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When you've got a firework with hundreds of little flammable bits inside making the star pattern, how do they all get ignited? Does the center fuse ignite some

When you've got a firework with hundreds of little flammable bits inside making the star pattern, how do they all get ignited? Does the center fuse ignite some main charge, which through heat and expansion ignites the rest of the bits? I mean, the puzzle to me is that the parts are not all connected by fuses, so how do they go off?

celticninja 6y ago
Read the article, explains it and shows cross sections of fireworks to aid understanding.
- supernova87a 6y ago
  Yeah, I saw that photo, and thanks. But it didn't really explain to me how pieces of disconnected carbon ignite each other without some physical link. Unless somehow the inner particles create a cloud of fire that ignites the larger balls? That's the part I'm not getting.
  - 1123581321 6y ago
    I agree the article doesn’t really explain it. The short answer is the burst from the shell generates enough heat to ignite the payload (the stars) before they’re blown out into the sky. No fuse is needed because the payload is flammable enough to ignite but not so flammable that nothing interesting is seen from the ground. That sounds like a cop-out but it’s why designing fireworks is a science and art. :)
  - hdjrklt 6y ago
    The photo seems to show a layer of the same material as the exploding core between the layers of spheres. I presume it's gun powder.
  - Sharlin 6y ago
    The purpose of gunpowder is to burn rapidly. Burning generates a lot of hot gas that tries to expand. The bomb's physical shell, along with the inertia of the stars, resists the expansion for a brief moment, creating pressure that's used to propel the stars away at high speeds, but also ensures that the burning gunpowder charge has time to ignite the stars before they fly away.
    - nijaru 6y ago
      Gunpowder is meant to burn at controlled rates, but traditional gunpowder, black powder, used in fireworks and older firearms typically burns very quickly. Smokeless gunpowder for modern firearms have controlled burn rates. Depending on barrel length, etc. you may want the gunpowder to burn faster or slower to affect the ballistics. I imagine they use certain ratios of differing ingredients to control the rate of burn in fireworks as well.
      - mirimir 6y ago
        Burn rate for black powder depends on particle size. Fine powder burns faster than coarse powder. So one characteristic of high-quality powder is uniform particle size. But yes, changing the formulation also affects burn rate. For example, replacing potassium nitrate with potassium perchlorate yields a much faster burn.[0] Also replacing the carbon with aluminum dust gives you flash powder.[1] 0) https://pyrodata.com/compositions/Black-Powder-Perchlorate https://pyrodata.com/compositions/Black-Powder-Perchlorate 1) https://pyrodata.com/composition/flash-powder https://pyrodata.com/composition/flash-powder
pengaru 6y ago
Everything is coated with highly flammable powder, so they have no trouble igniting from the burst. It's a challenge actually to prevent everything from igniting prematurely. Especially with mortars, since they're propelled out of a tube with an explosion that can compromise the shell, igniting its contents immediately rather than up in the air as intended. If you've ever seen a public fireworks display where the stars exploded awkwardly close to the ground instead of way up with everything else, it's likely because the explosion for thrusting it into the air managed to ignite the contents instead of the delayed fuse.
- sandworm101 6y ago
  >> they're propelled out of a tube with an explosion that can compromise the shell I've always wondered why large fireworks use explosive 'lifting charges' rather than a proper rocket design (slower burning fuel). Is it a legal limitation against creating missiles?
  - amluto 6y ago
    I haven’t done the math, but I would assume it’s more efficient. Ignoring drag, if you launch out of a tube, you don’t need to carry any of your fuel with you, and, at least for very subsonic muzzle velocities, you might be able to arrange for the pressure in the barrel behind the shell to be near atmospheric when the shell exits. In other words, most of the launch charge energy could actually go to kinetic energy of the shell. In contrast, rockets are very inefficient. Except in the special case where the exhaust velocity equals the rocket’s velocity, a large amount of the engine’s energy ends up as kinetic energy in the exhaust.
  - s1artibartfast 6y ago
    This is partially addressed by the article: >Simple stick stabilized rockets work out well for small pyrotechnics, but don’t scale well. If you want bigger bangs and larger bursts in the air you need to get more payload up there. A larger rocket, with a few pounds of excitement at the front end, would require a stick 20-30 feet in length; not very practical. En essence, rocket like designs are less stable, less predictable, and more complicated. It is hard to have something simpler and cheaper than a ball.

