Will my rockets lift 3" shells?

[psypuls]

Hi, i'm a fairly new hobby pyrotechnician

and i've been doing some rockets lately, with tubes of 15mm Inner diameter and 150mm length

I attach 2.5" shells to these rockets But i'm looking to upgrade them now with the same tubes but 3" shells, Will I be able to do this or do I need a new set of tools&tubes?

 

http://pyrobin.com/files/20140608_124404.jpg

[boule]

That´s a big question to answer without knowing your rockets and shells in detail. Generally speaking, 1lb cored black powder rockets should be capable of lifting a 3" shell to a decent hight provided they are properly dialed in.

How high are they going with your 2,5" shells, how much do those shells weigh, how much heavier are the 3" shells you make?

 

Now, if you want to be sure that it´ll work and your rockets are already flying high with your current shells, take a few 3" shells, weigh them. Build one of the same weight with just line chalk and a little BP burst charge without delay as a dummy shell. Put it on as a header and shoot it during the day. If your rocket flies properly, it will give you a nice colored splash in the sky indicating motor burnout, if it bursts at ground level, you don´t have to worry about burning stars igniting anything.

Edited June 8, 2014 by boule

[psypuls]

That´s a big question to answer without knowing your rockets and shells in detail. Generally speaking, 1lb cored black powder rockets should be capable of lifting a 3" shell to a decent hight provided they are properly dialed in.

How high are they going with your 2,5" shells, how much do those shells weigh, how much heavier are the 3" shells you make?

 

Now, if you want to be sure that it´ll work and your rockets are already flying high with your current shells, take a few 3" shells, weigh them. Build one of the same weight with just line chalk and a little BP burst charge without delay as a dummy shell. Put it on as a header and shoot it during the day. If your rocket flies properly, it will give you a nice colored splash in the sky indicating motor burnout, if it bursts at ground level, you don´t have to worry about burning stars igniting anything.

I'm planning to buy the paper balls for it, I think that 3" shells should weigh about 140g can anyone confirm this so that I can do a test? .

It's almost double the weight of a 2.5".

My rockets fly pretty high with a 60/35/10 ratio.

[Arthur]

Getting the delay between the rocket ceasing power and the shell breaking is crucial. It can only be done by trial and error. The delay must be the same as the coasting flight stage, so that the shell breaks at the top of the flight, too short or too long and the shell breaks too low.

 

This is one of the tasks that needs good safety distances, fire a test and see what it looks like.

[fredjr]

Pressing too large of an increment when making rockets will cause wrinkles in the tubes. While they may fly fine to start off, if stored for a length of time the grains will crack and then you'll get CATO's. So you need to use smaller increments. Waxing the tubes can also help eliminate the wrinkles. I put 3" ball shells on 1/2" ID x 2.5" long whistle rockets and they are actually a little to high. Easiest way to tell what a rocket will lift is just try it. Of course in a safe area.

[psypuls]

how much does your 3" weigh?

my increments are only 2g or 0.07oz of bp for each scoop do you think that's too much?

i'm working on building a tube support to eliminate any wrinkles because it seems that the tube can't handle too much pressure

Edited June 8, 2014 by psypuls

[boule]

I'm planning to buy the paper balls for it, I think that 3" shells should weigh about 140g can anyone confirm this so that I can do a test? .

 

That would probably be a little bit on the light side. Think 150-225g for most shells, a little bit lighter for charocoal stars, a little heavier for zinc spreaders.

 

My rockets fly pretty high with a 60/35/10 ratio.

 

 

You´ll be fine. Just build a dummy header that has around 200g weight, will pop open releasing a non-flammable substance and give it a try. Observe the flight and check for the following:

 

- Rocket flies straight up and deploys at zenith: no change needed

- rocket flies straight up, noses down and dives to the ground: too much delay. Reduce your last increments and try over

- rocket lifts only lazily, veers off while still under thrust: faster BP or bigger motor needed.

 

There is no way to theoretise how your rocket will behave short of putting the motor on a thrust stand or launching it with a load. Since the latter is easier to accomplish, go ahead and do it..... oh yeah, video plz.

[psypuls]

 

That would probably be a little bit on the light side. Think 150-225g for most shells, a little bit lighter for charocoal stars, a little heavier for zinc spreaders.

 

 

You´ll be fine. Just build a dummy header that has around 200g weight, will pop open releasing a non-flammable substance and give it a try. Observe the flight and check for the following:

 

- Rocket flies straight up and deploys at zenith: no change needed

- rocket flies straight up, noses down and dives to the ground: too much delay. Reduce your last increments and try over

- rocket lifts only lazily, veers off while still under thrust: faster BP or bigger motor needed.

