Spud Gun Fuels

Potato Gun Fuels, Or How to power the beast without blowing yourself up…

Your combustion driven spud gun needs fuel to…well…make it combust…and launch that potato into orbit. Selecting the right fuel for the job will make the difference between multiple successful, reliable launches, and singed scalps, hurt feelings, and unimpressed onlookers.

The Difference Between Canons and Grenades

Your potato gun is essentially a canon, taking its roots back to the very first black powder canons and mortars. Instead of cast iron with reinforced bands, you have an ABS or PVC barrel. Instead of an iron ball, you’ve got a spud or tennis ball. Instead of black powder, you’ve got an ignitable propellant. And therein lies the rub. When the propellant ignites, it pushes the spud out of the barrel towards the path of least resistance – straight out the open front. If you use too hot a fuel, however, the explosion will be so concentrated that the PVC itself will explode in hundreds of deadly fragments, turning your beloved canon into a giant grenade. You want a fuel that is powerful enough to thrust the spud out the end of the barrel but not so powerful that it blows up – which is why you want to avoid fuels like acetylene, hydrogen, or oxygen.

Safe Fuels for Spud Guns Mean More Fun!

There are plenty of safe fuels to power your spud gun, and many of them are sitting right under your nose – you may not even realize that some convenient home products are good for your gun. Some hairsprays, deodorants, air fresheners, colognes, and other similar fuels are decent choices to power the gun and are readily available – the drawback? Inability to properly meter the fuels so that the quantity is appropriate for good ignition.

Less Is More. No, Really!

Fuel metering is essential to reliable spud gun operation. You don’t want to pump the combustion chamber full of fuel because doing so eliminates the amount of oxygen available in the chamber, thus weakening the explosion. Lose oxygen, and the results will be anything from a weak launch to no ignition at all. You’ll find through testing that there are diminishing returns to adding more fuel, so start with a small quantity and dial it in until you get good results. There’s a much easier, more reliable fuel that’s easy to meter, however….

Propane – The Ideal Ball Launcher Fuel!

Propane is an ideal fuel to power spud guns with. It’s clean, reliable, combustible, easily metered, and doesn’t have the additional byproducts and additives that things like hairspray and air fresheners have. This results in clean shoots with the minimum of barrel fouling.  Propane is also inexpensive and comes in many different container sizes so it goes where you go. You can build a spud gun with a perfect combustion ratio by designing the size of the combustion chamber to hold a preset amount of propane, therefore making launch after launch a simple task – you’ll never have too much or too little fuel

I was Told There Would be No Math

Well, a little bit of math would go a long way to making your shoots reliable, so pay attention. Propane has some clearly established and time proven properties, and we know that it will only burn when it has a volume, mixed with air, of between 2.4% and 9.2%. What that means to you, oh spud cannoneer, is that if there is less than 2.4% of your combustion chamber’s volume in propane, it won’t ignite. Neither will it ignite if there is more than 9.2% of propane. You need to find the sweet spot – ideally about 4% propane. Buy our Ebook, How to Build Your Potato Gun Arsenal for all the information you need to calculate the size of your gun so it works best.

Houston, We Have Ignition…

In closing, stick to reliable, safe, and available fuels to power your spud gun and don’t get fooled into using powerful but unsafe fuels – you want to keep launching and launching, not wind up in a burn unit. Check out our plans and ebooks for the best spud gun fuel systems. Happy shooting!!

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