20-shot Mortar Rack 

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Consumer aerial shell kits contain up anywhere from 6 to 100 shells, yet usually include no more than 2 mortars to launch them from.  That means you have to run out, put in a shell, light it, run back, wait for it to shoot up, then repeat the process.  Even with beautiful shells, this might get a little old after awhile, especially if you have lots of shells.  In professional displays, the pyrotechnicians use mortar "racks"; wooden frames that contain multiple mortar tubes.  By using mortar racks and quick match (or any fuse), you can ignite many shells in quick succession, creating a very exciting barrage of effects in the sky.  The instructions below will tell you how to build a 20-mortar shell rack of your own.

 

Materials

- (1) 2x8, 24" long
- (2) 1x8, 13.5" long
- (6) 1x4, 24" long
- (20) 12" HDPE tubes
- (~30) 1½" screws
- (20) 2½" screws

* Before starting this project, be sure to plug the HDPE tubes (as shown in this section)

 Begin by marking a centerline lengthwise down both pieces of 1x8.  Attach both pieces to the ends of the 2x8, as shown in the diagram.  Attach two 1x4 pieces between the two 1x8s - one on the bottom, the other on the top.

Begin placing the HDPE tubes on the base of the 2x8, up against the dividers.  Ten tubes should fit nicely on either side, with little room to spare..

Once the tubes are sitting on the base, add the last four 1x4 pieces as shown in the diagram.

Note: though the tubes should be held in place (pointing up), they can still be removed for cleaning or storage - this is how professional racks are built.  However, if you want to permanently attach the tubes to the base, put a blob of construction adhesive (like Liquid Nails) on the bottom of each tube (right on the plug), put it back into place, then insert long screws (2 - 2 1/4") from the bottom of the 2x8 base up into the plug of each mortar.  

If you are using fiberglass tubes, do not attempt to drill into the plug - either let the tubes sit loose in the rack, or put glue on the outside bottom of each tube and slide it back into place.

The rack is now complete.  If you want, you can purchase a couple metal drawer handles and attach them to either end of the rack - it will make it a lot easier to pick up and move around.

To launch 10 (or even 20) shells, place a long piece of quick match along the dividers and hot glue or tape it down.  Put a 4" leader of Visco safety fuse in the end of the quick match. Use a knife to make slits in the quick match paper wherever there's a tube.  Insert the desired number of shells, slide their fuses into the holes in the quick match.  Light the leader fuse and run.  The quick match will ignite all of the shell fuses instantaneously, and the shells will fire in quick succession (about 3 seconds).  If you want to slow it down a little, you can connect each shell fuse to a long length of visco.  Since the visco burns slower, the shells will fire at a rate of about one every 5 seconds.

Caution: You must stabilize this rack before setting off the shells.  There are several ways of doing so:

1.  Attach two 1' pieces of 2x4 lengthwise across the end (to increase its surface area on the ground).  

2.  As shown in the picture, you can use two cinder blocks to stabilize each rack - simply put a block on either side, allowing it to lay across the bottom piece of wood that holds the tubes in place.

3.  Place two eye bolts on each side of the rack - one near the top, and one near the bottom.  Then you simply slide some rebar through the bolts and pound it into the ground with a sledgehammer.  The rebar doesn't have to be very long, and you don't have to hammer it down until you can't remove it.  Several blows should do it- a couple more if it needs it.  The racks won't anywhere... (thanks to Chris Giuliano for the suggestion)

 

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