Model Boat Mayhem

Technical, Techniques, Hints, and Tips => Other Technical Questions... => Topic started by: tonyH on May 17, 2006, 01:01:21 PM

Title: Gunfire smoke
Post by: tonyH on May 17, 2006, 01:01:21 PM
Now that the pyro route has well and truly been hammered out elsewhere, has anyone got a solution for gunfire smoke.
The bang, flash and recoil can be done electronically but smokeless propellant wasn't around when Victoria was a girl.
Any ideas pleeze?
Title: Re: Gunfire smoke
Post by: Colin Bishop on May 17, 2006, 01:54:07 PM
I tried talcum powder once...
Title: Re: Gunfire smoke
Post by: gary r uk on May 17, 2006, 01:56:31 PM
Hello
go over to modelwarshipsunderway
go to how to and look for geoff dixon
hth
cheers
gary rowe
BPMBC
Title: Re: Gunfire smoke
Post by: White Ensign on May 17, 2006, 02:18:22 PM
Gary, we have had a similar problem. The solution was ashes, which will be blown out by an pneumatic system which just opens via an electrial controled valve (opening time 0,7 seconds). The pressure will be kept in a piece of a tube from a bycicle, which can be filled by a standard pump. The ashes had been inserted with a small syringe.
But it was always a bad job to clean the decks after the "shots". Unfortunately the model was sold three years ago and no photographs had been made. But it looked very realistic.

Hope this was out of any help for you.
Happy modeling, J?rg
Title: Re: Gunfire smoke
Post by: johno 52-11 on May 17, 2006, 02:44:01 PM
Could you use one of the new smoke generators from jjc into a manifold and then use valves on a number of outlets to allow it to each gun or set of guns at a time.
Title: Re: Gunfire smoke
Post by: tonyH on May 17, 2006, 03:41:38 PM
Hello all,
Thanks for the ideas so-far. The glycol route seems the cleanest but the problem seems to be control i.e. waste smoke between shots, since the time between firings of a gunboat could be 60 secs or so and there's only one gun. The only thing I can think of is controlling the fluid rather than the smoke but this means a pre-heated generator and since the bloody boat is gas fired steam - AAAAAAAARRRRRGGGHHHH!!!
Title: Re: Gunfire smoke
Post by: johno 52-11 on May 17, 2006, 04:06:22 PM
Tony

The new JJC systen runs on water so there is no heat. take a look here http://www.modelboatmayhem.co.uk/Common/JJC_Smoke.htm

John
Title: Re: Gunfire smoke
Post by: tonyH on May 17, 2006, 06:34:44 PM
Hi John,

I see your point but I need to sort out whether it will produce a single puff on demand or whether there is a warm-up time. Have you seen/used one or have any of the others out there used one?

Tony
Title: Re: Gunfire smoke
Post by: Colin H on May 17, 2006, 10:26:05 PM
Tony is the gun barrel metal and will a single puff of smoke do.


Yours Colin H.
Title: Re: Gunfire smoke
Post by: tonyH on May 18, 2006, 09:06:15 AM
Hello there Colin,

Yes the barrel is 'stepped' thicknesses of brass tube with a breech i/d of 20mm down to a muzzle i/d of 8mm over a length of 250mm approx. Tubes are soft soldered together and trunnions are silver soldered on. Recoil is by servo on a 'Y' lead.
I was hoping for 4 or 5 'shots' with, say, 30 sec 'reload' gaps, hence the single puff control.

What have you in mind?

Regards

Tony
Title: Re: Gunfire smoke
Post by: Dave Leishman on May 18, 2006, 12:18:29 PM
What about using 'caps' like we used to use in toy guns?

I remember as a kid we used to load a paper roll into a toy gun and as it was fired there would be a small pop, a whisp of smoke and a 'gunpowder' smell.

I seem to recall that these paper rolls evolved into small plastic ones arranged in a circle and worked the same way, although they seemed to be a little more noisy, smokey and smelly!

