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Yes he ends up with a cute toy that flings a marble but sounds like a rifle. But in the video he explains the engineering process to start with the desired goal
by wscott 5y ago
Yes he ends up with a cute toy that flings a marble but sounds like a rifle.
But in the video he explains the engineering process to start with the desired goal and then optimized and derive the parameters he needed to achieve that result. It was a good example of engineering.
- bee_rider 5y agoInteresting how different his device is, from historical trebuchets. In particular, they seem to maximize arm length, while he seemed to go for the shortest arm he could. I wonder if it is entirely the materials difference, or if his optimization was also much better than theirs. It would be cool to see his design built in period materials.
- Robotbeat 5y agoHe built his arm first out of plywood and I’m pretty sure you could easily build the same design out of a high quality single piece of wood. It really comes down to an extremely well-optimized design.
- ggcdn 5y agoRight, but I think its the high quality elastic bands that would be difficult to replace.
- Robotbeat 5y agoThey could be replaced with either a weight, steel springs, or perhaps rope or sinew cords like the Romans used. Rubber is more effective and compact, but watch the video and you see there’s nothing particularly special about using rubber & he could’ve picked something else. The rubber puller itself does not exceed 10 m/s.
- creato 5y agoI agree he could have used some other spring, but I don't think he could have used a weight. The acceleration of springs/rubber is potentially much greater than a weight (at least one starting at rest).
- Robotbeat 5y agoYou can use mechanical advantage to get the same result.
- ButtSpark69 5y agoWhich means a giant physical structure to support that giant lever arm. When you scale up to things that can knock down castle walls I suspect the difference is incredible.
- mypalmike 5y agoI think there is something particularly special about rubber in the design. He stretches it extremely tight. Even with the leverage of a crank, he strains to compress it to the length required, and the rubber holds up. It might be possible to achieve the same result with older materials, but the design would likely be much less compact.
- CrankyCanuck 5y agoNo, I don't think so. His design respects the inherent latency to accelerate a looooog set of elastics. Instead of stretching a set of elastics over a long distance, he uses a heavy bundle and stretches them over a short distance. It still takes a lot of effort to get that stretch, but all that energy is released extremely fast..as the elastics don't have to travel very far to do so.
- mcguire 5y agoDidn't that break?
- salmonellaeater 5y agoIt might have to do with the fact that he's using rubber bands to turn the arm, while historical trebuchets used weights. A weight is limited in how fast it can accelerate so you need to use a lever (the arm) to increase the speed.
- krasin 5y agoSprings could be used instead of rubber bands. While "coil spring" is a relatively modern invention, other kinds of springs are known from the Bronze Age, accoding to https://www.designingbuildings.co.uk/wiki/History_of_the_Spring#Bronze_Age https://www.designingbuildings.co.uk/wiki/History_of_the_Spr...
- Retric 5y agoSprings are much older than that, the bow is perhaps the most famous example from antiquity.
- krasin 5y agoGood point. I somehow was thinking about metal springs (Romans used springs from lead, for instance), but there's no reason to restrict it to metal.
- throwanem 5y agoLead springs? They'd have to be absurdly oversized by modern standards to hold up to any kind of force without deforming, I'd imagine. I'd love to read more about them, if you happen to have a cite handy.
- TheSpiceIsLife 5y agoI don’t reckon. Surely the above comment is confused, misremembering leaf spring as lead spring. Leaf springs appeared as early as the Roman empire as a form of primitive suspension for chariots and other two-wheelers. Instead of steel, savvy Romans used flexible wooden sticks. https://connect2local.com/l/112910/c/478618/examining-the-fascinating-history-of-the-leaf-spring https://connect2local.com/l/112910/c/478618/examining-the-fa...
- fabianhjr 5y agoWell, this might be supersonic but doubt it would throw heavy boulders at fortresses anytime soon to be useful as a siege weapon.
- deegles 5y agoA scaled up version of this would be terrifying... I'm sure with the right materials (and budget) it could launch a cannonball at those speeds.
- kingcharles 5y agoI was thinking it would be more fun with a rotten cow.
- Someone 5y agoA rotten cow might disintegrate before it leaves the launch site. I wouldn’t classify that as fun.
- jacquesm 5y agoThat strongly depends on your vantage point. Definitely not from the point of view of the cow.