 

There is no way to theoretise how your rocket will behave short of putting the motor on a thrust stand or launching it with a load. Since the latter is easier to accomplish, go ahead and do it..... oh yeah, video plz.

I shot the video for you, the dummy was 190g and you can hear a small pop, which is where the shell would burst, does it look ok?

I was a little stupid to put a solid rock inside and it was just a risky location, what if I hit a car omg it would've gotten seriously dented with broken windows:P meh or not, it was fun anyway

https://www.youtube.com/watch?v=rfyKF52X8Hc

Edited June 8, 2014 by psypuls

[AzoMittle]

That´s a big question to answer without knowing your rockets and shells in detail. Generally speaking, 1lb cored black powder rockets should be capable of lifting a 3" shell to a decent hight provided they are properly dialed in.

How high are they going with your 2,5" shells, how much do those shells weigh, how much heavier are the 3" shells you make?

 

Now, if you want to be sure that it´ll work and your rockets are already flying high with your current shells, take a few 3" shells, weigh them. Build one of the same weight with just line chalk and a little BP burst charge without delay as a dummy shell. Put it on as a header and shoot it during the day. If your rocket flies properly, it will give you a nice colored splash in the sky indicating motor burnout, if it bursts at ground level, you don´t have to worry about burning stars igniting anything.

 

Oh my god, why have I never thought of this, this changes everything. Thank you a thousand times over! How dense is it compared to BP? Will a 3" shell loaded with chalk weigh roughly the same as a 3" shell loaded with stars?

[boule]

I shot the video for you, the dummy was 190g and you can hear a small pop, which is where the shell would burst, does it look ok?

I was a little stupid to put a solid rock inside and it was just a risky location, what if I hit a car omg it would've gotten seriously dented with broken windows:P meh or not, it was fun anyway

Well, the rocket was not that visible in the video due to light. Did it arc over or drop down significantly? It does not appear to do so in the video, so if real-life observation agrees with this interpretation, you should be good to go.

As far as the header and launch location are concerned .... well, be glad nothing happened and make a better choice next time.

 

 

 

Oh my god, why have I never thought of this, this changes everything. Thank you a thousand times over! How dense is it compared to BP? Will a 3" shell loaded with chalk weigh roughly the same as a 3" shell loaded with stars?

Ah, this is close to sarcasm.... but thank you anyways.

I lifted the line chalk idea from this website ( ...) when looking for easy-to-make daylight shells and have been using it as a dummy header since it is not flammable, presents no fallout hazzard - in fact, it will not even inconvenience someone on the ground and makes a nice visible splash in the sky. If you are even cheaper, you can use flour.

Line chalk will be on the heavy side of the spectrum. A full 3" shell (with 5g burst charge) will weigh in at approx 220g, so rather don´t fill them completely or simply weigh the required amount of chalk in a small paper (sandwich) bag before puttting it in the shell and break it hard (whistle or flash).

[dagabu]

Well, the rocket was not that visible in the video due to light. Did it arc over or drop down significantly? It does not appear to do so in the video, so if real-life observation agrees with this interpretation, you should be good to go.

As far as the header and launch location are concerned .... well, be glad nothing happened and make a better choice next time.

 

 

Ah, this is close to sarcasm.... but thank you anyways.

I lifted the line chalk idea from this website ( ...) when looking for easy-to-make daylight shells and have been using it as a dummy header since it is not flammable, presents no fallout hazzard - in fact, it will not even inconvenience someone on the ground and makes a nice visible splash in the sky. If you are even cheaper, you can use flour.

Line chalk will be on the heavy side of the spectrum. A full 3" shell (with 5g burst charge) will weigh in at approx 220g, so rather don´t fill them completely or simply weigh the required amount of chalk in a small paper (sandwich) bag before puttting it in the shell and break it hard (whistle or flash).

 

Chalk shells are indeed a great idea, I like 2g flash bag to break a plastic shell and spread out the chalk a little but very much the same idea. One word of caution: Chalk on a car or house can be trouble, shoot then over a field, never where people, cars, buildings are.

[nater]

Someone posted about it earlier, I think instead of chalk I will try the dyed cornstarch used for an Indian festival and the color run 5ks.

[dagabu]

Someone posted about it earlier, I think instead of chalk I will try the dyed cornstarch used for an Indian festival and the color run 5ks.

