Medieval Balista

Standard Model 300kg Draw Strenght

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Features and Data


A fully functional real size medieval ballista, an example of torsion powered artillery as used in medieval times.
The drawing of the bow-string is made with a winching system and the release with revolving nut trigger (like a medieval crossbow).

Technical Data

Net Weight:
75 kg
D(washers inside ø):
90 mm
Max Lenght:
1700 mm
Draw Strenght:
300 kg
Max Width:
750 mm
Spring Ropes:
10 mm ø Nylon Rope
Max Height:
1400 mm
Exit Velocity (m/s):
85-105 m/s
Break Strain (Wood Frame) minimum:
Max Range (30º):
350-400 m
Break Strain (Washers):
150 kN
Efective Range (0-10º):
Break Strain (Bow String):
-10º / +50º
Break Strain (Winch Rope):
Wood Frame :
Pine Wood treated with fungicide and 2 coats of UV and water resistant varnish.
Metal Parts:
Steel St37.2 passivized to prevent rust. Washers made of Naval Brass also to resist corrosion. All steel pins encased in epoxy.


- Can be folded and disassembled to fit an everyday car (at least 1550 litres of trunk space with the folded seats);
- Disassembled components can be transported by a single person;
- Security features allows disabling the winch or the trigger, or both (so that no-one is tempted to shoot it without permission).


The assembly can be done in 10 minutes or less*:
- screw the 3-piece stand;
- insert the crossbeam in the head section;
- insert the winch in the crossbeam;
-insert the bow arms with the string;
- use the spanner to twist the washers for the desired tension;
- place the ballista in the stand;
- connect the elevation “y” frame,
and you’re done.   

(* - with the pre-tension option)

(see the assembly video)


Operating the ballista:
- release the winch lock and pull the arming claw to grab the bow string;
- lock the winch and spin the lever until the bow string is behind the trigger nut;
- making sure the trigger is locked, release the winch and remove it;
- aim and shoot.

(see shooting video)


Included in the Pack

·         A ballista

·         Stand and elevation y-frame

·         Tools needed for assembly /disassembly

·         Six one-meter long bolts, one of them being a special tracer bolt (for ranging)

·         Comprehensive manual

Everything is shipped by international carrier in two units: the crossbeam, due to its size, and a wood pallete with the rest (the power frame, bow arms, string, winch, stands, spanner and bolts). The full pack will have a brute weight around 100 kg.

Costumization Options

These are wonderful machines that can be used as they are, with their good looks and performance and are fun to shoot at affordable prices.
If you have more demanding requirements, bellow are some options to beautify or change its performance.

·         Pre-tensioning of the torsion ropes

In the standard version, each machine is shipped with two rope bundles and instructions for winding them in the frames. It’s an operation that can be made manually as its only time consuming and not technical, and some clients are happy with that.
However, CERCO21 crew has experience in setting those spring-ropes and a special apparatus for pre-stretched them really tight. That increases the machine’s performance and so we offer that service as an option.

·         Bigger size

Sometimes bigger is better. By choosing this option, the Medieval ballista will be constructed in a larger scale, designed to fit a van like a Ford Transit.
This XL size machine has a D, diameter of the coil springs of 160mm, a dra of  750 kg and weights around 125 kg.
It also has bigger shipping costs.
Bear in mind that CERCO21 can build in other sizes (even bigger, or smaller), please contact us with your special requests, bear in mind however that in case of huge engines shipping restrictions might apply.

·         Natural fibbers ropes

As a standard, CERCO21 ballistas are fitted with nylon (twisted) rope for the torsion springs. Nylon has a good Young’s Modulus, it’s impervious to humidity with it's only drawback being degradation through prolonged sun exposure.
The historically correct sinew rope or horse-hair rope are not available (we do not favor gutting cats to produce rope). Plant fibber ropes are also an historical alternative (they were used in Western Europe in torsion springs in the Middle Ages), and are widely available.

If you wish your machine to have a more appealing historical look, the string ropes can be made in manila, hemp or linen.
Because they have a smaller Young’s Modulus this option diminishes the machines performance. Of the alternatives, hemp is by far the better, but some restrictions apply when sending it to some countries.

·         Medieval style winching

The standard medieval ballista uses a modern gear as part of the winching system, which is totally enclosed inside a wooden box. It’s a safe, reliable and of-the shelf solution, non-intrusive that plays the historical part.
A more rugged and crude look can be achieved, with the option of a simple winch with exposed gears.

·         Choice of wood and finishing

The standard machines are made of pine wood. As an alternative, oak wood or other rare woods can be chosen: that option will make it a heavier but sturdier machine.
Also we can try to accommodate a specific colour and hue of varnish or choose as an option to be dark-waxed instead. For those and other options please contact us with your requirements.

·         Decoration

Beautiful as the machines may be, you may wish to give it a more personalised touch. For instance, if you’re in a reenactment group, you may be interest in engraving the name or coat of arms.
There is such a broad scope of possibilities, so contact us with your preferences to learn about the conditions.