How to estimate entire length of time that it will take to shoot 10 shell rack

[buckeyepyro1]

I'm trying to choreograph a show and need length of time for a given effect to get timing right.

I have a 10 shot mortar rack. I'm using 10sec/foot fuse as lead fuse. The the canister shells have approximately 1 foot of the green visco fuse each leading to lift charge. I will be daisy chaining these fuses to the leader fuse with tape.

I presume that if I use 2 feet of the lead fuse going 10secs/foot, then I would take 2x10sec/ft=20sec PLUS the time it takes for the last canister to ignite which would be approx 25 secs since it is green visco fuse and 12 inches length total to get to its lift charge, and green visco burns at 25secs/foot.

Therefore, entire effect would take 20sec PLUS 25sec=45 secs in total.

Is my math correct?

[BMoore]

You are thinking correctly but lots of variables to consider:

1) The fuse on the last canister shell is not going to take 25 seconds. They average about 6-7 seconds but you'd need to test one of the same shell to time it. Just because it's green doesn't mean it's slow cannon fuse.

2) When taping fuse to your leader, the overlap is always going to burn at the rate of the faster fuse which could speed up your 10sec/foot slightly.

3) Are you trying to time for the lifts or the breaks? If it's the latter, you need to consider the lift time for the shells you are using.

4) Fuse timings can vary from batch to batch. Always best to test a section to figure out exactly what timing you have. Things can start changing in the field as well with humidity levels, etc.

In short, trying to choreograph with fuse is never going to be perfect. Sometimes close enough is good enough for what you are trying to do, but if you are really trying to precisely time affects, you may want to consider a firing system.