SCA Siege Engines and Structures

Types of Siege Devices

1. There are two types of siege devices: active siege engines and passive siege structures. For the purposes of this document, and to avoid confusion, siege engines shall be defined as those designed to deliver ammunition larger than the already established small arms ammunition.
   1. Siege engines are broken down into two categories. Type A engines shall be designed to deliver large ammunition to a range between 40 and 80 yards (36.6m and 73.2 m). Type A engines can use all approved ammunition classes. Type B engines shall be designed to deliver small siege ammunition to a range between 40 and 80 yards (36.6m and 73.2m). Type B engines may not use anything larger than small siege ammunition. For the purposes of administration, any device not designed to deliver these types of ammunition will not be considered a siege engine and unless acceptable for use as combat archery, shall not be usable.
   2. Man-powered trebuchets shall be considered Type B engines and must meet the requirements stated, with the exception that they shall not be required to have a mechanical release or cocking device. These engines may fire up to 2 small siege projectiles, or 2-8 small arms projectiles, per shot.
2. Siege structures will be defined as devices, such as towers or ramps, used to support personnel but not fitted with active weaponry.

General Siege Engine Regulations

1. The use and possession of siege engines may be affected by mundane law, and other policies. For example, anything resembling a crossbow will be subject to Crossbow legislation in Australia and New Zealand, and SCA Ltd's insurance policy prohibits the use of crossbows with moving targets in Australia. A full assessment of applicable legislation has not yet been done.
2. All engines shall have a maximum range of 80 yards (73.2m). This is especially important in direct-fire weapons, where range greater than this often results in safety concerns involving extreme minimum-range impact.
3. Engines and their projectiles shall be inspected by a rostered Siege Marshal before being used at that event and after any modifications are made to the engine during the course of an event.
4. Direct-fire engines shall not be discharged against personnel within a range of 30 feet (9.2m).
5. No engine will be discharged while any non-crew person is within 5 feet (1.52m) of the travel path of moving parts (e.g., a trebuchet will not be discharged while a fighter is standing anywhere in the path of the arm, front or back).
6. Engines must be equipped with a safety device sufficient to prevent accidental firing if they are to be relocated while cocked. Any engine without such a device shall only be relocated while un-cocked.
7. Except for man-powered trebuchets, all siege engines will be fitted with an appropriate mechanical trigger mechanism that shall be used for every shot.
8. Cannons or any replica of cannons are not allowed in SCA combat. Engines may not use compressed or ignited gasses or liquids or combusting materials of any kind to power projectiles.
9. Builders should attempt to visually and functionally recreate period siege engines. Engines shall be powered in a manner functionally consistent with their period counterparts. When period power methods are unsafe or not feasible, alternative sources of power may be used.
10. Any material approved for use in devices on the battlefield may be used in the construction of engines, provided that the materials are sufficient to ensure the safety of the engine. For safety, the following materials have special requirements:
    • Turnbuckles and eye bolts. When used in or attached to the source of power for an engine, these items shall be rated to withstand 150% of the forces produced (e.g., if the cable attached to a turnbuckle will support 100 pounds (45 kg) of tension, the turnbuckle will be rated at 150 pounds (67.5kg) static load). Hardware store and home centre hardware is often of low quality and rating, while aircraft or marine hardware is generally more appropriate.
    • Steel cable. While steel cable is useful for such functions as safe-tying a throwing arm, it will not be used as a bowstring for any type of siege engine.
    • All softwoods and non-laminated hardwoods.
      • When used as the throwing arm for a catapult, trebuchet, or the bow arms of a torsion ballista, they shall be secured against breakage with a minimum of glue-soaked sisal or jute cord wrapping (2-inch wraps every 6 inches [5.2cm wraps every 15.2cm]) over a section of rope glued along the full length of the arm. This will keep the arm from leaving the engine should it break. It is strongly recommended that all arms be wrapped in this manner, regardless of material used.
      • When used as the support for the main pivot axle(s) of a catapult, trebuchet, or torsion ballista, a minimum of two layers of wood, glued together with alternating grain directions, shall be used in order to avoid operating stresses causing a separation of the support wood along the grain. Using a structural metal plate through-bolted onto a single layer wooden timber is also an acceptable construction method if the axle passes through the metal plate.
11. Engines shall be durable enough to survive the rigours of combat and, while they should not be struck with hand weapons, should withstand either being struck with a full-force blow or being run into by a combatant.
12. All engines must be free-standing and may not use an operator as part of their support structure. Operators will not be included in measuring the footprint of an engine.
13. Siege Engines shall not have any bolts, or other projections (which may reasonable be expected to contact persons should they fall on the engine) extend more than 1/2" (13mm) into a legal face grill. Any items such as this must be covered with sufficient rigid material, a Tennis Ball, or a suitable rubber stopper, to prevent them from entering a legal face grill more than 1/2"(13mm). Triggers, release hooks, or other firing mechanism components, that would not normally be in a position that could cause injury should someone accidentally fall on the engine, are exempt from this.
14. All Siege engines and structures will be labeled with the name of owner, group, and kingdom, for the purpose of identification.

Type A engines

Type A engines shall:

1. Have a minimum footprint of 18 square feet (1.67m²).
2. Be able to deliver a large siege missile at least 40 yards (36.6m).
3. Have a mechanical cocking device, such as a winch or windlass and trigger and may not be cocked by hand.
4. Have a minimum crew of 3 people. Should crew size fall below minimum, the engine will not be operated.
5. Be able to fire 1 large siege projectile, or up to 5 small siege projectiles, or 2-20 small arms projectiles, per shot.

Type B engines

Type B engines shall:

1. Have a minimum footprint of 12 square feet (1.11m²).
2. Be able to deliver a small siege missile at least 40 yards (36.6 m).
3. Have a mechanical cocking device, such as a winch or windlass and trigger and may not be cocked by hand. Man powered trebuchets are exempt from this requirement.
4. Have a minimum crew of 2 people. Should crew size fall below minimum, the engine will not be operated.
5. Be able to fire 1 small siege projectile, or 2-4 small arms projectiles, per shot.

Siege structures

Siege structures shall:

1. Be able to support 300 pounds for every 4 square feet (135 kilograms for every 0.37m²) of platform area.
2. Be equipped with railings or walls at least 36 inches (0.91m) tall and able to support 100 pounds per foot (45 kilograms per 304mm) of railing length if the platform is more than 3 feet (0.91m) from the ground.
3. Be structurally stable (e.g., a wheeled siege tower should have a base big enough and wheels large enough to safely carry crew over the terrain of the field).
4. Battering rams and battering structures are permitted for use against authorised buildings and siege structures. Using a battering ram against a human target is expressly forbidden. Battering rams must be durable enough to withstand repeated impacts and light enough to be safe when carried or if dropped.
5. Siege structures that have a platform must have a base with a width and depth equal to or greater than 80% of the platform height. The platform may not be larger than the base, and may not extend past the base footprint in any direction. Structures that have a platform height of over 9 feet (2.74m) from standing surface to ground, may not have a platform that exceeds 75% of the base dimensions. For example, a tower that has a platform height of 10 feet (3.05m) must have a base that is no less than 8 feet (2.43m) in either direction. Additionally the platform dimensions may not exceed 75% of the base dimensions (e.g. an 8' x 8' base (2.43m x 2.43m) could only have a 6' x 6' (1.83m x 1.83m) platform).
6. Siege structures may not be made from industrial scaffolding, as it is not designed for the applications in which SCA combat operates.