Amount of burst charge "booster"

[boule]

OK, very noobish problem.

I am just building my first 8in shell and I know that my burst charge is not as good as it should be - frankly said the BP on the rice hulls is just a small step better than green mix but I usually like how it ignites the stars just fine. Downside is of course that the break is somewhat weaker and for 4in ball shells, I just spike with 1.5g of nitrate flash if I want a stronger break.

 

Now for the fun part: This time I want the shell not to become a weeping willow but the stars should be really flying out there. I know that scaling up from 4in to 8in gives me somewhat more volume for the burst charge but I am still using the same stuff and doubt that it will break as hard as I want. Thus the question, how much flash boost to use in the 8" shell?

 

 

Before someone starts nosing around:

- Ralph's glitter cavity stars with Phiko KP blue for an outer layer

- Phiko KP blue for the pistil

- might put a tail on it but not sure

 

 

Thanks a lot for your input!

[dagabu]

I have made very few large shells but I certainly have read about the break used in larger shells like that and I don't recall the use of a booster, the shell itself provides the containment. Are we talking paper or plastic?

[boule]

Paper - wouldn't know where to get plastic hemis that size from and they would need to be pasted as well.

 

I've seen people at the club shoots using boosted break charges in 8in shells and in my eyes (and ears) performance was drastically improved. Otherwise I would just throw in the break charge as it is and be happy to start pasting,

[Mumbles]

I'm not a fan of the over broken look, but according to Ned if you dust the hulls with nitrate flash and just use what sticks it should get it really going. With the double petal, a little harder of a break certainly can't hurt. I have no idea what kind of weight you'd need unfortunately. As a totally rough guess, I'd say 7.5g-9g. An 8" shell has roughly 8x the volume of a 4". Taking the additional confinement into consideration, I multiplied your 4" weight by 5 or 6 or so.

[cogbarry]

Sorry if I'm barging in to this thread. I'm new to this forum and it seems I can't start a new post and can only reply? Anyhow, my question is related to this thread, I'm wondering if I am bursting my 3" shells too hard. Here is the original post I tried to make along with a link to the youtube vid.....

 

Hi all,

I'm a bit of a newby - started doing this last summer. The link below is a 3" shell filled with the red rubber stars from skylighter. Burst was BP coated hulls, the BP made from skylighters air float charcoal (commercial FFG is used for lift). Shell contructed from cardboard hemis and pasted with craft/paste until it fit the 3" gun well. I had read that bursting the shell in the center is not so critical for smaller shells but it seems that only half the stars in this shell lit and I wonder if this could be the problem. I used 1/4 chinese time fuse which does not reach the center of the shell. I plan to build my next shells with a passfire tube. Also, I added about .5 grams of flash booster. Could it be that I broke this shell too fast/hard and half the stars never saw fire? I plan to eleminate the booster for the next shells, it looks like the shell burst hard and I think round. Any comments would be appreciated.

 

http://www.youtube.c...h?v=2U8ef8sSQjI

 

I now have the ability to start a new topic and will move this over.

Edited April 7, 2011 by cogbarry

[dagabu]

Just by sound I can tell that they are not over broken. It looks like the prime is having a hard time lighting as there is a pretty long delay before we see color. The burst pattern looks circular so fire is getting to the whole shell. My guess is that there was a barrier that kept the break from igniting the shell or that it under-broke and spilled the stars out one side.

 

Add a full gram to the break or use a flash bag for a more central burst.

[BJV]

Sorry if I'm barging in to this thread. I'm new to this forum and it seems I can't start a new post and can only reply? Anyhow, my question is related to this thread, I'm wondering if I am bursting my 3" shells too hard. Here is the original post I tried to make along with a link to the youtube vid.....

 

Hi all,

I'm a bit of a newby - started doing this last summer. The link below is a 3" shell filled with the red rubber stars from skylighter. Burst was BP coated hulls, the BP made from skylighters air float charcoal (commercial FFG is used for lift). Shell contructed from cardboard hemis and pasted with craft/paste until it fit the 3" gun well. I had read that bursting the shell in the center is not so critical for smaller shells but it seems that only half the stars in this shell lit and I wonder if this could be the problem. I used 1/4 chinese time fuse which does not reach the center of the shell. I plan to build my next shells with a passfire tube. Also, I added about .5 grams of flash booster. Could it be that I broke this shell too fast/hard and half the stars never saw fire? I plan to eleminate the booster for the next shells, it looks like the shell burst hard and I think round. Any comments would be appreciated.

 

http://www.youtube.c...h?v=2U8ef8sSQjI

 

I now have the ability to start a new topic and will move this over.

