KRNetHeads, I've been testing my fuel system lately, and have come to the following conclusions. My main (right tank) holds exactly 8 gallons from full to empty (in flying attitude) and the left (aux) tank holds the same, for a total of 16 gallons. I have about .4 gallons of unusable fuel in each tank (not counted in the 16 gallons), and when you consider the 10% "air space" at the top of the tank, that's what my "19 gallon" fuel tanks became.
The Facet fuel pump delivers .67 gallons per minute (40 gph) through the 3/8" line with no restriction (carburetor) on the end. Venting works great, as I emptied both tanks in 24 minutes with the caps sealed tightly. Not one drop leaked out from anywhere, including the vent line. The transfer pump is slightly slower since it uses a 5/16" line. I'm working on a simple 555 timer circuit that will run the transfer pump for 6 minutes, which will transfer half the aux tank to the main tank with one bump of the switch. It will be activated with an off/on/momentary switch so I can switch it off before the timer is finished if the tank runs dry (it's loud enough to hear while flying, I'll bet). You might notice (at http://home.hiwaay.net/~langford/wingtank.html ) that I left about 3" of wing tank volume "on the table" for no good reason by leaving a gap between wing tank and fuselage, so I could have easily gotten another 15% tank volume there, and if I'd used the AS5048 airfoil, I could have had another 20% on top of that, for a grand total of 22 gallons of useable fuel. Don't make the same mistake I did! When I originally designed these tanks I was going to use a VW engine which burns less fuel, and I didn't want to limit my gross weight by putting too much fuel in it. Now I'm running a thirstier (but more powerful) Corvair, and I know I'm going to set my gross weight higher than 980 pounds, so if I were going to do it again, I'd have every bit of that 22 gallons. 16 gallons will get me a "fer piece", even at the Corvair's max consumption of 6.5 gallons per hour, but especially if I throttle back to 5 gallons per hour or so. I think Steve Makish says his only burns 3.5 gallons per hour at what he calls "cruise" using the apparently efficient Ellison carburetor. I could still put in a small header tank, or another tank behind the seat, or even an aux tank that sits on the passenger seat and plumbs in with quick disconnects, put I probably won't bother. 2.5 hours in this plane is probably enough for me. In other news, I received my new Tiny Tach 4X (the X means it's filtered) and it seems to work fine on my Scirocco, so it ought to work on the Corvair as well. I can't test it on the plane until the Ellison comes in, which I've been waiting on for three weeks now, but probably still hasn't shipped. Believe it or not, I'm still finding wires that need to be connected to things like the flap motor, trim postion indicator, and that sort of thing, so I still have plenty to do. You know you're getting close when you order your tail numbers and start worrying about placards... Mark Langford, Huntsville, Alabama N56ML "at" hiwaay.net see KR2S project at http://home.hiwaay.net/~langford
