My main header tank vent tube returns back to the aux tank, so if I overflow my header, the fuel runs back over to the aux tank and doesn't leave the plane at all. The aux tank IS vented to atmosphere through a faired vent/drain under the wing, and the way you can tell the tank is definitely full is when it pees on your foot while you're filling it. That only has to happen a time or two before you catch on to quit an inch from the top! My aux tank pump is on a two minute timer that moves about 1.5 gallons to the header tank and then resets itself for the next operation. I put a float level switch in the tank to do that for me (and turn on an LED while pumping), but that float switch never worked. I'm guessing it's stuck to the bottom in that vinylester from my "hot cure" job.
Nobody's mentioned the ultimate in light weight fuel fillers, which is the top of a plastic one gallon milk jug epoxied into the top of the wing. I'm told this is what Ken Rand used, and helps explain the super light weight of the prototype. I wouldn't think that would be very durable, especially sitting out in the sun, and safety would be another issue. There's a cartoon of my fuel system at http://www.n56ml.com/fuel/index.html ... Mark Langford ML at N56ML.com website at http://www.N56ML.com --------------------------------------------------------
