Stratus & OS SZH header tank / fuel starvation problems

[jambo]

Due to the hatori being long I had to offset the main tank to one side. This leaves the tank hanging right over one side which isn't a problem in itself although becuase the main feed is not central on the tank it leaves the clunk line in the main tank very short and will not reach all corners of the main tank. I added a header tank to overcome this but since I started tweaking the engine in idle1/2 with higher head speeds I seem to get fuel starvation problems with the header tank connected. Disconnecting the header tank makes the engine run lovely.

So my questions are :-

can I use a header tank with the OS SZH pumped engine?

What problem is the off centred clunk line going to cause me not reaching the corners of the tank?

Can you see any problems in my plumbing?

http://www.helifreak.com/album_mod/upload/25d625a1e53097cfb1d2669dddfd84ed.jpg

http://www.helifreak.com/album_mod/upload/897d0728eb1860b4f635cd165741b73b.jpg

[DavidH]

So my questions are :-

can I use a header tank with the OS SZH pumped engine?

What problem is the off centred clunk line going to cause me not reaching the corners of the tank?

Can you see any problems in my plumbing?

1st. Why do you even need a header tank?

2nd. Did you install the Fuel Magnet in the tank as the clunk?

If your using the fuel magnet. Mounting the clunk off centered and not reaching the corners is not a problem. The fuel magnet will use all the fuel in the tank.

I don't see any filters in the fuel lines except on the vent line which really doesn't need a filter.

Just my opinion, but the plumbing in the above pictures is a lot more complicated than it needs to be.

David

[jambo]

Thanks for the reply,

I added the header tank becuase I was worried about the clunk line not reaching around the whole main tank and like the extra bit of fuel onboard

Yes I have the fuel magnet in the main tank.

I'm not a fan of inline fuel filters had several bad experiences, instead I always use a fuel filter when pumping fuel into the heli.

So the fuel magnet will do the job of my header tank?

[DavidH]

No one I have seen flying the Stratus is using a header tank. Except the F3C contest pilots that need extra fuel capacity to complete the F3C schedule of maneuvers.

I use fuel filters on the fuel pump also. But I use filters in the fuel line before it goes into the carb on the engine also. No matter how much you filter the fuel going into the main tank. There is little particles of debries that are inside the tank and pump on the bottom of the engine that can break loose and block passages in the carb.
Been there done that and have the T-shirt.

The fuel magnet will get every drop of fuel out of the tank and the engine will not lean out. When I run out of fuel with the fuel magnet in the tank. The engine will just quit like it was cutoff. There is no leaning before it quits. The tank will look like it never had fuel in it.

David

[DavidH]

The pilots here in the USA that are using Hatori Mufflers. They get them from Hatori USA. Hatori USA does not have three digit muffler numbers like Hatori Japan uses. Hatori USA uses SB designations and then a two digit number.
For example the SB 17 and 18 is the Hatori muffler that is being used here in the states with the Stratus.

There is a difference in the SB mufflers from Hatori USA and the three digit mufflers from Hatori Japan. If I am not mistaken the header on the SB mufflers is longer than the three digit mufflers from Hatori Japan. Yes the SB mufflers are made by Hatori Japan. Hatori USA has the SB mufflers made to there specifications. So the SB mufflers will mount out a little more from the mechanics than the Hatori Japan 3 digit mufflers. Also the Hatori USA SB mufflers are maximized to use 30% nitro fuel.

David

[sookainian]

those guys are right, the fuel magnet will suck up all the fuel. :glasses2:

[jambo]

those guys are right, the fuel magnet will suck up all the fuel. :glasses2:

Dont flame me for asking but will the fuel magent suck air up when its not submerged in fuel ?

[sookainian]

hmm that i am not to sure, as mine just work this way. Hmm mb it wont, when the sponge is still wet, but when it become dry yes :mrgreen:

[jambo]

I suppose it depends on how much and for how long the fuel magnet can supply fuel for. Perhaps I should move the main feed nipple on the tank so the clunk is more central, I think I would feel much better if I have to lose my header tank then :(

[DavidH]

Jambo,
When the tank is out of fuel using a fuel magnet. The engine will just quit. There is virtually no leaning out of the engine before it quits. The foam is saturated in fuel, so no air gets into the line.