- dredmorbius 5y agoRotten cows have limited perceptions.
- IntrepidWorm 5y agoSourcing?
- kingcharles 5y ago[citation required]
- Aunche 5y agoHis trebuchet is quite high off the ground, so the arm and sling has room to accelerate. This wouldn't really be practical in a medieval trebuchet, especially if you wanted to move it to a siege.
- dragontamer 5y agoMedieval Trebuchets didn't move. You hired engineers to cut down trees and build Trebuchets for a particular siege. Honestly, "Castle Drops" in AOE2 are more akin to how Trebuchets were used. You build an army, the army gains control of an area, and then you use your engineers to build a long-range siege device at that location. ------ https://en.wikipedia.org/wiki/Trebuchet#/media/File:Ms.Thott.290.2%C2%BA_016v.jpg https://en.wikipedia.org/wiki/Trebuchet#/media/File:Ms.Thott... See? No wheels. Those things couldn't move at all.
- Aunche 5y agoMy impression was that they were assembled on site, but they were pre-made and could be dissembled. From this thread, it looks like both methods could have been used: https://www.reddit.com/r/AskHistorians/comments/3z597l/in_medieval_warfare_how_were_catapults_trebuchet/ https://www.reddit.com/r/AskHistorians/comments/3z597l/in_me...
- deleted 5y ago[deleted]
- masklinn 5y ago> Interesting how different his device is, from historical trebuchets. It's more of an onager really: it's a torsion engine, whereas the trebuchet you'd think of is a gravity (counterweight) engine. > It would be cool to see his design built in period materials. "Period material" would be limited to sinew and / or hair, wood, and relatively small pieces of metal (mostly fasteners).
- toolslive 5y agoOnagers do not have slings.
- NikolaeVarius 5y agoYou are wrong. > It is commonly depicted as a catapult with a bowl, bucket, or sling at the end of its throwing arm. https://en.wikipedia.org/wiki/Onager_(weapon) https://en.wikipedia.org/wiki/Onager_(weapon)
- toolslive 5y agoI stand corrected!
- lmilcin 5y agoHe actually explained this in the video. You missed the best part.
- the__alchemist 5y agoThe book Structures describes how trebuchets are quite inefficient compared to the Roman Ballista, which the author alleges the medieval folks forget how to make. Much of the energy is wasted in the counterweight swinging. By contrast, he alleges bows, including hand-drawn, crossbows, and ballistas (or scorpions, or springalds for you AoE fans)are close to 100% efficient. This is relevant, since as the original com mentor pointed out what the video-maker built is arguably closer to one of those torsion weapons than a counterweight trebuchet.
- TylerE 5y agoSeems like efficiency is relatively less important (peasant labor is essentially free) and weight of fire more relevant. Trebuchets were usually siege weapons.
- jacquesm 5y agoThat cute toy would probably shoot the ball straight through you at appreciable distances.
- jaggederest 5y agoIt's about the same muzzle energy as a .38 special - definitely not a toy!
- SV_BubbleTime 5y agoSo with that in mind, his standing behind the loaded device, was akin to him muzzling himself. I would think the four rules of firearm safety would apply to supersonic trebuchets.
- curryst 5y agoI would think a prototype supersonic trebuchet would come with a lot more rules than a standard firearm. They would be much closer to the safety precautions for a prototype firearm, which includes things like being behind a blast shield because there is no safe zone if it fails catastrophically. I don't even trust that the sides of that thing are safe from shrapnel or the rubber bands whipping parts around. If one side of the machine gave way for some reason, it could absolutely swing sideways. That tiny string at the end is probably going fast enough to slice through skin and veins, and it's concerningly close to neck height. He should have parked his car off to the side and used the engine block for cover. The paneling of the car will stop minor wood shrapnel, and the engine block should be able to stop any metal pieces that come off. Ballistic barriers would be better, but at least you're not standing there tempting fate with your squishy and easily separable limbs.
- ISL 5y agoI found his lack of safety-glasses and ballistic shields disturbing, especially given that one of the rotors had already disintegrated. A piece of 3/4" plywood to stand behind would slow down a lot of lightweight shrapnel. Alas, one of the few useful things that comes with age and experience is an awareness of consequence...