building shells with delayed fuseing

[ST1DinOH]

this thread title sucks for describing what i'm actually asking but i can't think of a better way to phrase what i'm asking.

 

ok i'm planning a little 3 inch shell project piece for our 4th show this year. encouraged by my recient sucess in shell building (thanks to this forum and others) i plan on making all the shells.

 

the plan so far is to launch volleys of 3 shells in unison, but have them break one after another instead of right at the same time.

 

the reason for this is three fold.

1 to ease in fusing (just QM the rows of 3)

2 the comet tails on the shells should all leave the fanned rows in unison.

3 i want them to be red white and blue breaks (one of each) and i want them to break in that order.

 

so in order to eliminate the possibility of having the breaks going off at the same time, and to ensure the shells can leave in unison, but break in the color order (red then white then blue) i'm thinking of changing the fuse lengths to accomplish this.

 

the shells i launched sucessfully had a 1 1/4 inch time fuse on them, and they were slightly shortened on the lift cup side when i butterflied them. so i know this gives me good results.

 

this is the benchmark i'd be using for the white shells.

 

the question i have is what is a good length to shorten and lengthen the time fuse in the appropriate shells in order to prompt the red to break early, and the blue to break late.

 

whats too much, whats to little, will it be hard to accomplish this and have it still be effective?

 

what i'm thinking as of right now is altering the fuse length by about 1/16th of an inch. not having any experience in doing this i have no clue if that will result in the desired effect or what kind of time differences i would see in the air.

 

should i bump that difference up to 1/8?

 

my concern obviously is having the red break 1/2 way up, or the blue break 1/2 way down if i alter too much.

 

anyone have any experience in this? is it even worth going through the trouble?

 

the end goal here is to have a 12 shot 3 way fanned rack of 3's, and i'd be sending them up one row at a time. the way i figure it i can simply QM each row to one side, then run a length of fast yellow visco to each row and connect my e-match to the visco. the visco in turn would touch off each row of shells sending 3 fanned comets into the air which will then break red, white, then blue (probably peonys).

 

the best part about this whole concept (IMO) is i'd be able to swap the order around in each row if i wanted to, the effct would still be the same, but the position of each color could be changed so it didn't seem redundant. the first volley of three would probably be in order from left to right but then i'd change it up a bit to make it look real nice. no matter how i change it, so long as the fuses function as planned, it should look amazing.

 

thanks in advance for any and all help/advice.

 

EDIT: almost forgot...would it be overkill to color the comet tails to match the effects? or am i better off having the tails all the same color to suprise them on the break order. i ask because i cannot recall ever seeing a blue or red comet tail. is that even possible or am i trying to re-invent the wheel here? i want them to be real "fluffy" and leave long trails inthe sky on the way up...i've seen pearls of all colors of course...but don't know how possible fluffy red and blue tails are.

[InRainbows]

A really easy way would to just set up three mortars as usual, except have the QM sticking up about 1" over the top. Then chain it with Chinese fuse, or BM, so that you have a fan with BM over the top.

[ST1DinOH]

A really easy way would to just set up three mortars as usual, except have the QM sticking up about 1" over the top. Then chain it with Chinese fuse, or BM, so that you have a fan with BM over the top.

well i know how i want to fuse the rack once the shells are built, i need to know if my plan for altering the time fuse inside the shell will give me the effect i'm after.

 

if you read the post above i'm looking to launch volleys of three 3inch shells in unison, but have them break at different times in the sky. one just before the apex, one at the apex, and one just after the apex.

[InRainbows]

I can't see any reason for unison launching and timed bursts when it's much easier that last way but...

 

Yeah, your idea will work. It'd be better to just find three different grades of powder inside equal lengths of spolette, because if you make too long of spolettes in equal size balls you'd have to make sure the longer ones don't rip off from the forces during lift.

[hst45]

Taking into consideration that you'll want each color effect to have a chance to break and spread properly, I'm guessing that you'll need more than 1/8" difference. if your timing fuse is typical visco like mine, which should be burning at about 30 seconds a foot, you'd need an extra INCH of timing fuse to give the first shots a chance to give a 2-1/2 second delay between breaks if they were fired together. To get the shells to break at the same height when they were fired together you'd need to think of varying the lift charge too. You might have to fire the second and third shells with progressively more lift so that they would pass apogee and be starting back down when they broke. God, my head hurts from doing that math! If you're looking for sequential breaks I think you'll need to do the sequential firing thing. Anyway, the effect sounds like fun; good luck.

