How to Build a Supersonic Trebuchet 

This is going to be fun. Looking forward to working with you.

"An exciting new way to convert time and money into heat and noise" is a really outstanding phrase

Wow! Finally the YT algorithm showed me this masterpiece! I was running simulations to build a supersonic trebuchet around the same time you posted this video, however I found it to be near impossible (I think my simulations used a counterweight), but hearing that sonic boom was insane. Would love to see some high speed footage of this thing launching!

Can't believe I'm just seeing this. This is rad. The crack when it fires is wild

Hey David! We specialize in capturing super-sonic object with our high-speed cameras. We'd be happy to get some incredible footage of this!

I can’t get over how dangerous being at the business end of this thing cranking up that much potential energy is.

As an aerospace engineer that graduated in 1997, I am jealous that you young un's get to do all this with such great tools. It looks like playing a video game. Calculating this stuff by hand or even a programmable calculator was not nearly as cool. Those were the days of waiting in line to use the computer room.

So incredible that it's powered by rubber! JoergSprave would be proud!

i love how you go into the proper engineering process instead of oversimplifying everything and jumping straight into the build like a lot of big youtubers who optimize for mass appeal

It would take me a long time to understand all of this, but I love how you minimized the "hardness" of the design. This is an engineering master's thesis right here. Would love to see what you are working on now.

Slow-Mo Guys, right now! I would love to see that. What a cool project this is, seriously. It sounds like a gunshot almost, or rather, like the crack of a bullet passing at supersonic speed. Amazing work. I'm thinking about building one now.

As a grad student in fluids who's done some control theory, it was incredibly satisfying to see this idea cast as a constrained optimization problem simplified with scaling laws, and to see it work spectacularly. I saw that you even accounted for hysteresis in the rubber! It's awesome to see actual engineering used for this kind of project. Judging by the snow, I'd guess you're not near the LA area, but in case you ever are, I have access to a high speed camera and a small schlieren setup. I'm sure the shockwaves coming off the ball and sling would look incredible during launch

I'm really glad you decided to use LaTeX to describe a latex-driven catachet. Super impressive work. I had also recently started to gather supplies to make such a device but was planning on using just a less efficient simple catapult arm and brute-forcing the ratio between amount of rubber and the payload, with a properly tapered arm. Your design (and the process that went into it) is far more elegant, and the tell-tale supersonic crack on the video of the plywood version is unmistakable and very satisfying.

I’m hoping that this was a doctoral thesis. An accredited institution sure as hell should give you credit for this brilliant analysis, modeling and results. Well done!!

This is the old youtube quality in more modern times. Love it

You should contact either James the Hacksmith he is in Kitchner, Ontario or Destin from Smarter everyday from US. Love this video thank you for showing the engineering process, wouldn't mind seeing the actual build video if you have it.

Fantastic! I always love seeing engineering used for interesting stuff, and this is it for sure! Nice job! BTW I have a "fancy" high-speed camera but judging by your surroundings and that odd white stuff on the ground, I gather you're not too close to Florida. ;-)

Among the more useful guides on youtube, I couldn't find anything else on the web explaining how to build my supersonic trebuchet.

You say "turns out it's pretty easy" and then go completely over my head within the first 2 slides. Thank you for this video David, I loved watching this. Now I need to bust out the Lego and get started on a mini trebuchet :D

Wow the way it breaks the sound barrier is incredible. Thank you for building this!

Dude I am loving this way too much :D "Turns out its pretty easy" - and continues with the most awesome optimization procedure that I have ever seen for a mechanical design. Now I wish I had had a lecture in mechanical design optization :P I will definitely look into your data. Doing this in three weeks also seems fairly amazing.

As a fan of siege machinery this is about the coolest one I have seen. Of course watching the guys from Top Gear hurl a car and it presumably destroying a barn was very satisfying as well. 😊. Can’t begin to anywhere understand the math you presented but still very satisfying. Great job! Glad you didn’t take your head off with all the potential energy you produced!!!

I know it's been a while, but I'm sure the Slow-Mo Guys would love something like this!

Well done David. Loved watching this video. Only one thing made me cringe though, when you were cranking up the springs / rubbers, I kept on thinking, “You are standing in front of a loaded weapon”, and I cringed but took solace from the fact the video was produced meaning you survived safely. Cheers, Brian from NZ.

