You might do your own research, Manuka. Hugh Kennedy can fling a grand piano or a Hillman car more than 300m. Several YouTubes.
The throwing arm looks to be 40' long or so.
meaning that the 'real ones' were 10 to 20 times the size of Galgael's "Mighty Helen" .
The post that you have replied to was aimed at one particular member , and was in relation the rubbish that that individual has been posting on this thread .Well Earth, part of the reason i brought this topic up is because of my love of all things old. I make and use bows that can reliably hit targets 100 yrds away. its about balance, the arrow and the bow. the longbow men of old used bows that had draw weight close to 100 lb , today a modern compound bow is about 50 to 60. My bows are in the low 50s. but it was also the literal wall of arrows that would be shot. its not just 1 arrow its 300, and its not in well spaced times its 300 arrows about every 7 to 8 seconds. thats with a platoon of well trained and seasoned archers. now you may be correct in them not shooting over the river at Glasgow, but would you like to contaminate your water supply if you kill one.
No trebuchet were ever built within the size range that you listed .You aren't taking down 12 foot thick stone walls without the sizes I listed.. maybe lobbing dead, rotting sheep but not much more
Taking into consideration the stress and strain on timber , bolts strapping , and axles ,Bad. 'F' for the segway in this thread.
I feel sorry for the lot of you that don't have the opportunity to build trebuchet (what's the correct plural?) Whatever your inhibitions, you need to shed them. . . soon.
For me, it has made the reading of historical information all the more interesting. I've been there. I've done that 14 times. Plus, some contributed pictures of trebs, triggers and all. Build one like that. Try as you might, see if you can make those trigger work with 30,000 lbs in the counterweight. Horse-puckey. Don't you see? The trigger is the military secret.
Given the scaled geometry of a treb, can you imagine that I can carry the complete treb design, any size you can dream of, as a length of knotted cord in my pocket?
The largest functioning trebuchet that I know of is the replica of the "War Wolf," built and operated by Hugh Kennedy in England. He explained that he'd found an historical claim that the WW was capable to tossing a horse into a castle court yard from 300 yards away. He reasoned that if the account were true, it should be possible to replicate the feat. He did exactly that, using an assumption that the horse would have weight some 1,500lbs. Anybody who uses Hillman and Renault cars for ammo impresses me with their design skill.
Only from video that I've seen, the arm is jointed/assembled like a split cane fly fishing rod, possibly 4-5 feet in diameter over the counter weight and likely 50+ feet in length. That means that the tower must be 30-40 feet tall or more. Yes, it is almost indescribably immense.
Be that as it may, I enjoy the entertainment of any treb with payloads of 20 lbs or less. Designed at 200:1, 4,000lbs in the counterweight is not unreasonable.
If you haven't found them so far, I suggest you look at the results from the trebuchet section of the Punkin Chunkin Contest, an annual veggie tossing event in the United States. If memory serves me, the record for the air cannon section is 4,000+ feet/1,230m, across a freeway and into the filed on the other side. They have a contest site. That implies that all the siege engines have to be trucked to the site and assembled.
So , in answer to my original question you do not see any merit in building a wooden tree bucket any bigger , taller , longer , than those that have already been built , due to timber , iron and the technology of the medieval period not being fit for the task .I haven't given any thought to treb design for more than a decade. Yes, I am an experienced trebuchet builder with published pictures of examples.
Period Machines: I think that we've seen the best of them come and go. Were I to mount a campaign of conquest using trebuchet, you can bet your last dollar that my engineers would have the design figured out. Logically, that means that there was a lot of military research and development that we will never read about. The plans didn't come to them in a dream. Even the angle of the sling finger for proper release. The size limit might be reached by several things: the modulus of elasticity of woods available for the arm. Laminations are certainly superior to a log. They would have known that from long bow construction, even the correct orientation of the growth rings. Friction on the slide with the sling basket. Grease can only do so much. For my part, a little 5W30 motor oil on axle parts has quite a dramatic effect. Inertia = how do you get the mass of the projectile to even begin to move? A rock would have fewer and more intensly confined pressure points on the slide, than a horse.
Modern Machines: I am not, nor ever was, a materials engineer. As parts of university dendrology courses, I did teach the fundamentals of mechanical and non mechanical properties as they apply to wood. Look for specifics on your own time.
What would I try, from the materials I'm aware of?
Arm: Boron-doped, carbon fiber lay up. The design might be eliptical in XS, the long/strong axis parallel to the plane of rotation. Roller bearings. ball bearings (which is best?) for the two axle points.
Swinging counterweight, made of and loaded with the densest element in the Periodic Table (can't find my reference book but I know for sure it isn't Uranium.)
Limits: Besides friction on the slide (travelling carriage?), overcoming the inertia of the projectile is not going to go away.
Risks: The counterweight is falling due to gravity as the arm begins its rotation. When the sling loop comes off the finger and the projectile is released, the arm does not come to a sudden freakin' halt.
The overtravel goes into quite violent recoil oscillations (very disconcerting if you aren't ready for it.)
As you know from reading, both the arm and the counterweight are flapping about. This is where I think that the failure will occur.
Desires: give me an automated disk brake damping system on the arm/counterweight pivot point. It's delayed beyond the release of the sling loop from the finger.
If it wasn't my money, I'd try an arm, 60' total. The tower and slide are not an issue. Loading would be least risky by lifting the counterweight, not pulling down on the arm. You've seen those people-powered wind-up mechanisms? Why do you suppose they went that way in the design? Huh? What did they break most easily? It is one big Hello of a surprise when the arm breaks. Cable trigger, not some box-latch screw-up. Can you imagine an iron counterweight and an electromagnetic latch?
Find a materials engineer, young person. Bring them up to speed and pitch the same question to them.
If out of balance ammo such as beehives, clay balls loaded with small stone shrapnel , casks of tar and oil on fire, dead animals , and prisoners of war and spies all manages to hit the targets , why would stone shot have to be manicured ?You know, one thing just occurred to me. If trebs were popular and effective, how come it is that there aren't more identified artifacts in the form of BIG round stones/projectiles? I know that lots of big stones from various stone circles were cut up and carted off for building material.