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Hybrid Or Counterpoise? a Study of Transitional Trebuchets

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Hybrid Or Counterpoise? a Study of Transitional Trebuchets Western Michigan University ScholarWorks at WMU Master's Theses Graduate College 12-2004 Hybrid or Counterpoise? A Study of Transitional Trebuchets Michael J. Basista Follow this and additional works at: https://scholarworks.wmich.edu/masters_theses Part of the History Commons Recommended Citation Basista, Michael J., "Hybrid or Counterpoise? A Study of Transitional Trebuchets" (2004). Master's Theses. 4987. https://scholarworks.wmich.edu/masters_theses/4987 This Masters Thesis-Open Access is brought to you for free and open access by the Graduate College at ScholarWorks at WMU. It has been accepted for inclusion in Master's Theses by an authorized administrator of ScholarWorks at WMU. For more information, please contact [email protected]. HYBRID OR COUNTERPOISE? A STUDY OF TRANSITIONAL TREBUCHETS by Michael J. Basista A Thesis Submitted to the Faculty of The Graduate College in partial fulfillmentof the requirements for the Degree of Master of Arts Department of History WesternMichigan University Kalamazoo, Michigan December 2004 Copyright by Michael J. Basista 2004 ACKNOWLEDGEMENTS I would like to thank the many people who have helped make this work possib1e. iwould- liketo firstthank my parenis andfamily without whose supporti never would have made it this far. Also worth noting are my professorsof history at Edinboro University of Pennsylvania. My thesis advisor, Dr. Larry Simon, is especially deserving of thanks- as he- pushedme- to produce-work that he-thoughtwas up to my capabilities and put up with me. He even made the ultimate sacrificeand missed Bob in concert. Deserving of speciatthanks amt credit is my friend JustinPoore ·. It-was· throughhis generous help that the wonderfulillustrations at the end of this work were produced. I would also like to thank Dr. Steven Walton at Pennsylvania State University for helpingme withthe physics and engineeringwork, withouthis input and help my ideas would not have come to fruition. Dr. Paul E. Chevedden also deserves my thanks for serving as the starting point andinspiration of this research. Michael J. Basista 11 HYBRID OR COUNTERPOISE? A STUDY OF TRANSITIONAL TREBUCHETS Michael J. Basista, M.A. WesternMichigan University, 2004 This study investigates the engineering and use of a proposed type of trebuchet in the Middle Ages. A study by a prominent historian has suggested the existence of a type of siege weapon that made use of both human +md gravitational forcesto fireits projectile. My research will investigate this claim by examining select sources, reviewing the engineering principles involved, and determiningthe viability of such a machine. Afterdealing with this theory I will offer my own new intvrpretation made fromthe sources. This interpretation will center on the application of ancient technology to make trebuchets more efficient. The theory involves the idea of counterpoising the mass of the components and projectiles with the use of a small weight. Much of the prior work on this su}?jecthas been speculative and based upon unclear primary sources. My research will offera more solid basis forinterpretation based upon work in physical principles as well as historical sources. TABLE OF CONTENTS ACKNOWLEDGMENTS ............................................... :......... ;........................... n LIST OF FIGURES ···················································"·········································· lV CHAPTER I. INTRODUCTION AND IDSTORIOGRPAHY........................................ 1 U. TRACTION AND-COUNTERWEIGHT TREBUCHETS- ...................... 14- III. THE HYBRID TREBUCHET, FROM TRACTION TO COUNTERWEIGHT ENGINES............................................................... 33 IV. THE TREBUCHET IN SIEGES ............................................................... 67 V. C-ONCLUSIDN ....................... :................................................................. 79 APPENbIX............................................................................................................ 82 BIBLIOGRA.PHY................................ ........................... �...................................... 9-2 r' l1l LIST OF FIGURES 1. Traction Trebuchet ................................................ :...................................... 87 2. flybridTrebuehet ......................................................................................... -SS- 3. Counterweight Trebuchet.............................................................................. 89 4. Seesaw in-Equilibrium showing equal forces- on- both sides ....... :................. 90- 5. Seesaw now has twice the weight to the left, so the force pushingdown on the left is also doubled .......................................... .. ............ ..................... 90 6. Seesaw has doubled the length on the left .................................................... 90 7. Center of gravity for a· tractiontrebuchet shown loaded (left}and · unloaded (right).............................................................................................. 91 8. Ideal centers of gravityfor acounterpoise trebuchet shown loaded (left)- · and unloaded (right)...................................................................................... 91 9: Center of gravity fora counterweight trebuchet shown loaded (left)and unloaded (right)............................................................................................. 91 IV Chapter One: Introduction and Historiography The trebuchet was the largest and most fearsome weapon of the Middle Ages. It-s mere-appearance at sieges was sometimes enough to cause a castle garri-son to surrender. 1 For almost fivehundred years the trebuchet was the most powerful weapon in the world. Its use has been documented from-third-century A.D. China to Hernando- Cortes in the-New World. 2 NapoleonHI experimented with them andthey are still used today, though for very differentreasons. 3 Like all machines and almost all weapons the trebuchet did not spring fully formedinto the arsenals of the Middle Ages. 1-tunderwent a- constant chainof improvements and�terations from humble­ staffsling to formidable wall-crusher. A weapon of the size, complexity, and ferocityof the trebuchet cannot help but drawattention to itself, both fromcontemporaries and historians. The­ historiographic record of the trebuchet in Europe stretches at least as far back as the ninth century and up to the latest work of modem historians. The bulk of thiswork, 1 While besieging Stirling Castle in 1304 Edward I began construction of a large trebuchet. Seeing the huge artillery piece being constructed the garrison surrendered; Edward refused to allow the garrison to reave the castfe until the trebuchet, named Warwolf, had been tested. Michael Prestwich, Armies and Warfare in the MiddleAges: The EnglishExperience (New Haven, 1996), 300. 2 Joseph Needham, "China's Trebuchet's Manned and Col,lilterweighted," On Pre-Modern Technologyand Science: Studies in Honor ofLynn White, Jr. Ed. B.S. IfaITand D.C. West (Maliou, 1976), 107-&. Pauf Chevedden, ''The ffyorid Treouchet: The Halfway Step to the Counterweight Trebuchet," On the Social Origins of ·Medieval Institutions: Essays in Honor ofJoseph O'Callaghan. Ed. Donald J. Kagay and Theresa M. Vann (Leiden, 1998), 179. 3 Louis Napoleon.Bonaparte and I. Fave� Etudessur le passe et l 'avenir de l 'artillerie (Paris, 1846-1871.) 2 though, is devoted to detailing its use in sieges and not to its construction. This is not to- say that this- issue has beeni gnored; instead,it has- been-dealt withprimarily in the mixed realms ofphysics, engineering, and amateur reconstructions. Those sources that bridge the gaps between the aforementionedfields and hi-story provide the most insight into its construction and usagein medieval warfare. There are two main types of trebtichets,a human-poweredversion and a version- powered by a 1-argeweight. Both designswork on the lever principal and offsetmasses. A third transition type oftrebuchet that utilizes both human and I gravitational power has been hypothesized. The hybrid trebuchet, as it is known, is described-ashaving a- small counterweight thatadds gravi-t-ati-onat pul-1- t-0 the downswing of the throwing arm.4 The hybrid trebuchetdoes not functionin the manner described. Instead ofa small coutnerweight the sources instead are describinga- counterpoise. A counterpoise-does not add- powerto· atrebuchet, but, rather, it makes the entire machine more efficient. The earliest studies of the trebuchet are those that are contemporary with its usage. These medieval sourcesare varied in both theirscope and theiraccuracy. There is everythingfrom accounts of sieges written by monks to detailed illustrations with an eye towards reconstructing a trebuchet. There are a plethoraof sources detailingsieges - fromeither a defender"'s - or attackerspoint of view thatgive insight into their use. Most of these accounts areunclear to a modem reader, or provide little accurate detail about sizes and projectile weights. The sources most usefulto this 4 Chevedden, "Hybrid Trebuchet," 179-222. 3 study are those that provide accurate descriptions of the constructionand types of the trebuchet. Those medieval sources include the work of Conrad Kyeser, Bellifortis. Bellifortis was produced in its finalform in 1405- as a text ·ctescribing various siege machines and tactics. Many of the designs are fancifuland were never produced in reality. The work simply served as a way forKyeser to ·depict soqie ideas he had regardingengineering ·
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