Sometimes you just need to hurl things. It’s a fact of life as old as the art of hunting and gathering. Hurling rocks, hurling spears, discus, logs, people, tables, boulders, seeds—there's no judgment here as to what you hurl. But I will say, some methods for hurling things are better than others.
Our arms can only get so strong; our bodies are limited machines when it comes to launching large objects over great distances. This is not what human beings were made for. So we made machines that were made to hurl things. We built contraptions that enabled us to develop the very first catapults.
Survival Catapults | Applications and Designs
Catapults are special. The people who invented them some 2500 years ago had no idea how complex the physics behind their machines was – they only understood them as advanced killing machines.
But the technology, basic as it may seem compared to our computers and modern firearms, is still totally relevant today. That’s right, you can build catapults – and they are surprisingly functional in survival situations.
What could a catapult possibly do for me in a survival situation? You might ask. Well, that is the question that this article aims to address. That, the history, and the basic physical concepts that make these contraptions so useful in the first place.
A Brief History of Hurling Large Objects
We have the ancient Greeks to thank for these devastating inventions. They made “mechanical arrow-firing katapaltai” around 400 BC. They were the forefront of warfare tech in those days. Which is why they were adopted by the Romans after the Greeks created them. The Romans employed similar catapults as the Greeks, but they were the first to actually place them on their ships, revolutionizing naval combat at the time.
Medieval catapults are famously depicted in movies and art from the period. Castles and walled cities became very popular during this time period – so when someone wanted to lay siege to their enemy’s fortress, they needed catapults to do it. One might say that the medieval ages were a renaissance period for catapult technology.
Because up until this point catapults were typically just gigantic crossbows that launched huge bolts. But when the medieval ages rolled along, the world saw a proliferation of classical siege equipment. A whole family of different types of catapults each employing different forms of “potential energy” to launch their loads (we’ll get to the physics stuff in a second here).
Catapults were present throughout almost every conflict in history from that point forward, and are still used in the modern age. But catapults are good for more than just destruction and the siege of cities… This is 2017, and we’re experienced with technology. We know that there is always more than one way to ride a horse. So to speak.
The Basic Concepts
I know, no one comes to a survival website to read about physics. But, unwittingly or not, we use physics in survival all the time. In fact, I can’t think of a single survival/apocalypse preparation invention doesn’t use physics in one form or another. And if you plan on building a catapult (for fun, for survival, to lay siege to your neighborhood rival, etc.) you are going to need at least a basic understanding of the physics behind the contraption.
Throwing things is a pretty scientific endeavor: when something is at rest it has “potential energy” and when it is in motion it exerts “kinetic energy”. Think of it this way – a huge boulder sitting precariously on the edge of a cliff has a lot of potential energy. That is to say, if it started moving, it would really start moving… The more potential energy something has, the more kinetic energy it exerts. So when it comes to catapults, the goal is to increase the potential energy of the projectile as much as possible.
There are three ways to increase the potential energy of an object: tension, torsion, and gravity. As we move into the next section and discuss the types of catapult you might build, and how each works, I’ll reference each of these three contributors.
- Tension: a pulling force exerted “axially” along a cable, string, rope, or cord of some kind.
- Torsion: energy exerted through a twisting motion.
- Gravity: the downward pulling force exerted by the Earth. Heavier objects are more affected by gravity than are lighter ones.
The Many Different Types of Catapult
We’re going old school to start. Ballistas were employed by the Romans some 2200 years back. And they are based off of the ancient Greek’s designs: gigantic crossbows meant to fire deadly bolts – often engulfed in flames. The energy is created using torsion, whereupon winches twist already taught springs, which store potential energy. When that energy was released to become kinetic energy, the projectile was launched with immense power and infamously deadly accuracy.
This was another type of catapult utilized by the Romans in ancient times. This siege engine used torsional energy, stored in a twisted rope to fire its projectiles. Two men operated it using levers and pulleys to torque the rope around a beam, bending the oak arm of the catapult over. When it was released the rope would unwind and the beam would snap straight again, flinging its load towards its deadly goal.
These were one of the most effective engines of siege warfare ever devised by man. Their highly engineered design used huge amounts of gravitational potential energy to hurl bombs, and boulders with incredible accuracy. On one end of a very long beam, a rope with a leather basket would be loaded with the projectiles, while on the other end a massively heavy load was lifted high into position with gears and pulleys.
When the heavy potential energy was released the leather basket would be swung up and over with incredible force and speed, releasing its load at the apex of the arc and sending the projectile flying through the air to deadly effect.
These are the classic machines you probably picture when the word “catapult” is mentioned. They were designed to lob very heavy objects high into the air, to descend and destroy all that they fell upon. Large bowl-shaped buckets on the end of long wooden arms were loaded with boulders, rocks, explosives, even plague infested bodies, and hurled up and into enemy ranks.
Mangonel’s were operated similarly to Trebuchets (though their accuracy was significantly poorer), using gravity to fire the object. There would be an extremely heavy load on one end of the wooden arm, opposite the end where the projectiles were loaded. Using ropes, men would pull and lift the heavy end high into the air, where it was locked in place, ready to fire. When the load was released the heavy end dropped quickly, flinging the other side up and over. Mangonels were similar to trebuchets in many respects, but were smaller, less technologically advanced and far less accurate than their bigger cousins.
Why on Earth would someone living out in the wilderness need to build a catapult? That seems like a waste of time and energy. Well, just because something is useful in warfare doesn’t mean that it isn’t useful in survival situations.
Catapults are more than simple siege engines – they are tools, and just like any tool they can be used for a wide variety of purposes. Here is a brief list of several different uses for a catapult you may not have thought of.
- Communication: Launch different colored projectiles into the air to communicate with far-off neighbors. Or send a huge fireball up and into the night sky as a signal or sign of warning.
- Spreading Seeds: Yeah, agriculture – didn’t see that coming did you! But think about it, say you have a huge field of fertile soil but don’t want to waste time every year wandering around planting seeds… What if you had a catapult you could load a TON of seeds in, and fire up and over a large area? Sounds like some pretty badass farming to me.
- Delivery/Transportation: too lazy to get up and drive over to your friend’s house to give them something? No problem. You have a catapult – just load up and launch that business over to them. Just make sure you aren’t delivering anything fragile or mortal by catapult (ie china dishes or children).
- Home Defense: No one is going to mess with you or your property if they know you are guarding it with an incendiary loaded trebuchet.
- Entertainment: Catapults are just fun to shoot. I know a lot of people who’ve built them for no other reason than to entertain themselves. It is a cool science project that you can garner a lot of satisfaction from. Try building a catapult for no other reason than to try it – maybe it will become your new hobby. There are state, and even national catapult competitions all over. So if you get really good at building awesome catapults, you might have a chance to enter and win a competition for it!
Using Physics in Survival Situations
The point of all of this is kind of general: unusual, seemingly specific machines can often be applied to a variety of different ends. Yes, catapults were invented to destroy cities and massacre human beings. But they can be used for survival, agriculture, and even just plain old fun. Never underestimate the usefulness of a device – especially when it’s as awesome as awesome as catapults are.
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Editor’s Note – This post was originally published on March 24, 2017, and has been updated for quality and relevancy.