Header tank

[tx_swordguy]

I would like to increase the size of my header tank in my avid. I have a behind the seat tube type header that is about 3"x15ish" so it does not hold much fuel. I would like to put something in the 1.5-2 gallon range if I could and I am looking for input as to where I might find or have made a tank. Kitfox sells one but does not say how big it is. Thanks for any input
Mark

[jiott]

I believe the Kitfox tank is a little over 1 gallon. May be just what you need. A larger header tank really has little extra value other than a reserve when the fuel drops below the wing tank sight gauges. Cubs have been getting along fine for years with nothing more than a tee in the line.

[tx_swordguy]

Ya never gave it any thought until the other day when I was being tossed in some wind and ran the header dry. It was a long 15 seconds with the right wing raised waiting for the engine to perk back up. That was why I was thinking a bigger tank might be a good thing. Didn't realize I was flying right wing low long enough for it to happen on the way back to the airport. lesson learned (if below 5 gallons reserve watch my flight attitude even in wind.) Low time pilot lesson check.
Mark

[jiott]

Interesting scenario.

[tx_swordguy]

Yes it was, just figured up fuel burn to approx header tank capacity as about 6 min to empty. When I landed I drained almost 4 gallons before I trailered home. My left tank drains faster than the right and I had a 12 knot crosswind plus gusts that was keeping me busy. Can't complain though I look at it as a very good lesson and one I won't be forgetting any time. Landed with what should have been plenty of fuel if I was not flying wing low. I probably was, over the course of 30 min flying more right wing low than high and the header just didn't have time to fill up what I was using. As soon as I got the wing up and kept it there I got some fuel in the header. The fuel pump got the engine back up and never even burped the rest of the trip back (7 miles). It might possibly be something else but seems AWFULLY coincidental. new fuel filters all the way around 3 weeks ago (7hrs), sumped prior to flight and carbs as clean as new after the flight.

[Dave S]

Mark,

Glad you survived the fuel deal....more excitement than what a person needs:eek:.

Sounds like you have multiple fuel filters...curious if that is true, where they are located and what type they are. I know an Avid may be different; our kitfox uses a single filter just before the mechanical fuel pump on the Rotax engine.

[tx_swordguy]

I have fuel running from each wing with ball valve shut offs on each flowing into the header followed by an electric aux pump which runs to a fuel filter on cockpit side of fire wall then to mechanical pump running off of the 582. it runs from mech to screen filters on each carb with the fuel pressure sender. all filters were changed out 3 wks ago. only run non eth mo gas.
Mark
ps previous owner had the little brass insert clear filters on ea carb, I have had probs in the past with motorcycles clogging those very easily so I put simple screen filters like lawn mowers have in their place. not really doing much but will stop anything big that may make it that for *not likely* . one true filter prior to mech and two screen types prior to carbs

[jiott]

Good post Swordguy, that could happen to any of us in the same situation. Strange I haven't heard of it before because it could happen to most any high wing plane with fuel in each wing teeing together in a tee fitting or header tank (which is just a high volume tee). I guess the lesson is to fly a wings level crab thru a crosswind rather than a low wing slip method if it is going to last for any length of time.

[Dave S]

Mark,

I hear you on the little brass insert filters.....I think you did well to swap them out. I have also seen troubles with them plugging easily in non aviation applications...I speculate that is due to their small filter surface area.

I recently completed the annual condition inspection on our fox...replacing the hoses from the fuel tanks to the header tank, pulling the wing tank finger strainers and flushing the whole system. The finger strainers are very coarse and were absolutely clean. Fuel filter on the engine side of the firewall was clean and unobstructed. I find that the header tank (which is the low point of the Kitfox fuel system) settles out an insignificant amount of dirt and insect parts (presuming that comes through the Filler cap pitots). I've come to believe the header tank is what catches any foreign material and is important for that reason as well as organizing the fuel from the wing tank feeds and separating any bubbles. I believe there was more than one header tank design that has been used on kitfoxes; but, ours has about the same volume as jiott indicated... a bit over a gallon. In level flight, I found unusable fuel in the Kitfox wing tanks is about a pint in each; but, through fuel system testing determined that pitch attitude does change the amount of fuel that can drain from the wing tanks - particularly nose down pitch.

Fly well

[PapuaPilot]

Definitely that was a good lesson learned. A bigger header tank would have helped. The real solution to this is keeping the ball centered in all phases of flight, being extra aware of this when the tanks are getting low and not pushing your fuel reserves.

Was your left tank empty when this happened?

[DesertFox4]

You might consider installing the larger header tank and the low fuel warning system right above it. The small tank will empty first giving you early warning before your header even starts to empty.

11977
(Photo from my 7Super Sport build.)

[tx_swordguy]

Thanks for the pic Desert, thats a good setup. Papua, yes my left tank was dry L=8gl R=15gl left always drains faster for some reason. I am really thankful I realized what was happening and how to fix it when I lost power. Never had to do a full restart. While gliding all I did was raise the wing and just listen to it struggle severely to keep running for about 15 sec until it picked up enough fuel to run. Good lesson after only flying a champ with a single tank infront of the firewall with a fuel indicator. Definately not one to forget soon

[jiott]

I believe this same scenario could have happened even if the left tank was not dry. If both tanks were fairly low on fuel then sustained flying with right wing low would allow gravity to drain the left tank across to the right tank until the left was completely empty. Then the fuel in the right tank would stay to the far low side keeping the pickup port uncovered-then engine quit after header tank is run dry. I'm not telling you something you don't already know, I am just rehashing it to myself to burn it into my own brain.

[tx_swordguy]

Yes as a matter of fact I closed off my left tank so that by bringing the right wing up I wouldn't do that very thing.