I know this thread has been going on forever and those who have wing tank
filters will probably keep them. Fuel flow is probably one of the most
important parts of our airplane so talking this to death can't hurt a thing.
Here's my take, for whatever it's worth.
Ideally, "IMO" the lines from the wing tanks to the header should be as
large as practicable...3/8 ID would be good. To keep the head pressure as
high as possible there should be no (unnecessary) restrictions between the
tanks and the header, meaning no filters, valves, unnecessary fittings, or
reducing fittings that restrict flow. After the header, the same applies,
however, it's obvious that one needs at minimum a shutoff valve and usually
a fuel pump of some sort. Since most fuel pumps are meant to push fuel, not
suck, it should be at the lowest point in the system, generally just after
the header and as close to it as practical. After the fuel pump things are
not so critical as most pumps can push fuel pressure and volume far beyond
what static flow can provide. Obviously, the 582s with diaphragm pumps
wouldn't be very practical to be placed at this point, but to continue.
There should be a shut off valve, generally on the console or wherever it's
located that is easy to reach, again, IMO, the next restriction should be
the filter. This should be a high flow filter and could be located on the
firewall and be the last line of defense before it goes to the carb/TB/etc.
Again, I stated "ideally" and is only my opinion. There are many other
methods that work and some that don't, but as I recall a study was done at
some point about forced landings and most were caused by fuel starvation.
Everything that is put into the system between the fuel tanks and the engine
is a restriction of some sort. Add them all up and it can be significant
and even though the system may be working it may be marginally close to
failure without one knowing it.
Personally, I don't feel the filters in the lines from the tanks to the
header are necessary at all. Between the finger strainers and the natural
settling action of the header, plus the fuel sump at the bottom of the
header, there is more than enough there to clean up the big stuff. The
final filter at the firewall will take care of anything that somehow reaches
that point.
I expect that some will take issue with this, and that is fine and I'd like
to hear it. Just be nice. :-)
Have a great day!
Deke Morisse
Mikado Michigan
S5/Subaru/CAP 438+ TT
"If you put the federal government in charge of the Sahara
Desert, in five years there'd be a shortage of sand."
-- Nobel prize-winning economist Milton Friedman (1912-2006)
----- Original Message -----
From: "FlyboyTR" <flyboytr@bellsouth.net>
To: <kitfox-list@matronics.com>
Sent: Sunday, November 01, 2009 8:43 AM
Subject: Re: Fuel Flow Problems, Again! (Vixen, Series-5)
>
> Lynn,
> ...you get to read a lot of email! [Shocked]
>
> I really don't want to get rid of my filters either. We are still only
> talking about one filter between a wing tank and the header tank. Once
> the fuel is in the header tank it should then benefit from the "suction"
> of the mechanical pump.
>
> My last two hurdles are removing the wing tank outlet fitting to check the
> finger strainers and cutting the root rib on the wing so the fuel line
> doesn't have to have a hump in it before descending down towards the
> header tank. Thanks again for all your input...always appreciated!
>
> Travis
>
>
> Lynn Matteson wrote:
>> I've read all your posts, and all of any mail that comes into my email
>> box....I don't go to the "site".
>>
>> I doubt that the filter element is your problem. I'm keeping all of
>> my filters, no matter how much certain engineers might (for me)
>> confuse the issue with talk of surface tension, etc., my system flows
>> fuel as long as there's fuel in the system to flow...nudge, nudge,
>> wink, wink. ; )
>>
>>
>> Lynn Matteson
>> Kitfox IV Speedster, taildragger
>> Jabiru 2200, #2062, 804.3 hrs
>> Countdown to 1000 hrs--196 to go
>> Sensenich 62"x46" Wood prop
>> Electroair direct-fire ignition system
>> Rotec TBI-40 injection
>> Status: flying (and learning)
>>
>>
>>
>>
>>
>>
>> On Oct 31, 2009, at 11:58 PM, FlyboyTR wrote:
>>
>>
>> >
>> >
>> >
>> >
>>
> :D
>
> --------
> Travis Rayner
> Mobile, AL
> Skystar Vixen, N-789DF
> Continental IO-240, Prince P-Tip Prop
> ADI-II Autopilot
> AnyWhereMap Navigation with weather
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=270420#270420
>
>
>
