As this tank has become the defacto standard for many Pukey Profiles,
especially those powered by the 25LA and the 20FP, a few comments have come
First, availability. I have ordered mine from Hobby People, especially
as this is also my source of another defacto standard, Thunderbolt glow
plugs. I have also ordered them from a local hobby shop with no problem.
This morning I called Sig Mfg. and while there was a bit of hesitancy
at current stock levels ("We've got a few...") they are stocking
Another issue is the short, seemingly too-stiff internal feed line supplied
with these tanks.
It works just fine. Yes, I know that the clunk will not readily flop
to every corner of the tank when the assembly is hand-held and moved around.
Don't worry about it. During flight the clunk will readily follow
Last night I was going through several tanks in prepping them for the
new season. Hmmmm...
The oldest of these tanks has been on my Skyray 20 for almost
two years. The feed line in the tank has stiffened to the point of being
We flash back to the VGMC contest of 2005. The 20FP quit prematurely
and this should not have been an issue. No way, no how.
Derek Moran and I were flying together, like any Pit Dude who takes his
duties seriously, he picked up the model and announced there was still fuel
in the tank, certainly enough to have completed the pattern.
The contest was over, I blew it off as an anomaly. And probably didn't
have any further problems as I simply made sure to put in a little extra
fuel for the next contests.
In looking back the stiffened tubing was quite likely the problem.
Also a "problem" is that these tanks are so reliable one installs
them, adjusts the height of the tank and then treats them as bullet-proof.
Don't freak on me, but assuming I cannot find suitable silicone fuel
line--and I have not been able to do so in the past--I'm switching over
to surgical tubing.
Yeah, yeah, fuel gets to the stuff, turning it to junk. But this does
not happen right away; I'm betting a guy could easily get a half-season
out of each chunk of tubing.
Being a very conservative sort when it comes to model prep, I have already
cut to proper length a dozen pieces of surgical tubing, packed them into
my bag of spare tanks and fittings.
Remember, these Hayes tanks are nothing like the ubiquitous Pylon clunkers.
There are no screws, plugs, hard-tubing feed lines, vent lines and fill
lines to get positioned just perfectly.
Instead, one simply grabs the plastic fitting at the front of the tank,
pulls it free of the tank and has ready access to all of the internal
plumbing. It is a really simple task to insert a new piece of tubing. Simple
enough to do this at every practice session, the morning of every contest.
That should not be necessary, but might be a good idea in the beginning
and until one knows more about the effects of his fuel blend on this vital
Incidentally, there is also a 4-ounce version of this tank which might
be of interest and which seems to be more widely available. It's only .020-inch
taller than the 3-ounce tank; assuming you have any room at all for height
adjustment, it will fit.
The 4-ounce units are .120-inch wider and this would not appear to effect
the functionality of this tank for our application. They are about .445-inch
longer, which means they won't nestle behind the engine on any ARF Flite
Streak I have seen.
However, they will easily fit on the left side of a Flite
Streak fuselage, an increasingly popular option, even if it looks weird.
There is also adequate room for these 4-four ounce tanks to be mounted behind
the engine on a Sig Skyray 35.
One of the reason for mentioning the option of a 4-ounce Hayes tank is
that I am getting some questions from those flying 20FPs w/BB T-U at high
altitude and have suggested more potent fuel with 20% known as working well,
25% being a distinct possibility.
Fuel mileage will of course go down and might get to the point where
the 3-ounce tank--which is not actually a full 3-ounce capacity--will not
quite deliver a full pattern.
Finally, if you will be trying these tanks for the first time, at least
with 20FPs I have found positioning the tank such that the fuel-outlet nipple
is 1/8" low in relation to the engine centerline is a good starting
point. Be prepared to shim tank up or down with shims of 1/64" ply
when getting real serious about it.
Also mount these tanks such that the back end is kicked to the outside
of the circle about 1/8 inch.
This page was updated April