An Crioch Cala Spring Beast Feast - Saturday, March 20, 2004
"When Pigs Fly" Tabletop Siege Engine Competition
Siege Engine Specifications

Siege engines must use Period principles of operation such as rope torsion bundles, counterweights, flexing arms, etc. Period appearance is not an absolute necessity, although (at the whim of the Siege Marshal, judge, whatever) it may be considered for the purpose of breaking a tie or some such reason.

They may not employ tension or compression devices (such as bungie cords, elastic bands, coil springs) nor compressed or explosive gasses for their power source.

It is permitted to use some modern equivalents of period materials and parts, such as woodscrews (vs. pegs), pop-rivets, rubber pads, modern glues, nylon, aluminum, fibreglass (vs. horn), and plastic.

The maximum size for engines shall be 18 inches in height, width, and length while in the cocked state, not including any trigger lanyard that allows the operator to fire it from a distance. "Length" is defined as the dimension parallel to the flight path of the ammunition, so you may not tilt or turn the engine at an angle to fit inside the imaginary box and thereby gain extra length.

Once the trigger is operated, part(s) of the engine (eg. throwing arm, sling) may move beyond the 18" size limit, but shall not actually detach and leave the engine.

Due to the small scale of the engines they may be cocked by hand (although a working winch or windlass would contribute to the period appearance), but must be fired using a trigger lanyard while the operator stands to one side of the engine.

The operator may not touch the engine (excepting the trigger lanyard) to fire it. The trigger lanyard itself may not be the means of powering the engine, ie. the operator may not be the "energy storage system", such as used in traction engines.

The Competition

More than one engine may be submitted, provided they are of different types (eg. ballista vs. trebuchet, or onager).

This is primarily a test of accuracy. The target(s) will be something along the lines of a large panel tilted at an angle, with circular target zones plus a few high-value spot target zones. The target may be anywhere from 10 to 30 feet away from the engines - we're not sure, it depends on the overall performance level of the engines entered. You will be allowed five attempts for a given distance, with the opportunity to make adjustments between shots. The exact scoring system will be announced at the event.|

The engine may be placed on a table or on the floor. Again, due to the small scale and mass of the engines, the operator may use tape to anchor the engine to the floor or tabletop and prevent it from sliding around during firing. Any tape used shall be included in the size limit.

The ceiling is believed to be about 15 feet high. The ammunition will be a medium-density irregularly-shaped object with a mass of 20 grams. It is approximately 2" by 1.5" by 1", but may be manipulated and tied to form a more spherical shape.

Useful Links for the Fledgling Flinger

Siege Engines
A very good site on (mostly) ballistas, by Darius Architectus.

Ripcord's Trebuchet Stuff
an excellent collection of references and tutorials about trebuchets, particularly on designing, building, and tuning small-scale models on a budget.

Ron Toms "How to Build a Catapult"
the links page on Ron's site. -

Overview of siege engines

Ron Toms's kits:
Larger than permitted for the competition, but do inspect the photos for some construction ideas. (Note: Do not use a design similar to what he calls the "Scorpion" models - they use bungie cords. The object that he calls a "Petraria", while it is merely a fantasy of post-Period artists, does qualify because it uses technology that
was possible in Period)
the home of Team Tormentum. Check out the "Engines of War" section for photos of their engines, and the "Engineering" section for photos and tips on building specific parts, such as a torsion bundle for an onager.

"Dictionairy [sic] of Siege Engines"
Many useful terms and names of different types of siege engines and their components.

E mail me: hew *at*
"Cum catapultae proscribeantur tum soli proscripti catapultas habeant."