After a long pause I built my first 1,7KG multibreak 6" shell powered by a 400mm lenght BP rocket.
I used a reusable aluminum 30mm tube diameter, 2mm wall thickness, filled by a mix of classic 75-15-10 hot BP added with a 4% of phenolic resin,
slightly wetted with few grams of bio-ethanol 95°, pressed at 8000 PSI and dried for some hours in my electric dehydratator.
I done so to completely eliminate the fuel relaxation and to obtain a propellant hard like a stone.
The delay was made with the same mix plus 20% of 225-450µm Titanium sponge.
The hole was carefully drilled with a depth of 325mm and a diameter of 12mm with the help of a custom handmade tool
that permit me to make holes perfectly centered and parallel to the host.
With a conical cutter I also drilled a fake nozzle to create an enhanced exhaust.
First of all, gluing a lot of Titanium sponge with Titebound glue around the inner walls of the 2" hemises:
Half filling the shells with flash powder (Allen flash #3 formula) plus some grams of rice hulls, pasting it and creating crossmatched time fuses.
For this purpose I used some pieces of small fuses found inside a flat passfire fuses:
Placing the small 2" shells completely dried and hardened inside the two 6" hemises:
Placing a lot of small strobe stars (Shimizu formula) primed with Monocapa (replaced MgAl with German Dark and red gum with phenolic resin):
Filling the hemises with enhanced coated rice hulls (5 layers of hot BP and two layers of KP).
I wasn't able to use the classical tissue paper method due to the presence of the six 2" shells:
Putting a lot of dragon eggs (Kaotch formula):
Closing the 6" hemises and perfectly pasting them adopting the NeighborJ method:
Rocket finished and ready to be launched (it is indicated by the arrow ... the other rockets are already ready for the next 2021 LOL):
And finally the launch:
This firework was nice but had some issues:
1. Break too high, it appears too small for a 6" shell, dragon eggs not audible;
2. Two of the six 2" shells was not ignited, I dunno why because all the shells was made exactly in the same way and placed correctly.
Edited by MinamotoKobayashi, 13 September 2020 - 10:16 PM.