it anyway and never had a problem.=0AFuel gets heated
while it is in the engine driven pump, when the engine is hot the pump can
be as much as 75deg C.=0AWith low fuel flow, when taxiing for example, fue
l will heat up to vaporization point. Jabiru engine is problematic , isn't
the pump buried at the back of the engine?-=0AGraham=0A=0A_______________
_________________=0A From: Remi Guerner <air.guerner@orange.fr>=0ATo: europ
a-list@matronics.com =0ASent: Saturday, 22 June 2013, 8:50=0ASubject: Europ
a-List: Re: fuel return line restrictor=0A =0A=0A--> Europa-List message po
sted by: "Remi Guerner" <air.guerner@orange.fr>=0A=0ARowland,=0AI have test
ed several restrictor diameters- from .35 to .8 mm.- Here are my conclu
sions :=0AThe restrictor diameter- affects the fuel pressure, but not as
much as you would think. Even with a plugged return line you barely see a h
igher fuel pressure.=0AOf course the return flow is greatly affected. Retur
n flow with the .7mm restrictor is four times the flow with .35. Obviously,
the higher the return flow the better, for vapor suppression, provided tha
t the pressure is within the specified range.=0AThe .35 restrictor is easil
y plugged by debris. This happened to me twice. =0AIf you build your- fue
l system as described in the Europa Manual, using the .7 mm restrictor as s
upplied with the kit works the best.=0APersonnally after 8 years, 700 engin
e hours of testing different configurations of the fuel system, I am back t
o the .7 mm restrictor.=0ANow, why Europa specifies .7mm while Rotax says .
35 ?- This may be because in the Europa, the return line goes to the bott
om of the tank while the Rotax diameter is designed for aircraft whose retu
rn line goes to the top of the tank, which is the case in most other aircra
ft. I believe that returning to the bottom of the tank- offers more resis
tance, so a bigger diameter is necessary to ease the flow ?- It would be
interresting to hear the Europa designers on that subject. =0ARegards=0ARem
i=0AF-PGKL, XS Monowheel, 912ULS, 1018 airframe hours=0A=0A=0A=0A=0ARead th
is topic online here:=0A=0Ahttp://forums.matronics.com/viewtopic.php?p=40
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