Table of Contents Introduction.... 3 Using the Book.... 4 Safety.... 4 Siege History.... 5 The Catapults Tension vs Torsion.... 10 Experiment: Mass vs Distance... 11 Dueling Catapults.... 12 Conversion of Length.... 14 Calculating Averages.... 15 Elasticity.... 16 Experiment: Testing Rubber Bands.... 17 The Ballista Understanding Torsion... 20 Experiment: Materials Testing.... 22 Applying Ratios... 24 The Trebuchet Gravity & Levers.... 26 Prediction.... 27 Experiment: Right on Target.... 28 Force & Motion... 30 Experiment: Swinging Weights vs Wheels.... 32 The Challenge Laying Siege to the Castle.... 36 Standards Addressed... 38 Additional Resources.... 45 Bibliography.... 46 1
Introduction Siege machines might have been ancient inventions built to bring an enemy to the breaking point, but the modern world has found a great deal of delight in them as well. Trebuchets, catapults, and ballistae were once used to destroy castle walls, to break through a line of troops, or to throw objects inside castle walls or on enemy ships. Now, these devices are loved for their ingenious use of science and math and sometimes just for the sake of entertainment. From the Middle Ages to Middle Earth, catapults, trebuchets, battering rams, ballistae, and more have held our attention captive. Indeed, the entertainment industry has tapped into this fascination for some time: the British comedy Monty Python and the Holy Grail, the epic Lord of the Rings films, and kid comedy Night at the Museum have all featured these flinging devices. Many of the big guns of siege warfare are so popular that they are built all around the world either as models, life-sized constructions, or some variation between the two. From small models built in classrooms in Trenton, New Jersey, to towering reconstructions in French chateaux museums, these historic weapons are capturing the imaginations of young and old alike. Math, physics, engineering, problem solving, and history are all topics that can be enhanced by building and using siege machines. Even building small versions can open up huge doorways to learning. 3
Using the Book The Siege Machines book is designed to help students use Pitsco s Catapult, Torsion Catapult, Torsion Ballista, and Trebuchet Kits to learn history, construction skills, math, science, and even teamwork. Teachers can use this book to develop activities and lesson plans for the classroom, but it can also be used by a parent and child having fun together at home. Whether directing an entire classroom or helping a single child complete a science fair project, Siege Machines covers a range of math and science topics geared toward Grades 5-8. But this book also launches loads of fun for folks of all ages. Siege Machines is divided into three primary sections: The Catapults, The Ballista, and The Trebuchet. At the end of the book is a culminating activity as well as a listing of national standards addressed by the book s activities, resources, and a bibliography. Safety When using any of the Pitsco siege machine kits, always adhere to the following rules to prevent injury: The only approved projectiles for the Pitsco Catapult Kit and Trebuchet Kit are those made from modeling clay (available through the Pitsco catalog). The Torsion Catapult can fire Styrofoam balls or modeling clay balls. The Torsion Ballista fires only Styrofoam balls. Do not fire the catapult or trebuchet until everyone is clear of the target area. Do not fire directly at anyone. When launching either device, the operator should take care to not get his or her fingers in the way. The siege machine operator and anyone within firing range must wear safety glasses. 4
Siege HIstory The Flinging Begins The Greeks were the first to combine the science and engineering necessary to use siege craft as effective weapons of war. They built a variety of devices including battering rams, siege towers, and catapults. The first Greek to focus on these new weapons was Dionysius I of Syracuse, who lived in the fourth century B.C. Collecting the best men of science and engineering that he could hire, Dionysius I built an artillery that awed his enemies. His smaller catapults threw arrows, javelins, and small stones up to 250 yards. His larger ones could toss stones that weighed up to 55 pounds. Dionysius I s extra work on these devices came just in time to help a certain young Macedonian leader named Alexander Alexander the Great. Alexander s Conquering Catapults To be fair, it was Alexander s father, Philip II of Macedon, who actually started the refinement of the catapult and other siege weapons. Philip was the first to figure out that it was much easier to carry only the basic parts of the catapults and to build the rest at the Roman ballista What s in a Name? When reading the history of siege machines, it doesn t take long to realize that one person s trebuchet is another person s bricole! There are numerous names and nicknames for the siege machines. The trebuchet is sometimes called a blida, bricole, couillard, machina, petrary, or valsslonva. Some folks even call a trebuchet a catapult! That is, a gravity catapult. Speaking of catapults, they were also dubbed onagers, ballistae, and mangonel, just to name a few. site where it would be used. His army used trees in the area they attacked for the timbers needed to construct the catapults. At this time, the catapult and its variations were powered by tension. This tension could come from a configuration like the bow and arrow. The operator pulled back a wooden or animal horn bow that was built on a frame. They shot this by releasing the string holding this bow. Or, they could use the tension from a strong but flexible catapult arm that was pulled back to the catapult frame much like flinging mashed potatoes from a spoon. One of Alexander s great achievements was mixing large-scale artillery with the infantry and cavalry. His ingenious use of the various military forces was no match for the many armies he faced as he gained rule over much of Asia. Aside from how he used his military equipment, Alexander also improved it. Hiring engineers, Alexander s catapults soon found themselves aboard ships as well as on solid ground. After getting limited results from the tension catapult, his engineers developed the torsion catapult for added power. Alexander s troops were creative in other ways at times they catapulted barrels of poisonous snakes or hornet s nests onto enemy ships. 5