 

For rising comets any red, white and blue star formulas should work fine.

[ST1DinOH]

i'll be using 1/4 inch japaneese time fuse for the internal time fuse of each shell

 

http://www.cannonfuse.com/store/pc/viewPrd...y=2&idproduct=7

 

it burns at aprox 3 seconds per inch.

[InRainbows]

That still makes you put on another inch for each spolette. You could, possibly, stick your spolettes in deeper, but at the cost of an unequal break.

 

Maybe make your own spolettes, touch paper or something might burn slower.

[ST1DinOH]

i'm not using spoolettes, i'm using 1/4 inch japaneese time fuse. again, it burns at 3 seconds per inch.

 

an extra inch of this fuse is an extra 3 seconds difference.

 

i don't think subtracting or adding 3 seconds to a 3 inch shell is a very smart idea. thats either a flower pot of a ground break.

[Frozentech]

I think 1/8 inch difference between the time fuse on the shells would be OK. That will only give you .375 seconds between shell breaks though. You stand a strong chance of the white break overpowering the blue shell break. What is the timing *you* want for the effect ? Do you want the shell breaks to all be in the sky at the same time (white drowns out blue) or sequentially breaking in the same area of sky a second or two apart ?

 

I think personally, that having all the shells timed the same, but using delays in buckets on the QM between the shells would look better.

[ST1DinOH]

I think 1/8 inch difference between the time fuse on the shells would be OK. That will only give you .375 seconds between shell breaks though. You stand a strong chance of the white break overpowering the blue shell break. What is the timing *you* want for the effect ? Do you want the shell breaks to all be in the sky at the same time (white drowns out blue) or sequentially breaking in the same area of sky a second or two apart ?

 

I think personally, that having all the shells timed the same, but using delays in buckets on the QM between the shells would look better.

i figured i was potentialy over complicating this but i'm kinda stuck on the whole "3 comets in unison" concept. they wouldn't have to be perfectly "displayed" but to have them break about 1/2 or 1 second apart would be kinda cool.

 

as hst45 said my head is hurting from trying to do the math of possibly adjusting the lift to get them to break at the same height but have them going progressivly higher in the sky to time the breaks out.

 

hence the whole concepte of getting the middle to break like regular and the other 2 to break close to it.

 

the biggest problem in this whole concept is tha the shells are being launched from a fan rack, which seriously screws with the break positions. the short fused would be breaking short and tight, the long fused blue would be breaking late and wide from the spread.

 

so it'll look sloppy.

 

keeping them breaking in the fan formation is almost more important than the timing or break order, thats why i'm thinking a short seperation (1/2 second) between breaks is the most important aspect.

 

again assuming i stay obsessed with the concept of tanden 3way comets,

 

whats got me sold on that idea is not only the sight of the comets tails rising in unison, but the whole idea that once they are built i can pick and choose whatever pattern i want to put them in the rows. no matter how i load them the overall effect will remain the same, the only thing that changes is the position of the breaks.

 

if the blue is the last shell, and i'm giving the shells a 1/2 - 1 second delay between themselfs, then a white peony should clear in time for the blue to look great.

 

especially if we are talking a short lived "violent" star pattern like a peony that gets big quick and dies fast.

 

if i do go with alternating comet tails, rather than tandem, it would simplify everything in the sky, but then it would be predictable which shell was breaking where, and it would do away with that cool effect of having 3 comets leaping skyward together in a fan.

[justanotherpyro]

I have messed around a fair amount with precision timing. So far what I have found that has worked the best was electrical. After going through all the hassle to time fuses perfectly to achieve the desired effect and then having it all get thrown off by imprecise QM is very upsetting.

 

As far as the desired effect you want I suggest, if electric ignition is possible, a combination of modifying fuse length and launch times. If you have say three switches on a firing box then you can fire each one ~.5 seconds apart. It's a small enough gap that you would still get the rising effect of all three in unison ( as far as th eye can tell ) and in combination with slightly altering the fuse timing, I think that you could get a enough spacing to have them break in the fashion you want.

