countryboy7978 Posted June 3 Posted June 3 For those who have actually had success with Bombette type shells made from spiral tubes, what ratio of lift to weight of finished device do you use? There would be a 1/4" punched disk between the lift and the shell.
Mumbles Posted June 3 Posted June 3 This will require some trial and error based on your actual BP, but I find 10-15% of the shell weight a pretty decent starting point. I've heard of people using upwards of 20 or 25% though. It probably comes down to whatever BP they were using, and the exact effect or height they were looking for. With bombettes and things like that, 10 or 20% is probably only a difference of a few grams. I would use something finer grain like 2Fg (-16+30 mesh) or 4FA (-12+20) or even a little finer. I personally have had more consistent results using finer grain powder as it builds up pressure more readily in my experience
countryboy7978 Posted June 3 Author Posted June 3 Thank you. I always figured in a bit over on the 10%. Without a disk the height the inserts reach tends to be lower. I like a bit more height so the inserts break on the way up rather than the way down. The lift powder would be commercial Goex 4fa. The inserts weigh 37-39g. The timing is 2.25 seconds lift to break using punched time fuse with a dragon egg report as the effect.
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