Around the World Next to adopt the siege machines into their armies were the Romans. They began using the siege machines in the first century B.C.; many of their historians left detailed descriptions of the devices and their use in the Roman army. Catapults turned into quite the globe-trotting machine. In the sixth and seventh centuries A.D., the Chinese developed catapults that used weight pulled by gravity to power the arm the early trebuchet. During the ninth century, catapults were used throughout Europe. Even the Vikings used siege weapons when they attacked Paris in 885. Their siege was unsuccessful, but don t blame the weapons the Vikings failed to form a complete blockade around the city. Crusading Catapults In the tenth century, the Crusades began as Christian soldiers from Europe invaded the Middle East, attempting to take the area from the Muslims. Over the next two hundred years, the two forces fought many bloody battles. Perhaps the best-known rivalry was between Richard the Lionheart, king of England, and Saladin, the ruler of Egypt. From within the important coastal town of Acre, Saladin and his troops watched Richard s forces along with the French build catapults and massive siege towers. They began to worry about the siege soon to come. The Muslim soldier Damascus suggested they build their own catapult. The Muslims did build catapults and trebuchets. Instead of throwing rocks, they threw a chemical compound that was afire. The compound made short work of burning the siege towers to the ground. This new twist intensified the battle considerably. But after months of more fighting, Richard finally did take the city. Medieval Mayhem Catapults and trebuchets were the great artillery weapons during most of the medieval period used not only in the Middle East but also in Europe and other parts of the world. However, the siege machines were not always used on their own to attack a castle. They were often combined with other techniques. For example, attacking forces might also tunnel under a castle wall to weaken its foundation. Then, they would follow up with catapult or trebuchet artillery. As time passed, rulers learned to build castles that were better fortified they could take the abuse of the siege machines without as much damage being done. Some historians believe, overall, that sieges in the medieval period were not very successful. And when they were successful, starvation was often the tool used to defeat a castle. By blocking castle inhabitants from reaching supplies, attackers could starve the attacked to the point of surrender or defeat. But if siege machines didn t always bring down the castle walls, they could be used for primitive biological warfare. Besiegers would often find dead animals and try to spread disease by throwing them inside the castle walls. Built in 1068 by William the Conqueror, the well-preserved Warwick Castle in England has been witness to much history. It was rebuilt with stone in the 13th century, and in 2005 it became home to one of the largest modern trebuchets almost 60 feet tall and weighing 22 tons. Photo courtesy of MorgueFile.com 6
The heyday of the siege machine started to wane in the fifteenth century. Why? Gunpowder and cannons were starting to pick up interest by the military. Ultimately, the cannon put the catapult and trebuchet out of business. Catapults in WWII Think using the catapult for military purposes is only ancient history? Think again. The United States military used catapults during World War II. While trying to take Okinawa near the end of the war, Allied forces found the caves lining the coast to be troublesome. These caves provided the Japanese military places to take cover and to hide artillery. American soldiers used steel catapults to fling drums of fire into these caves, making them a less appealing hideout. Also, several WWII carrier ships were rigged with compressed-air catapults for launching seaplanes. A Return to the Past After slumbering for centuries, interest in siege machines has made a strong return not as an engine of warfare, but as an engine for learning and for historical reconstructions. Though it is reported that Napoleon attempted to build a trebuchet in 1851 as an academic exercise, reconstructions of siege machines did not make any serious headway until the 1980s. This reawakening did not come easily. Original siege machines did not survive to the present day, so reconstructions are largely based on studying historical writings and drawings. And many of the medieval drawings were not drawn with accurate proportions and details. ARMÉDIÉVAL, a French group that reconstructs siege devices for museums, started to build a historically accurate trebuchet in 1984. It was completely operational in 1987. ARMÉDIÉVAL has continued to make many impressive reconstructions that can be seen in museums throughout France. At the Chateau de Castelnaud in France, a museum of medieval warfare features several trebuchet reconstructions. Photo courtesy of Luc Viatour (www.lucnix.be) via Wikipedia Commons 7
