The Red Dragon Catapultlozengia.com/dcrackel/RedDragonCatapultDesign.pdf · picture of completed catapults and children firing at stuffed animals, taken by Donna Crackel at Red Dragon

The Red Dragon Catapultdoc ver 1.0

picture of completed catapults and children firing at stuffed animals, taken by Donna Crackel at Red Dragon 2011 The Red Dragon Catapult was designed to teach the basic mechanical engineering of a catapult in a fun way. It favors a Greek means of torque generation rather than a modern means such as bungee cords. The design is simple to make and cheap to produce. It makes for an excellent youth activity. For youth coordinators: (If you just want make a catapult, go ahead and jump down to “What You’ll Need”.) This design was finalized after many prototypes and much testing. Remember youth activities should sound crazy, not be crazy. This catapult is made with a goal of shooting about 20 feet so that it’s fun, but does not have enough power to hurt someone. It is also meant to be cheap to make and easy to mass produce. Mass production is simple as each catapult is made from 2 complete 2x4’s using only a table saw and a drill. Be sure to pre-drill all holes. I made 20 kits in about 6 hours. After measuring and making all the cuts, I made hole templates from cardboard for rapid drilling.

During my class, many of the children's parents would point out that if I had done X, then that would double the power. That would be true, and also why I didn’t do X. There are many ways to increase the range and power of this design. I encourage anyone who is interested to experiment with what they can do to improve the catapult. Looking at known period designs is a good way to learn how to improve your catapult. Please send me pics of your modifications. ([email protected]) Never use your catapult to shoot at people or living things. What you’ll need

● 1 3 foot long 1x1 (launching arm)● 2 2x4’s 8 feet long● 16 feet or more of small rope (clothesline will work fine)● ¾ inch dowel wooden dowel rod● Drill bit that can make a hole ¾ or larger.● Optional bit for making starter holes for your screws or nails● 1 plastic cup or other similar shaped container to cut to size, that will hold ammp while

the catapult is firing.● Plenty of nails or screws (screws are better, nails are cheaper)

Cutting up the 2x4’s All of the needed wood for the catapult body can be cut from 2 2x4’s. The cuts are listed below. Cut the 1st 2x4 into:

2 3 foot long sections (base sides)2 1 foot long sections (base ends)

Cut the 2nd 2x4 into

2 16 inch sections (inner legs)1 16 inch top, however I to cut mine to 15.5 section (top)2 18 inches long diagonal pieces, cut into a parallelogram at 45 degree angle (supports) A ¾ inch hole or larger needs to be drilled 15 inches from the front of the 2 3 foot long base sections.

Cut 2 4 inch long dowels, about .5 inch in diameter.

Assembly Step 1: Assemble base frameNail or screw together the 2 1 foot pieces in between the 3 foot segments as seen above to make the base frame. Step 2: Assemble launch deck Nail or screw the 16 inch legs, 15 inches back from the front of the catapult.Nail or screw the top. You may wish to cut off the extra so it doesn’t hang over the support arms. This should make the upside down U shape seen in the Duct tape cup image. Now attach the diagonal support arms. Step 3: Drill Large HolesApprox. 15 inches from the back will be the center of the hole that needs to be drilled for the cord to pass through. It should be at least ¾ of an inch; it could be larger. Before you drill, hold your launching arm in the upright position. The hole should line up with the middle of your launch arm. It’s better that this is correct than to be exactly 15 inches from the back; but, they should be pretty close. Step 4: Cords and Dowels Now that the body of the catapult is completely assembled, it’s time to attach launching arm.

Tie a knot around one of the dowels. Push your cord through each hole, around the launch arm, then around the outside of dowel on the other side and back. As seen in the picture below. You want to go back and forth at least 4 times, 8 is better, if you can manage it.

Once the cord can not be pushed through the holes any more times, tie off the end on whichever side the cord ended on. Tighten the cords by twisting them, one clockwise, one counterclockwise. They should try to pull the launch arm to its upright position again the launch deck. If it pulls the base, un-twist the cords and twist them in the opposite direction. If it pulls to a point between the launch deck and base, then untwist one side, and twist it in the opposite direction. Step 5: Attach the ammo holder Attach a plastic, paper, or duck tape cup as a holder for your ammo. It should be on the top of the launch arm. Duct tape works fine for this. Would it be a SCA project without duct tape? Step 6: Load some ammo, pull back the launch arm and clear the range Any questions, comments or just to share your story about how this project went, please email Gebhard at: [email protected]. Never use your catapult to shoot at people or living things.