Christmas Science-Geek Gift Alert

About three weeks ago, your humble e-scribbler wandered into The Tickle Trunk on Water Street and discovered some neat new toys.

Pathfinders Designs, a company from British Columbia makes kits of working catapults and trebuchets.

The Leonardo da Vinci catapult is based on a design by the great artist himself.  It uses the energy stored in two bent lengths of wood to crank the catapult.  The marketing materials say it will fling a ball made of modeling clay a distance of about 15 feet.

The kit is complete.  For $19.20 (taxes in) you get pre-cut wooden pieces, string, dowels, glue, a small piece of sandpaper, some modeling clay and a detailed set of instructions.

Allow about an hour to put the thing together, no matter what age you are.  The instructions are clear and written so a child under 10 could understand them.  That doesn’t matter though as one of the great potential values for this kit is a bit of bonding time between adults and children over the holidays.

There’s some information on da Vinci included with instructions.

Get it all together and what you wind up with is something that looks like the picture at right.

The finished model is about 33 cm (16 inches) tall, 25 cm (10 inches) long, and 14 cm (5.5 inches) wide.

Your humble e-scribbler bought one and then a second one.

And if that isn’t enough for you, they also have a trebuchet.

This one is a wee bit bigger than the catapult  - 26 inches (67 cm) tall by 18 inches (48 cm) wide  - and it can potentially hurl a ball of modeling clay out to about 20 feet according to the marketing literature. 

Again, you get pre-cut parts and all the stuff you will need except in two key areas. 

This kit supplies lengths of wooden dowels you will have to cut according to the instructions.  The dowels help to hold some of the parts together and give the finished model strength.  Since you need to use scissors, a hobby saw or similar tools, this one may require a bit of adult supervision or preparation, as well as some care with the measurements and markings.

But hey, as with all kits, this is a chance to learn.

Assembly time should be roughly two hours.  As soon as you are done, you can start flinging.

Well, once you add the second ingredient, namely weight for the big box on the end of the throwing arm.  This form of throwing device gets its energy from gravity acting on the weight.  You can use stones, pennies, old lead fishing weights or anything you’ve got laying around. 

Your humble e-scribbler used about 500 grams of pennies.  The box would easily hold about a kilogram of pennies.  Don’t worry.  the construction is strong enough to handle it.

These are safe enough for indoor use.  Flinging a five gram ball of modeling clay in the house didn’t case any damage chez Scribbler.  The trebuchet at full weight tossed the projectiles into the ceiling, producing a few scuffs that could be easily repaired. 

Cut back the weight in the box and adjust the sling and you can easily miss the ceiling and hurl out to the 20 to 25 foot range consistently (five grams with a 500 gram counterweight).  Note those ratios, by the way.

Aside from fun – and that’s the best part of it -  these kits are a good educational experience. 

One of the things you can do is experiment with different weights for the projectiles and, in the case of the trebuchet, of the counterweight that makes things fly.  You can also vary the length of the sling to see how that changes the flight characteristics.

Your humble e-scribbler found some information on line and made a modified sling.  Attached to the catapult with some minor modifications to the kit, the sling made some dramatic changes to performance.  Without a sling, the catapult would reliably toss a five gram ball about 17 feet.  With the sling, the catapult easily hit 27 feet  - we measured - and sometimes more.

So far, the oompah-loompahs at the scribbler household haven’t modified the sling on the trebuchet to see if they can boost its performance.  The results might not be as dramatic as with the catapult but the flinging distance should go up noticeably. The new sling design has a more effective pouch layout, attachment configuration and release.

The kits have turned out to be mighty popular.  A shipment of catapults that arrived last week went quickly but there are a few left.  As for the trebuchets ($21 plus tax), there are some left.  The manufacturer’s website notes they have sold out of the pre-Christmas production run.  More are on the way for January.

You can find the Tickle Trunk at 318 Water St, St. John's or by telephone at (709) 726-2535.

- srbp -

Photo credits:  (Tickle Trunk – google maps),  catapult and trebuchet illustrations from Pathfinders Designs)