Burnt Latke
miniL1 launcher
1/2 size launcher

Miniature potato guns, most spud gun enthusiasts build at least one. Minis make a perfect second or even first project because the smaller PVC fittings are affordable and widely available. Building a reliable mini requires the utmost precision regarding the fuel mixture. The smaller volume combustion chambers fill quickly, often producing a mix which is too rich to ignite. Spray propellants like Right Guard are difficult to use in this respect. Frequent misfires and 'lower than expected' performance forces many of these minis into an early retirement. Despite this, it is possible for a mini to fire consistent and powerful rounds every time, with the proper setup and a little planning.

Mini spud guns are usually designed as handhelds to be used in the field. BurntLatke's miniL1 was created as a test bed for future designs. The miniL1 is one half the size of the L1 launcher but the 360cc chamber is less than 1/4 of the L1's chamber volume. The small size of the miniL1 allows for manageable indoor testing , fuel savings, smaller ammunition and unheard of barrel extensions. Successful modifications can then be implemented into the expensive full size launchers. Despite it's test bed origins, the miniL1 is a well balanced, portable handheld.

complete setup
side view

The miniL1 was fitted with direct injection to control the minute amount of fuel needed. It was necessary to upgrade to a pressure gauge with 1 psi increments for accurate measurement. The ignition can be switched from dual spark to single front or single rear. Ignition source provided by BBQ piezo or stungun. The setup pictured here has already been fired hundreds of times with few, if any misfires. Reliability and consistency is on par with the full sized L1 launcher.

The first modification on the miniL1 was the addition of a chamber fan. A chamber fan helps to mix the fuel with the air inside the chamber. The fan also vents exhaust gasses when the barrel or endcap is removed. It is critical to use a fan motor that does not create any sparks as this would prematurely ignite the chamber. A brushless type fan used to cool computer CPU's shouldn't produce sparks but should be safety tested anyway. The fan is powered by a 12volt AC>DC adapter indoors or a 12volt battery cluster in the field. Surprisingly, the fan has shown no damage from pressure or heat although fans and wiring should be checked frequently for damage, melting and loose wires. The chamber fan has shown significant increases in performance.

internal mixing fan
gasket slugs

A mini is capable of shooting most any traditional spudgun ammunition. The smaller barrel diameters also open the doors for new streamlined ammo such as cone shaped, paper darts. A reliable, consistent and replaceable ammunition was needed for our miniL1 tests. Potatoes sliced in half then breech loaded proved to be inconsistent, messy and expensive. Simple slugs made inside slices of barrel pipe from Bondo were the next attempt. Although the Bondo slugs fit tightly, fuel was still able to escape past the smooth slug. A replaceable, rubber gasket was added to the slug eliminating the leak. PVC pipe is not perfectly round and these slugs would get stuck unless properly indexed with a mark on the barrel.

The solution was a wooden 3/4" slug which fits loosely inside the barrel but is attached to a tight fitting rubber gasket. The gasket slug is not designed to be aerodynamic as it only has to make it past the chronograph but could easily be modified. The gasket slug was able to penetrate 500 phone book pages per shot with a 30"x3/4" barrel. The miniL1, power in the palm of your hand.

miniL1 damage