This is it. The part of the war machine that means business. The Arm. You need: 6 segments of 2 ft.
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Our machine threw an official ft. The closest competition threw ft. We dominated! My office does a good job of having fun activities for us during the year. Here are the rules. No ready-made kits 2. Catapult devices cannot exceed 4 feet in height up to the pivot point 3. All catapults will be launched on a grass field. They must sit on the ground. No tables. The catapult cannot be staked into the ground. All catapults will launch a 4lb medicine ball. No combustion, explosions, compressied gases or air pressure may be used to enhance the performance of your catapult.
No electric motors allowed. Counterweights cannot exceed lbs. Each team will enter the best of 3 launches to determine the winner. We found a few simulators online and found out that we would need in the neighborhood of ft-lbs of torque on the rope bundle to throw the 4lb ball and distance so we scrapped that idea. The next idea was to build a trebuchet. This is the machine that the rules were written for. We had to find a way to bend the rules in our favor, and the trebuchet was close, but not quite there.
Enter the modified floating arm trebuchet. This machine lets you get your counterweight higher than a traditional trebuchet but keeps the pivot point low enough to keep with the rules of our competition. The plans came with brief instructions on scaling the machine up as the designs built a table top machine. We spent a good deal of time building our own plans and instructions based on the plans we had purchased. Picking up the lumber Building the inital frame.
Adding the columns to the base. Adding the runners to the top of the columns. The pivot wheels will run on these boards. Here we have test fit the throwing arm into the base.
You can see the 1" all-thread that will hold the weights at the bottom. The wheels are caster wheels with needle bearings and servicable grease zerks. More bracing, and the guide wheel for the arm has been added.
We later discovered that the wheel was too high. The wheel needed to be flush to the top of the runners in order to make a smoot transition for the arm. Here is the release pin for the sling. You can see that the pin is adjustable to allow us to change the trajectory of the projectile. A shallower angle means higher flight, and the opposite for a steeper pin angle.
More pictures and video to come.
Modified Floating Arm Trebuchet
Our machine threw an official ft. The closest competition threw ft. We dominated! My office does a good job of having fun activities for us during the year. Here are the rules. No ready-made kits 2. Catapult devices cannot exceed 4 feet in height up to the pivot point 3.
Floating Arm Trebuchet
Ensure that the shafts you choose have a diameter that mates well with your inside wheel diameter, as well as your inserts. Our shafts were steel bar. The weight bar was 1. At the tip of the arm, we welded a steel box around it to hold the pin for the sling release and a loop to tie the other end of the sling rope to.
Floating arm trebuchet