Sheer chance and silmultaneous invention, it seems, brought Trollhammer and Mjolnir together at the Oklahoma Renaissance Festival. Unbeknownst to each other, "Wulfgar" Johnson and Dr. Calvin Cole both began working seperately on individual trebuchets in the spring of 2002. Dr. Cole, working together with his students in the Physics Department at Northeastern State University Tahlequah, Oklahoma, first set out to construct a "fixed-bucket" protype out of pipe. Meanwhile, Wulfgar was busy building a six-foot-tall "swing bucket" working model of his own, whereby he learned the finer points of trebuchet construction by trial and error. The lack of detailed plans was the biggest challenge both men faced during the construction of their engines. It seems the old Medieval engineers never committed their experience and expertise to paper, but instead chose to teach their apprentices directly -- by memory, without blueprints -- during actual siege operations in the field! To make matters worse, historical machines were often custom-designed to meet the singular challenges of a particular siege, with each Master Engineer contributing his own ideas and "rules of thumb" on the best locking/firing mechanisms; throwingarm length; and counterweight construction, for example. Thus, individual trebuchets could vary widely both in detail and over time -- even those constructed by the same engineer! Old woodcuts, illuminated manuscripts and other surviving illustrations of the period didn't offer much more help, either. Since the artists of the times were neither trained nor terribly interested in the specifics of military engineering, their recorded observations of trebuchet construction are often contradictory, confusing and lacking in vital detail. Unfortunately, the last chance to actually examine an authentic Medieval trebuchet occured in England during the Nineteenth Century. According to Wulfgar, a dismantled trebuchet was discovered still in storage during a municipal inventory of one British town's assets, an inadvertent leftover from the old defenses of the city walls. Historians were duly notified but, before they could arrive on the scene, the ignorant townsfolk cut up the old siege engine and burned it as firewood -- and the secrets of its construction were lost forver (Photo, Below: spectators watch as a shot from Trollhammer lands just short of the "French" castle. Mud splashed up by another close miss can be seen on the base of the castle wall)!
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espite contradictory historical documention and the lack of authentic plans, both Trollhammer and Mjolnir are very similiar in design -- even tho both Wulfgar and Dr. Cole worked seperately without knowledge of each other during construction of their individual trebuchets. Of the engineering problems and their solutions encountered while building both engines, Wulfgar said: "There was really only one way to do it: whatever worked was exactly what to do." Needless to say, such a pragmatic approach would have done great credit to the old Medieval siege engineers themselves! For his part, Wulfgar choose a "swing-bucket" design for Trollhammer since such a scheme not only entails less effort to load, but the back-and-forth "rocking pendulum" motion of the throwing arm immediately after firing quickly dissipates the shock of firing the machine. Dr. Cole, on the other hand, choose a fixed counterweight system for Mjolnir. Since such a system does not absorb the recoil from firing like the "swing-bucket" does, wheels were added to his trebuchet (Photo, Above Right: As can be seen in this view, showing Dr. Cole's artillery team scrambling to load Mjolnir for another round during firing demonstrations at Muskogee. Team members were drawn from students in the Engineering Department at NSU (Northeastern State University). Thus every time Mjolnir was fired, the entire engine tended to jump forward a bit before rolling back into its' old firing position. As an elegant touch of engineering, Dr. Cole also installed a lockpin on Mjolnir's counterweight so that -- by simply pulling the pin out -- he could instantly convert his siege engine from a fixed- to a swing-bucket system as necessary. Once all the fine details of contruction had been worked out in the prototypes, the actual construction of each machine did not take long at all. Dr. Cole had the most able assistance of students from the Engineering Department at NSU (Northeastern State University) thru all phases of his project, for example, while Wulfgar noted that -- with the experience and expertise he's acquired already -- he could easily build another Trollhammer in just one week, working by himself; or just two days, if provided with a construction crew! But not until both men simultaneously submitted seperate proposals to faire management at Muskogee, offering to construct a full-scale working trebuchet for the renaissance festival, did Wulfgar and Dr. Cole learn of each others' efforts, however. Then, in a decision worthy of Solomon, festival management thoughtfully weighed the merits of their individual proposals -- before wisely accepting BOTH offers (Photo, Below: trebuchet engineers Dan "Wulfgar" Johnson, at left, and Dr. Calvin L. Cole, at right, pose in front of Mjolnir during the 2005 Renaissance Festival at Muskogee)!
Ufortunately, the insurance underwriter for the Muskogee faire decided in 2005 that "live fire" demonstrations of trebuchets was just too dangerous an activity even for renaissance festivals and so suspended coverage in the interest of public safety. This decision was most regretable. For one thing, Ryleh did not have video capability in 2004 when Trollhammer and Mjolnir were being demonstrated, so he could only record still images of these marvelous machines in action. Since these two engines are also unique to the American renaissance festival scene as far as Ryleh knows, he was bitterly disappointed to return the following year with camcorder in hand, only to discover that the trebuchets had been shut down! On the other hand, Master Wulfgar was more than happy to do a "dry" firing (i.e. without ammunition), showing how Trollhammer would handle normally under siege conditions. In addition, Wulfgar was most eager to explain the history of trebuchets, their operation and construction to every interested visitor and faire patron. In the not-too-distant future, we trust, a new insurance underwriter will be found so that live firings of these awesome seige engines may resume. If you are visiting The Castle at Muskogee, meanwhile, be sure to stop by the Jousting Field, greet Master Wulfgar and view both of these rare, working trebuchets on display. They are definitely one of the more unique exhibits and events you'll find at the Oklahoma Renaissance Festival!
TREBUCHETS IN ACTION -- This site features photo galleries of both the large Swedish "swing-bucket" trebuchet on the Isle of Visby as well as the Eketorp Traction Lever Engine located on the island of Oland. Downloadable video clips show both engines in action!
BOOKS AND VIDEOS -- Plans, construction tips, trebuchet simulators, message board, calendar of events and more will introduce you to the modern art of "hurling"! Even better, trebuchet videos from various television specials by the Discovery Channel, Monster Garage, Junkyards Wars and others may be ordered thru this site.
"DESTROY THE CASTLE" -- A fun game courtesy of PBS and NOVA! First design your own trebuchet, then fire it to see if you can bring down the castle walls. Experiment with different combinations -- wheels/no wheels; short/long slingrope; hinged/fixed bucket and other variables, then check out the section on "NOVA Builds a Trebuchet" to see how it should be done!
TAKE THE TREB CHALLENGE -- Play the Trebuchet Game online! Read "Treb Principles" first, then design your own engine and test it out in three seperate challenges: distance, accuracy and power. If your design is successful enough, your name will be entered in the Treb Hall of Fame! Submitted by Keith Charlet.
DOWNLOAD NOW -- Wintrep.exe, a free trebuchet simulator which allows you to first tweak a large number of construction variables -- including sling length, counterweight weight, projectile weight and more -- and then "fire" your finished siege engine against a castle tower.
Standard Disclaimer: This webpage is strictly an *Unofficial* look at the Oklahoma Renaissance Festival held in Muskogee, OK. The author of these pages is in no way, shape, manner or form connected with the Oklahoma Renaissance Festival (3400 Fern Mountain Road, Muskogee OK 74401 :: 918-687-3625 :: 800-439-0658), the Castle at Muskogee and/or any of the sponsors associated with this event. All opinions expressed are strictly this author's own. Unless noted otherwise, all photographs are copyright ©2000-2006 by George Laking.