Elias and His Catapult

Every year, Mr. Cash's 6th grade science class does a catapult project.  Katherine and Sarah both did one.  This year it was Elias's turn.

Elias incorporated a sling into his project.  Here is some text directly out of the essay he had to write.  He named his catapult the "Power Winder".

"My catapult, a roman torsion catapult/onager, is a combination of two catapults. I chose the Power Winder’s design because when I researched different catapults and how they work I found most kinds of catapults have one or two things that set them apart from others and make them work better. The torsion bundle, or rope twisted to create torsion, classifies my catapult as an onager and provides the power and strength my catapult needed. The Power Winder uses the sling idea from traditional trebuchets instead of a spoon shaped depression to hold the projectile. The sling action provides the momentum and length along the arm to fire the projectile faster."

I helped him some with the cutting of the pieces and drilling of holes for the screws, and offered suggestions as needed.  The catapult project is something I have enjoyed working on with all of the kids.  We have already starting thinking about Asher's, which will be in two years.

The boys have already starting thinking about useful applications for this catapult, such as using it as a pitching machine and launching water balloons at turkey buzzards.

There are two strings for launching the projectile.  One is a safety device to hold the arm down while getting ready for the launch (that arm is under surprising tension).  The other string pulls a trigger releasing the arm.

Here's another view.