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#projectile#system#https#supersonic#trebuchet#cool#don#energy#used#video

Discussion (38 Comments)Read Original on HackerNews

sdenton4•about 1 hour ago
Here's a direct link to the video, to avoid the blogspam cruft...

https://www.youtube.com/watch?v=Co57SfcT-h0

27183•3 minutes ago
It would be interesting to scale this design up. Not necessarily in terms of velocity--supersonic velocity for a large trebuchet munition isn't necessarily desirable. What I mean specifically is scaling up the multi-revolution arm and sling release technology to be capable of launching a ~1 ton projectile.

Could it be done reliably with traditional construction techniques (wood, treenails, lashings, minimal metal hardware)?

AFAIK these are innovations that were not explored historically. It would be interesting to see if they would have been viable. It seems like you could probably achieve a lot more downrange energy using the same amount of materials this way.

emptybits•about 2 hours ago
His trebuchet launched a 4 gram projectile at 776 miles per hour.

That's obviously extremely lightweight for trebuchet payload, but for comparison, his projectile is approximately 62 grains so approximately twice as heavy as 30 grain high speed 22LR rounds. And approximately 1.5 times as heavy as 40 grain subsonic rounds.

drcongo•24 minutes ago
What does grains mean in this context?
jihadjihad•20 minutes ago
It’s a super old unit of measurement for mass [0], idea being that a “grain” is a single seed of wheat etc.

1 gram is a little over 15 grains, and there are 7000 grains per (avoirdupois) pound.

0: https://en.wikipedia.org/wiki/Grain_(unit)

bjackman•20 minutes ago
It's a unit of mass used in the firearms world
daemonologist•about 3 hours ago
Also (mentioned by Tom), this elastic-powered supersonic trebuchet is an excellent video: https://www.youtube.com/watch?v=gdXOS-B0Bus
genewitch•about 3 hours ago
the "shot you've been waiting for" was sort of anticlimactic, but the two plywood arm shots after show what it actually sounds like. I think the grass and tree dulled the sound a lot on the metal arm.

I actually have a camera that can shoot that at high speed (1200fps), but i'm sure other people have better cameras these days, mine has very low resolution.

bookofjoe•about 2 hours ago
Scientific research systems like the SCARF achieve 156.3 trillion fps but at greatly reduced spatial resolutions.
red_admiral•about 1 hour ago
Is that the "nuclear potato cannon" one?
jijijijij•34 minutes ago
That device is so much more scary! Both really demonstrate the ridiculous amount of energy stored in a pinch of gun powder. And I presume gun powder is quite inefficient at driving the projectile, too.
felooboolooomba•about 3 hours ago
This guy absolutely amazing to watch. He also has a 2nd channel that I only found out a few weeks ago: https://www.youtube.com/@TimStation
noman-land•about 3 hours ago
Not only is it a funny name it also appears in my subscriptions list alphabetically right below the main channel.
MomsAVoxell•about 3 hours ago
Seems like such an advance in this ancient technology. It would be really cool to see it applied in interesting ways.

I really wonder just how effective this could be as a defense system .. the mind wanders with every update Tom makes .. I imagine an aiming/targetting system would make this an effective, easily replenished, low-resource weapon system for some applications. Attacking feral animals, perhaps?

How could an auto-loader work for this .. I'm sure there's a means.

Another thing that I keep thinking about, is whether this would be an effective way to launch seed-bombs, or deal with avalanche conditions on a mountain without requiring fire-arms training.

A truly fascinating bit of engineering. I hope to see it evolve into an effective delivery mechanism.

nkrisc•about 2 hours ago
I don’t think this has much practical application as an entire system. Nor is it supposed to. It was built just to achieve and artificial goal with arbitrary constraints. That doesn’t make it any less cool or interesting, but that doesn’t make it useful.

Some of the features he used are pretty cool though, like varying the winding drum diameter to vary the delivered torque over the course of the weight drop.

andrewflnr•about 1 hour ago
> without requiring fire-arms training.

You'd need trebuchet training instead, which is probably not better in the long run. I bet there's still lots of ways to kill/mangle yourself with one of these, especially once you've been around them long enough to get casual and sloppy.

red_admiral•40 minutes ago
> deal with avalanche conditions

Swiss solution: chuck some explosives out of a helicopter https://www.youtube.com/watch?v=H519qhLnRtM (start at 1:20)

(In the image at https://swisshelicopter.ch/de/aktuelles/721-lawinensprengen-... the explosive pack says "do not eat". I'm not reassured that we need this warning for people allowed to handle that.

toasty228•about 2 hours ago
Or we can just accept it as a cool gimmick, we don't have to kill animals with supersonic trebuchets really
gattr•about 3 hours ago
I also loved the video. But I'd think if one wanted to deploy "simple" mechanical projectile weapons at scale, pneumatic launchers would be easier, more compact and more reliable (way less cool-looking and operating, though!).
gcanyon•about 1 hour ago
I think the cycle time on this would be far superior to a pneumatic system: cycling this system effectively means lifting ~100 pounds ~8 feet, which a reasonably fit person (who could reach that high) could do several times a minute for extended periods.

