As y'all may remember I had strake failure (not flying yet) with Jeffco.  Much speculation was made to it being due to the ethanol.  When I rebuilt them I used the EZ84 that has been suggested as the most resistant.  Also, EZ84 is what the rest of the plane is build with and what the factory suggest.  The Jeffco was SUPPOSED to be my solution to such issues.  I sent some of the bad glass to Velocity and they couldn't provide insight.  I believe Jeffco had or was being sold and I could not reach them at the time.

When I rebuilt the strakes (also noting how complex and heavy trying to weld up aluminum tanks due to structural issues with the strakes and baffles) I placed a few cards in a can of ethanol fuel from my local gas station.  The last time I checked, a few months ago, the EZ84 was still exactly the same as when I placed them in the vat.  That being said, so were Jeffco samples.  I will try to remember to check again if I make it to the hangar tonight.  They samples have been fuel now for maybe four years. (fuel replaced once from the same gas station)

I still have an unopened five gallon kit of Jeffco that I purchased when I was considering reusing it to rebuild.  If anyone is interested, I am sure I can make a hell of a deal on it....

BTW, rebuilding most of the strakes is NOT fun.  Actually, I just removed the inner skins that had been coated with Jeffco, not the entire strake structure.  To this day, my build buddy, Dave Staten, and I are as certain as we can be that we applied the Jeffco properly and eliminated pin hole issues.  But, alas, I still had the problem.


Chris Barber
Houston
Velocity 17010
________________________________________
From: Rotary motors in aircraft [flyrotary@lancaironline.net] on behalf of Chad Robinson [crobinson@medialantern.com]
Sent: Friday, December 02, 2011 10:45 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Steve Brooks Cozy

I looked into what it would take to get these blow-molded, maybe with a
group buy from other builders. The complication is that the strakes are
a lifting body and are structural. The ribs are part of that structure.
They also serve as anti-slosh plates inside the tanks. Any solution
needs to include both of them. It's do-able: you just need a tank
blow-molded for each of the individual tank sections, then you
plastic-weld them together around the strake ribs. But it means you need
a bunch of molds...

At the time, I had already bought a batch of ProSeal, so I went with
that. It looks pretty good - guess we'll see how it holds up (it sure
wasn't cheap.) So I never finished the research.

The issue is there's a large group of rotary builders but a smaller
group of Cozy MKIV builders. Cozy builders with aircraft engines don't
need to deal with this - so it's an even smaller group. I'd be surprised
if you could get even 25 people together on an order, and you'd need
several hundred to make it economical to build the blow-molds.

One alternate plan I had tinkered with involved making a very
rudimentary mold in the shop, then heating a standard 5-gallon red
plastic gas can and using compressed air to "inflate/reshape" it. A very
thin wall is just fine (preferable, even). The structure comes from the
Cozy's strake structure - you're just making a liner. But it's a lot of
work and finicky to get it right. I also looked into bladders, but there
are maintenance and reliability concerns with them filling/deflating
properly in odd-shaped spaces.

Regards,
Chad

On 12/2/2011 10:48 AM, Ernest Christley wrote:
> I reluctantly made a decision to not trust sealing a gas tank to any petrochemical that is shipped to me in a liquid
> form.  You never know what all those petrochemical engineers in Congress will decide mandate to be put into our fuel
> next.  So I welded a fuel tank and glassed that into the place that was designed for a fiberglass tank.  I would have
> preferred buying a premade poly-ethylene or aluminum racing tank, but I couldn't find one that even came close to fitting.
>
> Aren't the Cozy tanks just big cubes sitting inside the wing roots?  Would it be safer, and possibly easier, to buy a
> tank, sit it in the, and glass it into place?
>


--
Homepage:  http://www.flyrotary.com/
Archive and UnSub:   http://mail.lancaironline.net:81/lists/flyrotary/List.html