The straight "L" has been okay on Howard's, sitting
outside on his airlift
beside the dock for 5 summers, and he has never
found any water in his fuel
that I know of. I know for sure that the engine has
never
quit...........!!!!
If you are concerned with L's, because the aircraft
is sitting as a
taildragger, and you think rain drops might bounce
up inside and run down
into the tank, form the ram air tubes as J's. Then
cut the open end on a 45*
angle so it still has ram air effect, but rain can't
run inside the tube as
it would have to go upwards first.
I have an ala'Cessna vent under one of my wings,
behind the wing strut in
the high pressure area. The required anti-siphon
loop (to not have to use
one of those leaky Cessna flapper valves) and
internal tube with holes tight
to the tank lid was more work than I would suggest
to be worth it to anyone
following this "thread". Can also cost some fuel if
parked full on a heavy
slant.
I think the best ram air vent is the way I have been
doing most of them
since building my own. That is to put an L or J tube
between the cabin and
the wing, tee'd into the tank cross vent line. Make
the tube about 5 inches
or so high above the fairing and use sealing caps on
the tanks. This way
even if you park on a hill wing down (like the Super
Cubs II video with the
Cole family) you won't loose any fuel as the vent
tube should still be
higher than your uphill wing tank. If you put it on
the outboard corner of
the wing tank you may very well have fuel pouring
out of it if you are
flying/parking to these extremes (mind you your not
likely to have full
tanks if screwing around like this either). I know
some guys have put them
right on the caps themselves (like Bob P's where
there was no other choice
due to the original builders plumbing system) as
they were concerned about
having a double vent source for safety. Good idea,
but if this is your
concern you could also put one in each wing to
fuselage fairing for the same
safety purpose and they wouldn't interfere with wing
covers. The weird thing
with bothering to do double redundancey is that when
the insects get into
the season for laying larvae, the usually get every
hole on the aircraft,
including the small hole in the tank drains. My
buddy Bruce, from the strip
next door to me, had his engine quite a couple weeks
ago on his Northstar at
about 200 feet. Thank god he was on floats, stuck
the nose down and just
re-landed in Midland harbour. Both vent tubes on his
caps were plugged, with
the nice grey cement like material that the insects
fill the tubes with.
This had happened in the 2 days since he had
previously flown!! I know, he
obviously didn't do a very good preflight, but I
know once most guys get on
floats, less and less gets checked at the dock with
the assumption things
are the way they parked it.......as I have cleaned
this insect crap out of
Howard's quick drains a few times when he has left
his plane here when going
away for extended periods of time (maybe it's the
fear of spilling fuel in
the lake, I don't know!!). Try to keep your screen
insert very close to the
end of the tube so the insects don't have room to do
this and keep the tubes
diameter up at 3/8", as they seem to prefer plugging
up the sizes of tube
below this. I have hundreds of lengths of tubing in
a 40' storage trailer to
prove this. They did all the small 3/16 and 1/4
tubes first, worked their
way up to the 5/16ths and now 3 years later have
started on the lengths of
3/8" stainless tube. All the tubing is on the same
5' high rack, on one side
of my storage trailer.
Cheers,
Wayne
----- Original Message -----
From: "Mike Davis" <
mike.davis@dcsol.com>
To: <
murphy-rebel@dcsol.com>
Sent: Monday, October 14, 2002 12:04 AM
Subject: Re: Venting Moose Tanks
Hi Don,
Yes, the tube is just outboard of the filler cap,
right in the corner of
the
tank. Robin told me they had one problem of
someone holding onto it while
filling the tank and bent the tube... he just
loosened the lock nut,
screwed
the tube out of the fitting in the skin and
screwed a new one in. 15
minutes to fix the whole thing.
Looks like your other questions pretty well
addressed already... I don't
see
that using an inverted J would hurt, but seems
that many people have
reported using the inverted L with no problems,
and the L will give you a
little ram air pressure.
Mike
195SR
----- Original Message -----
From: "Don Boardman" <
dboardm3@twcny.rr.com>
To: <
murphy-rebel@dcsol.com>
Sent: Saturday, October 12, 2002 9:11 PM
Subject: Venting Moose Tanks
Hi All,
Mike Davis writes
MAM has the demonstrator
set
outboard/forward corner of the
it, and screwed a L
simple, no plumbing to worry
fix.
Mike I need some clarification.
From your description I conclude that the whole
is drilled into the TOP
SKIN
of the tank. Is this correct?
Outboard/forward corner would put it near the
area of the filler neck?
How is it that rain is kept from being a concern
with such a L shaped
ram
air tube?
ANOTHER APPROACH FOR CONSIDERATION ..
Install a fitting in the bottom skin of the
tank, again at the
outboard/forward corner just behind the spar.
Install a stand pipe into
the
fitting that would reach to the top
outboard/forward corner of the tank.
The
bottom of the stand pipe would protrude from the
fitting and provide ram
air.
Pre-flighting a vent tube protruding from the
bottom of the wing is much
easier than one on the top of the wing. This
would be especially true
for
