Thinking this approach out, could someone correct me if I have this wrong.
So he gradually increases the energy transfer from the weight to the arm over the course of the drop. But that arm swinging around must have a lot of energy loss due to friction and air resistance.
This loss will rise exponentially with the speed increase right? So in a sense he is holding his energy budget in a very inefficient phase, with high losses.
Two things support this. A) he spent a lot of time trying to make the arm more arodynamic. B) The spool widening at the end, which is essentially changing back down gears, applying more torque, right at the end when you want speed.
An alternative would be to drop the weight, and let it fall unrestricted until it gets to it's highest speed (this would minimise friction and air resistance) and only at the end of its fall, transfer the energy into the arm.
In this case the arm would only need to rotate 180 degrees or whatever, and not waste energy rotating right?
And then, to take this a step further to make this work there would need to be some flexibility or elasticity in the system to take energy from the high speed falling weight to the arm.
And what you have ended up with is something that looks like.... A whip!
Energy loss from air resistance typically is quadratic, not exponential, with regard to velocity. So it’s worth much less than you’re arguing. And the arm has to rotate from what I can understand, so the end rotational velocity - and hence, rotational energy - would be the same?
If I'm picturing what you're explaining correctly, I think this would be difficult. Suddenly accelerating the arm from zero to hundreds of mph would put immense stress on the arm, not to mention whatever you're planning on using to transfer that energy (you kinda hand waved that bit).
I think your assessment is correct about the energy losses. I'm just not sure about the fix.
I think the fix is essentially a whip, that's what I meant by elasticity and flexibility.
If you want to accelerate a weight quickly in a single swipe, (simplified) gradually reducing the mass along the length of the whip imparts more kenetic energy at the end (the whip crack).
So the arm would no longer be rigid, although you can see in the OPs video it isn't actually fully rigid.
He has some great videos. I watched this one and was impressed at the calculations, the transparency and the celebration at the end when he reached supersonic speeds.
Or, in other words: There was some text to read and some pictures to look at. For topics in the range of "supersonic trebuchets", I'm absolutely okay with quickly reading some lines of text; dynamically deciding how quickly/thoroughly I read, what paragraphs to skip, etc. What I'll definitely NOT do: Watch a video clip about it.
Other trebuchet fans who dream of building one some day may be interested in googling "walking trebuchet" for a surprisingly high complexity/results ratio.
I think the idea is that at the end the sling starts to unwind too, increasing the effective arm-length (that non-linearity is one of the reasons trebuchets are so efficient to begin with). As a result it's possible that decreasing the spool to near zero is like putting the gears of your car too high. Reducing the spool size ensures there's enough torque left to put more power into the final swing.
I suspect that with a little iterative modelling of the whole system with derivatives, efficiency could be bought from ~40% to ~80%, giving you an extra few hundred mph...
I'm pretty sure the only reason the video trebuchet wasn't a proper bullet is because it's made out of plastic instead of a ball bearing. Aren't most handguns subsonic?
A LLM may produce OpenSCAD compliant syntax, I don't doubt that, but how do you make it produce designs that fit engineering constraints? How do you even express those to a LLM? How do you validate those? How do you iterate upon them?
The domain of ML-driven design optimization isn't exactly new, is quite specific, and I would need convincing that Claude has anything to contribute to it.
I’m pretty sure Claude has been trained on high school physics textbooks, yo. And if it hasn’t there are plenty of other models out there that have.
It’s not a problem of the ML model. It’s a problem of the human setting up the description of the problem in such a way that the model can operate. OpenSCAD gets a long way towards that target. Use it with a model thats been trained for the purpose - just the same way that ML has been used to produce optimal rocket engine nozzles and fuel transfer systems.
I would love for this to be optimized to the point that its portable and can be carried around, assembled on the side of the mountain, and used as a low-cost, efficient way to throw things from one mountain to another, maybe for avalanche control, or cloud seeding, or indeed for seed bombs intended for re-wilding hard to access places, or something.
It just seems like such an obvious tool, rather than a weapon.
