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.

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Yet the only one providing any real detail of header tanks.  

Jan,  Your message would probably be better accepted by all if you allowed a satisfied customer to refer to your web site vice putting all the information here and bad mouthing anyone that disagrees with you.  I  feel reasonably sure much of what you say is factual but also much appears to be highly opinionated.

No, you're not. You didn't even provide any specifications regarding your solution, you are promoting so aggressively, other than that it seems to working in a ULPower installation and that it doesn't draw much power. Will it also work if one of the pumps fails? During climb out? If the engine is heat soaked? Are flow and pressure provided by your pump(s) sufficient  for the pressure regulator on the engine to do its job? Maybe yes, maybe no, since we neither know the ULPower's requirement nor did you provide any hard data on your pumps.

The OP was asking for pros and cons of header tanks. Your response what pretty much 'the integrated Viking header tank solution is the only way to go, it is perfect, no disadvantages'. This doesn't even remotely answer the OPs question and is, in my opinion, nothing but cheap, blunt marketing and an abuse of your right to post in this forum, because your a Zenith builder yourself.

Only because your the most vocal guy in this forum and the only engine seller who is allowed to post here, doesn't make your statements right! What is particularly problematic, is that people might not be able to tell what is just sales talk and what is useful, unbiased information, particularly if you're the only guy responding, flooding the thread with your promotional material and videos.

I urge everybody to consult with you engine manufacturers as well as Zenith, to discuss the pros and cons of a header tank system. If you're interested in the Viking system, which also replaces the fuel pumps, discuss with them if it is compatible with your engine. Also, draw the system on a piece of paper, including all the valves you might want in your system and then weigh the pros and cons. If things would be as clear cut as Jan tries to tell us, we would see header tanks in much more aircraft, yet virtually no other company is using them. Not even companies with decades(!!) of experience and 10s of thousand engines and planes sold.

As I said before - I am neither opposing header tanks in general nor the Viking solution, but this is also nothing to take lightly. It is vital to understand the system and possible failure modes. Jan is very quick with selling his products, I doubt that he'll be just as quick with possible compensation payments, if a builder experiences unexpected side effects, maybe even leading to a crash.

I disagree.  The person who started this thread asked a question about header tanks, and Jan among others responded to the question with information on the subject.  Jan just happens to offer more detailed information than others, which we are free to disregard.  Moreover, I have not seen him pushing product, or read any rude scathing criticisms, but I suppose it's subjective..   

[...Keep in mind, that problems with the fuel shystem are the #1 reason of engine failures in experimentals!]

Keep in mind that mismanagement of the fuel selector is the number one reason for fuel starvation. Much better off if fuel system draws from both tanks.

A typical header tank installation also involves separate shut off valves for each wing tank, what certainly makes sense as there would otherwise be no way to shut off the fuel supply in case of a leak at the header tank. In case of the Viking solution, you also have the pumps which could potentially leak, as well as a plastic, non aviation type fuel connector. Being able to select a single tank is another reason why separate shut off valves make sense, if a header tank is used.

This however also means, that you will now have the main fuel selector plus two separate valves, which are usually installed out of sight and hard to access.

Unless your willing to not install any shut off valves between the wing tanks and the header tank, you have to weigh if it's more important to you to have a 'both' position or if you rather want a more simple system with a single valve and less fuel lines.

Btw.: In a system with a carbureted engine, one can have a 'both' setting on the fuel selector even without a header tank, as no return line is needed. 

A wing tank isolation valve seems like a good idea for maintenance purposes, regardless of a header tank.  We intend to install valves at the wing root, and lock open.   On our CH750, there is no need for a selector valve because all of the fuel gravity flows into the Viking header tank.  From the header tank, the fuel is pumped directly to the engine.  And no need for a gascolator as the header tank serves that purpose as well.  How much simpler can you get?  Like a carbureted engine, our Gas Direct Injected engine also does not have a fuel return line.

What's an aviation vice non-aviation type fuel connector?  I'm building an experimental aircraft and nothing is TSO'd.  Viking fuel pumps and fittings are the same used in millions of vehicles, and they seem to work fine.  

For me, all of the different options available is what makes experimental fun and interesting. 

And even for maintenance you might consider a push open drain at the header tank as the easiest method.

Put a large container under the airplane, open the valve and wait for the entire airplane to empty, then do your work

Keep in mind that if you want to have the ability to select between your two tanks, you would need individual shutoff valves for each tank, if you go with a header tank.

It additionally adds quite a bit of weight very far aft, what is also something to consider.

I understand that direct injected engines, like the Honda Viking is using, are very sensitive when it comes to air bubbles in the fuel system. A header tank is therefore mandatory, in addition to its single, mechanically driven high pressure fuel pump.

Port fuel injected engines, like the ULPower or the AeroMomentum are a lot more tolerant regarding air bubbles in the fuel line and it is pretty much up to the owner to decide which route he wants to go.

Personally, I like to keep things simple and will therefore not install a header tank.

[...adds quit a bit of weight very far aft...]

Aluminum ball valves are very light, just a few ounces. See this link for an example:

I was talking about the weight of the header tank, its fuel pumps and the fuel it contains.

Instead of a single, albeit more expensive, duplex fuel selector, one would need a valve for each tank and, if desired, an additional valve between the header tank and the engine. Quite a few connections and components which can leak and valves which can accidentally forgotten to be opened, particularly since the valves for the wing tank which will most likely be installed behind the pilot. Speaking about the valve location behind the pilot - if one intentionally want to draw fuel only from one tank, the shut off valve for the other tank might be hard / impossible to access.

It is also quite a bit of work and complex to assemble your own header tank system, if you want to stick with the fuel pumps suggested by the manufacturer of your engine.

Again, I'm not opposing header tanks, but want to point our that the pros / cons are nowhere near as clear cut as it might appear at the first glance.

I will use this fuel selector and other than that stick to the recommendations, laid out by AeroMomentum, from whom we ordered our engine and who actually advice against a header tank, mainly because of the added complexity.

You are much further behind the curve than we are.  I recommend you  listen to those that have been there, done that :)  Right now you sound like a defender of an engine choice, you have already made.  Not very helpful when it comes to being objective about a fuel system.  The Viking system took a long time to develop.  It went through the older systems you defend.  If you want a selector valve or not is not important. 

  • The fact that the system you try to defend has to gravity feed 35 gallons / hr is important. 
  • The fact that you want to do this to a main fuel tank is important
  • That you think your port injected engine is "forgiving" to lack of fuel is important
  • That your fuel pumps will draw high amperage on a system that depend on electricity is important
  • That you are not aware of the Andair fuel valve troubles is important
  • That you believe 6 fuel connections to the duplex valve inside the airplane is safe, is important 


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