I'm sure it would be possible to provide a hammer action using something like a sail winch servo (for the torque) to pull a hammer back and strike a 'cap'.

I'm not even sure if these 'caps' are still available in this day and age, but if so they've probably evolved again by now.
Title: Re: Gunfire smoke
Post by: Daryl on May 18, 2006, 12:51:25 PM
Interesting idea about the caps. Come to think of it I havn't seen them since I was a boy decades ago.

Daryl
Title: Re: Gunfire smoke
Post by: johno 52-11 on May 18, 2006, 01:10:16 PM
Hi Tony

The new JJC smoke system is actually a device that generates a mist from water so the unit has a very quick startup time and there is no heat. There is s a thread on here of it being used with twin funnels "JJC Old Smokey - Converted for twin funnels" it has a video of the output. its output is controlled by a fan. As you are using a servo for the recoil could use it to also control a valve to let the smoke into the barrel or use the movement of the barrel to open a valve.

You could always contact Jim at jjc-electronics.com and see if he thinks it would work.

Regards

John
Title: Re: Gunfire smoke
Post by: RickF on May 18, 2006, 01:36:41 PM
I've seen the "Cap Gun" idea in a book on radio control I borrowed a few months ago from the local library - can't remember which book, though. Might be John Cundel or Vic Smeed?

Title: Re: Gunfire smoke
Post by: tonyH on May 18, 2006, 02:56:40 PM
Thanks for all the further ideas. I actually tried caps some time ago when I was going to build an M class monitor, but there turned out to be too little smoke for a decent effect and the 'bang' was too sharp for a big gun. Limited to 6 shots, of course but twas fun trying and annoyed the dog!
I'll call JJC to see if it would work but I'm going to have a go dropping measured amounts of glycerol on a heated plate this weekend. The theory is that it should be easier to control a fluid rather than the smoke. I'll report back!

Thanks again for all your help

Tony
Title: Re: Gunfire smoke
Post by: Colin H on May 18, 2006, 10:18:40 PM
Hi Tony,


My idea would not work to produce multiple shot & I think some of the ideas already mentioned by the other chaps are better any way.

Good luck Colin H.
Title: Re: Gunfire smoke
Post by: White Ensign on May 19, 2006, 08:35:23 AM
Unfortunately the Cap-pistol just makes no "Bang" which matches to a big-gun ...., sound too much "toy-like"......

I remember that cap-pistols from my early childhood.......... about 35 or 40 years ago. Godness me, where has all the time gone....  :o
Title: Re: Gunfire smoke
Post by: sweeper on May 19, 2006, 11:50:16 AM
Out of curiosity, has anyone considered having a look at the gear that the large scale tank people use? They appear to be able to produce the required bangs and smoke.
Just a thought!
Title: Re: Gunfire smoke
Post by: flag-d on May 19, 2006, 11:10:53 PM
Too many years ago to think about comfortably, I remember setting up battles with 1/32 scale plastic soldiers and various Dinky(TM) type artillery pieces.  I can't remember how I came by the method, but I would pull a dozen or so caps off the old roll types (not sure if you can still get them) and push them into a straw, the waxed paper type.  Push the straw up the barrel and light the free end.  The straw burned very slowly and produced a thick, whitish yellow smoke which would spurt out of the end of the barrel (and some from the breech too ) every time one of the caps burned.  There was no real bang, but the smoke looked good, especially as it continued to curl out of the muzzle after the 'shot'.  I know you can get the plastic type caps still (try joke shops and fancy dress places), though I expect the straws are long gone now.  Perhaps you could just wax impregnate any old paper and roll it up.  Light the end and use a sail winch to pull back the 'hammer' which could also provide the 'spurt' of smoke out of the muzzle.  Just a few thoughts...

Mike
Title: Re: Gunfire smoke
Post by: Jonty on May 20, 2006, 09:51:41 PM
You're not alone, Flag D, in distant memories of playtime. I had a large Sherman tank, Triang I think, where you filled the gun barrel with talcum powder and it fired repeatedly. I think a hammer or something similar struck a diaphragm every ten seconds or so, and a puff of powder shot out of the muzzle. Happy pre-electronics days...

