Tanks for nothing (repost from Bearhawk list)

Well, not quite. Total investment excluding labor is about $80 of
aluminum (some of that went towards the main tanks, which I have yet to
assemble), rivets, a couple bucks worth of tubing, some 4043 filler rod,
and probably most of my argon tank by the time both auxiliary tanks are
completed. That also excludes the caps and their accompanying flanges,
which I have yet to choose.
I put a few pictures up on my project
pictures page (scroll to the bottom), which I will probably have to
subdivide soon if it keeps growing like this:
http://www.
rawlinsbrothers.org/planes/projpics.html
The decision on what to do
about venting essentially came down to engine choice. Since I'm not
going to decide on an engine until I absolutely have to, among the
options I am considering are the Deltahawk Aero-diesel, and that solar
turbine conversion that Budd posted about a while back (any new news on
that from OSH???), which both burn Jet-A. Because of the different
volatility of jet fuel and avgas (for more info, see the Deltahawk page
at http://www.deltahawkengines.com/), Deltahawk recommends
incorporating flow-through venting to evacuate fuel vapors. This means
that 2 vent points are required per tank, an inlet and an outlet. The
inlet is easily taken care of by use of a vented cap, but for the
outlet some sort of fitting is required. I basically copied Russ Erb's
idea of running a tube from the high point inside the tank to an outlet,
but added my own twist of welding a pipe thread fitting over the outlet
(
in the side of the tank instead of the bottom) which avoids the whole
issue of damaging an exit tube which is permanently welded to the tank.

So the plan is, if I use a gasoline engine the vent tubes from each
tank will be the sole vents and will be situated so as to provide high
pressure air, and if I burn jet fuel they will provide low pressure air,
with the inlet for flow-through venting coming from a vented cap.
Filler cap choice will be partially dictated by what type of fuel my
engine burns, but at least now the tanks can be trial mounted when the
wings are assembled.

[Note: I posted this to the Bearhawk email list, but thought it might
also be of some interest here. The pictures are of my auxiliary tanks,
which hold about 11 gallons each. The mains will hold maybe 27 gallons
each. Since I anticipate a lot of out and back trips here in Alaska
with no fuel at the destination, the extra tanks are necessary.]

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Del Rawlins-
Remove _kills_spammers_ to reply via email.
Unofficial Bearhawk FAQ website:
http://www.rawlinsbrothers.org/bhfaq/