Project Timespan
A few weeks in April – May 2018
Inspiration
I was never much of a gamer growing up, aside from a few classic real-time strategy gems on the PC such as Warcraft III and Age of Empires II. I recall, with much fondness and no regret, the many hours spent harnessing the hordes of Genghis Khan or the Teutonic knights of Emperor Barbarossa in my quest for conquest.
The gameplay is set in four historic ages: Dark Age, Feudal Age, Castle Age, and Imperial Age; with each passing age, the player gains increased economic and technologic capabilities. In the Imperial Age, players gain access to the mighty counterweight trebutchet, arguably the most formidable pre-gunpowder siege weapon in all of human history.
Ever since seeing the effect of a handful of such weapons of mass destruction against the city of a hapless foe many those years ago, I have longed to recreate this amazing piece of engineering in the real world.
Project Overview
1. Materials
2. Trebutchet Background
3. Trebutchet Design
4. Building the Trebutchet
5. Trebutchet in Action
1. Materials
I basically follow the PDF document of trebutchet plans I found online, but the rough components are as follows:
– A whole bunch of 0.5 inch x 0.5 inch square dowels
– A couple of hand saws
– Wood glue
– Quarter-inch Baltic Birch plywood
– Thin hemp rope
– A few dollars worth of pennies
I also incorporated the use of a laser cutter for certain aspects of construction.
2. Trebutchet Background
Historically, the treatment showed a marked the apex of siege engines before the advent of gunpowder. There existed 2 main forms, the traction trebuchet (mangonel) and the counterweight trebuchet. The first, and earlier form relied on manpower to pull down and swing the arm of the machine. The better known, and more powerful machine was the counterweight trebuchet. This type of siege engine dates back to the 12th Century BCE, around the time of the Crusades.
The trebuchet saw use in military warfare for the better part of three centuries, until early gunpowder devices began to supplant it in efficacy. A curious use of the trebuchet was by the Spanish conquistadors at the siege of Tenochtitlan in 1521, as the Spanish possessed a limited supply of gunpowder. The attack was a debacle, however, as the first projectile launched was the last one: it landed directly on the trebuchet itself and destroyed it!
3. Trebutchet Design
There existed a company called RLT Industries that produced tabletop scale models of catapults and trebutchets. Their top-of-the-line product was highly detailed 1:20 model of the famed Stirling Warwolf trebutchet. When I came across an image of the model while browsing designs, I immediately realized that that was the design I wanted to recreate.
I managed to find a PDF of the original plans that accompanied the kit, which sold for approximately $200 back in 2007. Unfortunately, the website that hosted this file is now long been extinct, defunct, but I was able to dig up the PDF that I saved during the making of this project. Although the plans mentioned that “Drawings not to scale,” I had my doubts as to the veracity of this disclaimer.
Therefore, I used a software conversion tool to convert the PDF into an SVG file, which allowed me to accurately determine the appropriate dimensions of the wood that I would need to cut out.
4. Building the Trebutchet
For the project, it seemed that the project scaled nicely with a 12 mm or approximately 0.5 inch cross-section squared dowel. I was fairly sure that this was the scale used in the original kit, as the final trebutchet size was spot-on to the one listed in the plans – approximately 2.5 to 3 foot tall.
I used a machinist vice and a hand saw and get to work, cutting out half lap joints for the majority of the build, and using a simple hand drill for the quarter inch circular dowels that would serve as the interlocking connection between pieces. I admit that my cuts were not, general speaking, perfectly square, as I had not yet had much experience with using a hand saw. I also had a old set of chisels that used to help clean up the mess, but there was some improvements to be made for sure.
For the actual carcass of the counterweight, I decided to resort to using a laser cutter for that purpose, as I started becoming rather bored of using the hand saw, and also spit up the process of cutting out the trebutchet arm as well.
The process was moving along nicely, and in the end I decided to stain the entire bottle with a darker walnut-like stain. I thought this contrasted well with a light brown hemp rope.
5. Trebutchet in Action
After completion of the model, I decided to test it out in my apartment in Philadelphia. It worked, quite well, but the wooden ball launched directly up into the ceiling, and once even hit the ceiling lamp, but fortunately did not shatter the glass. I slowly fine-tuned the settings of the trigger arm and counterweight until I was satisfied with the functioning of the device.
I decided to take the model all the way back home to Wisconsin, and while it crowded the space within our car, it managed to safely arrive back home intact. While home, I filmed a few short videos demonstrating the prodigious potential of this might machine of war.
The trebutchet model is capable of throwing a 1″ spherical ball approximately 50 feet. Given that the scale is roughly 1:20, this would correspond to approximately 1000 feet launch by the full-sized Warwolf. Of course, this does not take into account the changes in physics / dimensionality given the alteration in scale. I thought about attempting to tackle this question from an engineering perspective, but those days are behind me, and I’d rather not revisit the Buckingham Pi theorem again.
Lessons Learned & Improvements
To be honest, I think the end result of this project speaks for itself. It works perfectly well, and looks amazing. The only changes I would make would possibly be with regards to the execution of construction. Some of the half lap joints, and mortise and tenon joints were subpar, to say the least – I would like to think that if I were to revisit this project, I could have made the requisite cuts cleaner.
The other design choices I made with the project, such as staining, are all personal choices, and I do like the look. Perhaps, it would have been nice to incorporate a wood species that is naturally darker in color, such as walnut, but that would have been quite more in cost.
Reflection
When I first started building the project, I came across the whole array of various trebutchet designs, from those more accurate to medieval x 2 new were models that optimize the biomechanics/physics of projectile motion. Nevertheless, I have not yet found a design that, aesthetically speaking, I like as much is the one I made. I did see that there was a model made by someone else based off of this plan, but instead using half inch square dowels – essentially 8 times the size of my trebutchet. I have since lost that link, but one day I would like to revisit and upscale this magnificent war machine.
It has been more than 5 years since the completion of that project, and it still sits, gathering dust, in my home back in Wisconsin. However, the machine is ready, at a moments notice, for the next horde of invaders… beware!