Survive Zombie Apocalypse - Catapults

There comes a time in every gentleman's life when surviving a zombie apocalypse comes to the forefront of his thoughts.

This thought is often followed by pretty music and lights in your head (well, it does for me, anyway).

Some time ago I entered a challenge to make a miniature siege weapon capable of tossing a marshmallow. The challenge was to make a catapult no greater than 60cm in length and whoever's catapult could toss a marshmallow the furthest ... won.

WARNING! This instructable will help you to manufacture a catapult (or two) that will ONLY save you against zombies with both a sweet tooth, and diabetes OR very, very small zombies.

A Counterpoise Trebuchet is a siege weapon with a beam mounted on a pivot where the pivot is set approximately 7/10ths along the beam and with a counterweight designed to swing the beam through an approximate 200 degree arc. A Sling is mounted at the long end of the beam with one end fixed and with the other end connected by way of a loop and pin.

A hazelnut (or indeed a marshmallow) is loaded into the sling and the beam is drawn down to the base.

When the beam is released, the counterweight falls toward the ground, swinging the other end of the beam with tremendous force.

When the beam passes the zenith of it's arc, the loop slips from the pin thus opening the sling and projecting the ... erm ... projectile forward.

For this project, I used 20mm square pine, a small piece of cotton drill and cooking twine for the trebuchet. The counterweight is constructed from a small wooden box filled with fishing sinkers and covered with another piece of cotton drill.

The "trigger" is simply a bent nail to make a hook with a piece of cotton attached to effect a release.

Dimensions:

Base

140 mm wide x 300 mm long

Pivot Support

260 mm base width x 170 mm height

Pivot

160 mm x 8mm dowel

Swing Arm

280 mm long

Counterweight Basket

70 mm wide x 100 mm long x 35 mm high

Maximum recorded throwing distance (marshmallow)

8.5 m

This catapult is a simple frame with a butted stop. The stop is padded with a piece of 10mm felt to help to keep the catapult in one piece (reduce impact damage).

A hole is drilled through the sides of the onager to allow a loop of braided nylon cord to be passed through.

A nail is used to hold the braid in place with another nail used to stop the nail spinning. A brass washer is placed between the body and the nail to make turning the loop easier.

The forward force is created by twisting the loop several (actually about 20) times on each side with the end of the spoon in the middle loop. This is a "torsion" engine. The nail that holds the braided cord is bent into an L shape.

The spoon is brought down to a simple trigger (three eye screws with a nail to hold it in place).

A marshmallow is placed in the "basket" and the trigger is released. The twisted braid then twists the catapult forward sending marshmallow death to the undying minions before it. Crushing them like tiny little bugs.

Dimensions:

Base

140 mm wide x 300 mm long

Pivot Support
70 mm base width x 100 mm height x 140 mm stop width

Spoon/Basket Arm

300 mm

Braided cord

approx. 250 mm long

Maximum recorded throwing distance (marshmallow)
12 m