How to Make a Catapult Using Popsicle Sticks

A catapult throws a projectile mechanically using stored energy.

Teach kids about simple machines and castle sieges with one project. You can build a craft stick catapult in a few minutes. Small children can participate in the construction and everyone can use the catapult to launch light items into the air. Older children can study the ballistics of trajectory and weight, while younger kids will just have fun tinkering with aim and experimenting with different sorts of "ammunition."

Things You'll Need

• 7 to 15 craft sticks
• Plastic spoon
• Bottle cap
• 4 to 6 large rubber bands
• Hot glue gun

Instructions

1. 

   Wide, flat craft sticks work best for this project.

   Collect two piles of craft sticks, one with five to nine sticks and the other with only two.

2. Secure one end of the larger pile of sticks with a rubber band. Turn the pile and wrap a second rubber band tightly around the other end. You will have the equivalent of a very thick craft stick with bands wrapped around each end.

3. 

   In this project, rubber bands are used to secure a hold rather than to power the catapult, like in a slingshot.

   Taking up the pile of two sticks, wrap a third rubber band around one end, leaving the other end free. You should be able to open and close the open end, like opening and closing a crocodile mouth.

4. Slide the thick stack sideways into the open "mouth" of the shorter stack. The two stacks will now sit perpendicular to each other, with the thicker inside the thinner. You can see how pressing down on the top of the "mouth" creates a springy action.

5. Use a fourth band to tighten the two stacks together. Wrap first around one side of the large stack, then around the banded side of the small stack, then around the farther side of the large stack, repeating in the opposite direction if possible. Leave the open side unwrapped.

6. 

   Plastic milk or water jug caps can be used in place of the spoon.

   Glue the handle of your plastic spoon onto the top of the open short stack of sticks using the hot glue gun. Use the spoon handle to extend the arm of the top of your catapult and create a basket for the items you will project. You can, alternatively, glue a bottle cap directly onto the craft stick, leaving a small space for pressing the stick down.

7. 

   Light objects, like ping pong balls or styrofoam craft balls, project well.

   When all is solidly dried, place a small, light object into the cup of the spoon or bottle cap, press down on the upper craft stick, and release to project the item. Experiment with different projectiles and perfect your aim and arc.

Tips & Warnings

• Siege machines were often torsion catapults, using the power of an untwisting rope to project an object. A wooden clothespin uses a metal spring to store power in much the same way. Glue a clothespin to a thin board with your hot glue gun, then glue a craft stick on top of the clothespin and secure your bottle cap or spoon onto this stick to create a torsion catapult.

References

• Almost Unschoolers: Clothespin Torsion Catapult
• Supercharged Science: Catapults
• All About Catapults

Resources

• Easy Science Experiments: Machines
• Storm the Castle: How to Make a Small Onager