Supersonic Trebuchet

Re:Supersonic Trebuchet by jacquesm on Wednesday December 01, 2021 @05:32PM (#29410028)

Indeed, I wasn't comfortable watching it until I realized that he was the one that posted the video. But instant desintegration was definitely on the menu there and once stuff comes apart and starts flying it's impossible to predict trajectories. That's a very large amount of energy on what looks to be two run-of-the-mill boards, they're fortunately under compression but the joint at the bottom looks (far) less than ideal for this, especially with the holes drilled in line with each other (that's a definite 'no' if you want to avoid splitting the beams).

A++ for the theory, but the implementation is not something I'd want to be near when it is in operation, it is just too unsafe judging by my somewhat experienced DIY eye.

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Re:Supersonic Trebuchet by naikrovek on Wednesday December 01, 2021 @10:49PM (#29412354)

I'm sure the guy is aware of how much stress he's putting the wood under, and about how much it can withstand.

when I was a kid, my dad made an engine hoist frame out of wood. that thing creaked out some scary sounds when he lifted whole diesel trucks with it when load testing, and it didn't even faze the hoist frame at all.

it sounded like it was going to explode into a billion supersonic toothpicks and didn't even visibly move. we painted red lines across joints to see stress movement more easily and nothing ever moved.

his material of choice? 4x4 construction lumber.

it is amazing what wood can withstand when you understand what you're asking it to do, and design so that material properties are fully exploited.

my point: loud creaking is not necessarily indicative of impending failure.

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Re:Supersonic Trebuchet by tempestn on Wednesday December 01, 2021 @11:34PM (#29412600)

That's true, but you also can't know every possible point of failure of an apparatus under load just from design principles. That's why they flex the wings of new airplane designs until they break, for instance. So I expect testing under extreme tension while squatting right beside the thing without so much as a pair of safety goggles is taking unnecessary risk. I'd go for a heavy coat and helmet with face shield at least, if I needed to be that close. (But I'd rather find a way not to be.)

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Re:Supersonic Trebuchet by jacquesm on Thursday December 02, 2021 @12:17AM (#29412791)

I'm quite aware of what you can and can not do with wood, unless he's tested one to destruction the degree of variability alone makes this a particularly dangerous stunt.

It all looks fine right until it doesn't.

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Re:Supersonic Trebuchet by naikrovek on Friday December 03, 2021 @09:50AM (#29430614)

> I'm quite aware of what you can and can not do with wood

yes, I'm sure you are. you always seem to know everything about everything when it comes time to argue.

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Re:Supersonic Trebuchet by mcguire on Wednesday December 01, 2021 @11:27PM (#29412567)

Not necessarily, but it is the only warning you get.

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