 

I know that the idea of doing this electrically may be disconcerting, but when it comes to precision timing from as little as .5s - 1s it's important for the launch to be timed perfectly, which you can do electrically. Don't get me wrong it is possible to do with QM, but in my experience electrical is the way to go for things like this.

[TheSidewinder]

ST1,

 

I think you're going to want fusing at 2-3 seconds for the first shot. Next two fused to go off togther about 3/4 of a second later. Add an extra 1/4" spacing for the 3/4 second delay. If you want a 1-2-3 break, then step them each 1/4" more than the previous.

 

Needless to say, these require precise spacing, so measure carefully and use a sharp punch or awl to get the holes spaced exactly. Leave some extra fuse on each end just for strength and ease of use. Thermalite is my preferred crossmatch, but small diameter blackmatch works well. Insert in the punched hole carefully, then very lightly crimp the timefuse around the match.

 

As to the spread, is this rack adjustable? Can you reduce the fan angle to say... half of what it ls?

[ST1DinOH]

I have messed around a fair amount with precision timing. So far what I have found that has worked the best was electrical. After going through all the hassle to time fuses perfectly to achieve the desired effect and then having it all get thrown off by imprecise QM is very upsetting.

 

As far as the desired effect you want I suggest, if electric ignition is possible, a combination of modifying fuse length and launch times. If you have say three switches on a firing box then you can fire each one ~.5 seconds apart. It's a small enough gap that you would still get the rising effect of all three in unison ( as far as th eye can tell ) and in combination with slightly altering the fuse timing, I think that you could get a enough spacing to have them break in the fashion you want.

 

I know that the idea of doing this electrically may be disconcerting, but when it comes to precision timing from as little as .5s - 1s  it's important for the launch to be timed perfectly, which you can do electrically. Don't get me wrong it is possible to do with QM, but in my experience electrical is the way to go for things like this.

man...this is another problem i'm having...

 

i love e-fire. and matching the lift is something i'm also quite fond of...

 

unfortunatley i don't have a sequencer, let alone a pyromusical system, and the shoot site dictates i use a wireless system (on the water, from a raft.

 

so here's the problem with my e-fire capabilities...

 

the system i use, and love, is a 12 channel wireless board 36 cue system. it requires pressing 2 buttons to fire each cue. this is just opening up the relays on the firing box, and the relays need time to close after the firing of the cues. it was designed to fire 1.4, and as you know there ain't much in 1.4 that requires less than a second between cues. most things we fire with this system are cakes.

 

i;m also limited to a 36 cue setup un;ess i decide to utilize a second 36 cue system, but that requires a seperate transmitter.

 

we usually build our shows to maximise that 36 cues. most of the shows are between 30 and 36 cues, so we usually set up multiple chained boards to maximise our cue usage.

 

i was hoping, in fact, i probably need to fuse this whole 12 shot rack to one seperate cue. i may even be grabbing some passfire from this rack to touch off some low level effect to go under the 3's. but thats all a "week of the show" decision.

 

ST1,

 

I think you're going to want fusing at 2-3 seconds for the first shot. Next two fused to go off togther about 3/4 of a second later. Add an extra 1/4" spacing for the 3/4 second delay. If you want a 1-2-3 break, then step them each 1/4" more than the previous.

 

Needless to say, these require precise spacing, so measure carefully and use a sharp punch or awl to get the holes spaced exactly. Leave some extra fuse on each end just for strength and ease of use. Thermalite is my preferred crossmatch, but small diameter blackmatch works well. Insert in the punched hole carefully, then very lightly crimp the timefuse around the match.

 

As to the spread, is this rack adjustable? Can you reduce the fan angle to say... half of what it ls?

 

thanks for the suggestions.

 

i like that idea of sending the first row up using fast visco to give it a spread...might just have to do that.

 

i'll be using plastic shell hemi's to make these shells. and i'm not using any black match at all on the lift cup side of things. i simply butterfly the end of the time fuse with two bisecting cuts from a razor blade by rocking the balde bak and forth into the end of it. once i have the two cuts the end of the fuse is cut into 4 equal pieces and i spread it out a bit to expose the powder core using that same blade. no problems so far.

