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Tom Stanton's supersonic trebuchet breaks sound barrier with gravity alone

techeblog.com

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Re: Tom Stanton's supersonic trebuchet breaks sound barrier with gravity alone

#61

Post by magicalhippo »

throw310822 wrote: post #52
magicalhippo wrote: post #51

Earlier quoted context omitted.

It's a bit clumsily written, but I'm pretty sure that's a reference to what Tom mentions in his video, that since g = 9.81m/s^2 you're not getting close to the speed of sound just from falling from a reasonable height, even ignoring air resistance. Thus a traditional trebuchet design cannot reach that speed.

But since potential energy from gravity is mgh and kinetic energy of a projectile is 1/2 mv^2, calculating height and mass of a weight to power the projectile is absolutely straightforward. The terminal velocity of a falling weight has nothing to do with it (even historical trebuchets used a leveraged system in any case).

The point was the leverage can't be simple, like in a traditional trebuchet. Tom ended up with a rope pulling on a cone, with the arm being accelerated over many revolutions before the projectile is let go.

Tom explained it much more straight forward in his video, the blog author tried to be fancy and made it worse.

Re: Tom Stanton's supersonic trebuchet breaks sound barrier with gravity alone

#63

Post by genewitch »

qwery wrote: post #29
genewitch wrote: post #14

Earlier quoted context omitted.

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 fe…

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 t…

We moved on to oranges really fast after realizing that batteries coming out of the sky randomly was probably a bad idea, even if there were no apparent people around.

Don't get me wrong, oranges are dangerous too, coming out of the sky at terminal velocity, but at least when they hit the ground they disappeared into a fine, 3 meter wide mist.

Re: Tom Stanton's supersonic trebuchet breaks sound barrier with gravity alone

#65

Post by ahazred8ta »

drcongo wrote: post #39
emptybits wrote: post #20

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.

What does grains mean in this context?

325 mg aspirin pills were originally 5 grains. A carat was 4 grains. The unit was used by apothecaries, jewelers, and bullet makers.

Re: Tom Stanton's supersonic trebuchet breaks sound barrier with gravity alone

#66

Post by MomsAVoxell »

nkrisc wrote: post #25
MomsAVoxell wrote: post #2

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…

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.

I could for sure see it being used to launch seeds-bombs, or emergency rations, or make a pressure wave on a snow overhang - if the evolution of this interesting experimentation results in a portable version, it would be immensely useful. As a crop protection device, given some kind of energy-harvesting recharging method, a la wind.

A bit of imagination makes it very useful.

Re: Tom Stanton's supersonic trebuchet breaks sound barrier with gravity alone

#67

Post by MomsAVoxell »

andrewflnr wrote: post #27
MomsAVoxell wrote: post #2

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…

> 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.

All such weaponized technology carries the weight of danger, but de-weaponized technologies - which is what this represents to me - could mean some break-throughs, too. There are a lot of peaceful applications for a trebuchet.

And yes, it'd need training, but its not the training part of explosives training that I think needs to be rendered obsolete, but rather the explosives manufacture and distribution network, or in other words: peaceful applications for a trebuchet.

Re: Tom Stanton's supersonic trebuchet breaks sound barrier with gravity alone

#68

Post by MomsAVoxell »

red_admiral wrote: post #37
MomsAVoxell wrote: post #2

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…

> 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.

If the trebuchet is breaking the sound barrier, a small fleet of trebuchets set in place on the snowfield and set off in an appropriate wave beam, could provide less explosive-manufacture-distribution-usage solutions to the problem.

I could imagine this thing gets even more efficient and resilient, attains some kind of wind or sun-based auto-recharging mechanism, and then deployed on mounted areas to shock-wave snow layers. Yes, its possible, no its not real until someone does it. I could imagine it being done.

Note: I also like the idea of not having to use explosives, is the starting base. If you would prefer to blow stuff up, that's not what I'm talking about.

The evolution of this technology towards an automated, resilient, field-portable version would be interesting. Imagine having a 6-pack of them.

Re: Tom Stanton's supersonic trebuchet breaks sound barrier with gravity alone

#69

Post by MomsAVoxell »

toasty228 wrote: post #21
MomsAVoxell wrote: post #2

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…

Or we can just accept it as a cool gimmick, we don't have to kill animals with supersonic trebuchets really

Well, depends if killing the animal means having an actual ecosystem functioning again, afterwards. Some animals are living in the wrong place in the world; culling them requires special skills.

I get it - animal murdering is cruelty, mmkay .. but so is a wild boar, ripping up wombats and quokkas and witchetty grub-bearing paperbark trees ..

Anyway, I do see far more peaceful applications of this, if it becomes efficient and deployable. Could be a good way to launch things at sea, for example.

Or even certain forms of glider.

Re: Tom Stanton's supersonic trebuchet breaks sound barrier with gravity alone

#70

Post by MomsAVoxell »

fc417fc802 wrote: post #57
gcanyon wrote: post #35

Earlier quoted context omitted.

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,…

If the pump were operated by a bicyclist and the projectile feed automated I imagine the pneumatic system would win out by a very wide margin regardless of any reduction in overall efficiency.

Once this thing is dialed in, a wind- or stream- rechargeable version is the obvious next step.
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