David

[jambo]

David,
Great consider the header tank gone!

Steve

[Bert Kammerer]

Jambo, David is absolutely right. I fly 3D without a header tank in both my Stratus helis. The magnet doesn't reach all corners, but it sure will pick up any fuel that splashes around the tank. I have never had an issue with this.

Also, I highly encourage you to put a filter. I am not a fan of filters either, but without a filter I can almost guarantee you that your carb or pump will fail prematurely. The fuel magnet foam softens and occasionally breaks with fuel, if you start getting some of that residue into your pump and carb, you won't be happy.

[jambo]

Bert,

Ok, I took the heli out today without the header tank and with a fuel filter on! Didn't do nothing more than fast circuits and climb outs and its seems fine. Although I'm still thinking about moving the main clunk line feed over a couple of cm's

Its just change and I'm not used to it, I have always had a header tank from day one on all my helis. I shall bow to your greater experience.

Thanks guys

[Bert Kammerer]

Jambo, I also had header tanks on all my helis prior to the Stratus, I felt in a way the same way you do, but I got over it. You'll be fine! Just make sure your fuel line inside the tank is short enough for the fuel magnet to not get stuck in a tank corner and you won't have any problems.

Enjoy :)

[jambo]

Bert, No chance of that, the fuel magent is way over to one side and therefore the clunk line is very short, I think I am going to add another fuel nipple to the tank on the other side of the velcro if that makes sense. Is this a waste of time?

[Bert Kammerer]

Yes, that is definitely a waste of time. I am going to get a picture of my tank and will post it within a few minutes, you'll see how short that fuel line is.

[jambo]

thanks

[Bert Kammerer]

Jambo,

The last picture is blurry because my camera was having problems focusing that close, but you can clearly see how short the fuel line inside the tank is. I was initially concerned when I built my first Stratus just like you, but I can assure you that if you have a fuel magnet, that magnet will pick up all the fuel, you need to leave the fuel line short enough for the magnet not to get stock in a corner.

[WillJames]

Great pics Bert!! Easy to see the magnet/clunk line setup like that!!

[jambo]

Bert, Thanks they are great pics. How offset from centre is the main clunk line? Mine is around 4.5cm in from the exhaust side of the tank leaving a massive 7cm's the other side (not including the screw on cap) ?

[DavidH]

Jambo,
Your trying to over complicate it. I can assure you, as long as the fuel magnet is touching the bottom of the tank like in the pictures above. It will get every last drop of fuel out of the tank. And when the last drop is gone the engine will just quit. You will hear it lean out some for maybe 1 or 2 seconds before it quits when the fuel is gone.

The fuel magnet is fantasic. It helped do away with the problem of header tanks.

David

[jambo]

Well I have had a good chance to play with this now and it seems that the problem is still there even without the header tank. I thought it was running correctly without the header tank but found it to be rich in the middle. I have therfore leaned the engine out in the middle and it runs lovely until you put the heli through hard manouveres where it will go lean and the only way to get it running is to have it rich in the middle. Like this it is impossible to perfom tic toc's etc due to it being sluggish and running out of steam :arggg:

One thing I noticed from new is the idle screw is not set to its usual centre postion, but 10 degrees on the rich side. It idles fine so I have never touched it, could this be a prioblem? Where was your idle screw from factory?

I took it to a friend iyesterday who is a pretty good flyer here in the UK and he suggested that I should put a header tank back on it as it looks like a fuel starvation problem. Help........

[DavidH]

jambo,
Tmoore here on Helifreak told me he had the same problem with a friends SZ. He said it appeared to be a fuel starvation problem. They took the SZ carb off the model and sent it to OMI to have the Cline installed and needles modified. That is what I would suggest doing. It will cost approx $80 USD.

David

[jambo]

Thanks David, this maybe an option if I can;t get it sorted. I wonder is I haven't got the right shims in it :dontknow

[heliroller]

Thanks David, this maybe an option if I can;t get it sorted. I wonder is I haven't got the right shims in it :dontknow

What % fuel are you running? both shims with 30%..