For my 3" shell I use 5-1 hot bp on rice hulls with 5 grams of whistle mix as a booster.

How many pasted layers of craft paper did you use and what weight paper?

BJV

[cogbarry]

For my 3" shell I use 5-1 hot bp on rice hulls with 5 grams of whistle mix as a booster.

How many pasted layers of craft paper did you use and what weight paper?

BJV

 

Thanks for the response! Unfortunately, I'm not sure what the weight of the paper is. I bought it over a year ago from pyrodirect or another vendor. I would need to measure. I use the 3 strip method and keep pasting until the shell fits in the mortar without much room for blowby. My guess would be 7 or 8 layers. The shells are quite hard when I'm done. Did you watch the video? I use hot BP (ball milled, not just screened). I plan to make some of my own pine charcoal this weekend but I have been using skylighters charcoal which is made from hardwood. It's a bit slow when I granulate it and I don't trust it for lift. This is why I thought I should add the flash booster. However, I may have underestimated it. Seems the coated rice hulls are quite a bit faster than the granulated BP I made.

[cogbarry]

Thanks for the response! Unfortunately, I'm not sure what the weight of the paper is. I bought it over a year ago from pyrodirect or another vendor. I would need to measure. I use the 3 strip method and keep pasting until the shell fits in the mortar without much room for blowby. My guess would be 7 or 8 layers. The shells are quite hard when I'm done. Did you watch the video? I use hot BP (ball milled, not just screened). I plan to make some of my own pine charcoal this weekend but I have been using skylighters charcoal which is made from hardwood. It's a bit slow when I granulate it and I don't trust it for lift. This is why I thought I should add the flash booster. However, I may have underestimated it. Seems the coated rice hulls are quite a bit faster than the granulated BP I made.

 

Oh, and the ratio I have been using for coating the rice hulls is 7/1. However, not all of it sticks. I have been screening to remove the excess fine meal.

[cogbarry]

Just by sound I can tell that they are not over broken. It looks like the prime is having a hard time lighting as there is a pretty long delay before we see color. The burst pattern looks circular so fire is getting to the whole shell. My guess is that there was a barrier that kept the break from igniting the shell or that it under-broke and spilled the stars out one side.

 

Add a full gram to the break or use a flash bag for a more central burst.

 

Ah,

The opposite of what I thought. Thanks, I'll try that. One thought comes to mind when you say "barrier". One half of the shell had a layer of tissue paper to prevent spilling when I shut the two hemis together. Could this cause an issue?

[BJV]

Thanks for the response! Unfortunately, I'm not sure what the weight of the paper is. I bought it over a year ago from pyrodirect or another vendor. I would need to measure. I use the 3 strip method and keep pasting until the shell fits in the mortar without much room for blowby. My guess would be 7 or 8 layers. The shells are quite hard when I'm done. Did you watch the video? I use hot BP (ball milled, not just screened). I plan to make some of my own pine charcoal this weekend but I have been using skylighters charcoal which is made from hardwood. It's a bit slow when I granulate it and I don't trust it for lift. This is why I thought I should add the flash booster. However, I may have underestimated it. Seems the coated rice hulls are quite a bit faster than the granulated BP I made.

 

cogbarry the number of layers sounds good to me, 7-1 bp with flash booster is a little much. Try 5-1 with 5grams of whistle mix.

When making coated rice hull soak them in hot water for an hour, then drain them. Use 4 to 5% dextrin in your bp.

The bp should stick just fine to the rice hulls.

BJV

[cogbarry]

cogbarry the number of layers sounds good to me, 7-1 bp with flash booster is a little much. Try 5-1 with 5grams of whistle mix.

When making coated rice hull soak them in hot water for an hour, then drain them. Use 4 to 5% dextrin in your bp.

The bp should stick just fine to the rice hulls.

BJV

 

Thanks,

You're not the first one that said 7/1 was a lot. I read that shimitzu (apologies if I've got his name wrong) recommended it. I am using the dextrin at 4%. I think the leftover meal is because I used so much and the hulls only absorb what they can. I think this is working fine for me really, I'll tighten up the ratio though.

 

You don't mean 5 whole grams of whistle do you? That sounds like a lot although I have never used it. The flash I added was .5 grams. Is it important that I use whistle instead of the regular 70/30 flash?

[BJV]

Thanks,

You're not the first one that said 7/1 was a lot. I read that shimitzu (apologies if I've got his name wrong) recommended it. I am using the dextrin at 4%. I think the leftover meal is because I used so much and the hulls only absorb what they can. I think this is working fine for me really, I'll tighten up the ratio though.