ARMÉDIÉVAL also assisted in building a replica of Edward I s War Wolf trebuchet, Ludgar, in Scotland. The Medieval Centre in Denmark has also made great headway in the reconstruction of siege machines and medieval life in general. During the 1980s, many classes began building them as a physics activity. In 1986, a group of friends spurred by a newspaper article about a local college class throwing pumpkins with devices it built started a friendly competition to build a device to throw a pumpkin the farthest distance. Now known as the World Championship Punkin Chunkin contest, the event has grown from a few friends to 72 teams from around the US. In 2004, the event drew more than 20,000 people to Sussex County, Delaware, to watch or take part in the contest. Even in the Ozark hills of Arkansas, a traditionally built, fortified medieval castle is slowly coming together. The Ozark Medieval Fortress was started in 2008 and, when completed, the site will demonstrate how siege machines helped to attack and defend the castle as well as daily life in a castle. 8
The Catapults 9
Tension Vs Torsion An interesting thing about a catapult is there are two forces from which to choose to make it work: tension and torsion. Tension The original catapults as well as the Pitsco Catapult were operated with tension. They are also known as flexion catapults. Tension was created by using a device much like a large crossbow mounted on a frame. The bow part of the device would be made of wood or animal horns. These materials could both be bent back to create tension in the materials fibers. When the bow was released, the fibers would quickly spring back into place, flinging the attached object as a result. Torsion While using tension was a simpler and more obvious answer to powering a catapult, tension didn t offer tremendous power. The development of torsion as the driving force increased the catapult s power significantly. Increasing the power allowed larger ammunition to be used or increased the distance the standard ammunition could be hurled. Torsion, which powers the Pitsco Torsion Catapult (as well as the Pitsco Torsion Ballista) is the strain that develops in a material as it is twisted. We can create torsion by twisting ropes tightly around the catapult arm. At this point, the twisted material acts as a spring. Releasing the material allows the material to react to the strain by quickly unwinding allowing the catapult arm to fly up and release the ammunition. The torsion force built up in the twisted material actually has the energy to return the material to its original state. Tension catapult The Pitsco Catapult uses tension created by pulling back the arm attached to a rubber band. This stretches the rubber band. The fibers in the rubber band react just as the fibers in the wooden or animal horn bows. Releasing the tension makes the attached arm fling forward and release the ammunition. Other styles of catapults used a strong yet flexible piece of wood as the catapult arm. The arm could be pulled back to the bottom of the frame and then released to fling the ammunition. Uncommon Ropes Torsion catapult The ropes twisted to create torsion were made from a variety of materials. It was very common to use animal sinew, which is a tendon stretched to use as a cord, instead of the plant fiber rope or nylon rope we have today. Sometimes, the rope was even made from women s hair! 10
Experiment: Mass vs Distance The most obvious variable for the catapult is the mass of the ammunition. In this experiment, you will test clay balls of three different masses and record the results. Tools and Materials Needed Pitsco Catapult or Torsion Catapult built according to the kit instructions Tape measure Digital scale or balance Modeling clay 15'-20' of white paper such as the plain side of wrapping paper or Pitsco s Range Paper Tape Preparation 1) Make three balls of clay: one each with a mass of 1.5 grams, 3 grams, and 4.5 grams. Use the scale or balance to ensure the balls are the correct mass. 2) Find a long, narrow area approximately six meters (20 feet) long where the test can be conducted. A clear section of the classroom, a hallway, or the gymnasium are good choices. Roll out the paper so it lies flat. If using wrapping paper, make sure the plain side faces up. Tape down the corners of the paper to hold it in place. 3) Approximately 30 centimeters (one foot) from one end of the paper, draw a straight line or a mark on the paper. For each test, make sure the front of the catapult is aligned with this line or mark. This will help ensure the distance traveled by the clay balls is accurately measured. 4) Assign duties to several people: a person to hold the balls and to ensure the correct one is being tested, a person to load and launch the catapult, a person to spot where the ball landed, two people to measure the distance traveled by the ball, and one person to record the results. If necessary, some people can do more than one of these duties. Testing and Gathering Data 1) Line up the front of the catapult with the line or mark on the paper. Carefully load the 1.5-gram ball on the catapult arm. Taking care not to move the catapult, pull down the trigger. The clay ball should leave a slight mark on the white paper, helping to spot where it landed. 2) Label this mark with the ball s size and the test number (for example, something like #2 3 g for the second test of the 3-gram ball). 3) Measure from the alignment mark on the paper to the landing mark. Record this measurement in the table below. 4) Do this two more times with the 1.5-gram ball, and record the results each time. 5) Repeat Steps 1-4 for the 3-gram ball and the 4.5- gram ball. Record the results of each test. 6) Put away all the materials used for the testing. Test 1 (in.) Test 2 (in.) Test 3 (in.) 1.5-gram ball 3-gram ball 4.5-gram ball 11