Richard: I agree the deterioration of the foam is a show stopper for me.
thanks

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"Richard Riley" wrote in message
...
On Mon, 25 Jun 2007 07:35:36 -0400, Ron Natalie
wrote:

Stuart & Kathryn Fields wrote:
Is there anyone out there using fuel tanks filled with open cell foam?
I've
heard that explosions are tamed as well as fuel slosh. I've also heard
that
the foam must be replaced periodically. How often is the replacement
necessary? I'm using 100LL Av gas.

Fuel cells (bladders with foam) are pretty common in the auto racing
industry. They real purpose of it is to avoid the fuel from spraying
out if the tank is ruptured. Other than that I'm not sure what
"explosion" resistance you're going to get. I suppose it might
mitigate some sloshing. I'd make sure that I was getting the
max flow rate for takeoff if I were to use one in an aircraft.

The big drawback is that they drastically decrease the fuel
carried per unit volume.

I looked at the foam a few years ago. Google Reticulated Polyurethane
Foam Fuel Explosion and you'll find a few technical papers.

You take about a 3% hit on fuel volume, and you increase empty weight
by about the same. It does break down over time - the racing bladders
are only rated for 5 years. The breakdown occurs MUCH more rapidly in
the presence of an oxygenating fuel like ethanol.

I decided against it, I can't open up my tanks every few years to
replace it.