q8cub

I just wanted to share the excitement of accomplishing a challenging task of making a size 40 plane generate nice thick smoke. It is a blackhorse decathlon with os 70 4 stroke engine.

I had to use a pumpless smoke system to eliminate any extra weight (battery and pump eliminated). I first used muffler pressure to pump smoke fluid but then had to use the crankcase pressure which was more than adequate to provide enough pressure to pump smoke oil into the muffler. I also had to use pre-heating by rapping a half meter of bras tube around the muffler and then insulating it with insulating material and finally rapping this with a heat tape.


here are a couple of pics of the smoke,

MinnFlyer

My Feedback: (4)

Very nice. Do you have a way of regulating the oil flow?

q8cub

I got lazy about that although I already bought a 40 engine needle to use it for regulation of fluid flow. Currently, I am using a bras tube and bending it so that it is flat (like a whistle) so it does not draw much oil through, just enough to get the thick smoke. Still I believe I can make the smoke thicker by regulating the flow more accurately! I will try this next.

By the way, as I remember you had a famous smoke article which I also read before and was very beneficial to me and many others at RCU. Thanks!

I have a question also, I did many changes to reach the best outcome so far, however, currently, it kind of smokes at low speeds much thicker than high speed. When I give full throttle, the smoke gets less dense. Do I need to increase the flow?

Thanks!

MinnFlyer

My Feedback: (4)

It's hard to say. This is why it's important to have good control over the flow.

Set the throttle to full, turn on the smoke, and adjust the flow (Slowly) until you get the best smoke you can get.

q8cub

Thanks! I will try this.

I will take arial pictures this week and post them.

in the middle of smoke, I forgot to mention how sweet a decathlon can be especially in slow smooth aerobatics using its nice big rudder.

Nice smoke/aerobatic would be a nice vertical climb then a hammer turn and a dive with a slow roll then a climb and keep swinging from side to side through blue skies.

MinnFlyer

My Feedback: (4)

I look forward to seeing them!

q8cub

I did few test flights with smoke but did not get good quality pictures during flying (all were from a far distance - with no zoom). When I flew close and low, my buddy could not time the shot.


This one is the best available, (I tried to smoothen it after enlarging it),

MinnFlyer

My Feedback: (4)

Not bad!

q8cub

thanks!

I will try to use a better camera tomorrow (one with fast shutter speed) to get a closer shot. Maybe an inverted low pass will look good.

q8cub

Today I used diesel with 3% baby oil but smoke looked brownish and not as white as dri-smoke which I used yesterday,

I will try to increase the smoke fluid flow next time, and re-use dri-smoke.

The camera, however, this time was supposed to have better features (7 megapixels vs 2)than previous cam,

millerhill

My Feedback: (19)

Probably the best way to regulate the flow for you would be to use a remote needle valve. You wouldn't happen to have an up close picture of your tubing/muffler wrap would you?

Steve

q8cub

I am using a needle but it is manual and located inside the fuse, so I have to make the adjustment before I fix the wing.

I have been using different needle settings but I will try to open it more on the next test.

I will try to take pictures of the muffler tubing and post it here.


I am sure an os 1.6 can generate good smoke. Also, there is a smoke muffler that you can buy from TH which has an already built-in tubing. The reason I did not order one is that the way the engine is mounted inside the decathlon makes the smoke muffler hard to install (the engine is inverted 45%).

q8cub

Also, take a look at this,

http://www.rcdon.com/html/super_smokers_part_i.html

This guy did a great job explaining the smoke system for nitro engines,

millerhill

My Feedback: (19)

That's an impressive video for sure. I'm using a Slimline pitts smoke muffler specifically made for the 1.60 so I'm hoping that it will work well. I still haven't tested it. Maybe this weekend if it doesn't snow (freakin' Vermont spring weather...)

Steve

michael9054

My Feedback: (2)

Hi Steve,have you had a chance to try the smoke system on your OS 1.6'I have an Ultimate with the same engine and am looking at ways to do the same,but using diesel fuel only!

Regards, Michael

millerhill

My Feedback: (19)

Sorry, I haven't fired it up yet. I'll be sure to post my results when I do. I've read elsewhere that it's much better to use the regular smoke fluid rather than diesel fuel just as a heads up.

MinnFlyer

My Feedback: (4)

Mount the needle in the cowl with enough slack that you can adjust it. You need to adjust it WHILE the engine is running.

PS. watch out for the prop!

millerhill

My Feedback: (19)

I finally got to the point to run in my engine. It started up nicely and runs well out of the box. I'll run it in some more tomorrow, then this weekend fill up the smoke system, set the mixes and see what happens. Wish me luck!

Steve

q8cub

I got new pictures today. I used Dri-smoke and readjusted needle setting once leaner and another little richer (half a turn at a time).

Here are the pics,

q8cub

more pictures,

q8cub

few more,

MinnFlyer

My Feedback: (4)

Looks good!

millerhill

My Feedback: (19)

Nice!

michael9054

My Feedback: (2)

Hi q8cub,

Thanks for the nice pictures,looks like "richer is better" How was your fuselage after these flights,greasy or something similar? I thought it was not possible ot fly model airplanes in the middle east,except Dubai! Good for you[sm=thumbs_up.gif]

q8cub

Thanks!

Yes but not much. It was little greasy mostly at bottom of fuselage. It took a quick wipe to clean it.

Also, the dri-smoke I am using has a strawberry smell and is supposed to be safe for average model covering.