RunRyder - Question: JetCopter Fuel line Hookup and NH-90

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Got Jet Fuel? Turbine Helicopters > Question: JetCopter Fuel line Hookup and NH-90

edg
Senior Heliman
Location: San Francisco, CA

Just got my NH-90 test flown yesterday. Very nice, very uneventful! It's mostly cosmetics from here...

However, I have a question about the fuel hookups. I bought my JetCopter right from Josef as a demo model they had already built. The way they have the fuel hooked up is, there's a header tank, plus 2 main (32oz) tanks. Fueling goes into the header, then out from there into a Y coupling, and from the Y into the clunk lines of each main tank. Each main tank also has a vent line.

From the NH-90 docs it looks like they consider one of the main tanks the "header" and there is no small header tank as such. So the fueling is a bit different.

I'm not sure I like the Y setup with 2 vent lines. I can only imagine they did it this way as a safety. What I'd like to do is have a line going from header to clunk of Main 1, Main 1 vent to clunk of Main 2, then Main 2 vent to air.

Bad or good idea?

01-16-2004 Over year old.

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midwestpilot
Elite Veteran
Location: Crystal Lake, IL

That is the correct way...

Just make sure that the fuel tubing is the same length so it sucks the same amount of fuel from each tank.

Also make sure your header tank is a UAT (bubble trap) from BVM

In life there is no spacebar!

Rich Erikson AMA 6175

01-16-2004 Over year old.

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heliVoY
Veteran
Location: NJ

use the header tank you got from Josef, it most likely a BVM UAT tank with a special mesh filter. It will prevent bubbles in the fuel lines, and i would say is a must have in any turbine install ... Run the 2 tanks into the heaver either in paralel via the y split, or run them in series (the side to side CG shift from fuel use is not niticeable ..

On my bell 230, i run 5 tanks in series ... 4 40oz tanks, and a BVM UAT header .... my tanks empty as follows backleft --> forwardright --> backright --> forward left --> header --> fuel pump ... ...

i thuought of doing a 2 paralel, 2 series set up instead, but i have seen too many problems witha paralel set up, so im kind of not comfortable with it ... On my MB339 jet (with P80 for powre), my one saddle tank would always empty out, while the other was only 1/2 empty ... i checked all the tubing and connections, and there was not problem there ... i just went with a series set up, and i get to use all of my fuel ...

with the fuel pump for the turbine, you dont have to worry that much about tank location, presure etc ... just to give you en example, i one time (like an idiot) forgot to pull out my fuel vent plug, and flew that way .. the fuel pump sucked out over 100oz of fuel from the system, and actually sucked the tanks dry into a colapsed state !!! ... (these were dubro tanks, which are moderately soft )

Wojtek

01-16-2004 Over year old.

edg
Senior Heliman
Location: San Francisco, CA

Ok cool! Thanks for the info.
I think I'll go ahead and connect the tanks in series. That was
my main concern -- the pump wouldn't be able to suck where the
vent was further down in the series.

Also, I'm using my original dubro tanls in the NH-90. So, I have 2 spares from the NH-90 kit. Connecting more up is very intriguing!

01-16-2004 Over year old.

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heliVoY
Veteran
Location: NJ

just one more thing ... use large diameter fuel tubing and tank inserts , as well as the heaviest pick up clunks you can get .... this will give you a smooth fuel flow ... (the pump will handle anything, but might as well make it easy for it .. )

Wojtek

01-16-2004 Over year old.

Phil Cole
Veteran
Location: Redwood City CA

Ed,

If it makes you feel better, I use the series setup as well. I could never get a parallel setup to fill evenly, so I distrusted it to empty evenly.

The pump has no problem what so ever with the series arrangement. I thought the change in weight distribution might be noticable as the tanks empty one by one, but it isn't.

What finally got me to go series was when I tipped the model over to look at something underneath and the fuel started siphoning from one tank to the other, and then out the vent on the lower tank. The upper tank vent let the air in, so the siphoning kept on going when I set the model level again. I didn't see this happening until there was a big puddle of kerosene under the model.

01-17-2004 Over year old.

edg
Senior Heliman
Location: San Francisco, CA

Thanks Phil.

Yeah, I always had siphoning problems too and it didn't seem to use both tanks very well.

I just took the lid off the NH-90 and redid it to series. I'm giving it another test flight today down by the Dumbarton Bridge

Good thing I did this actually. I have my tail servo wire wrapped in plastic spiral and running along the alum drive tube. When I popped the top off, I noticed the plastic spiral wrap was quite melted. Now THAT could have been big trouble! Forgot to wrap insulation on it...

01-17-2004 Over year old.

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heliVoY
Veteran
Location: NJ

on m bell230, my tail servo wire runs 2cm over from the exhaust pipe .. i have it wrapped in plastic, and then in 2 layers of heat blanket tied around it .. i also (as per Sandy's suggestion) wrapped the actual exhaust pipe in heat blanket as well (actually , automotiv eheader wrap) .... even whn my turbine ran up to almost 1000c, the fuselage felt as cool anywhere near the pipe (some sopts with only 2 - 3 cm clearence ) as it did where there was no heat nearby ... If you wrap the pipe, this will cause the heat to gout out through the inside of the pipe, and not radiate throughout your fuselage ..

Wojtek

01-17-2004 Over year old.

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Got Jet Fuel? Turbine Helicopters > Question: JetCopter Fuel line Hookup and NH-90

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