to bring the speaker off-board and let it reach the
panel (Figure D).
Connecting four 22-gauge ground wires, all
soldered together in parallel to the heavy grounding
wire, splits the load (Figure F).
Panels and Wiring
The central control panel is built into a 36"× 11"
Lexan panel with two 9"× 6" triangles cut from the
top corners and reattached with angle brackets to
make a standing base (Figure E). The 2 side firing
panels were built into 5"× 30" Lexan strips, each
connected to the console by a 4-pin harness.
I used small zip ties to bundle wires together
throughout. Be sure to check the switch wiring
with a voltmeter prior to soldering.
Power for the system comes from a big 12V
battery that sits behind the control panel. With a full
charge, this 230-cold-cranking-amps battery lasts
well past 200 ignitions. To connect it to the circuit,
I used lamp cord and medium-sized clamps to grab
the battery terminals.
For easier storage, I used a 10-wire connector for
detaching the cable to the launch bar, and two 4-pin
connectors ( 3 launch, 1 ground) for disconnecting
the wire bundles leading to each side launch panel.
The 14-gauge launch bar grounding cable also
detaches via a 4-pin connector, in order to prevent a
current bottleneck at the disconnect point.
The launch bar is straightforward. To elevate it,
I built 2 foldable sawhorse legs using 2× 3 lumber,
a hinge, and a triangular piece of plywood. One side
of the triangle is fixed to one leg with wood screws,
and the other is drilled out for a removable nail, so
the legs can be folded for storage (Figure G).
The launch bar itself is an 8-foot 2× 6 board with 10
individual pads consisting of a metal outlet plate for
the blast shield and a 1"× 3' steel rod for the launch
rod. I used a drill press to set 1" holes 9" apart on
the board for each rod, and drilled 6" holes through
the plates to let the rods pass through. You could use
construction adhesive to glue the rods into the holes
and glue down the plates (Figure H), but I left them
unglued for easy storage and transport.
To allow pivoting of the launch bar for wind adjustments, I cut the heads off 2 large 13mm bolts, then
drilled the launch board ends and glued in the bolts.
The bolts pass through holes at the top of each
sawhorse triangle, secured with wing nuts on the