Michael JensenFirework Displays
May 28th 2009 00:56
Like I promised, I visited Disney and decided what to post on. Since I love fire and explosions, the obvious choice is fireworks. This may not seem like typical "engineering", but once you think abut it, you can see that pulling off a display is quite an engineering marvel. But I will try to cover a more "common" engineering feat, such as a roller coaster, later. I have seen Disney's firework displays before, and they are quite impressive. But how do they work?
Let's start with the actual firework shell. A very basic, typical ariel shell is a container made of cardboard or the like, with a tube in the middle filled with black or flash powder. Around this is stars, pea or dime sized circles or cubes made of a sparkler-type material. Filling in the space between the stars is more black powder to help ignite them. In professional displays, these shells can be about the size of cantaloupes.
The shells are launched out of large metal cylinders anchored to the ground. A propulsion charge of black-powder is either built into the shell, or inside the pipe itself. If it is built into the shell, when the fuel ignites, the hot gas expands and is forced through a nozzle creating thrust. If the powder is inside the pipe, it launches the shell like a cannon, shooting it violently out of the pipe.
When the propulsion charge ignites, it lights an internal fuse which is timed to explode the bursting charge right at the apogee of the firework's flight, sending the stars flying. The bursting charge in turn ignites the powder around the stars, which helps light the stars themselves. This creates a beautiful flower-like shape high up in the sky, the color of which can be varied based on the chemicals used in the stars. Shapes can actually be made by creating an outline in stars inside the shell, then with the proper fuses and ignition timing, the stars will form a colorful figure in the sky.
The tubes holding mortars can be arranged in all sorts of patterns, then, in professional displays, hooked up by wire to a computer that controls the sequence in which the fireworks are launched. In this way, amazing shows can be choreographed with music to create a spectacular event well worth watching.
So next time you see a firework display, be it on New Years or Forth-Of-July, or any time, just remember how much science and work went into every one of those beautiful exploding flowers you see.
Let's start with the actual firework shell. A very basic, typical ariel shell is a container made of cardboard or the like, with a tube in the middle filled with black or flash powder. Around this is stars, pea or dime sized circles or cubes made of a sparkler-type material. Filling in the space between the stars is more black powder to help ignite them. In professional displays, these shells can be about the size of cantaloupes.
The shells are launched out of large metal cylinders anchored to the ground. A propulsion charge of black-powder is either built into the shell, or inside the pipe itself. If it is built into the shell, when the fuel ignites, the hot gas expands and is forced through a nozzle creating thrust. If the powder is inside the pipe, it launches the shell like a cannon, shooting it violently out of the pipe.
When the propulsion charge ignites, it lights an internal fuse which is timed to explode the bursting charge right at the apogee of the firework's flight, sending the stars flying. The bursting charge in turn ignites the powder around the stars, which helps light the stars themselves. This creates a beautiful flower-like shape high up in the sky, the color of which can be varied based on the chemicals used in the stars. Shapes can actually be made by creating an outline in stars inside the shell, then with the proper fuses and ignition timing, the stars will form a colorful figure in the sky.
The tubes holding mortars can be arranged in all sorts of patterns, then, in professional displays, hooked up by wire to a computer that controls the sequence in which the fireworks are launched. In this way, amazing shows can be choreographed with music to create a spectacular event well worth watching.
So next time you see a firework display, be it on New Years or Forth-Of-July, or any time, just remember how much science and work went into every one of those beautiful exploding flowers you see.
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