NOVA/WGBH Trebuchet Project
| ||||||
|
To the left, is the fixed counterweight mangonel* that had been designed using a computer at the Virginia Military Institute (VMI), Lexington.
|
|
* Note here the differing conventions for describing a 'trebuchet'. French convention usually distinguishes the counterweight balance throwing machines with hinged, or movable-weight hutches, as trebuchets; and those machines with fixed-weight hutches as managonels. A large number of English works have developed the practice of refering to both as 'trebuchets' and of using the expression 'mangonel' for the medieval version of the Roman onager.** Reportedly, the most impressive of Edward I's 13 siege machines in his 1304 campaign was called 'war-wolf'. Edward was so proud of the machine that he refused to accept Stirling Castle's surrender until he launched at least one shot with the machine. | ||
Construction of these two machines was to examine fundamental historical and technological questions:
- (1) Was it possible to construct the large hinged-counterweight trebuchet using only medieval materials and techniques?
(2) Were these machines capable of projecting stone balls weighing 300 pounds over more than 160 yards?
(3) Were the machnines capable of breaching a 7 foot-thick granite wall?
(4) What was the potential firing accuracy?
(5) Why did the hinged-counterweight machine trebuchet essentially replace the fixed-counterweight machine as of the fourteenth century?- (1) Was it possible to construct the large hinged-counterweight trebuchet using only medieval materials and techniques?
The task of constructing these machines was in the hands of approximately 30 Timber Framers Guild (TFG) from America, who were joined by about 7 European framers. The participants split into two teams based primarily on the basis of the skills necessary to complete each machine. The TFG has a webpage on its "Highland Fling" that gives an extensive and well illustrated account of the entire project. Images of the machines and of Urquhart Castle used on this page were taken from the TFG page. See bottom of this page for a link to the TFG web sites.
Renaud Beffeyte was the only French representive in the project. With his unique experience of having built some thirty machines over the past fifteen years, he was entrusted with the construction of the hinged-counterweight trebuchet
Spectacular location for the project was Urquhart Castle, dating from the thirteenth century, and located on a promontory overlooking Loch Ness, Scotland.
|
Images and a description of the castle are available at the Urquhart Castle web site.
Renaud Beffeyte's written report is published as an article in issue No. 50 of Timber Framers Guild Journal. A copy of the TFG's journal from the Guild's webpage. See below. In his article, Renaud relates:
-
- "Construction itself began on 19 October, ending 5 November,
inclusive of four days for assembling the machine. Every bit was executed using
traditional tools and a hand-actioned lathe. The throwing arm was hewn from a
50-foot oak with an average diameter of 2 feet; over 2.3 tons of quality
wood, delivered uncut, it was worked on six faces solely with the axe. But it
only took four hours to set the mast in place 24 feet off the ground, using a
system of pulleys and a shear leg. These same lifting techniques exist in Europe,
but, unfortunately, they are rarely used nowadays. I was gladdened to
see once again this marvelous spectacle."
The following parpharses further parts of Renaud's report:
The counterweight hutch was loaded with a "few tons" of wet sand. A 300 pound stone ball was placed in the "braided hemp sling." An initial suite of well grouped shots were launched on the first day of firing, although these hit to the right of the target. The next day, the trebuchet was angled in order to shoot further to the left and the desired accuracy was achieved.
The project answered the originally stated questions as follows:
Although it took more wood that the fixed-counterweight machine, the hinged-counterweight trebuchet replaced the fixed-counterweight throwing machine as of the fourteenth century because it took less men to operate it. It took less costly ballast material [6 tons of lead for the fixed weight versus wet sand for the hinge-weight]. The mobile counterweight allowed the construction of a more reliable, more
robust, and more easily adjusted machine. Further, it permitted loading the counterweight
with readily available, free materials (earth, rocks...) found on site.
| Timber Framers Guild is an educational organization formed in 1985 and dedicated to promoting the craft of timber framing. Two of their very fine websites are:
|
|
|