 

again back to the whole concept of just cutting that time fuse at different lengths for the different colors. the lift cup side will be the same, the inside termination point is what will be a fraction different. i also use a 4F filled tube (thin walled rolled craft) to send the passfire from the time fuse to the dead center of the shell.

 

so a 1/8 or a 1/16 difference in the time fuse shouldn't matter as far as the performance is concerned...just the timing.

 

that adjustable rack idea is a great idea as well, i haven't built the rack yet so thats always possible, but to try and take the math out of the equation i'd like to simply build them all the same.

 

i guess i'm fortunate in the fact that every shell i've done so far has broken at the perfect height. my first efforts at dialing in the appogee were right on the money so i know 1 1/4 is perfect. this lets me shave a fraction off the fuse length and get a break at just under appogee, and add a fraction ofr a second to accomplis a break as it's begining to fall.

 

it doesn't have to be perfect. i mean shit lets be honest here these will only be my second batch of 12. expecting everything to be immaculatly timed will just piss me off. and for that matter i'd be the onlyone pissed because everyone else will just think it's cool to see something getting above all the 1.4 and breaking bigger than 60 gram cans.

 

the bottom line is a .375 second delay, + or - a little is probably perfect.

 

who cares if it's not all breaking in a perfectly straight line. so long as the breaks are getting up there above everything all 400+ of thoes people will be loving that.

 

then i hit them with a case of fanned salute candles

[Arthur]

Please calculate the balistics of the sphere as it travels. Most shells have a finite time arount the highest point of flight where they are fired. one second either way and a shell could well burst too low for safety before or after the highest point. Two seconds either way and you may put your audience inside the burst radius.

 

Also having mixed delay shells in your store later complicates using them for other shows.

 

S=Ut +0.5ft^2 ---------equation of motion

 

S distance

U initial speed

t time

f acceleration in this case gravity 32 ft/s/s or 10ms^-2 and a minus figure for the deceleratring action.

 

A small shell will have an air time of a couple of seconds, Larger shells will have a bigger flight time. Listen for the lift and burst cracks.

 

 

Added

It is probably more reliable to send up synchronised comets and delayed shells That's the tails together and the delayed breaks you want.

[ST1DinOH]

Please calculate the balistics of the sphere as it travels. Most shells have a finite time arount the highest point of flight where they are fired. one second either way and a shell could well burst too low for safety before or after the highest point. Two seconds either way and you may put your audience inside the burst radius.

 

Also having mixed delay shells in your store later complicates using them for other shows.

 

S=Ut +0.5ft^2 ---------equation of motion

 

S distance

U initial speed

t time

f acceleration in this case gravity 32 ft/s/s or 10ms^-2 and a minus figure for the deceleratring action.

 

A small shell will have an air time of a couple of seconds, Larger shells will have a bigger flight time. Listen for the lift and burst cracks.

 

 

Added

It is probably more reliable to send up synchronised comets and delayed shells That's the tails together and the delayed breaks you want.

i'm sorry for any confusion that me be taking place in this thread...

 

how can i put this without sounding like a prick.

 

whiel i appreciate you advice on assured safe distances i never would do anthing to endanger my audience. these people are all my family, friends, and friends of thiers. i'm not talking about adding or subtracting anything signifigant. jap time fuse burns very slow, 3 second per inch, cutting anything more than 1/4 inch would cause my shells to break far before apex. adding more than that margin would cause them to come back down before the break.

 

i've tested 10 shells now, and got my timing and lift dialed in for 3 inch ball shells. which is what i am making here.

 

the question here is when using japanese time fuse, launching 3 inch sphere shells, should i be using a .375 second gap in the breaks, or a .75 second difference.

 

we are talking at the most adding or subtracting 3/4 of a second to the total time (from lift to break) in that 3/4 of a second there's no way that 3 inch shell, will be able to travel back to the ground from it's peak height.

 

and i'm concerned that this may be too long for the effect to look right.

 

i'm thinking more along the lines of a .375 second delay, aprox 1/3 of a second.

