Roman Candle Construction and Delay

[Steigede]

Does anyone have any links to a good roman candle construction guide and/or a good delay composition? I'm only finding the skylighter page.

[Steigede]

I tried the skylighter delay composition and couldn't get it to light. Had to add more KNO3.

[kingkama]

Well delay composition can be a 60 30 10 but made up from ingredients worked in a blender, then sifted together, bigger particles slower powder,

[Steigede]

Yeah that sounds real close what I ended up using but a little less sulfur.

[Mumbles]

Many delay comps will have something like coarse charcoal or metal in them so there's something interesting happening between shots.

 

Some of the better roman candle guides are in books. Degn's Westech Fireworks Manual has a good procedure if I recall. Something like Weingart's Pyrotechnics or Lancaster's Fireworks Principles and Practice also probably have good coverage.

 

I'll see if I can dig it up, but there is an interesting different method some people have used to create roman candles more recently. Effectively each shot is created in a stand alone tube, which are then joined together, and pasted, taped or placed into a larger tube together for the final device.

[Arthur]

Big candles in the UK tend to be delayed by the use of a felt plug with a length of time fuse through the middle, then only fast powder is needed

[davidh]

This is a decent project page. http://www.brianredmond.net/dwilliams/romancan/romancan.html

[kingkama]

A simple roman candle is made up in a hand rolled 1.5 cm paper tube, 4mm wall thickness pressed comet of 1.2 cm the tube can be long as you can manage easily (ie 60 cm). Ram some clay at bottom (3-5 cm) then add 2 gram of fast bp then the comet, on top 5/7 grams of delay comp not granulated ram gently untill compacted, more compacted more delay, but attention to not use too much force or stars can ignite, then star again bp, comet, delay, bp, comet, delay and so on. This is a errors and correctiin process, cause anyone has different ingredients e charcoal so difderent results. Edited July 18, 2020 by kingkama

[Steigede]

A simple roman candle is made up in a hand rolled 1.5 cm paper tube, 4mm wall thickness pressed comet of 1.2 cm the tube can be long as you can manage easily (ie 60 cm). Ram some clay at bottom (3-5 cm) then add 2 gram of fast bp then the comet, on top 5/7 grams of delay comp not granulated ram gently untill compacted, more compacted more delay, but attention to not use too much force or stars can ignite, then star again bp, comet, delay, bp, comet, delay and so on. This is a errors and correctiin process, cause anyone has different ingredients e charcoal so difderent results.

Yeah I wung it and essentially did this yesterday. I plan to light it tonight and see how it works. If it comes out well I'll post instructions.

[Steigede]

Did a quick test last night. I tried my hand at hand rolling some tubes. I started with some butcher paper, a 3/8" dowel, some wood glue diluted with water, and a paint brush. I cut 2 feet of butcher paper and then split it in half lengthwise.

 

I placed the paper down, brushed on some diluted wood glue, and started rolling.

First tube I rolled was awful and promptly put into the garbage. The second was passable after I did some trimming.

 

Ended up making 4 tubes total. They came out each a little different length due to rolling accuracy.

 

I 3D designed and printed some spike stands. The tolerances were pretty loose so I used two drops of super glue to secure the tube in the base. The tips were a bit melted because the hot end of the printer is working in a small area with very little filament being extruded. Not that big of a deal. Stuck in the ground perfectly. Rough estimate on cost is about $0.15 a spike. As long as you don't put too much super glue in there, I think you should be able to pull the spent tube out and reuse the spike since the tube and clay insulate the spike from any heat.

I then poured in a small amount of powdered clay cat litter and rammed it solid with a second 3/8 inch dowel that I sanded down to reduce the diameter a bit. I 3D designed a small scoop to load the roman candles and printed out a couple. One for the delay and one for the lift.

 

I alternated 1 scoop of black powder, one star, and two scoops of delay. Ended up with 6 or 7 shots I think but I lost count. This is the end result:

 

The first shot was an electric violet star, which I really like. It burned up fully, even though it was not shot very high. The green was a bit delayed and may need a thicker coat of prime. The third star was Independence red and it didn't ignite (definitely need to prime those stars more). The force of the black powder going off extinguished the layer of delay. The delay composition from skylighter was trash. It was essentially half and half KNO3 and charcoal with a tiny amount of sulfur and dextrin. I couldn't even light the original ratios and ended up tripling the KNO3. Even that did not keep it from being extinguished by the black powder lift charge for the red star.

 

I plan to re-do the test. I will add more sulfur to the delay (because if my memory serves me right, that helps with flammability)? Hopefully that stays lit. I'll also use two scoops of lift, two scoops of delay. Hopefully the extra lift will throw the initial stars a bit higher. Since the scale of my devices are so small, it's hard to use gram measurements for lift charged. The stars don't even show up on my scale that has a 0.1 gram sensitivity. We'll see what happens. Thanks for all the help and comments!

[SeaMonkey]

Steigede,

 

Your test result is encouraging in spite of the flameout!

 

Here's a Delay Comp formula which may work well.

[Steigede]

Steigede,

 

Your test result is encouraging in spite of the flameout!

 

Here's a Delay Comp formula which may work well.

Thank you! That's about what I ended up with after messing around with the original formula! I'll write that one down in my notebook for the future!

[Steigede]

More progress. Think I have it down. First one had a few un-primed stars. Second one I used some electric violet stars that I knew were easy to light. They look a bit red on the camera but they're a really cool neon purple in person. I was actually able to just repack the spent tube for the second fire.

[kingkama]

Cool result, but BP is slow or granulated too big,seeing scoop you used you have had heard a sharp shot, not pouf.

[Mumbles]

One hint I was given when I was looking into these is to use proportionally more lift on the first few shots. The smaller amount of tube leads to the first few shots being underlifted, or the last few being shot to the moon.

[Steigede]

Cool result, but BP is slow or granulated too big,seeing scoop you used you have had heard a sharp shot, not pouf.

The scoop's volume is is about the size of a star. The tube is also bigger than the star and there's quite a bit of room around it. Does it matter if I don't get a sharp shot? I'd rather have a pouf than a sharp shot. My neighbors and their dogs would probably agree

 

One hint I was given when I was looking into these is to use proportionally more lift on the first few shots. The smaller amount of tube leads to the first few shots being underlifted, or the last few being shot to the moon.

That's a good point! I do notice that. I'll give that a go on my next one.

[kingkama]

Sharp shot indicates that stars fly in air and not fall like gerbs sparks.

[Richtee]

Steigede,

 

Your test result is encouraging in spite of the flameout!

 

Here's a Delay Comp formula which may work well.

Hey... all I get is a blank page on this.. can ya post the formula here? I’m gonna do some small rockets... thanks!

[Steigede]

Hey... all I get is a blank page on this.. can ya post the formula here? I’m gonna do some small rockets... thanks!

Yeah it looks like the page is down for me as well. I'm not sure what the formula was unfortunately.

[dynomike1]

I use Tiger tail in rockets for a delay between bp and whistle or report

Edited January 18, 2022 by dynomike1

[dynomike1]

Here's a better one

[Richtee]

I use Tiger tail in rockets for a delay between bp and whistle or report

YA know..I was f’ing around with BP and hardwood sawdust- about 20-25% dust. Rammed it into a tube. Works pretty good actually. And lots of pretty sparks