Make a spud gun

Make a spud gun

Ready...aim...fire that potato!

BBC's Bang Goes the Theory has a great experiment showing you how to make a spud gun.

What you need:

  • Copper piping (ask an adult to buy this at a DIY store if you don't have any spare at home)
  • Large raw potato
  • Metal nail file
  • Dowel or garden cane

How to:

Remember: never fire your fun at people or animals. The spud gun can fire a long way at high speed. The best place to do it is outdoors.

  1. Ask an adult to saw the copper piping to the size you need (sometimes the DIY store will do this for you).
  2. Check the copper pipe is straight and smooth.
  3. Ask an adult to file any rough edges on the ends of the copper pipe.
  4. Place a large potato on a table and hold it with one hand. With the other hand, push one end of the pipe all the way through the potato.
  5. Do the same at the other end of the pipe.
  6. Line the pipe up an aim at your target - make sure there are no people or animals in the way!
  7. Poke the end piece of potato with the dowel.

Fire! The piece of potato at the front of the gun should fire out.

To fire again, remove the piece of potato that's still inside the pipe and repeat from step 4.

Too much effort to get a piece of copper pipe? Go to Bang Goes the Theory to find out how to make a mini spud gun using a ball point pen.

What's happening?

Plugging both ends of the spud gun creates an airtight seal, trapping air inside the pipe.

When you push one piece of potato along the pipe, the air between the two potato pieces becomes compressed. This increases the air pressure.

When the force of the air pressure on the front potato is large enough, it will overcome the friction that keeps the potato in place.

Your potato fires out of the tube!

To find out more about the science behind spud guns and what scientists use the science for, go to the Bang Goes the Theory website.

Curriculum information