Pyro Cake?

[jexjexjex]

I will start by saying that I know very little about pyros, but...

 

...I've been asked by a local group to make enquires about something they're calling a Pyro Cake.

 

What they're describing is a small item, a bit bigger than a drafts piece, that is placed in a bucket of sand and lit with a match/lighter.

 

The "effect" that they're looking for is akin to a ships distress flare, but with less smoke, and maybe not quite as bright, as they want to place one on either side of a small stage area outdoors.

 

They want the effect to last for about 10-12 mins.

 

I'm trying to distance myself from this (literally!) but if anyone can give me any pointers as to whether this type of item exists, is legal, sfe, etc., I'll pass it on.

 

That way, I've done my bit and they can get on with it.

[Brian]

Not something I've ever come across. 12-14 mins is an awfully long time for something that small to burn. Even something slow burning like a smoke pellet would only last less than a minute at that size.

 

If they don't want smoke, and don't want it too bright why not use something like a 12v 50W capsule halogen lamp of the type fitted into smaller projectors (A1/220).

 

[EDIT]

Just to add to this, in the firework world a 'cake' is a load of separate devices, made into a single block (cake shaped) and lit by a single fuse.

[andy_s]

I've just used the smoke pellets sold by flints, which sort of fit the description you give, and although they do exactly what they say on the tin, I would hesitate to recommend them. They make very dense smoke, they don't last very long (less than a minute) they produce highly noxious fumes which you are recommended not to inhale, and they were quite tricky to light (ignite, that is, rather than shining a source 4 at it!). For the smoking goblet effect we wanted, we ended up using a smoke generator sold by model shops for adding realism to your model railway. This might be a bit "whispy" for your purposes.Le maitre smoke cartridges come with different burn times, but again produce very dense smoke that is difficult to get rid of when used indoors. 14 minutes worth of smoke is a whole burning building's worth - I've seen tech rehearsals come to grinding halt for half an hour while we tried to clear the auditorium of 1 minute's worth of lemaitre smoke cartridge. I've not seen flare-type pyros that produce light and smoke for the duration you require, but perhaps contact lemaitre for their advice. I also have a vague recollection of a thread either here or on the ABTT forum talking about using "real" hand-held flares on stage - might be worth a search.

[andy_s]

just read your post again jex - missed the "outdoors" bit - of course this does solve any room clearing issues, but leaves you at the mercy of the wind , which will be invariably either too much in the wrong direction or not enough. I would think if you could hide smoke machines and a light source in the buckets, you've got control over the amount of smoke produced and providing the operator can see, you could use the density control to regulate the actual amount hanging around while still making it look like a continuous stream of smoke.

[Brian]

I also have a vague recollection of a thread either here or on the ABTT forum talking about using "real" hand-held flares on stage - might be worth a search.

You can certainly get hand-held flares which burn a gel type fuel. Don't know about 12-14 minutes. I know Lincoln at JustFX has got some. You could always PM him if he doesn't pop up here.

 

Trouble is, they look nothing like a ship's distress flare.

[wilf]

The type of thing you are looking for is called a Bengal Flare.

not to sure about 15 mins maybe 5.

[Jivemaster]

15 mins is a long time for any pyro. and the firewirk term cake means an assembly, premade in a licensed factory, of lots of devices all on a single fuse.

These are usually cat3 and can have a 25 metre safety distance!!!

 

NO pyro the size of a draughts piece will last for 15 mins.

even pyros of the same batch will burn for slightly different times light two and one always outlasts the other - makes for odd cueing!!

 

can the effect be created without pyro, What is the actual requirement.

[the kid]

I am just wondering essentally its a cake of black powder. Why not ask a fireworks company about it because im sure that they can point you in the right direction.

[Brian]

I am just wondering essentally its a cake of black powder.

Problem is that the slowest that compressed black powder will burn is in the order of 15mm/sec.

 

So for a 14 minute burn you'd need a cake of blackpowder 12.6m thick <_<

 

[EDIT]

 

I offer you today's interesting, but mostly useless, equation for the burn rate of black powder.

http://www.aux99.co.uk/blue-room/blackpowder.jpg

Where RB is the burn rate in mm/sec and p is the ambient pressure in psi.

[lonfire]

hi,

I run a firework company and the only thing I can think of that might do the trick is a bengal flare as stated above.. nasty smoke off them though.. companies like kimbolton do some stuff and wells pyrotechnics also..

 

you may be able to find a low smoke flare or something like that..

 

rgds

chris

[jexjexjex]

Hi all

 

Thanks for the information.

 

I've passed it on and will now retire to a safe distance whilst the group in question spontaeously combusts <_< .

[Jivemaster]

Thinking laterally, could you fabricate the effect - not as pyro - using a bare tungsten halogen capsule lamp at the top of a say 50mm cylinder topped with flame coloured glass and perhaps blow a little smoke up the tube. -- A 12v 100w lamp is very intense and 12v is more friendly than big pyros.

As long as its electric we can find a control system. If its pyro theres only a go button you cant stop them.