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HSD L39 Jet smoke system

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HSD L39 Jet smoke system

Old 02-24-2021, 02:43 PM
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HSD L39
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Default HSD L39 Jet smoke system

Hi guys, Iím just wondering if anyone can answer my problem regarding jet smoke systems. I have a HSD L39 with a new Xicoy X90, L39 goes well but the new X90 is giving us grief at the moment. The problem Iím trying to solve is the smoke system continually bleeds the smoke oil unless I manually turn off the tap, it has a tank, a pump, a shut off valve and a nozzle to squirt the oil into the jet exhaust but when the tap is on and engine running its drawing the oil out on its own, I tried putting a chamfer on the nozzle which is facing forward into the exhaust thinking that will fix it but no. This is a standard smoke setup on the HSD L39 and there is no shut off solenoid and I think the oil can just run straight through the pump. Anyone out there have a simple fix ?Thanks, Martin
Old 02-24-2021, 03:46 PM
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joeflyer
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You need to add a check valve.
https://www.towerhobbies.com/product...ve/SUL756.html
Old 02-24-2021, 04:47 PM
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Originally Posted by joeflyer View Post
Check valve won't fix the problem. If you get a Kingtech Smoke pump it won't do that because it has a valve built into the pump.

If you don't want to do that try adding a header tank for the smoke system

Last edited by Desertlakesflying; 02-24-2021 at 04:49 PM.
Old 02-24-2021, 05:44 PM
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Why do you think that it matters whether the check valve is built into the pump or plumbed in line?
Old 02-24-2021, 07:38 PM
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Originally Posted by HSD L39 View Post
L39 goes well but the new X90 is giving us grief at the moment
Just want to throw this out there, but none of what you're describing has a thing to do with your engine of choice.
Old 02-24-2021, 08:13 PM
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ravill
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Is your smoke tank much higher than your smoke outlet tube?

Is your smoke vent flush/straight with your fuselage?

Have you checked to make sure you have not mixed ANY smoke with any other channel?

That all I got.
Old 02-24-2021, 11:03 PM
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Try what joeflyer says. It will be enough to stop the siphoning and the pump will overpower the valve.
Old 02-25-2021, 04:08 AM
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Yes use a check valve between the pump and your smoke nozzle. You can pick up a one way check valve at a local auto parts store. I have used the ones that are for a vacuum line on a car. they work great. What is happening is when the engine is running and the gases are blowing by the smoke nozzle, it creates low pressure which will siphon the smoke oil like blowing over the end of a straw in a glass of water. the check valve will close and stop this from happening. when you turn on the smoke the pressure will push the check valve open.
Here is my F-15 with smoke and running a check valve. I also have a 2 oz header tank as well so you don't get the "dashes" of smoke when first turned on.

Joe
Old 02-25-2021, 02:07 PM
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Thanks guys for the replies, looks like a check valve will be the answer, I’ll check out the auto supplies vacuum line check valve first.
Hey Jetpilot24, can you be a bit more specific which check valve I should ask for before I go shopping, I’m presuming it’s the one that goes in the vacuum line that operates the heater controls. Thanks.
Old 02-25-2021, 05:02 PM
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Desertlakesflying
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Originally Posted by joeflyer View Post
Why do you think that it matters whether the check valve is built into the pump or plumbed in line?
Because the valves in the pumps are not check valves. Check valves are one way valves that will not stop this particular problem
Old 02-26-2021, 07:08 AM
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Some pumps have built in check valves and some don't. The Kingtech pump has a built in solenoid on/off valve which would resolve the issue. He could add an in-line solenoid valve to do the same thing, however the cheaper solution is to add an in-line check valve.

The purpose of a check valve is to maintain the pump prime and to prevent syphoning, which the OP is experiencing. A check valve will add enough flow resistance to prevent syphoning. When the pump is turned on pressure will open the valve. Perhaps the OP can report whether or not is fixes his concern.
Old 02-26-2021, 12:29 PM
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HSD L39
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I purchased a 4mm windscreen washer check valve, it appears to have a steel ball with a spring keeping it seated, not sure if it’s fuel tolerant or not but time will tell.
When the problematic Xicoy X90 returns, I’ll give it a try and report back.
Old 02-26-2021, 02:29 PM
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This is the one I have used
https://shop.advanceautoparts.com/p/...E&gclsrc=aw.ds

Joe
Old 02-26-2021, 04:39 PM
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Originally Posted by HSD L39 View Post
I purchased a 4mm windscreen washer check valve, it appears to have a steel ball with a spring keeping it seated, not sure if itís fuel tolerant or not but time will tell.
When the problematic Xicoy X90 returns, Iíll give it a try and report back.
I would recommend not using one that is specifically for the washer system. The materials may not be compatible with petroleum products. Buy one that is universal or specified for use in an engine vacuum system, such as a distributor check valve. If they list the material specs one with a Viton, FKM, or fluoroelastomer seal is best.
Old 03-08-2021, 02:34 AM
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HSD L39
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Hi Guys, the windscreen washer check valve works perfect, I’m confident it will last as it’s main body is plastic and has what looks like a stainless steel ball and spring, time will tell but in the mean time I’m having fun leaving chem trails.
Old 03-26-2021, 02:46 PM
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Time did tell, the windscreen washer check valve failed, not sure why as it’s sealed but I recon joeflyer is correct.
The idea of the check valve worked great so I now need to find one in Australia that is compatible with petroleum products as whats mentioned in previous posts.
Sadly the new X90 turbine has failed for the 3 rd time now and the Xicoy agent has agreed to a refund, so I’m going back to either a Kingtech or Swiwin 80 size, any suggestions ?
Old 03-26-2021, 03:41 PM
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Sullivan makes one specifically for this purpose. That's your best bet. It's available at most hobby shops (at least in the US).
https://sullivanproducts.com/product/s756/

Or an automotive one that's made to be used in an engine vacuum system should be compatible with petroleum products.

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