Blue View - How a Fireworks Display is Synchronized to Music

Marcie and I were on the road over the New Year’s weekend and ended up spending New Year’s Eve in a hotel in Tallassee. There were some local celebrations going on, but we opted to watch 2022 arrive with a bottle of champers in our room, watching fireworks on the tube.

A few weeks ago, I wrote a blog on the anatomy of fireworks… how those fireworks are constructed, launched into the air and how they are timed to explode at just the right time. Watching the fabulous fireworks displays on TV reminded me, however, that what is still a mystery to me is how those massive fireworks displays are choreographed. How do they plan the display and synchronize every one of the tens of thousands, or in some cases, even hundreds of thousands of shells to explode at precisely the right point in the music? How long does it take to set up?

I do understand the basics. When I was a young man, I had the opportunity to volunteer with my town’s fire department in setting up a July 4th fireworks display. The process was simple, but tedious. The overall plan was to start with a barrage of shells to get everyone’s attention, followed by fifteen or twenty minutes of single shells, alternating between circular patterns, weeping willow displays, whizzing whistles, flashes with big bangs, fountains, etc. The finale was a hundred or so of every type, fired in quick succession – many almost simultaneously. Rudimentary by today’s standards, but not bad for a 1970s era small town display.

In total, there were probably 250-300 shells fired in the display that I helped set up. Since each firework shell had its own launch tube, the first step was setting up all those tubes. If I recall correctly, these were fiberglass tubes, capped on one end and arranged in wooden frames, called mortar racks, with each rack holding maybe 20 tubes. The shells were placed in the tubes in the order in which they were to be fired. Each shell had a fast fuse attached – similar to but much faster burning than those Black Cat firecrackers we used to play with when we were young - and then the fuse was draped over the end of the tube.

using fuse to time a fireworks display

Each shell was connected to the next shell using a fuse. The timing of the launch of the shells was controlled by the length and type of fuse attached to the shell’s fast fuse. Fuse material comes in several ‘speeds’… ranging from quick fuse that burns at a rate of about 0.2 seconds per foot, to slow fuse that burns at about 35 seconds per foot. So, if we wanted to fire several almost simultaneously, we could connect their fuses together with a few inches of quick fuse; if we wanted to fire one shell every ten seconds, we could use 5” of 24 second per foot fuse.

That was how it was done in the 70s and it is still done that way for smaller events. It’s just not possible, however, to plan and time the detonation of the shells precisely enough using this method to synchronize the fireworks display to music. Enter modern electronics…

Let’s start with firing modules, which connect to electronic ‘fuse igniters’. These are attached to and ignite each shell’s fast fuse electrically. A firing module may have one or up to dozens of individual fuse igniters. By sending an electronic signal to the firing module, one or any number of shells can be fired.

Control modules are the brains of the system. These send the commands to the firing modules that signal which shell or shells to fire. Communications between the control module and firing modules are usually wireless, and practically any number of firing modules can be connected to a control module. The control modules may have a number of buttons that can be manually pressed to fire the shells, but are more commonly software controlled.

Software is used to program the special effects and timing of the display. Suppose your display is being launched from the tops of several buildings on the Strip in Las Vegas in concert with a medley of oldies. At a particular point in the music being played, you want three shells to launch from Caesars, four from Paris, eight from NYNY, and three more from Ballys. You can’t possibly push all those buttons, so you need to generate the software commands to make it happen.

Audacity waveform

A very simple approach to generating the software commands is to use an app like Audacity to view the music waveform and an Excel spreadsheet to generate the software commands to control the firing sequence. Maybe during a soft passage during Beethoven’s Ninth, you want to display several weeping willows, or during the livelier sections of an Abba song, you want a dozen sequential fountains. You determine how many seconds into the music you want the particular effect to occur, make the appropriate entries in the Excel sheet, and add to the list of what shells are to be connected to which terminals of each firing module. (It’s slightly more complicated - depending on the type and size of the shell, it takes varying amounts of time from the instant the fuse is lit to the time the shell reaches its apogee and explodes, and this has to be considered when choreographing the display.) This method is straightforward, but quite tedious and error prone.

Excel worksheet for programming a control Module

There are also several software packages available that totally automate the process. These apps know, for example, the lag times, heights, colors, shapes and durations of most commercially available fireworks, and provide an animation of your show as you build it. Once the show design is completed, the software provides lists of connections, where each shell should be placed, labels for each tube, and a file with the software commands for the control module. Pretty cool!

There’s one more level of complexity if the fireworks display is to be synchronized with a live orchestra. Since the tempo of the music will likely be slightly different each time it is played, the fireworks display can’t be pre-programmed. In this case, the design of the different effects is done, and each effect is given a number. For example, suppose you want four horsetail waterfall shells fired simultaneously at a particular point in Vivaldi’s Four Seasons, and this happens to be the 24th effect of the program. You’d put the four horsetail waterfall shells into their launch tubes and connect the fuses to four fuse igniters. Then you’d program the control module to fire these four shells when given command #24. The display director would mark up a score of the music with the effects that should occur at different times. At show time, he’d then listen to the concert while watching the music score, and communicate to the fire control person when to send command #24 to the control module. Pretty complicated. If it hasn’t already been done, I’m sure it’s only a matter of time before the software becomes smart enough to follow the score and initiate each effect automatically.

Horsetail waterfall shells

Just to put things in perspective, for that half hour fireworks display I helped with 45 years ago, we hauled all the fireworks, launch tubes, fuses, fire extinguishers, etc. in a half ton pickup. The Sydney New Year’s Eve display required 18 shipping containers and weighed more than 8 tons. Our display took the better part of a day to set up, most of which was spent cutting and connecting all those fuses. The Sydney show took 15 months to plan, design and set up… they started working on next year’s show three months ago.

Have a sparkling week...