 

You don't mean 5 whole grams of whistle do you? That sounds like a lot although I have never used it. The flash I added was .5 grams. Is it important that I use whistle instead of the regular 70/30 flash?

 

Yes 5 grams of whistle.

BJV

[jwitt]

I like whistle mix for booster, but have not tried flash booster.

 

People like whistle mix because 1) it doesn't produce a bright flash and 2) it's not quite as powerful.

 

Power can be an issue, because, from my understanding, we want to "ramp up" the pressure inside the shell as opposed to "cracking" it open. Flash booster can tend to burn too fast, cracking a shell open. It can also act too fast, preventing 100% of your stars lighting. From my understanding, this can either be "blowing stars blind" or breaking the shell before hot gasses ignite the prime on your stars.

 

In my 3" shells last year, I used something like 4-1 or 5-1 decent red alder BP on rice hulls, and something between 1g and 5g of whistle mix depending on the star load. 1g for color stars, since I'm afraid of blowing them blind. 5g for something like a nice rock-hard hard C6 or similar.

 

From my understanding, you would not want to use anywhere near 5g flash to boost a 3" shell. A booster charge is primarily to "round out" the break and the shape of the burst. Definitely look into whistle mix instead of flash! Safety precautions with whistle are roughly similar to flash, but do your research.

 

 

 

Rice hull tips- after soaking and spinning your hulls, add BP+Dex in 3-4 increments. I spin 'em over my head in a piece of window screen to good effect. Applying the BP in increments keeps things from getting too "gloppy." Save a little BP without dextrin for the final application- that prevents the grains from sticking together from the dextrin. I picked that tip up from skylighter and got the rest of my method from Dagabu.

Edited April 7, 2011 by jwitt

[cogbarry]

I like whistle mix for booster, but have not tried flash booster.

 

People like whistle mix because 1) it doesn't produce a bright flash and 2) it's not quite as powerful.

 

Power can be an issue, because, from my understanding, we want to "ramp up" the pressure inside the shell as opposed to "cracking" it open. Flash booster can tend to burn too fast, cracking a shell open. It can also act too fast, preventing 100% of your stars lighting. From my understanding, this can either be "blowing stars blind" or breaking the shell before hot gasses ignite the prime on your stars.

 

In my 3" shells last year, I used something like 4-1 or 5-1 decent red alder BP on rice hulls, and something between 1g and 5g of whistle mix depending on the star load. 1g for color stars, since I'm afraid of blowing them blind. 5g for something like a nice rock-hard hard C6 or similar.

 

From my understanding, you would not want to use anywhere near 5g flash to boost a 3" shell. A booster charge is primarily to "round out" the break and the shape of the burst. Definitely look into whistle mix instead of flash! Safety precautions with whistle are roughly similar to flash, but do your research.

 

 

 

Rice hull tips- after soaking and spinning your hulls, add BP+Dex in 3-4 increments. I spin 'em over my head in a piece of window screen to good effect. Applying the BP in increments keeps things from getting too "gloppy." Save a little BP without dextrin for the final application- that prevents the grains from sticking together from the dextrin. I picked that tip up from skylighter and got the rest of my method from Dagabu.

 

I've been using my girlfriends nylon stockings . Thanks, that all makes sense. Well, you just got me to make another skylighter order. All kinds of stuff is on sale, you might want to check it out. Unfortunately, I can't spring for overnight shipping, I won't be able to use whistle mix in anything I make this weekend.

 

I've read of lots of folks using whistle mix for the exact reasons you stated. Never used it because I didn't have the chems and because I also read of lots of folks using a pinch of flash. However, if there's one thing I've learned it's that you can't take shortcuts. I'll try this but I may try dagabu's advice this weekend.

[TheEvilGod]

I think flash works very well as a booster, and the bright break it gives I have no issues with either . Here's a video of a guy using flash powder as a booster:

He uses 3g of dark flash as a booster in these 4" shells. For a 3" shell I'd recommend to use bright flash and around 2-3g but to get a really even break you should use whistle mix or H3....

Edited May 5, 2011 by TheEvilGod

[Mumbles]

In the comments he states he uses a normal flash, not dark flash.

[Bilbobaker]

In the comments he states he uses a normal flash, not dark flash.

 

I'm pretty new to the terminology used but exactly what is the difference between normal and dark?