 

Do you have a link for that?

[nater]

Here is one link: http://www.littlepassports.com/blog/2013/03/celebrate-holi-with-a-colorful-powder-recipe/

 

There are other recipes, some using cornstarch or tempera paint powder.

[boule]

 

Chalk shells are indeed a great idea, I like 2g flash bag to break a plastic shell and spread out the chalk a little but very much the same idea. One word of caution: Chalk on a car or house can be trouble, shoot then over a field, never where people, cars, buildings are.

Ah, dagbur, I think you are worried a little bit too much there. A 3" shell breaking above 300ft will not leave any noticable residue on the ground that could be identified as colored chalk unless you look at it with a microscope. Matter of fact, chalk is also quite non-reactive and if it is pure chalk, whashes off easily unlike a number of other potential substances in the fallout from pyro displays (pumpkin fallout..... yuck!). Nonetheless, it should be standard practice to keep your fireworks as far from things they could potentially harm as possible.

 

Someone posted about it earlier, I think instead of chalk I will try the dyed cornstarch used for an Indian festival and the color run 5ks.

There is a pattern to the madness displayed by using chalk. Cornstarch, flour or even non-dairy creamer will act as a cremora pot. Fire one of the shells at night and you will see some burning sparks. Fire one during the day and you probably won´t notice them until you put a really decent burst in it and a comet on the shell to aid in ignition. About 1 in 5 or so will show a nice black cloud telling you that the aerial cremora worked.

[dagabu]

Ah, dagbur, I think you are worried a little bit too much there. A 3" shell breaking above 300ft will not leave any noticable residue on the ground that could be identified as colored chalk unless you look at it with a microscope. Matter of fact, chalk is also quite non-reactive and if it is pure chalk, whashes off easily unlike a number of other potential substances in the fallout from pyro displays (pumpkin fallout..... yuck!). Nonetheless, it should be standard practice to keep your fireworks as far from things they could potentially harm as possible.

 

There is a pattern to the madness displayed by using chalk. Cornstarch, flour or even non-dairy creamer will act as a cremora pot. Fire one of the shells at night and you will see some burning sparks. Fire one during the day and you probably won´t notice them until you put a really decent burst in it and a comet on the shell to aid in ignition. About 1 in 5 or so will show a nice black cloud telling you that the aerial cremora worked.

 

Boule,

 

I was actually relating my experiences from a shoot where a barrage of colored shells (daytime) were shot and covered several spectator vehicles. The "damage" was significant enough to warrant a wind check before more are shot. The color was very noticeable on the pink Cadillac Escalade that was white when she drove it to the lot to watch us.

 

Not worried myself but optimistically cautious.

[boule]

 

I was actually relating my experiences from a shoot where a barrage of colored shells (daytime) were shot and covered several spectator vehicles. T

 

See, the important part there is "barrage" and any damage done can be remedied by just hosing down the vehicle. If you use leftover toner powder, you gotta scrub a lot to get it off an RV and that is after just one shell!

[psypuls]

Pressing too large of an increment when making rockets will cause wrinkles in the tubes. While they may fly fine to start off, if stored for a length of time the grains will crack and then you'll get CATO's. So you need to use smaller increments. Waxing the tubes can also help eliminate the wrinkles. I put 3" ball shells on 1/2" ID x 2.5" long whistle rockets and they are actually a little to high. Easiest way to tell what a rocket will lift is just try it. Of course in a safe area.

I try hard to get minimum amount of wrinkles on the tube, you were saying the rockets will CATO if the tube has wrinkles and it was stored for a length of time, how long? a year?

[dagabu]

I try hard to get minimum amount of wrinkles on the tube, you were saying the rockets will CATO if the tube has wrinkles and it was stored for a length of time, how long? a year?

 

Look for the 'waxing tubes' posts. The simple task of waxing the inside tubes all but eliminates the wrinkling and "relaxing" that happens over time. The time depends on how much elasticity the paper has, I found chipboard tubes to actually crack internally when wrinkled while NEPT tubes seem to stay together but have a lot of elasticity causing grain cracks in a as little as a few hours to several days.

[psypuls]

can't find that post after searching for wax tube, wax, waxing tubes, , anyway i do use vaseline on all of my tubes in order to remove them easily from the platform, but how does waxing tubes work?

[Mumbles]

I think he was talking about this thread.

 

http://www.amateurpyro.com/forums/topic/9372-wax-coating-rocket-tubes/

[dagabu]

And thats why you get paid the big bucks.