Combat Smoke System

[Mr.RC-CAM]

I had more to add to the Sonic Module Combat Smoke system discussion, so I decided to start a new thread (so that the Combat AWS thread could be preserved).

Rysium's original smoke circuitry starts here: http://www.rcgroups.com/forums/showthread.php?postid=1533561#post1533561. It allows an IC engine's smoke system to be controlled by the nifty HobbyZone Sonic Combat module. This was inspired by the other discussions concerning the Hobbyzone combat product and the various hacks that have been used.

In a nutshell, I spent a little more time with Rysium's posted circuit (which was functional as-is). However, with the addition of a four more parts, remote activated smoke could be restored (Tx control was lost with the simplified circuit).

The FET transistor allows the signal coupling cap (C1) to be isolated from the servo pulse during normal use. This eliminates the pulse degradation (pulse stretch issue). But, when a weapons hit occurs, the FET switch is turned on, which effectively puts the cap back into the path.

A pot was included to allow for adjusting the smoke servo position during the hit state. The Tx stick/switch is used to adjust the servo position for non-smoke operation. As mentioned, the Tx can still be used to turn the smoke on & off for additional (non-combat) functionality.

There are no serious bad habits that I noticed, other than a tiny bit of interaction when R3 is tweaked. It seems to work on the bench after my quick attempt to cobble it together before T-Day shopping. Perhaps the circuit will survive duplication on the other end. :)

Below is the original circuit, to be followed by the modified version.

RC-CAM

[Mr.RC-CAM]

Here is a snippet of the new circuit:

[Mr.RC-CAM]

Finally, here is the full schematic:

[rysium]

It was such simple circuit, and you had to complicate it again :D
But serious, I can't test it (I'm sure you have done it already) but the way I read it, this should work. Makes sense, to cut off the capacitor when not hit, therefore system is transparent during normal operation, therefore smoke servo is controlled by input smoke signal. When hit, the RC is cannected again and passes the short signal spikes to smoke servo. I got it.

Now what do you think of that idea to simplify it again. Again I can't test it now, but this might work if timing will not become weired. I don't have program to draw electronic circuits, (and I hate AutCad) so I will describe the changes:

1. Remove R5, Q2, and R6
2. Connect gate of Q1 to leg 10 of U1C (FET will be controled by NAND of smoke signal and hit indicator)

Therefore FET will be closed for all peeks (logical 1) of smoke input signal and open for iddle (logical 0) of that signal. So for the capacitor input signal will always be logical 0 when not hit.
When fit, leg 10 of Q1 will go to 1 what will open FET until hit signal goes off again.

Again timing (nano seconds delay in gates) might create some ghosts in signal but might not.
It is cool, isn't it? :cool:

RysiuM

[Mr.RC-CAM]

I can't test it (I'm sure you have done it already)Yes, I built the revised circuit and it worked on the bench.

Now what do you think of that idea to simplify it again.That is one of the configurations that I tried to do. It did not work well, so I introduced Q2 and the required two resistors. There is probably a lower part count solution if you spend the time to Muntz it.

BTW, there are many ways to build this circuit and you could eliminate the FET using more CMOS gates. But, what you see was easy for me to prototype on short notice. In retrospect, I should have just modified the AWS's PIC code (would have been less work).

At this point there are a couple of functioning circuits for you to use. If you want to keep it simple then you should build your original design. A smoke system is now just a matter of tossing some parts onto some perfboard.

RC-CAM

[rysium]

Right, the simplest solution (counting the number of parts and connectios) is the PIC version. And then we wouldn't need the channel dedicated for smoke - PIC would do it all.
But this is something for the future for "long winter evenings":)

I will be putting my original circuit (using the pot for addjustment as you suggested). There will be no smoke control from the radio - if I would want to fly smoke I can connect the smoke servo directly to the receiver. At the same time I'm still experimenting with the right smoke oil, and reliable tubbing.

Then I have to finish my next corostang (I have ARF already build up), so me and my son can do some "real life combat".

BTW. This Sunday we have Toys for Tots at MASM. You are very welcome here. Among the other planes I will have my smoking corostang with me.

See our website for more info:
http://masm.inc.home.comcast.net

RysiuM

[opualuan]

how do these systems generate smoke, anyways?

[rysium]

Originally posted by opualuan
how do these systems generate smoke, anyways?

