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Anyone use a header tank??

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Anyone use a header tank??

Old 12-07-2003, 09:07 PM
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privatepilot
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Default Anyone use a header tank??

I'm finishing up my GP Extra 300 .60 right now and am trying to decide on what to do with the fuel system. I bought a 14oz sullivan slant tank for it. I noticed that the clunk does not flop to the front of the tank. My concern is that on maneuvers that require any extended nose down attitude, that the fuel will all run to the front of the tank (thanks to gravity) and the clunk will not, allowing the clunk to suck air. I have a small tank laying around so I was thinking about just adding it as a header efficively eliminating the problem. I've run header tanks on helicopters, but in fixed wing craft. Pro? Cons?
thanks
Old 12-08-2003, 01:26 AM
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CafeenMan
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Default RE: Anyone use a header tank??

PrivatePilot - I've thought about exactly what you're talking about, but in practice I've never had a problem with the fuel feed drying up during or immediately after vertical diving maneuvers.

A header tank is just one more thing that can go wrong in the fuel system. What I would do if you're really concerned about it is to make provisions to install a header tank, but try it without at first. Then if you do need it you won't need to perform surgery later, but if you don't need it then you've saved yourself a little trouble and avoided having other problems potentially.
Old 12-08-2003, 07:07 AM
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njl
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Default RE: Anyone use a header tank??

When your in a dive the fuel will be pushed to the back of the tank not
the front so you don't need to worry about a second header tank.

Nick
Old 12-08-2003, 07:14 AM
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polstery
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Default RE: Anyone use a header tank??

WHAT?? does gravity work the opposite in the united kingdom
Old 12-08-2003, 07:57 AM
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Kaos Rulz
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Default RE: Anyone use a header tank??

polstery,

This has more to do with inertia than gravity. The fuel will be towards the rear of the tank as the plane dives because the plane will be accelerating (if at fulll throttle), or the fuel will be floating around in the tank (if at an idle), yet mostly still at the rear. In the case of diving at an idle, there will be enough fuel left in the line to maintain an engine run during the dive. In fact, you'll bury the plane before the engine stops running due to lack of fuel.
Old 12-08-2003, 09:27 AM
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privatepilot
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Default RE: Anyone use a header tank??

Admittedly, I've never had a flame out due to an extended dive, but all of the clunks in those tanks were able to flop to the front of the tank. I agree with what you guys are saying about fuel tending to stay at the back of the tank due to acceleration, but I just wanted to play with the idea of a header tank. Thanks for your input all. I'll decide what I want to do for sure tonight when I work on the plane again.
Old 12-08-2003, 03:36 PM
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Kaos Rulz
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Default RE: Anyone use a header tank??

privatepilot,

If the truth be known, in all likelyhood your clunk never fell to the front of your tank during a dive. At least it's not supposed to. To prove the point take your next assembled tank and point it down to see what happens to the clunk. If it bent in two and fell to the tank's stopper, you would have to straighten it out by going verticle, otherwise it would not pick up the remaining fuel in the back of the tank. Unless you put a small piece of brass/copper tubing half way down the pick-up line to prevent the clunk from being forced to the front, the only way it would bend in half is on a very rough/abrupt landing. When this happens, you have to force the clunk back to the rear of the tank by violantle shaking the fuse.

Please don't think I'm trying to be argumentative, just informative. (at least I hope so)
Old 12-08-2003, 03:58 PM
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privatepilot
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Default RE: Anyone use a header tank??

No offense taken Ed. I've just never really paid that much attention to the clunk before other than to notice that most have all flopped around freely in the tank. Never had any fuel related problems either though. My intention with this plane is to do extreme aerobatics, so I just wanted everything to be in check. I decided to stay with the single tank, but I'm going to add a smoke system, so that will be my second tank. Thanks for the input all.
chad
Old 12-08-2003, 09:24 PM
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CafeenMan
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Default RE: Anyone use a header tank??

Usually if you find the clunk in the front of your tank it's due to the airplane coming to a sudden stop - like running into a fence or a figure 9.

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