Online Community of Zenith Builders and Flyers
Installing a UL350is in a Cruzer and am pondering a header tank. There seems to be a lot of good reasons to have one a only a few not to. The possibility of voiding a fuel line during uncoordinated flight is not a worry with a header tank. A duplex fuel valve is not required. A header tank adds a bit to the expense and has a couple of gallons of fuel in the fuselage.
I would appreciate hearing from anybody with some experience and advice with this method.
I have no experience with them but anything extra added to plane is an extra failure point. I can't think of any good reasons to have one, especially on a high wing plane. Perhaps you should look at all the certificated aircraft that use them to get an idea. With both tanks selected I don't think you would be able to void a fuel line unless inverted.
I did run out of gas on short final with a strong crosswind one time. However, that was due to my instructor changing the fuel selector to a single tank without my knowledge and when I ran landing check list I did not actually look at or touch fuel selector as I knew I had left on both after take off. Actually touching and looking at check list item would have prevented that. Luckily, I had managed my energy properly and landed on runway dead stick.
Excuse the typo in the subject!
Being a fuel injected engine, the duplex valve is normally a left or right and not both as the return is routed back to the supply tank. A header tank allows for both tanks in service with the return line back to the header tank.
I can see me being a little lax on the fuel selector which is why I use both all the time as well.
I didn't think of that Jeff. However, my first instinct is still "no" on header tank. I will have to rethink this reasoning but still think all those Cessnas out there would have header tanks if there was any real benefit. I have seen some Rube Goldberg contraptions that really added a lot of complexity with little to no benefit. I also see no benefit in using every drop of fuel as Mr. Harrington appears to be interested in doing. Any plane I have owned and likely to own or fly in the future can out fly my bladder. :-) I will watch the video. Thanks for providing the link Joe.
You can not compare the Cessna carburetor equipped engine, or even a mechanically injected engine with the fuel injection system used on the UL engine
My opinion is counter to Joe's opinion. I am a strong proponent of using a header tank with these high wing airplanes. That is primarily because they have flat bottom tanks. The biggest reason in my mind to have the header tank is that you have less un-useable fuel. I have a header tank in my 912iS fuel injected 750 and I routinely use all the fuel from all but my last fuel tank (I have 4 wing tanks). To do this you will need an indicator in the header that will tell you when it is anything but full. I have the Skytek header tank that has an optic sender to warn when the header tank is not flooded. I routinely run it until the light goes on and then switch tanks. The tank in question less than 1/2 a litre of un-useable fuel. After switching the light goes off within 5 seconds. If you have not watched this video, I recommend so:
If I build another one, I will again install a header tank. YMMV
Great video explaining fuel requirements for injection types and the reason I am leaning towards a header tank. The stock fuel tanks in the 750 are pretty flat bottom as well and if you were low on the one selected, it wouldn't take much to void the feed. Thanks for the input.
The flat bottom tank is not the big problem. The real issue is the 35 gph fuel flow out of the tank
The UL manual declares a return flow of 26 US gal/hr. Additionally, that is being returned to the header tank with the Skytec system and not the main tanks. How goes the testing with your header tank/pump system and UL engines?
At full throttle / 130 hp the flow is then 26 + 10 or 36 GPH of fuel to gravity feed.
If the header tank the fuel is being returned to is 3-5 gallons, then the fuel will not become excessively hot as it circulate. Anything smaller is worrisome. The fuel picks up a lot of heat from the pump and more from the long fuel rail on the engine.
The Viking does not have any fuel returning from the engine fuel rail. Not on the port injected engines and not on the direct injected engines.
For the UL / Rotax adaptation of the Viking fuel system, there has to be some return but it is kept at minimum and the fuel pumps only draw 1.6A to produce the required pressure, providing very little heat.
Just watched the video. That is the cleanest header tank install I think I have ever seen. Especially like there being no left right selector valve.
However, I am not convinced header tank is a necessity. If one is happy to not have a selector for left/right for high wing plane I think one could connect what comes from/to engine and header tank directly to the tank plumbing and all would work well. Of course one would not have the warning that header tank was not full. I don't want to fly down to only 7 minutes remaining anyway. :-)
That is NOT a CLEAN anything. It is a mess of huge hoses of fuel, ALL INSIDE the airplane.
Jan, I have the Skytek header tank and similarly designed fuel system minus their duplex valve which is really just an off/on valve. I do like what you are doing with your header tank and immersed dual fuel pumps. May eventually retrofit once you have the system "proofed" for use with a ULPower engine! Regardless, to answer John's question, the first thing I thought of when I saw the 750 fuel tanks (flat bottom) was that the fuel delivery system needs a header tank (esp for anything fuel injected) - what are your thoughts toward the original question posed by John?