Cascading Firework Comet Mortar Rack

Thanks to Geoffrey Kassin for this one.

"One summer, during the weekend following 4th Of July, some friends of mine who have a band were scheduled to play a private party. I furnished some flash pots, some small soup-can cremoras (fireballs), and about 80 Class C artillery shells. Everyone loved it.

Then at the Pyrotechnics Guild International convention in Fargo, North Dakota last August I saw the R.E.S. close-proximity display. WOW! I was inspired to try and figure out how I could do a similar show on a dime-store budget. I had about 400 1/2-inch diameter dragon egg (crackling) firework stars, about 300 3/4-inch emerald green to white flitter firework stars. The question was how could I fire them in precise, rapid succession? I do not have the money for 700 electric matches and thousands of feet of shooting wire; and I cannot get quick match. I lay awake in bed for many hours trying to think of a solution.

The solution for the tubing came quickly. I would use 1/2-inch and 3/4-inch I.D. schedule-40 PVC conduit (you could also use 1/2-inch ID cardboard tubes from Skylighter, a little safer than PVC). That solved the tube problem, but how was I going to fire them in precise, rapid succession? Friday night, I finally figured it out.

Saturday, I began building one short rack of 50 1/2-inch tubes. I went to Home Depot and bought two 12-foot lengths of 1/2-inch I.D., schedule 40 PVC conduits and one 12-foot long 1 x 3 maple board. (I chose maple, because it is hard, the surface is smooth and straight and I can get a good seal between two pieces of it.) I cut the PVC into 4-inch lengths. I cut the 1 x 3 in half into two 6-foot pieces. Next, I drilled a line of 47 13/16 diameter holes about 1.5 inches apart, all the way through one piece of 1 x 3. It’s important that all the holes be in a straight line. Using my Dremel tool and a sanding-drum bit. I slightly enlarged each hole enough so that I could glue each 4-inch length of PVC tightly into a hole. Once the glue dried, using the router base for my Dremel tool, and a slotting bit, I routed a slot 1/16-inch wide and 1/16-inch deep down the under side of the 1 x 3 mortar tubes base board. Now there was a 1/6-inch deep channel joining all the mortar tubes together. I then drilled a 1/4-inch diameter hole through the end of the 1 x 3 into the first mortar tube. I tightly screwed the blank 1 x 3 to the bottom of the mortar tube rack, so that the 1/16-inch channel was now completely enclosed.

Next, I loaded one gram of FG black powder into each of the mortar tubes, then dropped one dragon egg into each mortar tube on top of the powder. I then took the whole thing to a friend’s house that has a big front yard. I inserted an electric match into the 1/4-inch hole in the end of the board, all the way into the first mortar tube. I have a small electric firing system I made from radio shack parts. A length of visco fuse can also be used.

I hooked it up, pushed the button and 47 dragon eggs launched 30 feet into the air in about one second! It was beautiful. The fire traveling down the 1/6-inch channel from the black powder in the first mortar tube is enough to ignite the 2nd lift charge and so on.

Materials Needed
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