633 replies to this topic

[al93535]

Is a strontium nitrate based star harder to light then barium nitrate, or copper oxide stars? I thought I had the perfect mix, but when I tried it again tonight the red one didn't light. All the other colors did. I did only use one thin coat of prime though. Here is my comp, anyone see any problems with it?
Strontium Nitrate 31
Potassium perchlorate 42
hexamine 11
saran resin 8
325 mesh al 2
airfloat charcoal 2
dextrin 4

My green star comp is almost identical, and it lights with ease!
I use a mix of milled BP, and green mix with 10% aluminum added for prime.
Any suggestions?

[Creepin_pyro]

I have no experience with Barium Nitrate, but Strontium Nitrate stars have proved relatively hard to light for me. I would suggest avoiding meal for priming, in favour of a hotter burning, Perchlorate prime. I can imagine these stars are hard to light as I can remember something about stars bound with Saran being harder to light, and Hexamine inhibiting ignition, but again I have no experience with these chemicals.

I would suggest something similar to Veline's prime. I haven't had any stars blown blind while using it. It seems to work fine with or without a dusting of green meal over the prime.

[Yugen-biki]

I don't think there is a big difference between Ba(NO3)2 and Sr(NO3)2 stars if very similar in composition. I would look for other factors first if it has worked before.

The hexamine and Al will make it harder to ignite. I have not tested the same star but one similar without the hexamine and Al. I have used Perc+C+dextrin prime with good results. I don't see why your prime shouldn't work.
First of all, I would have tested a thicker layer of prime (1-2mm). (And if I were useing a strong burst, maby I would have used something else). Another prime like Velines is an alternative.

Cu(II)O stars with perchlorate are very hard to ignite. Not as hard as a metal fueled star though. I have used perc+C+dextrin prime with blue stars of this kind without problems.
The prime you use is quite hot and should work. I have managed to light perc+KNO3+Al comets with a "green mix+Al prime" like yours (!).

Edited by Yugen-biki, 25 April 2005 - 04:01 PM.

[al93535]

I tried three layers and no ignition!! If I replace say, 50% of the hexamine in my above formula with airfloat charcoal, will that make it easier to ignite?
I don't have all the chems for the veline prime, so how does this sound?
Perchlorate 65
airfloat charcoal 26
325 spherical al 5
dextrin 4
Two layers of that with one layer of my original prime over that? I will test this out tonight if you guys think it sounds good.
Thanks again Creepin_pyro and Yugen-biki

Oh also, the red stars do ignite on the ground when not moving, does this mean anything?

Edited by al93535, 26 April 2005 - 09:10 AM.

[aapua]

I tried three layers and no ignition!! If I replace say, 50% of the hexamine in my above formula with airfloat charcoal, will that make it easier to ignite?
I don't have all the chems for the veline prime, so how does this sound?
Perchlorate 65
airfloat charcoal 26
325 spherical al 5
dextrin 4
Two layers of that with one layer of my original prime over that?

Well, here's actually another method to ignite smth with practically everything. It needs a bit more work but it helps and the ignition should be guaranteed. Take say 2-3 parts of your original star mixture (dry) and 1 part of primer. This would be a first layer. Then, say 1 part of star and 1 part of primer comp, and finally 1 part of star and say 2-3 parts of primer comp. The final layer should be pure primer. Depending on the differences of how much energy will give your primer and how much energy needs your star comp, using only 1:1 mixture of these 2 comps between star and primer layers may not be enough. So, you may even need more mixtures (like first 4:1, then 2:1, then 1:1, then 1:2, then 1:4, and pure primer).

[Yugen-biki]

The layer method is proven to work, but more elaborate to make.

If the star ignites on the ground, it tells us that the star is blown blind in the air, and the prime is not hot enough.
I would use closer to 10% Al in the prime. Maby a layer of prime with 5% Al on top of the 10% one to ensure ignition.


Or try the "layer combination": Make a 50:50 mix of your prime and star and prime the star with this (1-2mm). Then finish with a layer of the prime with out star in it (1-2mm).


By the way, how long do you let the stars dry? You have to let them dry in room temperature for at least a few weeks. This is the same if you use wate or alcohol or any combination of them both. This is very important! Any moisture inhibits both ignition and "color production" of the star.

