36 replies to this topic

[Bonny]

I have done the knot tying technique.

Some American firers in the past have used "Buckets". These are thin paper tubes about 2.5 inches long and 1 inch dia. These give a delay.


They are hard to explain but basically there are short lengths of match running along the length of a mortar rack between the shells. Where each shell leader comes out of the mortar tube one of these buckets is tied.

The match is tied into each end of the tube but an airspace is left so the flame has to flash over. This gives a delay. The shell leader is then poked through a hole made in the side of the tube half way along its length.

I haven't used this method but I believe that you can adjust the delay by changing the length of the "Bucket" tube.

I forgot to add that visco is sometimes used between buckets. This explains it far better than I can. Look about 2/3rds down the page.

http://www.pyrosocie...st=0#entry51491

I did try adding a diagram to this but it was pants when I submitted my post..

I've used 2 different types of fuse "chains". The chains come premade with buckets (open ended QM that you slide the shell leader(s) into) as stated above. I've never seen them used open to create a delay, but I'm sure it works as long as the QM doesn't get blown out of the bucket by the gases.

A straight chain is simply used to quickly and easily connect a set of shell leaders without any delay. It is premade with It is much easier than splicing and extending QM, as well as the fact that multiple shell leaders can be inserted into one bucket.

The other type is a "delay chain". The ones I've used are made for 3 sec delays between shells. They use a short pc of timefuse in between QM. I have tried to draw the idea below. All fuse is QM other than timefuse delay.

(Starting end) -----------timefuse delay-------------timefuse delay------etc...
l l
l l
shell #1 shell #2

Edit: My drawing didn't seem to work. I'm sure you get the idea, but shell#1 should join starting QM and shell #2 should join after 1st delay.

Edited by Bonny, 25 November 2008 - 08:33 PM.

[Mixologist]

The most "realistic" sounding way ive managed this was with a sequencer. It fires at 0.1 sec intervals... i made all the leaders the same length, obvious problem with it is the cost of every det!!

Im now off to try both of these techniques!!!

[Spyrotechnics]

you don't see the method in the video you posted, just the results. From what you posted it sounds like the same method however experienced a faster firing, 4 or more shells a second

[karlfoxman]

Hello folks,

Ill get my friends in Malta to give me some info on the way they do it. I have fired some batteries of 3 + 4" beraq shells while I was there. Its done in bundles as far as I remember.

Edit:

Not spoke to Maltese mates yet but have a photo of the shells, and they are called Kaxxa. Most are Beraq or Colour shells.

http://pyroreports.c.../factory17.html

Edited by karlfoxman, 20 November 2008 - 06:10 PM.

[teaboy]

I'd be interested to know how reliable this method is. Personally I'd ALWAYS join QM to QM, and 'ripple' things with a gaffa-taped 's' bend.

[Arthur Brown]

Actually I'm not happy about having sequential fire from one cue ignition. If a rack were to fail and some more shells fire in the order the tubes fell over to.....

[Mixologist]

With this speed of firing.... do you think the shells would have left the affected tubes before they fell into a potentially critical angle? 0.1sec a shell...?

[pyromaniac303]

I'd imagine from the force of a shell flowerpotting a lot can happen in 0.1s, but the good news is that the quickmatch leaders would be ripped from the rest of the chain as the remaining filled mortars are scattered, so the sequence should stop firing.

[Bonny]

I'd imagine from the force of a shell flowerpotting a lot can happen in 0.1s, but the good news is that the quickmatch leaders would be ripped from the rest of the chain as the remaining filled mortars are scattered, so the sequence should stop firing.

I think if the leaders were assembled in a chain, a flowerpot would not likely stop the sequence.

[karlfoxman]

Ok after speaking to one of my friends from Santa Marija, not Mqabba. The way the Kaxxa are fired is as follows:

They have a string of shells only 4 or so matched with a bucket, the these go into a row of tubes. You place all the shells like this in the row of tubes. I have fired a row of about 200 3" shells. The fuse used to link them is quickmatch and the match is folded twice and string used to tie it. Much like already mentioned. This is the way both Santa Marija and San Guzepp fuse the Kaxxa. This is the known way of doing it. I also asked if the Kaxxa had any accident rate, he told me know nothing ever went wrong (that he can remember or knew of) Sometimes a flowerpot but nothing like tubes falling over. This did not interupt the firing I guess due to the use of buckets on the 4 or more shells.

Here are some links

http://uk.youtube.co...h?v=JpuOeuyycYI

http://www.stcatheri...2666_normal.jpg

[Spyrotechnics]

Actually I'm not happy about having sequential fire from one cue ignition. If a rack were to fail and some more shells fire in the order the tubes fell over to.....

interesting, so you would always have a full rack firing at once, no use of delays, pyroclock etc??

[Arthur Brown]

NO! I'm very cautious about delays lest a rack failure leads to a random spray of shells, BUT separate igs in devices seems preferable to me. Delays may be OK in some situations but are they the safest way of doing the effect is the use of delays insurably safe.

I've even been mulling over a rack design with a connector box and using a foil tape (window alarms!) to detect structural failure, and break circuits should the woodwork disintegrate.

One day I'll find a happily insurable, risk reduced, way of running a profitable display company.

Til then the maxim from the airline industry seems OK:- If you think safety is expensive think of the cost of an accident. I suspect that for most of us the first accident will also be the last due to the cost of insurance cover.

Edited by Arthur Brown, 26 November 2008 - 10:08 PM.

[teaboy]

The trouble is, Arthur, you get to the stage where you're only using Mortar Tubes once, and individually securing them well away from all other tubes. This will, granted, make things safer, but it isn't economically viable let alone profitable! I wouldn't fancy crewing a show where some much time and effort are required (usually in the rain, if this year's anything to go by!!). You'd also need a large capacity electrical-firing system and it'd eat igniters like there's no tomorrow.

I agree we should ALL be striving to improve safety, but eventually you find the 'safest' option is not to use fireworks at all.

[Night Owl]

If theres a failure of say a rack of 10 shells on ripple effect timed with electrics of 0.2 of a seconds each I doubt there would be enough time to pull the plug!

As teaboy says its not vaible to use seperate tubes or build B--- proof screens and the like!

Edited by shell shooter man, 28 November 2008 - 05:49 PM.

[Arthur Brown]

True it's impossible to be perfectly safe, but things that improve safety may be of increasing importance.