Guinness World Record

Current project state for 2024:

Hurricane was moved from it's previous location to a safer and more approperiate one, where it will stay. The construction was successfully finished and had a changed bottom platform on which it stands firmly, reaching it's full height of about 7 meters. In August of 2024 it was tuned and callibrated and managed to throw a 6 kg projectile for a distance of 252 meters.

Further tests and bigger counterweight will be applied soon to reach even farther shots. 

Motivation

The Energon science association was formed so that we could try out our engineering skills by creating our own kind of trebuchet, based on the MURLIN trebuchet project. Our Circle's biggest ambition was to win at least one Guinness World Record. We had three categories for trebuchet throws and they depended on the weight of the projectile. 

- Throwing with a projectile weighing less than 1 kg

- Throwing with a projectile weighing between 1 and 20 kg

And the most challenging:

- Throwing with a projectile weighing more than 20 kg

The last type of record had a clearly established throwing distance needed to break the record. The current one belongs to the Sierra Nevada Brewing Company of the United States and is 133.75 meters (438 feet, breaking the previous record of 253 feet). In both cases, the trebuchets threw a full keg of beer. We decided to take up the challenge and aimed...at all these records. With the help of the Spirit of the San brewery, we sourced kegs that weighed about 10 kilograms empty and over 20 kilograms full, which made them ideal for trying to conquer two categories already. 

However, to break the record you need a trebuchet. We undertook to build a seven-meter high machine with components made of wood, composite and metal. In our innovative design, we used a frame that was shaped like a Fibonacci spiral, which allowed us to optimize energy transfer. After all, a trebuchet is a throwing machine that imparts kinetic energy to a projectile at the expense of potential energy stored in a raised and then dropped heavy counterweight.

Any trebuchet, whether modern or historical, can throw projectiles with masses of within a certain range, closely corresponding to the size of the machine. It is also extremely important to perfectly match the ratio of these masses so that the trebuchet can transfer all the available energy to the projectile and eject it at the desired angle from the sling, at the moment when the movement of the throwing arm momentarily and completely stops - this is the so-called stopping point ("stall point") and is one of the key parameters affecting the trebuchet's efficiency.

Our large-scale trebuchet "Hurricane" is capable of throwing projectiles from a few to more than twenty kilograms. So it does not meet the assumptions of the first category, in which the projectile is supposed to weigh less than 1 kg. 

However, in our arsenal we still have a prototype of the "Hurricane", which we colloquially call "Kasia". This is a four times smaller model, measuring less than 1.5 meters in height, which has been instrumental in gaining a better understanding of the dynamics of this type of trebuchet and optimizing our design. "Kasia" throws projectiles weighing between 60 and 150 g, so it fits perfectly into the first category of the record.

Record attempts

The first official attempts to break the record took place on July 2 at the "Days of the City and Municipality of Dubiecko" in this very town, and involved only our large trebuchet - the "Hurricane".  Although the satisfactory range was not achieved, which was related to the reduction of the weight of the counterweight and the projectile for safety purposes, the demonstration was clearly appreciated by the audience. 

The last and best documented tests came on August 19, after minor modifications on both trebuchets. "Kasia" managed to reach a range of 68 meters with a 100-g projectile, and "Hurricane" over 100 meters throwing an empty 25-liter keg. The throws were documented on recordings and described by witnesses, and the range measured by a surveyor.  

The documentation has been sent to the judges and is awaiting review.

Science Of  "Hurricane"

The tests also proved an important hypothesis - the ratio of the masses of the projectile and the counterweight is almost constant, regardless of size, with identical proportions of the length of the propelling arm to the size of the spiral. Its value is still influenced by the mass and the location of the center of gravity of the propelling arm assembly with the spiral. During the last tests in the "Kasi" this ratio was 0.0150, and in the "Hurricane" 0.0154. Both machines then showed almost identical throwing dynamics.

The ratio also changes when the weight of the counterweight and the weight of the projectile are progressively increased, so one has to take correction for this. We intend to use the "Kasia" to empirically calculate this tendency, and then verify it on the "Hurricane."

Further plans include:

- stiffening the structure of the "Hurricane" with two vertical beams so that the weight of the counterweight can be safely increased

- throwing a 6 kg projectile with increased aerodynamics to achieve maximum range

- an attempt to throw a full keg

- further development of the "Kasia" design : increasing the radius of the roll, changing the diameter of the line, as well as experimental research on the mass ratio factor described earlier and the effect of the length of the sling on the throwing cycle.