Don Tuite wrote:

So what happens if you fill your wings partway with auto gas, add a
bunch of water with a lot of splashing, wait a few minutes and then
drain the sumps until no more water comes out? Can you extract the
ethanol from the gas that way?

Short answer: Yes. This is called "washing" (no, I'm not kidding).

Slightly longer, qualified answer: Can you extract *enough* alcohol from the autogas
to make the remainder effectively alcohol-free? Yes, given enough washings. Each
wash will remove less alcohol. At some point the alcohol left dissolved in the auto
gas will be negligible. What else would you be washing out? Damned if I know.
Probably some detergents.

(What about the octane number?

It will go down. If you care, add MTBE (it doesn't conflict with either the EAA or
Petersen STCs).

Well, suppose you only need 80/87 like Jay. What if you start with premium?)

It may not be necessary. Depending on the supplier/distributor, the premium gas may
not be oxygenated with alcohol. If it is, then you may end up with rather expensive
regular unleaded, as the alcohol is likely the major octane boosting component.

Note: This is a gedanken experiment only. Do not try this at home.

Good, because intentionally introducing water into an airplane fuel tank seems like a
terribly risky proposition. I wonder if either the EAA or Petersen STCs mention
water as an unacceptable gasoline component...

Russell Kent