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The Walking Arm Trebuchet
- drallison 7y agoOf course, everyone has wanted to build a Trebuchet. A classic book about the experience is Jim Paul's CATAPULT: Harry and I Build a Siege Weapon (https://www.amazon.com/Catapult-Harry-Build-Siege-Weapon/dp/0394585070 https://www.amazon.com/Catapult-Harry-Build-Siege-Weapon/dp/...).
- roel_v 7y agoI 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'?
- drallison 7y agoJim 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.
- Twirrim 7y agoThat'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.
- debatem1 7y agoI 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.
- klyrs 7y agoIt looks fairly unreliable to me -- it appears that a successful shot requires it to fall just right, and even then it might miss a barn. OTOH it looks like a single person can carry it around, which could make for quite the ambush
- r00fus 7y agoMight make sense where range is important but accuracy is not needed.
- pnutjam 7y agoThis 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.
- b0rsuk 7y agoIt could also be easier to mass produce.
- cellular 7y agoThe pumpkin market is really rising.
- pontifier 7y agoTo 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.
- nkurz 7y agoIs 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?
- elliottkember 7y agoThis video was an interesting experiment in optimizing trebuchets: https://www.youtube.com/watch?v=-gn2RGPqe_A https://www.youtube.com/watch?v=-gn2RGPqe_A Edit: and the followup with wheels: https://www.youtube.com/watch?v=KpFTyE-wiNo https://www.youtube.com/watch?v=KpFTyE-wiNo
- kstenerud 7y agoVery 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...
- scarejunba 7y agoWait, so this is a novel design of an age-old siege weapon? That sounds crazy inventive!
- JoeAltmaier 7y agoI'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.
- ourmandave 7y agoThese two mentions... TEACHER NOTES Teachers! Did you use this instructable in your classroom? ... 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.
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