You have not lived until you've shot a spud into escape velocity. I launched my first spud in 2005 and went big right from the start.
The first design, the Boom Stick, is strictly no-frills. It sports a 6 foot length, 2" diameter Schedule 40 PVC barrel, end chamber screw cap, and the classic barbeque ignitor switch. Approximate cost of construction: 40$, and 3 hours labor.
Despite its disregard for ergonomics, and general lack of flourish, the Boom Stick makes up in bang. During live artillery testing, the field pictured above lies almost entirely within its range of destruction. The fuel of choice is AquaNet hairspray, which excels not only in affordability, but also in price and fragrance.
This design has a major flaw. In order to ignite the AquaNet fumes, the barbeque ignitor must generate an arc between two ordinary screws installed through the wall of the combustion chamber. With use, these screws corrode, or become covered with hairspray.
Although it is fun not knowing just when "she's gonna blow", predictable operation is preferred for safety reasons.
The Boom Stick currently lives in Epsom, NH, maintained and routinely operated by my friend Scott. Some interesting facts:
- A Vaseline coated dill pickle has been shot out of this cannon.
- A grade stake has been shot 200 yd into stadium seating with this cannon.
- Fireworks have been shot out of this cannon.
- A serious (very) injury has resulted during operation of this cannon.
- This cannon has shot a potato through a shed.
- This cannon contributed to the eviction of a friend from his house.
The next cannon: The Boom Stick 3000, was a major performance upgrade, although still plagued by the intermittent ignitor. Basically, the barrel diameter was stepped down to 1.5" Schedule 40 PVC, and the combustion chamber was enlarged by at least 30%. Some creature comforts were incorporated, including a front mount "street sweeper" handle, rear grip, and sling.
Believed to be completely unsafe, this cannon was not shot for almost two years after being constructed. The narrow and long barrel may not prevent adequate pressure venting for such a huge combustion chamber. Around Christmas of 2011, and reinforced with strap clamps and duct tape (in case of shattering), the Boom Stick 3000 was launched.
With initial ignition difficulties (this used the same faulty design as before), a myriad of different fuels were tried: Deodorant, brake cleaner, starter fluid, etc. Eventually, poor wiring was replaced and AquaNet was reinstated.
The design is more compact and theoretically, more tuned for generating higher potato velocities. This fact has yet to be proved beyond a reasonable doubt. However, the Boom Stick, I believe, is still favored for its unmatchable shotgun-like boom.
The Boom-Stick 3000, if nothing else, is easier to load, easier to hold, and due to its smaller diameter barrel, can shoot all the small potatoes in the average grocer's bag. Potatoes are not cheap, and a smaller barrel can pay for itself in time.
In honorable mention, a potato cannon so unthinkably large was one created in my presence by my friend, who, in a Frankenstein-like rage, sought to build a cannon-to-end-all-cannons-. This particular cannon was over 12 feet long, the combustion chamber is shown above. Upon completion, and realizing its destructive capacity was too great, it was set aside in a barn. Later that year, perhaps in an act of God, the barn was collapsed by a heavy snow and the cannon was never found. Thank God.
In the early January of 2011, I helped my friend set out upon his brainchild. It was a cannon incorporating all the technological spoils of modern day: propane, pressure gauges, extreme high voltages, and quick release couplings. If executed properly, this would be the Boom Stick upgraded to a reliable ignition system, metered and clean fueling, and quick reloading. For everyday carrying purposes, the cannon would disassemble into shorter sections, and reassemble quickly.
The fueling system was simple. Ordinary propane fills a storage chamber to a predetermined pressure and is held by a ball valve. During potato cannon reload, the storage chamber releases its contents into the cannon's combustion chamber via a regular Shrader valve. It is quick and clean.
The electrical system was also simple. A 50,000V taser was taken apart and soldered to screws which penetrate the combustion chamber wall and approach each other in the propane environment. A series connection results in three individual 1/2" arcs inside the chamber, thus maximizing the chance of combustion.
A quick-release pipe fiting (banjo fitting) between the chamber and the barrel allowed for easy reloads, and no tamping whatsoever. This is the best feature. In order pass the potato, the banjo fitting must be at least equal diameter as the barrel itself. We used a lathe to bore out the ID.
Here the cannon is modelled, aptly named the Moon Raper. Initial test runs took place during the NH winter and temperature fell to the low 20's F. We had some difficulties during initial firing tests in generating desired pressures. There are suspicions that the storage chamber is undersized relative to the combustion chamber. I have since got word that improvements are underway and a performance report will be available soon.