Ancient Engineering
Ballistic Technologies of Antiquity

Science Project Experiments Catapult Kit - S.P.E.C.K. (tm)

No Glue Required!

The Ultimate Science Project Experimenter's Catapult Kit! It's fully adjustable, multi-configurable and repeatable.

This outstanding model is manufactured from top-quality half-inch thick (1/2") solid oak plywood. We use only USA manufactured, non-toxic formaldehyde-free and void free plywood. It is a stronger, more dimensionally stable kit, and a lot less expensive than similar kits made from natural wood.

No glue required! All parts can be assembled in about five minutes using rubber bands for fast and speedy modifications. Rubber bands and wooden projectiles are included!

    -- In one configuration it's a counterweight trebuchet. You can shift the counterweight or adjust the main fulcrum to change the lever ratio of the throwing arm.

    -- In another configuration it's a class-one lever catapult. Also adjustable for multiple lever-ratio options.

    -- Or change it to a class-three lever catapult.

    -- Try it with wheels or without- What effects will it have? Which way will it recoil?

    -- Use a sling or try it with a cupped arm. Which is more effective? Which is easier to use?

All in all, there are more than 400 different configurations and tuning options possible with this kit. Suitable for hundreds of experiments and learning opportunities.

What you get:
All the parts needed to assemble every configuration of this kit. 3/4" and 1" wooden projectiles (the 1-inch balls weigh approx. double what the 3/4" balls weigh), Rubber bands for assembly and power in the lever configurations, leather sling pouch and nylon sling twine, and a welded steel ring for consistent sling release timing.

The completed frame is 14.5 inches long, 7 inches wide and 11 inches tall. The arm measures 20.25 inches long with multiple axle and power attachment points. This machine can hurl projectiles up to 40 feet, depending on configuration, tuning, and lots of other variables!

What you can learn:
This kit provides a real world, hands on example of many aspects of basic physics. It exposes the student to concepts of mechanical advantage, levers, gravity and energy, to name a few. It can demonstrate the storage and conversion of potential energy to kinetic energy through levers, and it is equipped with optional wheels, to demonstrate conservation of momentum. All
in all, the concepts of efficiency, power and work can be demonstrated and applied.

This kit is useful for teaching engineering, science, design of experiments, problem solving and Cause/Effect relationships. It was designed to get students to think about physics in a real world, tangible context. Theories can be made and tested; this process, and analyzing why the observed results occur can ultimately lead to other, more advanced concepts in physics, mechanics and mathematics. Carrying out the experiments teaches the scientific method, and contextualizes statistics. Analyzing the data can make use of statistical methods from basic averages to much more advanced topics if desired.

With 18 pages of instructions including assembly of every basic configuration, suggested experiments, tuning guidelines, independent and dependent variables to record and measure, data tables, historical information about trebuchets and catapults, and more, it should be easy to get started with this Ultimate Science Project Kit!

* SPECK, S.P.E.C.K. and Science Project Experimenter's Catapult Kit are trademarks of RLT industries.

Tools required:
Scissors, Glue, Ruler, and a utility knife. Sandpaper is optional.

Assembly time:
For a Master carpenter doing a sloppy job: about 30 minutes.
A person with no kit building experience being extremely meticulous: about 1 hour.
The model in these photos was built by Ron Toms in under an hour.

Assembled Size:
- Height: 11"
- Length: 14.5"
- Width: 7"

- 10 to 40 feet depending on configuration, projectile choice, tuning and lots of other testable variables!

Shipping weight: 5 lbs.
Box dimensions: 16" x 12" x 4"

Quantity pricing info:
0 to 4 kits, standard price.
5 to 9 kits, 10% off
10 or more kits, 15% off

Orders of $200 or more get FREE ground shipping!

WARNING! This is a functional model catapult. It contains a fast moving arm that can cause injury if you make contact when firing. Use only under strict adult supervision.

* Can throw 40 feet when properly constructed and tuned. Your performance may vary.
* Wooden missiles, rubber bands and counterweight box are included. You must supply the counterweight material, about 320 pennies recommended.
* Actual item may differ slightly from the photos on this page.
* SPECK, S.P.E.C.K. and Science Project Experimenter's Catapult Kit are trademarks of RLT industries.

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    Price: $59.00
    Minimum age: 10
    Availability: out of stock

    Item code: 10821

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A catapult is any kind of device that shoots or launches a projectile by mechanical means. In England, a catapult is what we call a slingshot in the US. A catapult is also the part of an aircraft carrier that launches airplanes off the deck.

But for our purposes, a catapult is any of the ancient types of artillery, including Onagers, Scorpions, Trebuchets, Ballistae, Springalds, Coullards, Bricoles Perriers and more.

But most people tend to think of a catapult as the one-armed torsion machine used by the Romans. This is also known as the Onager or Mangonel.


The word Mangonel derives from the ancient Greek word "Manganon", literally meaning "engine of war". The Romans called it a Manganum. In pre-medieval French the word Manganum was changed to Manganeau, and the English changed that to Mangonel in the 1300s.

The history gets a little sketchy in the middle ages, but some historians believe that "mangonel" was shortened to the word "gonnel" about the same time that cannons were being developed, and later still, "gonnel" was shortened to "gun." And still today, in the military a "gun" is strictly a piece of big artillery.


Onager is originally the name for the wild Asian donkey. This donkey bucks like a bronco if anyone gets too close to it, and it is known to kick stones at people and predators too. So when the Romans needed a name for their one-armed torsion catapult, they called it the Onager!

The Onager (catapult) has a single arm that is powered by a large skein of twisted ropes. The ropes were usually made from hair or sinew for their elastic properties.


The word "Trebuchet" is originally French, and meant something like "to fall over or rotate about the middle" as in a see-saw rotating on its axle. It also seems to have meant a big, heavy beam. Today a Trebuchet is any kind of catapult that is powered by a massive counterweight on one end of an arm, and a sling on the other end. This includes Perriers, or "traction" trebuchets which are powered by a mass of people pulling one end of the arm with ropes.


This is a two-armed torsion device invented by the Greeks. It works similar to a crossbow, but instead of a flexible bow, it uses two stiff arms powered by twisted rope skeins like an Onager. The ballista predates the Onager by several centuries and was used to hurl stones (lithobolos style ballista) and also bolts or darts.

Obviously, this is where we get the word "ballistic".

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