Inside: Can you build an Ewok catapult from sticks and stones with your little Star Wars fan? You bet! Plus, learn the science behind this wonder of mechanical engineering and try Types of Energy word search and Kinetic/Potential Energy crossword puzzle.
Star Wars movies offer plenty of inspiration for an enthusiastic inventor, from homemade lightsabers and self-build droids to DIY starfighters and battle tanks …
A store-bought kit is perfectly acceptable. And you have plenty to choose from: LEGO blocks Star Wars sets, snap-fit model kits from Bandai, and glue-and-paint display kits from AMT. (Disclaimer: the above Amazon links are affiliate links). But what my twelve-year-old Star Wars enthusiast finds most satisfying is to come up with his own inventions.
One of my son’s favorite Star Wars events is the Battle of Endor. One day, as my son was eagerly telling me about catapults that Ewoks used to defend against Imperial forces, I suggested we try to make one.
Well, let me tell you, it turned out to be an extremely fun project. And not only was it pretty easy to make a catapult, but my kids have been playing with it for hours at a time ever since. If you are looking for a handmade toy to help your kids spend more time outside this summer, this is it!
Just make sure to go over safety rules to prevent your kids from hitting each other in the eye with a stone. They can fly really far!
Ewok Catapult from Sticks and Stones
We started by sketching different models and then experimenting with sticks arranged in different shapes to find the most effective design. What we discovered is that there is more than one way to go about it.
For us, the most stable and reliable model was the one with a square base, so this is the one I will tell you about today. But feel free to use our design as only a starting point and invent your own way of doing it.
What you need
Crochet cotton thread (this one works for a variety of projects)
2 Rubber bands
What to do
- The first thing to do is to go for a walk and collect lots of sticks and stones. How many? Pick up a few more than you think you’ll need. We found that when you build a catapult, you have an instinctual feel for what kind of stick will make it more stable, so we liked having a variety of sticks to choose from. And, of course, having lots of stones is useful if you want to keep shooting the target without having to get up and restock your pile.
- Grab four sticks and connect them in the shape of a square with a thread. They don’t have to be particularly straight or the same size, the only thing you need to worry about is that the square stays flat on the ground. If a bend in a stick is lifting one side of your base up, it will make the whole catapult unstable.
We used a thread to connect the sticks. You can also try rubber bands in place of thread, but my son felt certain that Ewoks wouldn’t approve.
How to wrap the thread
My son just wrapped the thread around both sticks until it felt secure, but if you want to be really professional about it, then google “lashing knot-square” and do that. Your catapult will truly be indestructible.
- Connect two sticks to the base vertically and lean them toward each other to create a triangle on one side.
- Repeat on the other side.
- Now turn your attention to the horizontal stick that rests on top of two triangles. We decided that this stick had to be really long for two reasons: to provide a place for a hand to grab it and keep it stable while shooting, and to be a handle for carrying it around.
You could choose to stabilize your catapult some other way (i.e. by resting something heavy over the base), and maybe you don’t have to carry your catapult around as we do.
It’s up to you!
My kids really love to move, so they shoot from one spot of the yard, then quickly run to another spot and “attack” from there. When they run around and held any other part of the catapult (for example, the side triangles), there was some kind of shift in the structure that necessitated an adjustment in a new spot. But the horizontal stick didn’t pull or disarrange anything.
- Now let’s connect both sides of the catapult with a rubber band. I hope it’s clear from the picture how it’s done. This rubber band will help us create tension.
- For the throwing arm, we picked the thickest stick we had. To build a projectile holder, you can use a spoon or an empty yogurt container, but my son felt that it didn’t go well with the Ewok theme, so we ended up creating a mini shelf with a thick, short stick.
We used a rubber band to attack the stick, but this still allows the shelf to move left and right. This necessitates an extra step: when you place a stone on the shelf, you have to make sure that the stone is pointing straight. If your kids are easily frustrated, then go ahead and use a thread to secure the shelf in place, so it stays in the same spot without shifting.
- Place the throwing arm (that is, the large stick with a shelf) between the horizontal stick and a rubber band. Make sure the bottom of the stick is inside the square base.
Time to test the model!
- Place a stone on the “shelf.”
Pull back the throwing arm to produce the tension. Don’t forget to keep one hand on the horizontal stick to provide stability.
Release to fire.
The first time I did it, I almost hit our dog. She suddenly ran into my line of fire, and I didn’t take any precaution beforehand because I simply didn’t expect the stone to fly so far away! So, be more careful than I was and instruct your kids not to point their catapult toward anyone when catapulting the stones.
If you want to turn catapult shooting into a science experiment, test if you can predict with any degree of accuracy where your stone will land. You could even set up target and see if you can hit them.
Ewok Catapult Discussion Questions
- What controls how far stones fly?
- Can you easily hit your target? (we enjoyed shooting stones into a baby pool filled with water. Just make sure the baby is not in the pool 🙂
- What does a catapult do?
- What is a projectile?
- Which projectile launches the furthest?
- What happens when you replace stones with cotton balls?
- What type of energy has your catapult used?
The Science of Catapults
The first documented use of catapults goes back to 399 BC. The Greeks used them in siege warfare, as did the Romans and the Chinese. The French used them in England during the famous Siege of Dover, and pirates during the golden age of piracy. Grenade catapults were used in World War I, and today catapults are used to launch airplanes from aircraft carriers. That particular use is very interesting to watch.
The grossest use of catapults we read about was when the bodies of those who died from the infectious disease were hurled over the city wall to infect the residing residents. The first use of biological warfare!
Why did catapults endure through the centuries?
Because they were very effective in getting the job done – hurling a projectile a great distance. The design of catapults changed and improved in step with technological advancements, but the main idea stayed the same – it uses stored energy. To take our Ewok catapult as an example, it works because the potential energy stored in a stretched rubber band is converted to kinetic energy as it snaps back to its original shape.
But where does that potential energy come from? Isn’t it true that energy can’t be created!? As we talked about in our Yoda experiment, energy can’t be created or destroyed, but it can be transferred. To pull the catapult arm back, thus stretching the rubber band (aka elastic potential energy), you use the chemical energy of your body. And where does the chemical energy of your body come from? From the yummy and nutritious food you eat.
Are you clear on forms of energy, energy transfer, and potential Vs kinetic energy? If not, go to our Yoda experiment. In that post, we discussed these topics with examples.
Do you want to print out Types of Energy word search? Go here to get access to our library of printables.
Do you want to print out Potential / Kinetic Energy Crossword Puzzle? Go here to get access to our library of printables.
We wish you a happy and safe catapulting!