17 replies to this topic

[cooperman435]

Im currently working on a project for a friends company which involves electrically firing an indoor gerb.

Restrictions are very clear on smoke and we are struggling largely because of the smoke emitted from the e-match rather than the gerb its self which is 99.9% smoke free.
There is also a secondary issue that if the e-match protrudes across the top of the tube it disrupts the very gentle flow of gasses out of the top and splits the fountain into two when lit, to cure this we intend to side mount the e-match and use something to pass the fire across the tubes surface.

This is where I come in. I'm experimenting using my pyrogen-less e-matches to ignite them without smoke, but as most of us may know the tip of the e-match glows for but a split second and this is proving less than reliable in igniting plain NC on its own

Has anyone any suggestions as to VERY low or non smoke producing comps I could try as a pyrogen and passfire to the top of the tube as there is no fuse but only flash paper across the top of the tube (as in tight across the tube not like touch paper which is loose and twisted)

Any suggestions or help are appreciated.

[CCH Concepts]

i do have a thought about the ignitor. i have been thinking of a way of having an wireless ignitor. if you have a small secondary coil attached to nichrome wire and a large primary coil wrapped around the tube.

if you have a 4:1 ratio at say 49vac @ 1amp to 12Vac @ 4amp. even with 50% losses this would be enough to ignite the nichrome. the advantage of this is it could be placed inside the gerb so it wont obstruct the nozzle.

there are ways of getting the losses very low by matching the reactance of the secondary coil to the frequency of the primary.

[dave]

phil,
if you are using flaspaper, i would guess that a small amount of flash cotton would ignite from the very quick/small glow from the nichrome on the e-match
(loosly press a bit around the e-match and extend some onto the flash paper)

any use ?

dave321

[Creepin_pyro]

Mabye try a 1.5v glo-plug from LeMaitre?

Works every time igniting flash cotton / string which will happily ignite the paper.

[RFD]

possibly reloading shotgun or rifle powders,can be dissolved in acetone,single,double or triple base powders have different levels of NC,different types also come in different mesh sizes,have used it as an igniter comp and its always worked.

[fruitfulsteve]

The igniters they use for 'Estelle' model rocket motors are fairly low smoke... and B.S tested !!!

[cooperman435]

Cch I'm not sure what you mean mate? I have igniters already but with my standard pyrogen it creates unnaceptable levels of smoke.....

The tops of the tubes as the pic shows are flush fitted paper and as sensative as flash paper is it still takes a little prompting to get it lit reliably, I can use tiny amounts of my standard pyrogen to act as an initiator but still see the need for an intermediary, smokeless comp to passfire. Ideally one that can be applied wet to the top of the e-match and the tube too to connect them properly

even esters igniters have smoke and a main issue will still be that it needs to be on the top of the tube which effects the output flame too much into a split jet.

[BrightStar]

Given that they're self-dip igniters, why not try just dipping the very tip in a minimum amount of Dark Flash pyrogen (only just enough to cover the 1mm bridge wire). Less pyrogen = less smoke!

Maybe glue this to some 'Flash Cord' (no smoke, no residue) with NC laquer and glue that to the touch paper for ignition.

IFIRC, stage smokeless gerbes usually have a hollow core all the way through with the igniter at the bottom, wired through the base.

Edited by BrightStar, 22 April 2010 - 07:37 PM.

[CCH Concepts]

copperman what did you think to my suggestion before about wireless igniter, that would solve you problem about being at the top of the tube?

check this out, its got some interesting possibilities

http://en.wikipedia....sonant_coupling

[parabolic]

Phill,

could you try this as pyrogen?

Smokeless flash powder
Source: "Mengen en Roeren"[6], page 224
Comments:
Preparation:

Zirconium.........................................28
Zirconium hydride.................................7
Magnesium.........................................7
Barium nitrate....................................30
Barium oxyde......................................25
Rice starch.......................................5

[dave]

phil,

keep it simple.
flash cotton will work great, and if you have to use a glo plug instead of an uncoated ignitor, no sweat.

it will work.

(also, far easier to buy flash cotton than make your own........stabilisers need to be added to improve shelf life)

dave321

[cooperman435]

Parabolic - wow that looks exotic! If anyone has any views on that comp then please be heard or can help source Zirconium, Zirconium hydride and Barium oxyde.

Dave - an igniter will happily and reliably ignite flash cotton but as I said before flash cotton wont ignite the gerb reliably. I have tried.

[CCH Concepts]

this is the basic idea, i small LCR resonator made of a small cap and inductor with a piece of nichrome acting as the resistor will work very efficiently. if its tuned the the frequency of the source coil it will be in the 90% region. idea being that the igniter could be like you self dip ons but with s SMT cap and a small coil and the whole thing dipped or maybe in the center of some flash cotton. this Way it can be on the base of the gerb and never obstruct the nozzle.

[cooperman435]

!

CCH sorry but your no where near the mark mate.

I have ignition and its reliable already so I dont need an igniter at all, your idea as abstract as it is doesnt cure my issue as flash cotton as I said before wont passfire to the gerb.

[BrightStar]

I suppose you could crush up a spare gerb and try the composition itself as a smokeless pyrogen. It would probably dissolve in acetone and you could add an extra pinch of Ti, MgAl or even Silicon if needed for some hotter sparks...