[al93535]

I tried 50/50 prime/star comp, with a layer of pure prime on top already But I may try the 4:1 2:1 1: 1:2 1:4 prime method. Damn red star. Well these are 5/16" stars, they dry within 24 hours. Green and blue work fine after 24 hours. But I also thought maybe they were not dry, so I let the red ones sit for 4 days. The humidity is around 10% or less here. I think I will try the perchlorate prime as well, with more aluminum like you suggested. And then try the step method with it. If that doesn't work then either the formula needs to be re-done, or the strontium nitrate is not drying, or producing some other problem.
Thanks again,

[Yugen-biki]

Oh yes Sr(NO3)2 does not dry if you use water when you make stars!

5/16*25=8mm stars. Dry them for a week...

Maby you should try another recepie as the one found in "Best of AFN II" on page 66 named DEEP RED, by SC.
Very good star with similar inredients.

KClO3 (or KClO4) 6
SrNO3 6
Red gum 1
Stearine ,25
Dextrin ,5
C 2
PVC or Parlon ,25

The KClO3 can be replased but makes the star a bit harder to ignite nad the flame a lttle bit smaller I guess.
I used a perc+c+dextrin prime (2mm) with this one in a 3" shell with H3 and "flash booster" with 100% ignition!


This is a video of a crappy shell with the "DEEP RED" stars:
http://www.a0tu.com/...er/RedSrNO3.avi

[aapua]

Recently came out a question: how to make white or silver stars WITHOUT a tale. I guess somebody have done something, here I'm gonna give my solution.

Al powder 64
S 36

As a binder I used nitrocellulose, even as much as 25%.

So, my favourite mixture was:
Al - 48
S - 27
NC - 25

It burns very bright, quite slowly and gives like "glowing" effect when flying. Just it is pretty hard to ignite. I use hot prime (Ba(NO3)2 + Al + ...) and step priming. But looks pretty nice.

[Richard H]

I imagine antimony might come in useful. You are looking for a peony formula.

To reduce / remove a tail you want to ensure the components of the formula are consumed immediately in or surrounding the flame and do not continue to incandesce in the air. e.g. use a fine metal powder.

[paul]

... and no exess of metal powders...

[al93535]

Ok the perc and charcoal prime ignited the red star! Thanks guys!
One more question. I will be firing 4" shells, would a 3-second long burning star be good for them? Think they might hit the ground? Or should I only stick to 2 second burn time? What are your guys opinions?? I will be constructing my shells this week, and my dilema is to use 2 or 3 second long burning stars. I will make some 2 seconds to create a crysanthemum effect. But also I want to use the 3 second stars to make a drooping longer lasting effect as well. But I really don't/can't have the stars burning to the ground. The 4" shell will be timed to burst after 3 seconds rise time.
Please give me your opinions/ideas... Thanks!!!

aapua: Here is my tailless white star:
KNO3 57
sulfur 23
milled BP 20
Gives a nice white star that burn fairly rapidly.

[Yugen-biki]

The burn time of the stars and the duration of the time fuse does not really have a direct connection.
The lift chare has a greater impact. You can lift an identical shell with the same time fuse to different hights useing different lift charges.
The time fuse sets the time wich the shell trawels in the air and the lift charge how fast it will trawel.

Generally a star in a 4" shell is about 9mm, depending on what composition is used. In your case you have allready timed your stars, and they were in the size range suitable, as I understand it.

Conclution:
If you know you have a strong lift charge, use the 3 sec stars.
A week burst and a long time fuse will allow the shell to reach it?s apex, and then drop down again before bursting.
If you are unsure how strong the lift powder is, use 2 sec stars. You can allways change this in the future when you have got more experience. But a fire on the ground may result in land or property damage, and give you a negative experience.

(I use 35g of lift for my 4" with a time fuse of 1,5-2 sec depending on how high I would like it to trawel. I use stars in the range of 2-3 seconds with no problems, both peony and charcoal based.)

[al93535]

Thanks so much Yugen-biki! You have been alot of help.

[Yugen-biki]

Thanks! Your are wellcome.

Just be carefull!