 

again...no possible way a shell is going to indanger my spectators with this small of a time frame.

 

also i am using approved spectator distances anyway. so even if a shell were to have a 6 or 7 second time fuse on it for some reason, it wouldn't be anywhere near my crowd.

[InRainbows]

Well, look. If your going to lengthen the time fuse/spolette, it will work. It's just that you might want to test this a few times over. Don't screw with the lift too much if you have a fan rack. With the time fuse, make sure for the longer ones, that you have some Kraft or some kind of reinforcement. If you add even like .375, it might get ripped off during lift.

[Bayarea510]

st1 dude, here's my take on all this. I think you need to play a little more with your time fuse. I'm thinking that 1/4" add on should be fine for break the shells one right after another. Trying to get precision timing on time fuse can be done. Just look at the guy who did it with the rocket header on passfire. Its going to take some practice! I have a "open shoot" coming up in 3 week and maybe I will try this my self and see what kind of results I might be able to make of it. Another thing is this, I know your thinking all your shells are breaking at the apex but are you sure about that? Its kind of hard to tell at night. shoot a dummy shell during the day maybe and again play with the time fuse this way you can see what is the true apex of the shell. You might be able to shorten up the lift charge and still add time to the time fuse and get them to break right next to each other like planned. Again I will try this out and 3 weeks my self and we will see what happens!

 

George

[ST1DinOH]

st1 dude, here's my take on all this. I think you need to play a little more with your time fuse. I'm thinking that 1/4" add on should be fine for break the shells one right after another. Trying to get precision timing on time fuse can be done. Just look at the guy who did it with the rocket header on passfire. Its going to take some practice! I have a "open shoot" coming up in 3 week and maybe I will try this my self and see what kind of results I might be able to make of it. Another thing is this, I know your thinking all your shells are breaking at the apex but are you sure about that? Its kind of hard to tell at night. shoot a dummy shell during the day maybe and again play with the time fuse this way you can see what is the true apex of the shell. You might be able to shorten up the lift charge and still add time to the time fuse and get them to break right next to each other like planned. Again I will try this out and 3 weeks my self and we will see what happens!

 

George

hey bay...

 

ok so i was thinking about that time issue as well. less than half a second diffefrence in the breaks will just be overlap, the 1/8 sounds better than the 1/16, but i agree, 1/4 will be better. thats a little under a second right? 1/3 of an inch = 1 second so 1/4 of an inch should be a little less than a sec and that might be the ideal time.

 

so the time fuses would be 1 inch, 1 1/4 inch, and 1 1/2 inch.

 

have you shot a 3 with a 1 1/2 time fuse before? i don't want the blue breaking on the water.

[justanotherpyro]

Another thing to take into consideration is how snuggly the shells fit into the mortar. My three inch shells pasted with 2 layers of gummed kraft tape and quickmatched fit very loosely in my mortar so I have to use about 11% of the weight for lift. Whereas my four inch shells fit much tighter ( still loose falling down the mortar though) and only need about 8-9% of the shell weight for lift.

 

So if you are worried about them coming down to much from apogee, maybe either paste the long fused shell with an extra layer, add more lift or do both.

[Mumbles]

I'm glad everything got more or less figured out here.

 

I'd have to second the 1", 1.25" and 1.5" lengths. With butterflying the fuse, it should be less than you'd think. Even with a 1.5" fuse from end to end and no butterflying, you'll be fine with getting it to break in the air. It may be on it's way down, but it should still be up at a reasonably safe height. I've put up 3" shells with a 4 second delay, and they've worked fine.

 

One way to help with the precision is you mark off your lengths with a marker, say .75", 1" and 1.25" for the burning length. Cut them a bit longer than this. You'll have a guide to do the butterflying by for slightly more precise timings. I personally use crossmatch in my time fuse, but the theory is the same.

[ST1DinOH]

I'm glad everything got more or less figured out here.

 

I'd have to second the 1", 1.25" and 1.5" lengths. With butterflying the fuse, it should be less than you'd think. Even with a 1.5" fuse from end to end and no butterflying, you'll be fine with getting it to break in the air. It may be on it's way down, but it should still be up at a reasonably safe height. I've put up 3" shells with a 4 second delay, and they've worked fine.