Jonty
Title: Re: Gunfire smoke
Post by: tonyH on May 21, 2006, 06:49:03 PM
Update 1.

A. Glycerol on filament - gentle 'dribble' of smoke. Not awe inspiring. MarkII version to be tried later in the week.
B. Maplins Smoke Aerosol - amost empty can but reasonable plume, just takes up a lot of space. Might work though.
C. Steam Generator (I'd forgotten that the boat had a boiler on board) - fed steam though capillary tube into small container of glycerol with funnel. Fair plume once heated up but I presume that it would be quicker when fed from the boiler at 40psi!
D. VERY small amount of black powder from a 'banger' sold without limitations in a toy shop in France (For comparison purposes only, of course). Lovely, as you might guess.

This leads me to two points which are 1. When does a cap become pyrotechnics, because the large tank boys use flash cotton for their toys and 2. Why are we so SAFE!

Tony H

Title: Re: Gunfire smoke
Post by: aston on May 21, 2006, 11:48:55 PM
when I first saw the JJC units demonstrated, one of the control circuits he was looking at making was for gunfire effect.  As has been mentioned, as there is no heat, the mist is instant, formed inside a tank, and blown out the exhaust etc by a fan.  It doesn't build up its own pressure so will just sit in the holding tank until pushed out. he was looking at a circuit to creat the bang, and "blip" the fan to give a puff of "smoke" at the same time.  Shouldn't be too hard to have the smoke generator running all the time and just flip the fan on and off with a servo.  Problems arise if you have several barrels involved.  Pipework isn't an issue as it has no heat involved but you would need to have valves to redirect the airflow carrying the smoke.

Aston
Title: Re: Gunfire smoke
Post by: tonyH on May 22, 2006, 03:54:53 PM
Thanks for the note Aston, I sent an e-mail off to JJC yesterday since it would, if it works, be the answer. Luckily its a single gun and it may just be a case of enough puff. The daft thing is that I have to use another fan at the other end of the boat to draw air through the hull for the steam plant i.e. the smoke generator will be in a partial vacuum!

Tony H
Title: Re: Gunfire smoke
Post by: flag-d on May 22, 2006, 11:00:46 PM
Hey Jonty, that brings back memories!  I had a US Long Tom (I think they were called) 155mm Howitzer and got into all sorts of trouble using up my poor Mum's talcum powder in my battles (mind you, very sweet smelling battle field!)

Mike
Title: Re: Gunfire smoke
Post by: Jim C on May 23, 2006, 09:24:43 AM
I'ts in prototype mode at the moment (sorry it's being tested in one of my boats) and can be linked to the gunfire sound module, via a predictive , adjustable timer on the board, it can accomodate different sizes of gun and lengths of tube. As the smoke is instant, all you have to think about is the length of the piping and the time it takes for the smoke to travel down it.

Once I have time (dam day job getting in the way again !) I'll post a bit of video of the prototype.

regards

Jim
Title: Re: Gunfire smoke
Post by: tonyH on May 23, 2006, 10:13:15 AM
Thanks Jim,

Obviously leads to questions such as - How Big? and what diameter is the outlet (so I could pre-plumb). I presume that it would also allow connection to a micro servo for recoil?

Time, fortunately, would not be an issue as long as I could get an idea whether it wouldl fit.

Regards

Tony
Title: Re: Gunfire smoke
Post by: Daryl on May 23, 2006, 12:49:14 PM
Hi jim,
Will you soon have any details like cost, likly use in multiple barrels, estimated date for when you can sell some etc.

Thanks
Daryl
Title: Re: Gunfire smoke
Post by: Jim C on May 26, 2006, 06:17:44 PM
working on productionising (real word?) it at the moment, so will post in the traders section when ready, I'm planning to demo it at the Bury Warship day in July