Rowland,
I have tested several restrictor diameters from .35 to .8 mm. Here are my
conclusions
:
The restrictor diameter affects the fuel pressure, but not as much as you would
think. Even with a plugged return line you barely see a higher fuel pressure.
Of course the return flow is greatly affected. Return flow with the .7mm
restrictor
is four times the flow with .35. Obviously, the higher the return flow the
better, for vapor suppression, provided that the pressure is within the
specified
range.
The .35 restrictor is easily plugged by debris. This happened to me twice.
If you build your fuel system as described in the Europa Manual, using the .7
mm restrictor as supplied with the kit works the best.
Personnally after 8 years, 700 engine hours of testing different configurations
of the fuel system, I am back to the .7 mm restrictor.
Now, why Europa specifies .7mm while Rotax says .35 ? This may be because in
the
Europa, the return line goes to the bottom of the tank while the Rotax diameter
is designed for aircraft whose return line goes to the top of the tank, which
is the case in most other aircraft. I believe that returning to the bottom
of the tank offers more resistance, so a bigger diameter is necessary to ease
the flow ? It would be interresting to hear the Europa designers on that
subject.
Regards
Remi
F-PGKL, XS Monowheel, 912ULS, 1018 airframe hours
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=403137#403137
|