Truss bridges have been a mainstay of civil engineering for many years. From early railroad structures to modern spans like the Bluewater Bridge in Port Huron, MI, truss bridges continue to be indispensible to our transportation network. This kit features all-wood construction. The materials have been carefully selected, accurately cut, and precisely drilled to allow easy assembly without tools or glue. The included instructions demonstrate how to build any one of six different structures using the color coded parts. The finished truss bridge measures 13" x 4" x 3.5" (33cm x 10cm x 89cm), with a structural span of 12" (30 cm).

The science project catapult kit allows you to tinker with the design of a medieval siege weapon, and provides you with the information needed to analyse your results. The catapult can be changed from a wheeled, sling type trebuchet, to a bucking spoon-arm onager in minutes. Power the siege engine with a free-swinging counterweight or fixed rubber bands. Vary the counterweight mass, projectile mass, or sling length. Install the optional crash bar or let the arm swing free. Compare the results of all the different configurations, and draw your own conclusions about which design is the ultimate medieval artillery weapon.

Catapults have been used throughout history. Its simplest form was the onager or mangonel, where a projectile was placed in a cup or spoon on the end of a throwing arm. The arm would be powered by twisted ropes of hair or fibre. When fired, the arm would swing up and slam into a stopping block, causing the entire catapult to buck, and sending the payload on its way. This tabletop catapult draws inspiration from this design and is powered by a powerful twisted rope skien, and features a simple spoon and arm type arrangement. Each piece has been accurately machined from carefully chosen lumber, and precisely drilled to allow easy assembly. The completed model measures 20.3cm(8") x 10.1cm(4") x 15.2cm(6"). A how-to section demonstrates loading and firing the completed catapult, including tips on tuning the finished kit.

The trebuchet was most highly evolved catapult type weapon of its time. Built on location, it was able to hurl carved stone balls weighing up to 300lb (136 kg) at enemy fortifications and at a safe distance from enemy fire. This tabletop trebuchet kit is designed to withstand rigorous use, safely and reliably when using the included projectiles. Each piece has been accurately machined from carefully chosen lumber, and precisely drilled to allow easy assembly. The completed model measures 20.3cm(8") x 10.1cm(4") x 15.2cm(6"). A how-to section demonstrates loading and firing the completed catapult, including tips on tuning the finished kit.

A magnetic accelerator is a chain reaction device. It is built in a series of stages, each containing a magnet, a spacer, and a projectile. To start the chain reaction, a steel ball is released, which accelerates towards the first stage magnet. When it strikes the magnet, its energy is transfered through the magnet and spacer into the projectile which speeds off toward the next stage. The process repeats until the last projectile leaves the end of the device. The more stages an accelerator has, and the more powerful the magnets are at each stage, the faster the ball bearing will leave the final stage. This four-stage device features powerful rare-earth magnets, steel ball bearings, and 25cm firing trough.

A magnetic cannon is a chain reaction device. It is built in a series of stages, each containing a magnet, a spacer, and a projectile. To start the chain reaction, a steel ball is released, which accelerates towards the first stage magnet. When it strikes the magnet, its energy is transfered through the magnet and spacer into the projectile which speeds off toward the next stage. The process repeats until the last projectile leaves the end of the device. The more stages an accelerator has, and the more powerful the magnets are at each stage, the faster the ball bearing will leave the final stage. This four-stage device features powerful rare-earth magnets, steel ball bearings, and 22cm firing trough.