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6 Inches Shell With Strobe And Multibreak

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#1 MinamotoKobayashi



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Posted 13 September 2020 - 09:07 PM


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.



That's all!

Edited by MinamotoKobayashi, 13 September 2020 - 10:16 PM.

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#2 Zmuro



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Posted 14 September 2020 - 12:04 AM

Nevertheless, beautiful shell. It looks like your motors are to strong for 6" shell, but I guess the header itself didn't weigh 1,5kg. I like that you document every step of building process, which can be used as tutorial for others, so thank you :)

#3 kingkama



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Posted 16 September 2020 - 01:22 PM

Caotch formula, can you share?

#4 MinamotoKobayashi



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Posted 16 September 2020 - 04:25 PM

Hello Kingkama.

It's better that You ask him the formula by PM ...

#5 kingkama



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Posted 17 September 2020 - 02:00 AM

I cant find him

#6 Mumbles



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Posted 17 September 2020 - 08:04 AM

Try spelling it with a K.  "Kaotch"

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Just so you guys quit asking, here is the link to the old forum. http://www.xsorbit2....forum/index.cgi

The sky is my canvas, and I have 2,113 pounds of powdered paint in the workshop.

#7 kingkama



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Posted Today, 08:40 AM

I find but he doesn't want share,

so thanks to mumbles to the right spelling, i will endure on my mix with alcohol solvent and change some variables, to obtain a crakling and not a big boom (my mix works in 3x3 mm pieces but are suitable only for dragon flowers)

Edited by kingkama, Today, 08:53 AM.

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