The problem isn't just an issue of ethanol weakening the tank. The larger problem is the fuel tanks rupturing and causing a fire in an otherwise survivable crash/hard landing. Over the past few years this has happened several times. We need to develop and use fuel cells/tanks that won't be easily ruptured in a crash or tip over. I don't know how much an aluminum tank would cost to be made for some of these 2 place machines but it would certainly be worth it if it increased the survivability rate.
Tim, you hit the nail here.
Unfortunately there are not enough SHs out there to justify making a mold and forming PEX fuel tanks. Custom aluminum tanks are a good second choice, especially if some form of energy absorption were built in between the seats and the tank. Aluminum is easily deformed by load and not very puncture resistant,
Picture a nasty 10g, near vertical impact. two 200lb pax =400lb x10g = 4,000lbs. You have to engineer a seat mount to give in an accident like that , but not allow two tons of pax to cave in fiberglass, carbon fiber or aluminum.
If I had the time or was the owner of a SH. I would look for an industrial (PEX) fuel tank that would fit the fuel bay of a SH. Many automotive fuel tanks have been made from PEX over the years, I'll bet one might make a good candidate.
Failing that, if enough SH owners got together they could probably convince one of the aircraft fuel cell rebuilders to make them a bladder that would fit their application. You would still need to brace against compression of the fuel cell in an impact.
Next year I'll put together a crashworthiness seminar Powerpoint for the PRA web site and Mentone.