He got an efficiency over 40% (if memory serves, I watched this video yesterday) -- I wonder between pumping and discharge how efficient a pneumatic system would be, but I can't imagine that it's higher.

genewitch•about 2 hours ago
like a potato cannon?

I helped design the "reloadable" part of a golf-ball shooter that used acetylene as the accelerant. I don't think it went supersonic, though. There's videos (embarassing ones) on youtube. He eventually designed one that can shoot full cans of monster energy hundreds of yards.

the reason i bring it up is we used to design and build pneumatic ones, that could send C and D batteries thousands of feet if you arced it right. that was with ~125psi, we always wanted to build out to 200+ psi, but instead went into accelerant-based cannons and he got a job doing machine drawing with autocad. the rest is history.

edit: https://nextcloud.projectftm.com/index.php/s/cobra5x we show off the part i designed, toward the end on the "reload" - he designed and built the entire thing.

qwery•about 1 hour ago
Sorry to be a bore [that's a firearms joke], but -- while I encourage everyone and their family to experiment with building such devices, with safety in mind of course, it is a lot of fun -- please don't dispose of your old batteries in the natural environment!

Really not trying to call you out here, as a teenager I once had the idea to load up my marble cannon with dead AAs (they're free!) and got a "do you really think that's a good idea?" from an environmentally conscious adult when I went asking for dead batteries.

monster_truck•about 2 hours ago
Basically anyone can go buy a pellet rifle that will easily and consistently clear 1500fps. They're still pretty cool, and will go through both doors of a car
MomsAVoxell•about 2 hours ago
I dunno, takes a lot of energy to get a pneumatic system up to the same speeds that this trebuchet can accomplish. I see it really as a super-efficient machine requiring very little effort to load ..

But yeah, the fact that it's super cool looking - and sounding - is a key factor in my willingness to play with one too, one day. ;)

jijijijij•about 1 hour ago
I think the only real advantage of this, compared to gas driven projectiles, is the lack of need for gas sealing and explosion resistance of the projectile. The projectile is accelerated much more gently. You can launch combustible, rather fragile and irregularly shaped projectiles. That said, I don't think there is much need for supersonic exit velocities for most scenarios. Maybe you could use it for impact testing without introducing a gas blast or the need of a gas sealing delivery vehicle. But I don't think you would opt for a gravity powered, purely mechanical device then.
zellyn•about 2 hours ago
Drone defense? :-)
monster_truck•about 2 hours ago
All of these things are thoroughly solved problems with embarrassing levels of cost effectiveness, far from interesting.

Please keep your thinly veiled murder fantasies to yourself

hinkley•about 3 hours ago
How do you responsibly test something like this? The payload isn't going to follow a ballistic trajectory, it's going to follow an aerodynamic one. You'd probably have to design something special to load into it to aim the damned thing.

Which is a road trip to some place very empty in something like a 180º arc. Maybe 225º.

myself248•about 2 hours ago
Very early in the video, he explains that while previous builds used steel ball-bearings, that's not responsible at these energy levels, so he switches to lightweight balls made of biodegradable plastic. There's comparatively little energy in the projectile after release, and it's only supersonic for a few feet.

Further, you test in an enormous empty field, as he's doing.

dofm•about 3 hours ago
He has fairly specific mechanically timed release control over it — within 0.5 degrees.

But he also used an extremely lightweight ball projectile — a few grams of 3D printed plastic — because he was only interested in the launch speed. And he pointed it in a direction where there were no people for miles.

RevEng•about 2 hours ago
He explains that the field he is shooting towards is over 5km of empty field. He also started his tests with much lower weight and speed to ensure proper behavior before getting up to full speed.
thot_experiment•about 3 hours ago
It's shooting 3d printed balls, I imagine they don't stay supersonic for very long. Significantly less dangerous to others than driving a car.
hinkley•about 3 hours ago
You'll shoot your eye out, kid.
thot_experiment•about 2 hours ago
It's absurdist to be concerned about this and be okay driving a car from a total harm to society perspective.
glitchc•about 1 hour ago
One possibility is to mount the trebuchet on a tiltable platform and tilt it to a suitable elevation, say 45 degrees.
ungreased0675•about 3 hours ago
Projects like this are inspiring. Love it.

I should build something this weekend…