 

One way to help with the precision is you mark off your lengths with a marker, say .75", 1" and 1.25" for the burning length. Cut them a bit longer than this. You'll have a guide to do the butterflying by for slightly more precise timings. I personally use crossmatch in my time fuse, but the theory is the same.

just for clarification...

 

if i were to make a batch of black match, and use short lengths for cross matching my time fuses, would that increase the lift - break time of no?

 

in other words is the blackmatch burn rate near instantaneous or is there a burn rate to calculate in. i ask because i've been ommitting the crossmatching and i've had no problems with butterflying. but at the same time i know there's more reliability in the crossmatching.

 

am i just fone butterflying the time fuse or should i be bothering with the blackmatch?

 

quite frankly the less work the better.

 

whiel we are at it, how much more reliable would butterflying the time fuse be if i were dusting the flared end with some sort of comp. i've had suggestion on dusting the end with flash, whistle, or meal. is there any bennifit in doing so or would the extra effort of crossmatching be better?

[Mumbles]

I personally like crossmatch for extra reliability. It adds no extra time to the fuse. The stuff lights very very easily as it is. While there may be an inch of blackmatch through the time fuse, all the hot lift gases will light every part of it nearly instantaneously. I've never simply butterflied the fuse, so I can't speak about it's reliability. I'd say stick to what works.

 

One thing I've seen people do is to brush a blackpowder slurry onto the end of the split. Often times this was done with NC lacquer for quick drying times, and no possibility of the water soaking into the core. Cutting the fuse on an angle, and doing the same thing is also commonly practiced. I think cutting the fuse on an angle compromises the precise timing though.

 

I don't think simply dusting it would really help much of anything. Dipping it in NC lacquer and then dusting it could help however.

 

The way I think about it is I've spent 10+ hours making a shell, I don't want the fuse to fail on me. That has happened once, and it sucked, though I think it was more of a fire transfer from the fuse to the burst type of problem. Regardless, I'd much prefer an extra 5 minutes to make a redundant ignition source. I'd much prefer to blow the stars blind, or flower pot the shell than have an ignition failure. I'd honestly feel much safer flower potting a shell than disassembling it.

[justanotherpyro]

It's all a gamble man. I can't really imagine a significant delay from the cross matching. The method I sometimes use is slathering the end of the time fuse with some wet BP.

 

Another thing that I have thought of that would almost guarantee ignition is to make a small baggie of dry BP using saran wrap and taping onto the end of the time fuse that is in the lift, but making sure that the fuse is actually in the powder and doesn't have a layer of plastic between it and the powder core. Sorry if this is hard to envision with my poor description.

 

At any rate it is more of a personal preference I think. I fired a shell the other night that was not primed and it took fire just fine, but again I don't think that cross matching will add a very noticeable delay.

 

*beat my be a few minutes Mumbles*

[ST1DinOH]

thanks for all the help guys. might give the cross match concept a go. doesn't hurt to add the extra insurance. i'm just a bit behind the 8 ball needing chems. not even sure which star formulas would be best to use...just trying to dial in the concept and go from there. along the way i'll give black match manufacture a try. there's a wonderfull tutorial on pyrouniverse on a back match machine. here's a link.

 

http://www.pyrouniverse.com/show/fusing/quickmatch.htm

 

the little plastic tub with the dowel rod in it is probably what i'd make to get me started.

 

sounds like a fun weekend project.

[Bayarea510]

st1 1st off all my 3" shells start off with about 1-1/4" time fuse. I do the butterfly fuse about a 1/16" on each side. I have been fusing this way now for over a year with well over 150+ shells with out any issues. I have turned many of others onto this way of doing the time fuse with out any issue again. I like the "keep it simple stupid" aka "kiss" method in things i do. A lot of people swear by priming the time fuse with the simple nc/bp dip...I have seen this done many of time also with out any issues. Again take what works for you and run with it! Hey mumbles 10+ hours? dude I would love to see what your doing all that time lol Most the time with pre made stars we can put together a nice 8" plastic shell in less then 20 mins We used 9 of our 5" shells this past Friday in a shoot and people loved out shells over the "store bought" ones lol

 

My 2 cents.

G