potato gun science experiment

Air Powered Potato Cannon

Introduction: Air Powered Potato Cannon

Step 1: Materials

Step 2: Construction

Step 3: Safety

Step 4: Firing!

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Build a DIY Potato Cannon: PVC Spud Gun Instructions

Last Updated: November 25, 2024 Fact Checked

This article was co-authored by Patrick Johns and by wikiHow staff writer, Eric McClure . Patrick Johns is a Home Improvement Specialist and the Owner of CatchAll Handyman Services. With more than 28 years of experience, he has worked on a variety of home improvement projects, such as carpentry, plumbing, and door and window installations in both commercial and residential properties. This article has been fact-checked, ensuring the accuracy of any cited facts and confirming the authority of its sources. This article has been viewed 1,121,417 times.

You may love to eat potatoes, but firing them out of a massive cannon is way more exhilarating. Building a potato gun (also known as a spudzooka, potato cannon, or spud gun) makes for a fun DIY project that also demonstrates a few laws of physics along the way. In this article, we’ll break down everything you need to do to construct a basic potato gun. Feel free to put your own spin on the design, though! Follow along with us to construct your own spud gun in no time.

Building a DIY Potato Gun

• Assemble your potato gun using a 3 in (7.6 cm) wide PVC pipe (14 inches (36 cm) long) as the main chamber.
• Attach a 4 ft (1.2 m) long 1.5 in (3.8 cm) wide PVC pipe to the chamber using a coupler and reducer to form the barrel.
• Install a spark generator or BBQ ignition switch to the chamber to make the trigger.
• Potato guns are dangerous. Never fire a potato at a person and stay clear of the muzzle when you’re igniting the gun.

Buying and Cutting the Pieces

• This build will create a potato gun that fires 1.5 in (3.8 cm) baby potatoes. If you want to craft a huge potato cannon that fires russets and Yukon golds, go up at 1–1.5 in (2.5–3.8 cm) for each PVC pipe you use (i.e. use a 3 in (7.6 cm) barrel instead of a 1.5 in (3.8 cm) barrel).

• 3 in (7.6 cm) wide PVC marked at least 14 inches (36 cm) in length. This will be your ignition chamber.
• 1.5 in (3.8 cm) wide PVC marked at least 4 feet (1.2 m) in length. This is going to be the barrel.

• If you don’t have a hacksaw, you can use a PVC pipe cutter , handsaw, or miter saw.
• If you don’t have sandpaper, you can clean up the burrs at the cut edges using a utility knife.

Assembling the Launcher

• Whenever you apply PVC glue or cement, use a clean towel to wipe away any excess glue.
• The section you’re assembling will be the very back of the launcher.

• Just to clarify, this is the end that’s opposite to the end you just plugged up.

• You should feel the end of the reducer pressing against the coupler.

• This might look kind of silly since the barrel is 4 ft (1.2 m) long. You need a really long barrel to maximize the velocity of your spuds, though!

• You can keep working and add the spark generator or ignition in 2-3 hours, just don’t fire the gun right away.

Adding a Spark Generator

• You can buy a spark generator or BBQ ignition online or at a local hardware store.
• Most generators may have two prongs, or a single double-pronged extension.
• Many generators require spark-emitting prongs to be within 2 ⁄ 5 inch (1.0 cm) of each other.
• Alternative: If you don’t want to mess around with an electrical switch, drill a hole in the chamber big enough for a long lighter. You can manually light each shot this way if you prefer.

• Do not use duct tape. Duct tape is conductive and may catch on fire. Only use electrical tape for this. You can use electrical putty instead of electrical tape if you prefer.
• Connect positive leads (+) to positive terminals on the generator and negative leads ( - ) to the negative terminals if they aren’t already pre-wired.
• Once the leads and terminals are attached, prevent accidental shocks by covering any bare wiring or components with electrical tape.
• Check your spark generator by unscrewing the PVC plug from the female adapter. While looking inside the combustion chamber, press the generator trigger several times. If you see a spark, it works.

• Mount the gun on their dominant shoulder to make aiming easier.
• Hold the gun against their hip to minimize kickback.
• Take a knee and brace the gun against the ground or their knee.

