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Home✈️Aircraft🚁HelicopterHelicopter Main Discussion › Uniflow.... I am confused
11-07-2005 12:15 PM  14 years ago
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gkoutsis

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Athens Greece

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Uniflow.... I am confused
I used these photos as a guide....

So, I have the same QUK header tank on a Shuttle with an OS37.

I've been reading over the past days that the second line is supposed to be hooked to the manifold pressure nipple. But the way I see here, the second line goes to the top of the header tank.

How is this going to help me maintain a constant pressure no matter what the level is.
George
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11-07-2005 01:05 PM  14 years ago
PaulJC

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Hertfordshire UK

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From the main tank you should have 3 lines with 2 clunks, one clunk line would go to the exhaust, the other to the header tank and the 3rd is a breather that should be blocked.

The header should be setup the same way, i rarely uniflow the header as there pretty small to have 2 clunks inside but may do with good results.

When fueling the main tank (asuming no uniflow header) you need to open the main tank breather and close off the line to the exhaust or you'll fill the exhaust with fuel and not the tank.
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11-07-2005 01:12 PM  14 years ago
gkoutsis

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The header should be setup the same way
Thats exactly why I am confused. I though the header was supposed to have 2 clunks as well.

Where does the upper hose from the header go then?
George
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11-07-2005 01:14 PM  14 years ago
dkshema

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Cedar Rapids, IA

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http://www.fraserker.com/heli/unifl...iflow_works.htm

That's the explanation for why a uniflow should work. But from the pics you posted, I/m not sure what that second vent line to the header is all about. I think this is what is confusing you as well.

Dave
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11-07-2005 01:27 PM  14 years ago
PaulJC

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Hertfordshire UK

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Where does the upper hose from the header go then?
Knowhere, its to be blocked off, the same as the 3rd line on the main tank, if you add something to close the line to the carb you can use if for fuelling.
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11-07-2005 01:29 PM  14 years ago
gkoutsis

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Athens Greece

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I've read this article and it explained a lot. I am just going to use the uniflow setup with the header tank and plug the top nipple on the header tank as before.

Only problem is I have to wait 5 more days to find out if it works or not

Damn I hate winter time
George
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11-07-2005 02:26 PM  14 years ago
PaulJC

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I would have thought that uniflowing the header by itself was pointless, the main tank is where the problem lyes, if you've got the header uniflowed the pressure in it would vary anyway as it takes its pressure from the main tank regardless.
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11-07-2005 03:05 PM  14 years ago
DrDan

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Potosi, Missouri

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From what I understand, you don't have to uniflow the header. You can if you want too. You'll have to install the same setup as you have on the main with 2 lines. One header clunk line would come from the main tank and one header clunk line would go to the carb.

If you don't want to uniflow the header, just set it up like normal. Your header setup will not achieve anything.


With your main tank setup, one clunk from exhaust, one clunk to the header, and clip the top fuel line. Open the top when you fuel. Other than that, you should be good to go.


Dr. Dan
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11-07-2005 03:08 PM  14 years ago
w.pasman

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Netherlands

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Paul is right, it makes really no sense to make a uniflow setup for the header.

First, the header is only to capture bubbles. Once the main tank is out of fuel, you need to land and refuel, the headertank will not function as supposed if it is not filled. Uniflow is only to compensate fuel height CHANGES and as the header is always full there is no height change to be corrected in the header.

Second, -- I have not tried this the theory about what would happen is a bit complicated for so many lines and pressure levels -- I think you are risking that the pipe blows all fuel out of the header into the main tank. In unfortunate configurations, this might happen only when you fly inverted.

For another uniflow description, check my web pages:
http://graphics.tudelft.nl/~wouter/...ow/uniflow.html
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