Wanted to do a little test comparing different boosters that I was interested in for bursting small shells. Here's the first 3:
KNO3 - 5 parts
S - 3 parts
Al - 2 parts
KNO3 - 3 parts
KClO4 - 3 parts
Al - 4 parts
KClO4 - 40
S - 20
Mg/Al - 25 (200 mesh)
Al - 15 (325)
For both the '5-3-2' and '3-3-4', Eckart 5413 was used and the Nitrate was only blade milled.
For Chinese burst, Mg/Al used was 80-200 mesh and Al was Eckart 120 (200-325)
These were used as boosters in small 1.4" canisters. The outer measurements were 1.4" diameter and 3" long. From what I understand this is not optimal, as you do not a canister to be much longer than it is wide. IMO this is immaterial for this test as we are only comparing bursts, not shell design.
Each canister was filled with:
10 grams BP
5 grams Burst powder
35 grams stars
7 grams lift
3 gram spolette
These were essentially bulk-filled except for around the spolette where some symmetry is inevitable in the design. The burst powder was mixed with the diaper method, and then the BP was added and diapered with it. The process of making all 3 canisters was followed to as close as possible, resulting in 3 shells within 1 gram of each other. The Chinese burst shell weighed 1 gram less than the other 2 after adding stars, which IMO is almost inevitable using a bulk fill method.
Main body is made from 3 turns of 60#, then 8 strands of spiking, then 1 more turn of 60#, then 1 turn of 20# computer paper.
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Titanium was added to each spolette for easy tracking. BP used was a slow ERC that I made; I messed up and got ash in my charcoal but I still decided to use it. Result was a much longer spolette time, almost double the norm. Lift (and burst) powder was douglas fir with 1% dextrin. The first mortar was destroyed but luckily I brought a backup for the last 2 shots. That's what happens when you use a salvaged spiral tube for over a dozen shots. I love masking tape.
Burst Test Part 1.mp4 9.41MB 53 downloads
The video for the 5-3-2 canister was taken from a different camera as my normal one failed for that shot. Sorry about the obnoxiously loud wildlife.
My personal thoughts here are that the 5-3-2 should be milled first (the Al being left out of course) and also I used slightly coarser metals than suggested for the Chinese Burst, resulting in a slightly slower reaction.
It should be noted that more confinement will have resulted in better results for the 5-3-2 and the Chinese Burst, but the point of this test was only comparing the power of each, not necessarily to get the best results from each.
Also, the 3-3-4 can be adjusted a number of ways to dial in what you want, let alone just simply using less of it. For instance, going 2-4-4 (2 KClO4, 4 KNO3, 4 Al) would give you almost all the oxygen with a little less speed. Getting the biggest burst isn't always the goal, so I do realize you should tune each burst according to the effect. I hope to be doing some more testing soon. Any input is welcome!
Edited by PhoenixRising, 04 June 2016 - 02:15 PM.