Firing the Launcher

• Too much propellant is as bad as not enough. If there’s not enough oxygen, ignition will not occur. Use trial and error to determine how much propellant is right for you.

• Always operate your potato launcher with caution. Improper or reckless usage could cause harm or property damage.
• You can seriously maim or injure someone with your potato gun. It’s just as dangerous as a real weapon, so don’t treat it like a toy. [17] X Research source

Community Q&A

• It’s very important that you let the glue dry before firing your launcher. Most accidents with these guns happen because an anxious builder does not let the glue dry. Let it dry a full 24 hours before shooting. Thanks Helpful 0 Not Helpful 0
• Make sure you glue every single fitting. If you don't, the gun will fly apart when you fire it and you risk serious injury. Thanks Helpful 0 Not Helpful 0
• Never look down the barrel of the cannon or pointing it at someone when it's loaded. Thanks Helpful 0 Not Helpful 0

Things You'll Need

• 3 in (7.6 cm) wide PVC at least 14 inches (36 cm) long
• 3 in (7.6 cm) wide female PVC adapter
• 3 in (7.6 cm) wide PVC coupler
• 3 in (7.6 cm) wide threaded PVC plug
• 3 in (7.6 cm) to 1.5 in (3.8 cm) PVC reducer
• 1.5 in (3.8 cm) wide PVC 4 feet (120 cm) long
• Electrical tape
• Sandpaper (medium grit) (optional)
• Spark generator or BBQ ignition

You Might Also Like

• ↑ https://cpb-us-e1.wpmucdn.com/sites.psu.edu/dist/0/3445/files/2013/04/How-to-build-a-Potato-Cannon.pdf
• ↑ https://www.burntlatke.com/safety.html
• ↑ https://www.bobvila.com/articles/cutting-pvc-pipe/
• ↑ https://www.bobvila.com/articles/gluing-pvc-pipe/
• ↑ https://www.chicagotribune.com/news/ct-xpm-2013-04-27-ct-met-potato-guns-20130427-story.html

About This Article

To make a potato gun, cut a PVC pipe so that it's 4 inches wide and 2 feet long, and another pipe so that it's 2 inches wide and 5 feet long. Next, glue a female adapter to 1 end of the 4 inch pipe and a coupler to the other end as you prepare the launcher. Continue to assemble the PVC pipes to form the combustion chamber and barrel. Then, drill holes in the combustion chamber for your spark generator, which should have electrical tape covering it to prevent shocks. To learn how to spray propellant into the combustion chamber to launch your spud, keep reading! Did this summary help you? Yes No

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Ingredients

Instructions.

First extract the inner part of your biro.

Then saw the ends off so you have a tube that is the same diameter all the way along.

Clean up the cuts using a pair of nail scissors. (It may help if you make the edges slightly conical).

Now jam each end of the biro about 1cm into the potato; so you get a lump of potato stuck in each end.

Point one end somewhere safe, and push the lump of potato in the other end down the tube, using the rod. 

You should find that one of the lumps of potato fires off at an impressive speed.

Explanation

The lumps of potato make a good airtight seal against the inside of the tube, because as they are jammed into the conical hole, they are compressed. This means that if you push one of the lumps along the tube, the gas between them is compressed, increasing its pressure.

The pressure increases until the force it exerts on the second lump of potato is high enough to overcome the friction that is holding it in the tube. As friction drops when something is moving (this is why it is often much harder to start pushing something than keep it going) there is now a very large pressure force on the potato, acting almost unopposed by friction, so the potato accelerates out of the tube very rapidly.

This is based on the the same principle as how toy spud guns work, but they use something more engineered to compress the air. Air guns also work in a similar way; pulling the trigger releases a large spring which pushes a piston down a cylinder. This compresses the air behind the bullet until it overcomes the friction holding it there, and then it fires down the barrel.

In fact, based on this same principle, there are designs for a gun used to fire projectiles into space. The prototype was called SHARP (Super High Altitude Research Project) and worked by using a methane-oxygen explosion to fire a piston down a tube. This then compressed hydrogen to enormous pressures, which forced the bullet/satellite up the barrel. Compared to current rocket technology, only a third of the rocket's weight would be taken up by the equipment used to project it, allowing it to get into low earth orbit far more efficiently than using present rocket technology.

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