Designing a test shot shell?

[Smokelvr]

Tuning powder to tubes is a thing and I'd hate to burn actual Pyro, plus fuse is getting rare. So my idea, works on 3 fundamentals, while only burning replaceable black powder. Starting with a heavy cardboard tube of appropriate size (I have a 100? Feet of 1.25" PE natural gas pipe, 18-24 festival ball tubes, 12 2", 12 3", and I discovered that my 4" PE pipe is really 3.5" - so I still need to order some actual 4")

 

Using the cardboard tube with a heavy bottom bulk head as body/payload carrier, have an appropriately timed spollette running the center to a top cap that holds a bright streamer (like model rocket) use the extra room in the spollette to carry granulated smoke compound as an ejection charge. The top cap would be a cardboard disk lightly pressed into place.

 

My idea would be, you'd get a puff of smoke and a streamer, watching the streamer would tell you if it was apogee and help you locate it when it came down. The payload could be tuned to the average of whatever shell you are building by adding sand or such with the spollette removed for replacement.

 

Building a spollette is a basic skill, as is BP, and smoke is a simple variant of BP (I think a quick smoke/dirty BP would work best, instead of a slow smoldering one). Fuse it with black match and quickmatch to save on visco.

 

The goal something simple to construct in minutes that you can reset in about 60 seconds, by pulling the used spollette and putting in a new one with top (streamer etc.) Pre-bag the lift charges to the quickmatch with them clearly marked. It's as simple to reset as pushing in the spollette assembly and taping the lift charge on.

 

Thoughts?

Edited November 28, 2021 by Smokelvr

[Arthur]

Lots of tube is nominal size for the outside measurement. AFAIK the nominal size of the bore of the tube is the basis for all firework traditions (eg. 3" shell rides in a 3" bore tube the shell is slightly smaller).

 

If you live in a dry place, card tubes are fine for several shots, and cheaply available from all the usual supplers of pyro goodies. https://www.skylighter.com/collections/mortar-tubes-1 amongst others.

 

For dummy loads, be careful. The weight must be right and for larger items you don't want a big weight descending from your test altitude. If you include a burst charge then the descending pieces will do a lot less damage.

[Smokelvr]

That's the idea behind the streamer, slows the fall of bigger stuff and let's the test shell land soft enough to be recovered and reused like finned hobby rockets. I prefer fiberglass or PE tubes for larger stuff, was complaining because the stuff I salvaged and was so excited about... wasn't the bore the outside said.