Well, this past weekend (January 24-25), we went to visit my brother-in-law, Patrick, who is headed to Iraq. On the way there, I sketched out an improbably catapult, which we built and fired a couple of times. It was powerful yet a bit unsatisfactory. It used a bungy cord for the power and had a firing arm about 2 feet long. While we were building the trebuchet, Brennan snuck over and fired the catapult himself:
The nice thing about the catapult (Falcon 4) is that we made it completely out of scraps and recycled material. The bad thing is that only fired a gumball about 10-15 feet. If you decide to build one, please make sure that you don’t leave your kids alone around them as they definitely have some snap-back. That said, we challenged ourselves to something bigger … and Falcon 5 was born.
We spent a few minutes on the Internet and found some substandard free plans for miniature seige weapons and were unsatisfied so we sat down and drew this one out. Luckily, it worked only after about two or three modifications to the original design.
The first step was to build the frame – a 54″ by 27″ box made out of 2″x4″ lumber. As you can see, it is also the perfect size for Brennan to lay down in.
You can see in the picture that there is a cross lap joint which is about 3.5″ wide to fit and hold the uprights. This was a pretty cool experience to see Brennan working with tools really for the first time mostly by himself. I was impressed to see him using a hammer that was about as big as he was. And don’t worry he didn’t operate the chop saw in the photo.
After chiseling the joint and cutting a half lap in the uprights, we attached the 40 in uprights with drywall screws. For a crossbar, we bought a steel rod from Home Depot and cut it to fit the width. For the swing arm, we cut a 8 ft 2 by 2 down to 6ft. The cross bar split the swing arm at about 41 inches.
Instead of creating a trough specific for the projectile to slide down, we just put a piece of plywood to the cover the entire surface of the frame. For the counterweight, we used a 10lb diving belt weight and the pouch which was cut from a shop towel was attached to the swing arm with twine. This was definitely a pretty simple trebuchet to build but then again, we did it with no plans and no help. At the end of the day, we were able to consistently launch a 0.1 lb ball of kidney beans wrapped in aluminum foil about 35-40 ft.
Here it is all finished and being fired for the first time. If you look to the left of the swing arm in the second picture, you’ll see the first gumball we launched and the first pouch which we made out of duct tape (it didn’t work well at all).
I’ll post a video now that I am back in Charlotte and have my video camera. I have to reassemble the trebuchet when Jill isn’t looking so wish me luck. 
Dana
