Which trebuchet-type is the best

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Which trebuchet-type is the best

Postby Mihaela20 » Fri Jan 24, 2020 9:00 am

Good morning,
I have to build a trebuchet in class and don't know which type is the best. The conditions are that it has to be max 1x1x1 meters (or each 41 inch). I've searched for ideas, but I don't know, what is the best matching type for such a small size for an wide range...
I've been thinking about these models:
    - the MURLIN
    - the walking arm
    - or a normal trebuchet :?:
    - if you know better types...
There are no conditions for the projectile or the CW... it should only have a wide range and not be to hard and costly to build. Because of few experience, I don't know where to start and how to choose the right one. I'd be glad, if you could help me out :D

Thanks in advance
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Re: Which trebuchet-type is the best

Postby madmattd » Sat Jan 25, 2020 12:04 am

Any other requirements/goals? "Best" is pretty subjective, and depends on requirements, goals, etc. Without any experience with trebuchets, a standard HCW (hinged counterweight) is the simplest and easiest to learn how to tune. Whippers are finicky, the walking arm is mainly aimed for an event where there is a total machine weight limit (thus putting as much of that weight limit towards counterweight as possible), MURLINs aren't that bad conceptually to tune but are tricky to build optimally.

Does the 1x1x1 meter max include the arm sticking out at rest, or a cocked dimension?

The "one with the CW over the arm" is a whipper by the way.
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Re: Which trebuchet-type is the best

Postby Mihaela20 » Sun Jan 26, 2020 4:52 am

Thanks for the hints and the reply.
We didn't get much of information, so I think the size limitation is for the cocked dimension and the machine should throw an projectile our choice as far as possible. So you say that a HCW or a MURLIN are appropriate? And if the MURLIN is build correctly, does it throw then further than a HCW?
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Re: Which trebuchet-type is the best

Postby madmattd » Sun Jan 26, 2020 6:55 pm

Mihaela20 wrote:Thanks for the hints and the reply.
We didn't get much of information, so I think the size limitation is for the cocked dimension and the machine should throw an projectile our choice as far as possible. So you say that a HCW or a MURLIN are appropriate? And if the MURLIN is build correctly, does it throw then further than a HCW?


No limit on projectile huh? For that size a golf ball seems like a good plan to me, but I'm sure there are others.

If you think the size limit applies to cocked and not at rest, then performance-wise an HCW won't be the best performing, but again it will be the easiest to learn on so still a good choice.

The best performing would be to find a way to get as much of the 1 meter limit used for your drop as possible, that does bring whippers or MURLINs among others into play. Basically anything where the CW when cocked is the highest part of the machine, and make sure it goes as close to the ground as possible during firing regardless of what design you go with.

I don't have any personal experience with the MURLIN design other than seeing videos/pictures, though it does seem like a solid choice for the parameters you have laid out. The actual tuning of a shot shouldn't be much worse than an HCW, but finding the right node lengths will likely require some trial and error.

I have tons of experience with whippers (among others, I designed and tuned NASAW), but they are tricky beasts, not one I recommend as a first trebuchet (there's extra things that affect tuning that HCWs don't have to worry about), and I definitely advise steering clear of wheeled arms (floating arms) for now! (Though the FAT variants and floating whippers are a ton of fun once you've learned on something simpler!)
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