As a mechanical engineer myself (thou i oriented towards IoT and automation), this was honestly humiliating. What you have achieved in the given timeframe is pretty respectable!

This is remarkable. The report is even better!

Only supersonic trebuchet on youtube, only 1 video to the channel, 1.6 million views in 3 years and 16.6k current subscribers. The man is doing things. Thank You

How on Earth, has this video not taken off as fast and hard as those shots? Brilliantly done!

As a student of ballistics for 30 years, I had no idea that was possible. Great explanation of the math application.

I like the sonic boom. You know positively when Mach is achieved. And a nice deep dive into critical parts before fabrication. And minimal ‘trial and error’.

when I was 15 my uncle and I built 4 ton weighted trebuchet on our ranch and would throw 10lbs cinderblocks like 500 yards at a half loaded bucket (it was like a 20 ft tall machine). A fully loaded weight bucket would throw a brick out of the property line and into the state road. That thing moved in slow motion when it fired, and I can not imagine a full scale version of this set up. It would be a menace. Amazing stuff even after 2 years, great work and great math

Mate this is sooo bloody cool, can't wait to see the collab with you and Destin. Thank you for sharing the drawings/simulations thou, if i were still into making loud noises (use to use a capacitor bank to see how loud I could make components/wire atomically cover the containment box) I'd totally build one 🤣

I love how you engineer the engineering. The meta-analysis is great, its like instead of just walking towards a goal (naive approach), or using a map (engineering) rather finding the best tool to select the best map to decide the best way how to get to the goal with the least total effort.

I love the fact that you actually talk about the math behind it, too few engineering youtubers do that

Hats off Sir!, what an excellent analysis on how to achieve this result. You took most of the trial and error out of the equation and it shows in the end!

Love that you show the math and relevant equations. The understanding of the relationships involved will stay with you a lifetime.

This is amazing! I love how your solution vs. the Smarter Everyday guy's to throwing something over Mach 1 illustrates the difference 10M subscribers make to your design choices.

Never thought of optimizing an engineering problem with a difficulty function. Beautiful modelling work!

Ahh, good ol knex. I remember building powerful rubber band powered guns out of these in my early to mid teen years. My best design was an almost 5 foot long rifle that was powered by those massive and thick rubber bands you frequently see holding broccoli together. To withstand the extreme force of these bands, it was rather chunky and had four "pistons" rather than just one to reinforce it which pulled the launch rod along with it. It fired the medium sized yellow rods with fletchings added to them out of tape. To cock the thing I originally had a rotating crank ratchet system which I later upgraded to use two knex motors to crank it back for me. It could fire all the way across my yard which was pretty big, probably about 400-500 feet long. Your design is absolutely badass! Keep it up!

Ahh, a video, that really feels like it's made for just sharing what how like, how you like it, for others to like too!

That is some PROPER engineering. Fantastic job.

This was really fun to watch, but it was also nerve wracking. I have a suggestion: When working with a machine that can accelerate a projectile to speeds fast enough to cause injury don't stand in the path of the projectile after it's loaded. For example, I would not load the projectile on the machine until AFTER preloading the rubber bands. Call me a worry wart, but I've seen firearms discharge in all kinds of different situations where they were not supposed to.

Great engineering feat. Would love to see some slo-mo and impacts of the projectile.

One video and you've caught the eyes of a solid half-dozen of my favourite creators! I imagine your capacities are better spent offline but should you return to RU-vid there are thousands of nerds eagerly awaiting your next project!!

To be honest I was most surprised that the rubber was able to move itself fast enough. Even with such a large motion amplification that the arm and sling give, I somewhat expected the rubber to have too much mass relative to its stored elastic energy. I suppose thats the beauty of the optimization approach - that it quickly guides you to the correct intuition. I am now 100% signing up for the optimization elective at my school!

THIS IS YOUR ONLY VIDEO ?!!?! I'm honestly so surprised. This has such a good production quality I thought you've been doing this for at least a while. Please post more :D this was awesome and I honestly desire more. Also, if you keep this up, you'll probably eventually get up there in the fun youtube science part along Mykull, Nile, William Osman and his friends and all the big boys

Hearing the sound I'm familiar with of the projectile breaking the sound barrier is proof enough for me. Good job.