Simple answer is:
1. Smoke oil is pumped from the tank into engine exhaust where the hottest gasses are.
2. In the extreme heat smoke oil evaporates (sometimes burns) crating a cloud of smoke which is coming out of the engine muffler with exhaust gasses.

The effect is the same as a car engine that leaks the oil. Hopefully our planes don't need to pass emission test for DMV:)

The example simple system (like mine) is as follows:
1. Smoke tank
2. Picking line from smoke tank to smoke valve
3. Smoke valve operated by servo
4. Line from valve to smoke pump
5. Smoke pump pumping the oil from the tank into engine exhaust
6. Line from pump to the muffler (at the engine exhaust)

Sometimes pump may be operated by radio, then valve is not needed.

See the following pictures

RysiuM

[rysium]

Next picture

[rysium]

the last picture

[rysium]

Originally posted by Mr.RC-CAM
Yes, I built the revised circuit and it worked on the bench.

There is probably a lower part count solution if you spend the time to Muntz it.
RC-CAM

You know, the less parts, the more reliable thing is. Especially, that the "thing" will be inside the fast combat plane, and WILL BE abused:D

RydsiuM

[Mr.RC-CAM]

The nice thing about the FET is that it allows your Tx channel settings to remain as you would expect. Without the FET, you need to adj the smoke servo related ATV/EPA mix to accommodate the exaggerated pulse for the non-hit operation.

So, if you build the simple version and find the setup a bit too goofy for your tastes, then all you have to do is install the FET.

Thanks for the MASM invite. Sounds like a blast, but I will be out of town.

RC-CAM

[rysium]

Originally posted by Mr.RC-CAM
So, if you build the simple version and find the setup a bit too goofy for your tastes, then all you have to do is install the FET.
RC-CAM
The only drawback from this solution is: No servo reverse. I don't know how my servo-valve is set, but I will have 50% chance, that it's rignt :confused:. If not, I will have to rverse servo-valve conection.
With PIC it is not a problem. You can program servo reverse into PIC on the jumper.

RysiuM

[Zvika]

do you have a picture of the smoke it generates ?

[rysium]

do you have a picture of the smoke it generates ?

I had a video some time ago but it's gone now. The only video I still have is the flying with just a little smoke at the very end.
http://masm.inc.home.comcast.net/corombatp51.wmv (http://masm.inc.home.comcast.net/corombatp51.wmv )

Since then I've changed the setup a little. As you can see the RC smoke valve is between the pump and the tank. When the smoke valve was closed the motor sucked the oil from the pump replacing it with exhaust gases. So the Perry pump lost its priming and then didn't work well.
As a solution I put a check valve between the motor and the pump. Now it's working every time.

Here is the picture taken from the smoking video clip.

RysiuM

[Zvika]

Very nice video, As we have tried to make smoking system for 46 engine that takes pressure from the muffler and is operated by bending the oil tube coming from the tank back to the muffler, but we get no smoke. what type of oil do you use ?

[rysium]

Very nice video,

Thanks.


As we have tried to make smoking system for 46 engine that takes pressure from the muffler and is operated by bending the oil tube coming from the tank back to the muffler, but we get no smoke.

I tried that before I get the perry pump. I had two check valves - one between the muffler preasure fitting and the smoke tank (vent). The second valve between the smoke tank (pickup) and smoke fitting (at the exhaust). It just didn't work. Check valves didn't work dry and somehow the preasure at the exhoust was always higher than the preasure at the muffler. Perry pump solved the problem.


what type of oil do you use ?
The best is "Smoke train oil", the stuff you use on model trains. However it is very expensive ($5 for 4 oz bottle). I'm still trying all kind of stuff, but the problem with small glow engines is that they run "cold". They have to because otherwise they got damaged. So the exhause is not hot enough to "burn" oil. "Train oil" can burn in low temperature, so that's why it's the best. I'm going to experiment with prheating the oil from the cylinder by running the oil through aluminum tube around the motor's head.

RysiuM

[Zvika]

Hello RysiuM

Thanks for the info, as we have chacked with some heavy oils the pressure from the muffler was unable to push it trough the pipe. now we are trying lighter oils (Hydraulic 10W oil) hopping it will flow.
As we have chacked with WD40 service oil, the fluid was driven out by the pressure fut no smoke generated.