JPAnderson;n1138016 said:
I'm not real turned on about sitting on a plastic tank of 5-8 gallons of fuel in a gyro crash. A friend died in Gyro crash, probably at impact, but there was a nasty post crash fire that assured no open casket. Any thoughts on the issue appreciated. John
Hello John,
As a former manufacturer of "plastic" seat tanks, I feel I can comment more believably, as I no longer sell them. This is what I gleaned from my research over the years.
Fuel tanks should be built to contain the fuel, before, during and after an impact. You need a strong, but relatively "soft" material. (Ideally, a combination of both) for fuel containment, ALSO, and VERY important is how the fuel exits the tank. I found that if the tank was not compromised, the usual cause of fuel loss was by lines (in, out or vent) ripped from the cell and released fuel, providing the second point of the fire triangle.
The military and the auto racing community appear to lead the field in fuel tank research, and they have produced some spectacular results. The military is primarily concerned with a fuel tank surviving taking hits from bullets (or fragments), or survivable crash landings. SCCA & NASCAR auto racing organizations are more interested in post crash fires.
The ideal fuel tank should be made from a strong, yet semi-flexible material. The best way, as proven by auto racing fuel cells, is a container of steel, aluminum or cross-linked polyethylene.
A compromised tank structure can result in an atomized spray of fuel.... not at all what we want. A hard, yet yielding to the blow enclosure, is the most desirable. Most fuel cells are steel, or aluminum, or PEX "plastic" and, especially in the case of the first two, contain a very flexible "bladder". A third component is often found in fuel cells is a foam that absorbs the fuel (like a sponge) the fire foam must be left out in the area of the fuel level sender, displaces some fuel reducing the quantity and often disintegrating, which leads to filter clogging.
Racing fuel cells are widely available in many sizes and capacities, they are often heavy, expensive and not appealing appearance wise.
Chances are that your farm tanks, pipelines, airport fuel farms and your vehicle fuel tanks are made from PEX.
Most gyroplane fuel tanks are, today, made from PEX. The earliest seat tanks were made of fiberglass, as are current molded in tanks or stand alone tanks. My opinion is that if fiberglass tanks receive a hard blow, they will rupture. I believe it is imperative that any fiberglass fuel tanks need an internal bladder installed. I wrecked my first gyro and the fiberglass seat tank split open at the seams and doused me with gasoline. I did not like being part of the fire triangle and I was awfully lucky the third part wasn't around. A properly roto-molded PEX seat tank, under your butt, is in one of the safest fuel tanks in one of the safest places it can be mounted.
Wikipedia:
Cross-linked polyethylene, commonly abbreviated PEX, XPE or XLPE, is a form of polyethylene with cross-links. It is used predominantly in building services pipework systems, hydronic radiant heating and cooling systems, domestic water piping, and insulation for high tension (high voltage) electrical cables. It is also used for natural gas and offshore oil applications, chemical transportation, and transportation of sewage and slurries. PEX is an alternative to polyvinyl chloride (PVC), chlorinated polyvinyl chloride (CPVC) or copper tubing for use as residential water pipes.
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