Double lift shell system for max lift.

[TheSandmanIsMe]

Let’s think of a 4” aerial shell, in a 46” tube. For best lift height with a single BP lift charge. Your looking at maybe 600” tops. I’ve been thinking about, why not 1,000’ or higher?
For a single lift charge, in a 46” tube, without destroying the shell, your limited. What if.....lol....there was a secondary lift charge that went of a fraction of a second after the first? The first charge would put the shell at a measured velocity, at a measured fps, correct?
Lets make the tube 80” now. And let’s place the shell on its way up after the 1st charge, about 40” up the tube. At that millisecond let’s have a secondary lift charge, of perhaps flash powder velocity kick in. The shell is already accelerating at high speed. Another ‘kick’ wouldn’t destroy the casing, but rather increase its velocity. Yes?
So, a second lift charge, of greater force than the first, would only shift the velocity into warp speed compared to nominal. Theoretically, this looks good on paper, gonna be experimenting with digital firing system to get the fractions of seconds right with the lift charge compositions. Anyone ever heard of this thought before? I think it’s the future of lifting fireworks higher than they have been before. But I could be wrong, probably am. But I haven’t seen or heard of anything like this before. Have you?

[Fulliautomatix]

Based on the 600' altitude, I assume you're talking about a 4" diameter display shell (1.3).

Just curious, what is driving the desire to get the shell another 400'+ of altitude?

I think what you're suggesting could likely be accomplished with slightly less complication of double ignition by looking at a lift charge that burns a slower than black powder. With a longer tube (and tighter shell/tube fit) the lifting forces pressure would be able to act upon the shell a longer time giving it more velocity and max height. This is commonly done in firearm cartridges. Short barrelled firearms typically use a very fast burning powder because there is only a very short time that the expanding gasses can act on the projectile to get a specified velocity. In longer barrel rifles, powders burn more slowly to allow the projectile to accelerate while having the expanding gasses continue to push all the way to the end of the barrel... achieving maximum desired velocities without having extremely high pressures which would likely require an extremely strong chamber/action (or be blown apart.)

[Arclight]

You can also get slower-burning black powder (i.e. cannon grade) and compress the charge tightly in the gun. Smokeless powder can develop a lot more pressure and usually isn't recommended for cannons or signal/pyro stuff.

[PyroJoeNEPA]

Not to burst your bubble---but a 4" shell breaking at that height would look like a 2 1/2" shell in the sky. The average burst/break heights have been experimented with for many, many years. Optimum distances have been settled on.Getting them any higher will not have any practical advantage.....Soooooo-the question is "Why would you want to?"
Brocades are timed to break just before their apogee, horsetails just after their apogee, and peoneys, chrysanthemums, and rings, hearts, smiley faces, etc. right at their apogee.

FYI--Disney uses compressed air to project display shells into the air & altimeter chips in the shells to ignite the break charge. I saw the "launchers" many years ago on a "behind the scenes" tech tour in Florida. Back then they said it was to eliminate smoke and increase "shell placement" precision. I recall reading somewhere that Disney Florida is back to using BP lift, and only using the air canons in CA. I may be wrong---anyone have any input on this? Rick?

[Fulliautomatix]

FYI--Disney uses compressed air to project display shells into the air & altimeter chips in the shells to ignite the break charge.

Wow, talk about adding a level of complexity! Integrated circuits and ignition systems onboard the shells. I guess why not, the tech exists, I know the military uses grenade launchers that can be programmed for distance so they can detonate on either side of a barricade at the operators need.

So now instead of smoke they're throwing electronic circuitry and I assume a stored energy device (battery/capacitor). I can certainly see the value of reduced smoke though.