[Mumbles]

Dark flash is exactly what it sounds like. It is a flash powder that produces very little to no visible light. These are typically made from potassium chlorate, sulfur, and/or antimony trisulfide. It clearly is quite dangerous compared to other compositions. It has it's uses in breaking crossettes, and a few other specialized applications. It's used fairly infrequently compared to others. There really isn't anything called bright flash. There is normal flash which more often than not, is potassium perchlorate and aluminum. There may be some confusion resulting from the aluminum. There is bright aluminum, and dark aluminum, but these do not impart those representative descriptions to their final products. Dark aluminum is typically quite fine, ranging from -325 mesh to the single micron size. Bright aluminum is the kind of stuff that is in silver metallic paint. It is very silver in color, usually larger in mesh, and often much less dense. Most flash for concussive effects is made with the dark variety. There is also something called slow flash. This burn slower, and is gaining some popularity as a shell booster. It is somewhat more gentle in some people's eyes. This is often made with the bright aluminum I mentioned before.

[cogbarry]

Here is a 3" shell constructed exactly like the one in which half the stars failed to light.

 

http://www.youtube.com/watch?v=wMYbDRVQaZM

 

Below are links to vids of two green rubber star shells I made after getting some advice here on this forum. The changes I made were.....

 

 

1) Used pass fire tube.

2) stopped using flash booster and added 5 g's of whistle mix 70:30 PP Potasium Benzoate, both chems in fine powder form and diapered to mix.

3) Used 5:1 BP coated hulls made from my home made charcoal. Tested this BP after granulating to ~ commercial ffg size or slightly larger (ran through kitchen seive). 20 g's of this bp launched a baseball into the air for 11+ seconds.

4) Also made a few shells using KP coated hulls with 5 g's whistle. I didn't see much difference in the burst.

 

All of these shells were made from cardboard hemis and pasted with 14 layers of virgin craft paper. I used 3 strip method and kept pasting until they fit well in the gun.

 

 

http://www.youtube.com/watch?v=FGb97VSU03U

http://www.youtube.com/watch?v=67ghwE3USFE

 

I don't have footage but I still had some ignition failures with both the red and green rubber stars. I am using fence post for first prime layer on my next batch followed by a layer of BP. I guess my question is "what's wrong with my burst?". Seems pretty soft still and not as round as it could be.

[dagabu]

They dont sound like they are breaking hard enough... I'm not a ball shell guy but all the commercial shells seem to break a lot harder then that. I wish I could help more, sorry.

 

-dag

[Mumbles]

My best guess would be that diapering the whistle isn't mixing it very well. Try adding a little iron oxide if you have it around. Copper oxide or oxychloride will work if you have it around too. They both catalyze the mix, and color it. It makes it much easier to tell when the two main components are well mixed. Two white powders look the same if integrated well, or just dumped on top of one another. Dagabu could confirm or deny this, but I'm under the impression that most people screen their whistle mix. I do at least. With good whistle, your shells should be breaking good and hard given your seemingly good construction techniques.

[dagabu]

My best guess would be that diapering the whistle isn't mixing it very well. Try adding a little iron oxide if you have it around. Copper oxide or oxychloride will work if you have it around too. They both catalyze the mix, and color it. It makes it much easier to tell when the two main components are well mixed. Two white powders look the same if integrated well, or just dumped on top of one another. Dagabu could confirm or deny this, but I'm under the impression that most people screen their whistle mix. I do at least. With good whistle, your shells should be breaking good and hard given your seemingly good construction techniques.

 

Yes, I find that ball milling the Benzo with the catalyst helps greatly in getting the perc integrated though I am not sure why. I run the perc through a 60 mesh screen all by itself and then add the solvent (white gas and mineral oil) to the perc alone then fold in the benzo.

 

Then I screen the whole mess through a 20 mesh screen. Its very hard to push it through but it works very well for me. I do think that dry screening is not a risk worth taking since it is prone to static build up. IMHO

 

-dag

[cogbarry]

Thanks guys, you're comments are helpful as usual. I was diapering the whistle mix as it was the first whistle I made and was unsure about the safety of other methods. I don't have any chems on hand for a catalyst but I don't think there's any doubt that my shells are bursting a bit soft. I'm actually not too worried about it because I would think this should be any easy issue to resolve one way or another. When I tested the whistle mix, it didn't seem as energetic as I had expected it to be but I didn't know if this comp needed containment before it became energetic. I need to make up a bunch of shells this weekend for an up coming NHPA event. I may simply use a flash boost for these. Any recomendations on the amount? 1-2 g's perhaps? I was using 1/2 g in the past and don't think it was enough. I would use a "flash bag" in order to keep it in the center of the shell. I will be building with a friend that uses a whistle boost this weekend so I'll find out what he does. He's got a WASP too!

[Mumbles]

Adding a bit of charcoal, red gum, etc should be enough to color it as well. You just don't get the added performance benefit.