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Flames have trouble propagating up fuel core


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#21 JMan

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Posted 21 April 2018 - 09:13 AM

Ive found some material by jimmy yawn about using flash paper (paper or paper towel soaked in kno3). I dont know what percentage of kno3 to water was used so Im going to do some testing on that and Im sure I can roll a small tube to stick up a core to help it ignite.

Also looking into stixs sugestion if using cat 5 wires for an extra small e match.

#22 stix

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Posted 21 April 2018 - 10:24 AM

cat 5 wires are excellent for the job. If you know someone who has some old ethernet cables - then grab them. For the igniter wire, very thin nichrome, or very thin copper wire from an old transformer?

 

The ignitor wire I use came about by pure accident. It's used as a take-up real (corona wire) in a digital printing press. It's gold coated tungsten wire about the thickness of thin human hair. Nichrome wire is a poor cousin to this stuff.

 

Tungsten Bobbin

 

It needs not much voltage to glow white hot - amazing!, and I stumbled across it by pure accident. The roll above would hold around 100 meters I think. I've got 2 rolls, and at this point I have an unlimited supply.

 

So, If you (or anyone else) is interested in this wire, then PM me and I'll post off 10 or so meters of it. It's very thin, strong, and therefore hard to work with, but doable. I'm sitting on a gold mine of the stuff and it's superb for small delicate pyro igniters.

 

Cheers.


Edited by stix, 21 April 2018 - 10:28 AM.

I just start the conversation - someone else has to question them.


#23 Baldor

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Posted 21 April 2018 - 10:25 AM

Hummm... Flash paper is not paper soaked in KNO3. It is nitrocellulose paper. Actually,  paper soaked in KNO3 burns very slowly. But you can try paper soaked in KNO3 + sugar. Make a dilution of a little bit of your propellant in boiling water, soak some paper, let it dry  and try it, it's a cheap match.



#24 NeighborJ

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Posted 21 April 2018 - 12:27 PM


Here's what I've been tinkering with for use as a rocket ignitor.
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#25 Baldor

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Posted 21 April 2018 - 12:53 PM

Would´t the pirogen composition act as an insulator and negate the spark? This is just an spark plug, and spark plugs doesn't perform when dirty.



#26 NeighborJ

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Posted 21 April 2018 - 01:00 PM

I suppose it should get some more description. I don't plan on using any pyrogen or thermitic prime. Bare wires only.
Its 400,000 volts, there aren't many insulating materials which can insulate against that. If the bare ends are too far apart then it will break down the insulation somewhere else. Too far apart is a distance of about 3".

#27 Baldor

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Posted 21 April 2018 - 02:19 PM

This made me start thinking about a Tesla coil rocket launcher... Double awesome, Tesla and rockets!! :-)

 

On a more serious note, I'm also thinking about industrial kitchens piezo igniters. Must see if I have some in the scrap pile at work and test them. I thing the sparks will be too weak, but worth a try.



#28 NeighborJ

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Posted 21 April 2018 - 02:48 PM

The sparks can be intensified by using a saltwater capacitor. That's what I use for my Tesla coils.

#29 MinamotoKobayashi

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Posted 21 April 2018 - 02:57 PM

Usually I use Talon ignitors:

 

s-l1600.jpg

 

for the rockets with fuse, or the electric matches:

 

1mematch.JPG

 

to ignite directly the core of my rockets.

The second choice is much better, faster, lighter, and, more or less, with the same price of the Talon ignitors.

Also it requires less current, so are suitable for a wide variety of power units.


Edited by MinamotoKobayashi, 21 April 2018 - 02:57 PM.


#30 JMan

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Posted 21 April 2018 - 10:23 PM

Stix, Im messing around with some...well free stuff first. If it seems to be best/cheapest (most value).

Baldor I totally forgot flash paper was a term for something else but I do remember jimmy yawn referring to this as something along a flash tube.

This is his page:
http://www.jamesyawn...aper/index.html

And I remember now he released a few videos on how to make a basic sugar rocket and that is where I heard him refer to it as flash paper. I do thank you on correcting me for anyone who may read this in the future baldor.

#31 Arthur

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Posted 22 April 2018 - 12:17 AM

A short length of genuine flash string would help propagate the flame along the core quickly. 

A special igniter made from 24 or 26 gauge enamel covered wire, would go a long way down the core, but be fragile.

 

I'm cautious of high voltage systems because rockets are usually fired outdoors and the effect of 1000v on a human in the dampness of a typical field is catastrophic. If you feel the need for HV ignition then you should be very aware of the risks and and how to control them.



#32 Baldor

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Posted 22 April 2018 - 01:02 AM

No need to thanks, Jman, everybody have lapses of memory. Have you tried the fuse paper you described? I just tried to burn some cotton tread soaked in a saturated KNO3 solution and it burns worst than the tread alone. Maybe with paper it is different? What worked in the past for me was cotton impregnate in KNO3 + sugar.

 

EDIT: I just got out and wrapped the thread in paper. The confinement helps, and it burned slowly, so maybe rolled paper will self confine. Still, very slow to ignite the core of a rocket. As seen in your link, and at the top of the core, maybe could release enough hot gas to ignite the entire core fast.


Edited by Baldor, 22 April 2018 - 01:14 AM.


#33 Arthur

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Posted 22 April 2018 - 04:29 AM

Paper soaked in KNOis slow match or touch paper. Brits used it as delay fuse before regulations tightened up and needed the speed consistency if visco.

 

Flash paper (or flash string) is moderately nitrated paper or cotton string and is faster than QM. It's available wet in sealed pouches from SFX suppliers and magician's supplies shops. It's also available from China by air in a wide variety of speeds, I can't see it being legally shipped though.



#34 JMan

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Posted 22 April 2018 - 10:26 AM

Heres his video:

https://m.youtube.co...h?v=Sri5kTnFLmA

He actually always refers to it as fuse paper, my mistake. But you can see this stuff can burn quite quickly. I think it might be because it lights the inside of the tube and throws flames outwards (unlike lighting the end and throwing the flame the opposite way it needs to travel) so it ignites almost all at once.

Doing a little mixing of stix and the fuse paper today Ill get back to you all.

#35 Arthur

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Posted 22 April 2018 - 11:58 AM

Can you develop a top fusing method for you motors where the igniter is not through the nozzle but manufactured into the grain from the closed end.



#36 JMan

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Posted 22 April 2018 - 06:36 PM

Interesting idea. Id have no clue how to do that other than wire and epoxy. With a metal top Id rather not try along with the whacky aerodynamics of two wires sticking out the top.

Honestly I thought of using a fiber optics cable and point a laser through it...might actually work but an interesting idea.

My tests today provided a very conclusive result: bigger rocket. I ordered an 22mm Cassini rocket case so I can have a bigger core and igniter and what not. Thanks for the ideas though everyone.

EDIT: new case also allowles for a washer to be used for a nozzle so no need for super long and thin rockets.

Edited by JMan, 22 April 2018 - 06:38 PM.





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