Guys,

How many people successfully inject their smoke oil at the rear of the thrust tube? I will be installing smoke on my P200 powered AirWorld MB339 and would like to have the smoke fluid injected in the scale position for 2 reasons - a) it's scale and b) drips/overfills etc won't end up in the thrust tube/bypass.

What is the best way to achieve this. Should I use stainless steel tubes to the tail? Do they need to be held up against the thrust tube to 'pre-heat' the fluid or will this get too hot etc?

Any advice welcomed.



Rgds,
Mark

Mark it will work but you will have to pre-heat the fluid, so run 4mm brass tube inside the outer pipe.

m

I have heard of it being done by running the supply tube inside the inner tailpipe but I have no experience myself of this.

There seems to be an echo round here! lol

m

Run the tube down between the inner and outer pipe

My Foxjet has no jetpipe and I can't get a good smoke density, despite pumping a lot of smoke fluid into the efflux (using 2 of Tam's injectors). The efflux cools rapidly and doesn't vapourise the fluid...so I think injecting it close to the engine and letting it vapourise in the jet pipe would give better density. You could still put scale smoke injector pipes at the back end anyway.

Cheers,

Dick
England

Hi Mark i am using brass tube 4mm at the back of the engine with no problems,temps here are around 500c,at the end of exhaust duct you will find there are around 250/300c so i would be very surprised if you will get any sort of good density,i have not found putting it in the front of the exhaust pipe a problem not really messy regards Keith

I run it between the walls of the exhuast, really thick and dense smoke:

it works . . .and works very, very well. Bill Hatcher and I (at my insistance) have installed this system on each and every jet that leaves his shop. To name a few, 2 large Futura Jets, 2 small Futura Jets, CARF Tutor, DJM Vampire, CARF Ultra Flash and so on.

Pre heating is not necessary as this is accomplished by running the stainless steel tubing down the pipe between the inner and outer pipe walls. We use the 10 o'clock and 2 O'clock positions or the 9 - 3 positions. The ends of the nozzles are compressed almost flat as they would be in standard smoke nozzles.

The smoke put out is equal to or greater than spray bars inside the jet just aft of the turbine nozzle. . .and the big benefit is SAFETY ! No more chance of smoke oil fires due to residual drip inside the bellmouth assembly. I have witnessed more than one jet flame out during a smoke on pass. The pilot forgets to turn off the smoke pump, maintaining his focus on landing the plane. Smoke oil ignites and is being fed by a full flow of oil. You know the rest.

Try this system. . .you will never go back to internal smoke systems again.

Regards,
Eric Clapp

I will ask Bill to post some pictures

Mark.. I ran my Roedel models CT114 Tutor with the smoke outlet in the scale position ,, never had a problem , made great smoke ... I simply ran a 3/8 0/D brass tube right down the pipe in between the outer and inner pipes out to the end of the exhaust tube and then curled the outlet up into the center of the the exhaust stream about one 1/2 inch out from the end of the pipe and installed a brass cap with side outlets made from a Robart schrader valve air inlet , looked scale and worked very well......MK

Hello Everyone

We run just 4mm festo tube down the fuse to 2 X injectors connected to a Tamjets smoke system, no preheat.
Using Robart smoke fluid in this picture.

Skymaster Gen 1 MB339, PST 1300R.

Do you think is two injectors better than one?

Hi Eric,

Thanks for the info. Just what I was after. Only question is my pipe is double walled for the last 12-14" (like the large Futura pipe I believe). I guess that's no issue from what you say.

Would be interested to see how you secure the injector tubes to the pipe in these cases?? Any Pics?

Regards,
Mark

Mark if you use a 3/16th inch tube between the walls the fit is tight enough to secure it. you can also use a piece of glow fuel blue fuel line around the outside of the tube and wedge it between the pipe at the back. it will stand up to the heat. I also use a one way check valve. I found that the pressure from the tail pipe will actually cause the smoke pump to lose its prim in flight. I also set up a header tank so I don't get the negative G on and off smoke through maneuvers.

Joe L.

Mark, Here are a few shots of different planes.
1st photo Small Futura On this one I just safety wired the smoke tubes to the pipe mounts at the bell mouth.
2nd Photo Comp ARF Tutor. As you can see in this one The smoke injectors are not run between the walls of the pipe just down the Fuse sides and out the back, This also works well.
3rd and 4th photo Large Futura. We just used Safety Wire in 2 spots around the inside pipe.

When we run the 4mm stainless tubing between the walls of the pipe we cut a small notch in the inner pipe at the rear so the stainless smoke tubing has a lock to keep it in position, we then pull if forward into the notch.
Hope this helps.

GREAT INFO...<span style="white-spacere"> </span>

Hi guys,
Using it on my JMP Firebird - two stainless steel tubes of 4mm dia guided to the back between thrust tube walls. Harris pro pump. Skydry as fluid !
Works just fine ! (well, above 250mph the trail is getting thin though)
see you
Hans

Where do you get the long stainless tubing??

planecrazy232:

McMaster - Carr is the source we use. The stainless tubing comes in several lengths. Our good friend Andy Herold usually does the ordering for this part. I will contact him to see if i can get a part number.

Regards,
Eric