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Author Topic: making a smoke unit pulse  (Read 5666 times)

Steve Dean

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Re: making a smoke unit pulse
« Reply #25 on: November 26, 2016, 05:13:18 PM »

Hi G6SWJ,

Thanks for your reply and the link. I have read the link and wasn't surprised by some of the knowledgeable comments. I'll continue with some experiments in the 'safety of my own garden' least I wipe out some of my boating chums or the nations exhibition halls !!!!!

If all else fails then I still hope to impress you all with copious amounts of the white stuff coming out three funnels on a large model.
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andyram

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Re: making a smoke unit pulse
« Reply #26 on: November 28, 2016, 10:31:27 PM »

Thanks everyone for your input. I am currently digesting the info and choosing my options.At least it is less of a mystery now.


Andy.
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Martin [Admin]

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Re: making a smoke unit pulse
« Reply #27 on: November 29, 2016, 05:28:23 AM »


I once saw an article in a very old model boat magazine , for a puffing unit.
It basically consisted of slow motor connected to a very basic piston unit, it was about 10-20% volume of 'smoke chamber' and
it introduced just enough 'umph' to simulate a 'puff' as it worked.

Something like this: https://youtu.be/YZKJVsik6co

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andrewh

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Re: making a smoke unit pulse
« Reply #28 on: November 29, 2016, 06:04:37 AM »

Hmmm.


I have a plan for an old Puffer in MBoats (cardboard hull over deal formers) - it has a sorta smoker using (I seem to remember) smouldering cotton wool soaked in baby oil or similar (!)


But it has a home-made vane fan which could easily be replaced by a recip with a big piston and variable speed


Having said all that the mag in question is in a repository, quite safe: so not easily accessible :((


not difficult to make a large piston air puffer - its not a compressor - just a pusher;  so the piston seal could be nothing or a layer of foam plastic on to of whatever the piston turned out to be.
I would probably use a sharpened tin can to cut a chunk of thick PP foam and call that the piston! 
The tin would be the cylinder
[Carruthers!  DON"T use a corrugated tin for the cylinder!]


drawing-pin valve on the piston for air admission, maybe no valve at all or a shuttle valve (again foam) in the delivery pipe
I'm a great believer in trying ideas for free, if possible


Sketch possible, but not till tomorrow (Aus time) as I know the internet is not working at home.  I'm thinking big tin, big flexi pipe for delivery, short stroke using eccentric and spring return.  variable speed drive for the rate-of-puff


worth a try,
andrew



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ballastanksian

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Re: making a smoke unit pulse
« Reply #29 on: November 29, 2016, 09:11:52 AM »

But for the inherant dangers of excess heat getting to parts of your model that you don't want melted, maybe using parts of a hot air gun would create the hot exhaust gas effect?

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Arrow5

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Re: making a smoke unit pulse
« Reply #30 on: November 29, 2016, 04:33:00 PM »

Slightly more of an engineering exercise but would the crankcase of a model aircraft 10cc glowplug engine with piston and crank, con rod etc be the basis for a puffing device ?   Smoke in carb (might need bored out bigger) and out plughole , exhaust port blanked-off, or vice versa.  Electric drive on prop-shaft. Longer life than foam piston in a can %)  Just brainstorming :embarrassed:  Bigger boats could use a stripped strimmer motor 20cc.     Now I come to think on it, a rich running complete two-stroke diesel or glow motor running at idle speed might be the answer, complete with a tank of appropriate smokey fuel,  water-cooled engines exist to keep thing cool.
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g6swj

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Re: making a smoke unit pulse
« Reply #31 on: November 29, 2016, 10:20:54 PM »

If you use a PC fan to force vapour out of "smoke generator" - it is very simple and cheap to "modulate" the speed of the PC fan.

The level of modulation I am suggesting allows you to individually effect control* of these parameters: (*there are some issues as for example without braking you can't bring the fan to an immediate stop)
  •     A - time taken for the fan to reach full speed
  •     B - time at full speed
  •     C - time taken to reduce speed
  •     D - time at low speed or stopped (not stopping the fan may be beneficial?)
If you liken this to playing with the stick on a RC system controlling the throttle channel of a motor - if you blip the stick up quickly you get an immediate burst of acceleration, if move the stick up slowly you get a smooth acceleration.

I guess that playing with the 4 parameters A,B,C & D you can perhaps "shape" your puff of smoke!

I don't have a smoke machine so can't test this but I would be interested if anybody thinks there is any mileage in this possible solution.

Regards
Jonathan
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g6swj

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Re: making a smoke unit pulse
« Reply #32 on: November 30, 2016, 10:46:47 AM »

Example of PC fan control - timings are for demonstration purposes only

https://youtu.be/ec2Lpmfsvz0

Regards
Jonathan
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NoNuFink

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Martin [Admin]

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Re: making a smoke unit pulse
« Reply #34 on: November 30, 2016, 02:31:55 PM »


Well found / remembered NoNuFink !
   :-))
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Big Ada

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Re: making a smoke unit pulse
« Reply #35 on: November 30, 2016, 04:51:47 PM »

If anyone can come up with a simple solution Krishna can.

Len.
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