Hi.

I guess there are other too, who want a effective smoke system, wich all the smoke is coming out of the wingtips?
I don`t know if there is allready developed a system for this, I guess not.
But in lack of knowledge if there is, I did some thinking around the subject that might bring us closer.

The base for the whole idea must be the usual smoke-needles/pump allready used in our jets.
Next, the system must be reliable, and maintance free, not to heavy, but effective. I don`t think a parachutists smoke-cardridge will do it, meaning the powder itselves..
It won`t be the massive effect we want, at least not for moore than 30 seconds.
Problems with handling the powder into the "missiles", and firing it is some of the problems.

The cardridge mentioned above is weighing 450 grams....

The only way I can imagine this can be done (yet), is to have a alutube (app.12 mm diam) from the exhaustcone of the engine all the way to the wingtips (two, one for each wing.)

This must nessacerlily NOT be fully temp-isolated in the wing.
One smoke-needle for each tube, and needles is placed in the middle of the jetstream, pointing paralell to the elevator axis, to secure a really good pre-heat of the oil before leaving the needle.

The needle-tip is entering the tube (app.1cm), and tube is barely placed in the jetstream, app. 1/6 th of the diameter.
Alutube is bending 180 degrees, and now pointing forward to reach height for the rest of the tube, wich is going to the wingtips. Overlapping tube-connection at wing-root.Closer to the wingtip, the tube is following the thickness of the wing, by making the tube oval.

Now, the alu-bend at the nozzleend has a inviting opening to push the smoke through the tube. Not to hot, and the next
clou is to get a ejector effect from the actual airspeed, at the wingtip-end of the alutube, as this end is supposed to point directly backwards.
And since we now have a push-effect in the engine end of the tube, and a pull- on the wingtip, I would say the basic needs are covered..?

The breaking point would be to find the exact location of the tube in the nozzle-end, and balance this with acseptable temperature. As it`s just partly inside the jetstream (App.1/6 th of diam), it will get a cool airmix from the airflow of the duct while airborne, while the smoke needles are HOT. This idea can only be used inflight though.. Adjustments would of course be needed.

To find out the maximum positions and locations, a simple test-rig would do it.
Two air-guns would fix the airspeed at the tips..


Silly, or wort a try..?
What do you think?

Gudmund

Hi Gudmund

I have wanted to do that forever too. One of our friends put smoke out the wingtips of his big stinger. He put aluminum pipes through the foam cores and ran the smoke off his muffler with slicone tubes that pluged into the wings.

Due to the usual wing tip vorticies there should be enough negitive pressure there to suck out the smoke if the outlets are pointing and are shaped correctly.

1. Agreed with the cartriges.

2. Interesting idea. You might need stainless tubes for the initial smoke tube, I dont think that the aluminum will hold up in the exhaust duct too well.

3. I wonder if you will have enough flow for decent smoke, also how long does the oil need to be suspended in the hot gas to make good smoke?

4. FYI you most likely know this already but the full scale planes use smokewinders. They are self contained smoke generators. Check this out only if they could make them for us.

http://www.sandersaircraft.com/smokewinder/index.shtml

5. Go for it and good luck!

well, it is something that is missing in jets.
Try this: http://www.regin.com/rcsmoke.html
Im not sure it that will work on jets, but I dont see why now.

I have also seen another way: People used Estes Rockets in
EDF aircarft. Put two of those on your wingtip, and you get the extra thrust
and a nice smoke trail Only problem with that is, they dont last long.

V

Well this is the effect on my big TOC extra. 4 mins of vivid colour. Electric fired. Great stuff. Fitting now to my 1/7th scale twin F-18.