Ratio on how much lift to use in a shell

[Bgreen]

Hey guys I was wondering if any one had like a rule of thumb on how many grams of lift to use per how many grams a shells weights? Ik it all depends on how good your lift is made an how high you want it. But is there a formula you guys like to use or are you guys just winging it hahaha

[PyroManiacs]

General rule of thumb is 10%.

[PyroJoeNEPA]

Ditto on what PyroManiac said----10% for ball shells up to 8". Larger than 8" has a few "tweaks" involved for height, break, etc. Cylinder shells are completely different. What size/type shells [ ball or cylinder] are you building or planning to build?

[Bgreen]

I'm going to start off with 1.75 ball shells an work my way up. When I was younger I experimented with shell building but was like I said I was young an impatient an realy didn't appreciate the art or put forth much effort. But now I catch my self watching a shell an saying man that was cool. So yea I'm going to start off small an then work my way up. And the few can shellsbi ever tryed allways failed... now like insert sized one id 9/16 5/8 3/4 I never had a problem with but every can shell I made that was a shell not an insert blew up in the tube making one hell of a mine effect lol but yea any tips on can shells?

[Kenny East]

When building cans, you want a very tight spiking to hold it all together... Also try fusing them on the top with several discs of cardboard separating the lift and the shell... .. I usually air more on the ratio of 11% total shell weight, kinda depends on your lift though, as well as shell size, type, and how well your shells fit your mortars... My first shells cato'ed, take your time, do a good job on the construction and don't skimp on the glue around the time fuse.

[vegassalute]

It was helpful for me to use the baseball test. E-fire a baseball out of a 3" HDPE mortar. If you don't have an electronic firing system you can always light it with a long piece of visco. If you achieve 7 seconds of flight you're on the right track with your BP formula.

[Bgreen]

My friend was telling me that's how he did it also. I'm thinking using a golf ball in a dr11 tube to scale it down thank you for the response

[PyroJoeNEPA]

In a smaller ball shell you will want a finer grain of BP--typically 4FA. In 3" & up you will use a larger grain size--2FA. Most times the shell flowerpots it is like Kenny said--the glue around the time fuse is the weak link. Make sure you have a good seal around the time fuse inside & outside of the shell. I don't do 1.75" shells anymore--except for Lampares....but if you are doing 1.75" ball shells make sure you have a good tape paste overall. On my 3" shells I use a small piece of PEX tubing [3/8" for an outer collar around the time fuse filled with hot glue & then pasted over. Haven't had a flowerpot since I started doing that a couple years ago. Prior to that there were some nice "mines". LOL. Hot glue can have air bubbles that open up from the heat of the lift gas & cause a pass thru to the shell causing a flowerpot. So many little "tricks" to pick up on. Let us know how things progress.

[Kenny East]

I may try the pex tubing for a fuse collar... I usually roll craft paper around a dowel rod for a similar fuse protector. That and a good amount of high temp gorilla hot glue