Flames have trouble propagating up fuel core

[NeighborJ]

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".

[Baldor]

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.

[NeighborJ]

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

[MinamotoKobayashi]

Usually I use Talon ignitors:

 

 

for the rockets with fuse, or the electric matches:

 

http://www.pyrogarage.pl/img/fuse/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 April 21, 2018 by MinamotoKobayashi

[JMan]

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.net/ignitors/fusepaper/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.

[Arthur]

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.

[Baldor]

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 April 22, 2018 by Baldor

[Arthur]

Paper soaked in KNO₃ is 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.

[JMan]

Heres his video:

 

https://m.youtube.com/watch?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.

[Arthur]

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.

[JMan]

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 April 23, 2018 by JMan

[MinamotoKobayashi]

Here is the nice launch of my 1.5KG core burner r-candy nozzleless rocket mentioned in my first post.

The two long sticks glued in the opposite sides of the walls allowed a very stable and linear launch.

For unknown reasons the 5" shell attached on the top did not ignite and was lost in the middle of a big field .. very frustrating to have wasted a lot of working hours for nothing

 

https://www.youtube.com/watch?v=Gm-kahluvtQ

Edited April 27, 2018 by MinamotoKobayashi

[stix]

With all due respect, Minamoto - perhaps best left to discuss in your own thread?

[stix]

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.

 

I guess what Arthur is saying is that "top fusing" would be the ultimate method to ensure that the fuel core is lit reasonably evenly without any hindrance of the fuse getting stuck in the core, therefore negating un-even ignition as the reason for a failure. My view is that in small motors, it's best to use an electronic igniter.

 

Just make a good, thin electronic fuse and shove it in - all the way up. This is where "electronic fuses" have the advantage and therefore no need to wonder if the core was "prematurely" lit via a somewhat dodgy fast-paper/bp fuse.

 

.

[Arthur]

A number of rockets have igniters less than 2mm dia. Add some length with 20 gauge enamelled wire and some very tidy soldering and you have a efficient small ig that can be pushed into a small bore.

 

Make a through hole and insert the igniter from the top, seal with fuel mix and possibly clay. neatly trim the igniter wires to follow the stick to the bottom and find a suitable connector.

[MinamotoKobayashi]

Sorry Styx, I promised to post the launch of my big rocket, as mentioned in my first post in this thread.

It was an user of this forum to suggest me to post my r-candy experiences in this thread ..

[stix]

No need to be sorry Minamoto - I was just getting confused to what the point was.

 

I wonder how JMan has progressed? It would be good to know.

 

Cheers

Edited May 22, 2018 by stix