This is so obviously wrong. Show me a field-rechargeable gunpowder-based device for launching things, and I will show you someone who is about to run out of ammo on the side of a mountain they’ve just climbed after a single day of work.
Honestly, what the hell. Where do you think gunpowder comes from, thin air? Oh, is gravity a subscription service in your country?
Come on, try to at least be sensible about your response.
Seed bombing is pretty fun. Re-wilding is a huge industry. Field-reloadable ultra-trebuchets that can be carried and deployed across the landscape, instead of stored in a weapons depot, also a big win for energy harvesters, everywhere.
Seed bombs aren't consumables, they're reproducibles. I could harvest a thousand of them in the time it took you to make a kilo of gunpowder, from local (mountainside) resources ..
>Also pretty sure several parts of the mechanism would need to be considered consumable if operating over a long period.
Well, that remains to be seen after the optimization steps complete. Fine with me if it takes a year before I have to replace a string.
Meanwhile, I'm guessing you are suggesting the "ma' gunpowder" deliveries happen via drone, or helicopter, or methane-powered rocket ship or some such nonsense, lol ..
So he gradually increases the energy transfer from the weight to the arm over the course of the drop. But that arm swinging around must have a lot of energy loss due to friction and air resistance.
This loss will rise exponentially with the speed increase right? So in a sense he is holding his energy budget in a very inefficient phase, with high losses.
Two things support this. A) he spent a lot of time trying to make the arm more arodynamic. B) The spool widening at the end, which is essentially changing back down gears, applying more torque, right at the end when you want speed.
An alternative would be to drop the weight, and let it fall unrestricted until it gets to it's highest speed (this would minimise friction and air resistance) and only at the end of its fall, transfer the energy into the arm.
In this case the arm would only need to rotate 180 degrees or whatever, and not waste energy rotating right?
And then, to take this a step further to make this work there would need to be some flexibility or elasticity in the system to take energy from the high speed falling weight to the arm.
And what you have ended up with is something that looks like.... A whip!
I think your assessment is correct about the energy losses. I'm just not sure about the fix.
If you want to accelerate a weight quickly in a single swipe, (simplified) gradually reducing the mass along the length of the whip imparts more kenetic energy at the end (the whip crack).
So the arm would no longer be rigid, although you can see in the OPs video it isn't actually fully rigid.
He has some great videos. I watched this one and was impressed at the calculations, the transparency and the celebration at the end when he reached supersonic speeds.
Other trebuchet fans who dream of building one some day may be interested in googling "walking trebuchet" for a surprisingly high complexity/results ratio.
I would think you want it decreasing to near zero to extract all the kinetic energy from the mass, leaving the mass stationary as it hits the ground.
The domain of ML-driven design optimization isn't exactly new, is quite specific, and I would need convincing that Claude has anything to contribute to it.
It’s not a problem of the ML model. It’s a problem of the human setting up the description of the problem in such a way that the model can operate. OpenSCAD gets a long way towards that target. Use it with a model thats been trained for the purpose - just the same way that ML has been used to produce optimal rocket engine nozzles and fuel transfer systems.
Not that difficult, really.
- structural: There are height and size limits on things you can build without a permit
- trespassing: flinging objects onto others people property is illegal
- endangerment: any activity that can endanger other people is illegal
All of these three depend on how rural you live I guess. So in a suburban neighborhood I would assume they get involved very quickly.
https://youtube.com/@SteveMould
But seriously, it's one of those things we had preciously little of before online video became a thing.
It just seems like such an obvious tool, rather than a weapon.
Honestly, what the hell. Where do you think gunpowder comes from, thin air? Oh, is gravity a subscription service in your country?
Come on, try to at least be sensible about your response.
Is gravity a subscription service in your world?
Also pretty sure several parts of the mechanism would need to be considered consumable if operating over a long period.
>Also pretty sure several parts of the mechanism would need to be considered consumable if operating over a long period.
Well, that remains to be seen after the optimization steps complete. Fine with me if it takes a year before I have to replace a string.
Meanwhile, I'm guessing you are suggesting the "ma' gunpowder" deliveries happen via drone, or helicopter, or methane-powered rocket ship or some such nonsense, lol ..