I suspect Delusional is referring to Phase Separation. The phenomenon where an amount of absorbed water in ethanol will, under given atmospheric conditions, separate from that ethanol. It is my understanding that those given atmospheric conditions are not constant. Dan
That's about it. Sorry for the jargon. Here's the plain english:
Take some gasoline and add a little water. The water mostly does not dissolve in gasoline so it sits at the bottom, hopefully near a drain where it can be drained off by the pilot during preflight. No problem.
But now, add some drygas, aka alcohol. Then add a little more water. The water will disolve, which is how the EAA test kit works, no rocket science here. So far so good if you gaskets and other compnents don't dissolve just like the water, or swell or soften etc.
But now comes the scary part. Remember what happens to water vapor in air when you cool the air off? First clouds then rain if you cool the air enough. Well, the same thing _could_ happen in gasoline with enough water dissolved in it because the solubility of water in fuel depends on temperature. Take a little warm auto gas with 10% ethanol, add some water and shake until water is all dissolved. Then cool the fuel just as it would say during a winter flight up to 8000. Will "clouds" or "rain" form in your tank during flight?
Follow up questions:
How does Rotax know this is not a problem? Are they assuming that the aircraft they run in only stay low where temperature gradients aren't so steep? Then what are the limits? Or maybe they know something that renders this theory pointless?
Or, maybe they are just relying upon the fact that nobody has reported any such incidents and they just figure they'll wait until one of us "proves" this is another real problem with ethanol in your fuel.
There is more on this subject in this thread
http://www.vansairforce.com/community/showthread.php?t=62947