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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?
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