celticninja 6y ago

Read the article, explains it and shows cross sections of fireworks to aid understanding.

supernova87a 6y ago
Yeah, I saw that photo, and thanks. But it didn't really explain to me how pieces of disconnected carbon ignite each other without some physical link. Unless somehow the inner particles create a cloud of fire that ignites the larger balls? That's the part I'm not getting.
- 1123581321 6y ago
  I agree the article doesn’t really explain it. The short answer is the burst from the shell generates enough heat to ignite the payload (the stars) before they’re blown out into the sky. No fuse is needed because the payload is flammable enough to ignite but not so flammable that nothing interesting is seen from the ground. That sounds like a cop-out but it’s why designing fireworks is a science and art. :)
- hdjrklt 6y ago
  The photo seems to show a layer of the same material as the exploding core between the layers of spheres. I presume it's gun powder.
- Sharlin 6y ago
  The purpose of gunpowder is to burn rapidly. Burning generates a lot of hot gas that tries to expand. The bomb's physical shell, along with the inertia of the stars, resists the expansion for a brief moment, creating pressure that's used to propel the stars away at high speeds, but also ensures that the burning gunpowder charge has time to ignite the stars before they fly away.
  - nijaru 6y ago
    Gunpowder is meant to burn at controlled rates, but traditional gunpowder, black powder, used in fireworks and older firearms typically burns very quickly. Smokeless gunpowder for modern firearms have controlled burn rates. Depending on barrel length, etc. you may want the gunpowder to burn faster or slower to affect the ballistics. I imagine they use certain ratios of differing ingredients to control the rate of burn in fireworks as well.
    - mirimir 6y ago
      Burn rate for black powder depends on particle size. Fine powder burns faster than coarse powder. So one characteristic of high-quality powder is uniform particle size. But yes, changing the formulation also affects burn rate. For example, replacing potassium nitrate with potassium perchlorate yields a much faster burn.[0] Also replacing the carbon with aluminum dust gives you flash powder.[1] 0) https://pyrodata.com/compositions/Black-Powder-Perchlorate https://pyrodata.com/compositions/Black-Powder-Perchlorate 1) https://pyrodata.com/composition/flash-powder https://pyrodata.com/composition/flash-powder

pengaru 6y ago

Everything is coated with highly flammable powder, so they have no trouble igniting from the burst. It's a challenge actually to prevent everything from igniting prematurely. Especially with mortars, since they're propelled out of a tube with an explosion that can compromise the shell, igniting its contents immediately rather than up in the air as intended. If you've ever seen a public fireworks display where the stars exploded awkwardly close to the ground instead of way up with everything else, it's likely because the explosion for thrusting it into the air managed to ignite the contents instead of the delayed fuse.

sandworm101 6y ago
>> they're propelled out of a tube with an explosion that can compromise the shell I've always wondered why large fireworks use explosive 'lifting charges' rather than a proper rocket design (slower burning fuel). Is it a legal limitation against creating missiles?
- amluto 6y ago
  I haven’t done the math, but I would assume it’s more efficient. Ignoring drag, if you launch out of a tube, you don’t need to carry any of your fuel with you, and, at least for very subsonic muzzle velocities, you might be able to arrange for the pressure in the barrel behind the shell to be near atmospheric when the shell exits. In other words, most of the launch charge energy could actually go to kinetic energy of the shell. In contrast, rockets are very inefficient. Except in the special case where the exhaust velocity equals the rocket’s velocity, a large amount of the engine’s energy ends up as kinetic energy in the exhaust.
- s1artibartfast 6y ago
  This is partially addressed by the article: >Simple stick stabilized rockets work out well for small pyrotechnics, but don’t scale well. If you want bigger bangs and larger bursts in the air you need to get more payload up there. A larger rocket, with a few pounds of excitement at the front end, would require a stick 20-30 feet in length; not very practical. En essence, rocket like designs are less stable, less predictable, and more complicated. It is hard to have something simpler and cheaper than a ball.