The Under $40 Rail Launcher

Brief:
After seeing an article on the world's simplest launcher in the February 2001 issue of High Power Rocketry and finding Matt's D.I.Y. Rail at www.railbuttons.com, I decided to combine the two budget ideas for "The Under $40 Rail Launcher." Unfortunately, the flying season in the Colorado mountains is over, so this budget rail will have to wait until spring for a full field test.

Design:
The basic design is a 4"x4" base supported by shelf brackets. A steel rod attaches to the rail section with bolts and wing nuts and then the lower part of the rod slides into the 4"x4" base. The rod is secured in the base by a horizontal eyebolt.

For storage or travel the rod is removed from the base and slides up the rail. Rocks or other heavy items can be used to anchor the legs in windy conditions.

Materials:
(1) 10" length of 4"x4"  
(4) 10x12 shelf brackets
(1) 1/4x20 t-nut
(1) 1/4x20 6" eyebolt
(13) #8 pan head wood screws
(2) 1/4x20 1 1/2" hex head bolts
(2) star washers
(1) 26" length of 1/2" steel bar
(2) 1/4x20 wing nuts
(1) McMaster-Carr 1" x 1" x 6' rail, #60585K41

Construction:
I decided to make my 4"x4" base 10" tall with a 1/2" hole drilled all the way through the center for extra stability. A 7/64" hole was then drilled perpendicular to the 1/2" rod hole for the t-nut and eyebolt which locks the steel rod in place. A #8 screw was used to secure the t-nut. I installed the shelf brackets offset to the right of center with the long sides down on the ground for a bigger footprint.

Next I used a drill press to drill two 7/64" holes in the steel rod. I cut my steel rod to 26" in length. The (2) 1/4x20 1 1/2" hex head bolts need a small bit of grinding on the hex head itself to fit into the rail channel.

I'm still waiting to find the right piece of scrap metal for making a blast deflector.

The McMaster-Carr 6' rail comes in a long and super stout paper tube. Freeing the rail from this container proved to be the most difficult part of the project. Once cut down to a reasonable size the container made a nice holder for threaded rods and wooden dowels.

Costs:
The most expensive item is the McMaster-Carr 6' rail at just over $20 plus another $10 for the shipping. However, this is one stout rail and should last for years. The remaining $10 of the $40 budget should get you pretty deep into the rest of the parts list, subtracting of course, the cost of parts that any good rocketeer might have lying around the garage.