To me, the most interesting thing about this design is that the counterweight comes to an almost complete stop as the projectile launches, putting a high portion of the initial energy into it. A normal trebuchet seems to be less efficient, because you often see the counterweight swinging after the launch.
Getting the large one balanced stably seems difficult, and repeatability might suffer as well.
Is there something about this design that makes it inherently more efficient? Or do the weights come to a stop because it is better tuned (or more tunable) than most traditional trebuchets that one sees?
That's a really interesting design. Not sure if "World's simplest" applies or not, but surely has to be contender. Wonder how practical that is from a siege weapon perspective.
This could be very accurate if it was, for example, set in a sort of guide bed. You could dig one with some wooden supports, or use concrete for a larger version.
I feel like anything that can throw more than a few pounds nearly 1000 feet has to be good for something. I kind of want to make one out of square section steel now-- I'm guessing that at 20 feet and 2000 or so pounds you could get quite a bit of velocity even on a bowling ball.
Very cool! It would be a lot easier to use if the "arm" part had an inverted "T" base to make it more stable on the ground. Although he may have needed to forego that modification to keep maximum efficiency within the competition's rules...
I built a trebuchet once when I was 10 or 12. It was about as high as I was tall at the time, and it was on a platform with 6 wheels. I shot some of the neighbors' prunes into a meadow next to our house, and then when I went for a massive load of IIRC pebbles, shot myself straight in the face. I wobbled home, had a headache for 3 days, then tore the thing down.
Not sure what my point is - maybe 'careful what you wish for'?
Jim and Harry's Trebuchet was built in part at the Exploratorium and was tested in the Marin Headlands. They were not allowed to chuck rocks into the ocean so they marked all of the rocks used for their tests with the tag "This is not a rock", a paean to surrealist Rene Magritte.
I've often thought, much of the trebuchet energy goes into pushing at the pivot point in a non-tangential way. Creating waste heat instead of velocity.
Another design, is to wrap the rope once around a round pulley at the hub, run it to a tower and drop the weight straight down. Now all the force is applied tangentially, going into rotational energy.
TEACHER NOTES
Teachers! Did you use this instructable in your classroom?
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The racquetball that my son was launching in the videos above was partially filled with water to bring it up to a regulation weight of 3 ounces. Water-filled racquetballs make fun projectiles.
I had wood shop in middle school. Imagine a shops teacher assigning this as a final project to his 8th grade students.
Getting the large one balanced stably seems difficult, and repeatability might suffer as well.