That was an excellent presentation of the engineering design process, along with a very exciting demonstration. Very very cool!

This falls into a huge vat of projects wherein my ambition, and desire, are whelmed over by my impatience, talent, energy, persistence, and other attributes to break the sound barrier. But having spent a month attempting to build trebs and cats, to hurl tennis balls for the pupster to chase and retrieve, I can appreciate the raw awesomeness of your efforts, and final success. As others have noted, the 'thud' is very satisfying. Like an applause from the cosmos.

That's pretty amazing

Strange I haven't seen this yet. Strange that you don't have more videos. You've got my subscription, I really enjoyed hearing your highly technical descriptions and explanations, without watering it down for people who don't understand it. I didn't understand it, by the way, that's me lol Very interesting, hope you continue.

Rally great understanding of kinetic and physic. Extraordinary work.

Loved this! Buy yourself a blast shield and some safety goggles, then make more videos! I'd happily watch.

I got completely nerd sniped by your design process. Absolutely love that parametric optimisation design approach.

Very well done! Should the need ever arrive, it's possible to replace the rubber bands with an electric motor with a gearbox and a variable cam to maintain a strong and steady yet accelerating pull on the arm.

This guy is next level brilliant. You can almost see the gears and calculators inside his head when he rattles off those numbers.

I love that you go more in depth with the math and modeling than most build channels on youtube! Good way to stand out!

Now that you've got the object at supersonic speeds how about the more difficult problem of getting it to repeatedly impact a distant stationary object at a precise location?

Very cool! I remember just over 20 years ago, I set out to design and built a spud gun that would fire a potato at supersonic speed. One of the problems that I had to overcome was the structural integrity of a potato. Turns out, they are poorly suited to withstanding the forces at that velocity... Every time I fired the prototype, it only created supersonic mashed potatoes. The solution cam in up scaling the machine and changing to a tougher bit if ammunition... the locally easy to acquire southern Idaho sugar beet. The fibrous body is much tougher and held structural integrity forward of the cannon muzzle. The camera recorded a muzzle velocity of mach 1.2 and when fired it made a sound like I had never heard before, or have ever heard since.. I was an engineering student at BSU at the time and I offered to bring it for show n tell, but was turned down... the college thought it too dangerous... they were probably right...

This thing is so awesome!! That crack is one of the coolest things I've ever heard considering it's only powered by rubber bands. Great work!

This is awesome. I remember building a ~2 foot tall trebuchet out of KNEX back in the 90's as a kid. This is pure nostalgia right here

You have a rather soothing voice, a charming personality, and the machine itself looked like a rather outstanding piece of engineering. While I'm about as dumb as a bag of rocks on the design optimisation stuff, it's clear you put in a lot of thought and calculations on the project and the video was a joy to watch as a whole. Excellent content!

I enjoyed David's deep stiffness in the to camera bits. I bet they someone shouted "don't get up!" right at the end. Excellent video although I think you should have showed some of the shop work, folks love that. Great vid.

OK, I see you made this about 2yrs ago, but it's new to me. At first I thought it was just another yahoo making things go bang, but then you hit the analysis and maths. Now, sadly, I'm hooked. I hope you're still making vids.

This is fantastic. The trebuchet community will be very excited. Thanks!

Beautiful lesson on how to approach real world optimization problems. Why introduce parameters into a design when one can simply derive them from root constraints like an absolute chad. Great work 👍

I don't think it would be useful for hunting pheasants but hey it is a pretty AWESOME work of engineering. Great work! :) You have GOT to get some high speed footage!

David, that is impressive. The projectiles sound like a bullet crackling when fired from a gun.

it's so interesting to me how similar the sounds are to a gunshot for what you hear as the sound echoes out. mechanically it's the same factor that causes it, the projectile breaking the sound barrier, but achieved completely differently. you would still then, presumably hear a ballistic snap in the direction the projectile is moving. would love to see a camera put out there to hear it and confirm

Great work! Now that you have proven the concept, the crank effort at the end is another design optimization for scaled production. In industry we always design to 50% engine capacity so that if we have to step outside job parameters we don’t break the system.

Dude has some serious faith in those components, standing nearly on top of the thing winding and firing it.

I can't believe this is your only video, it would be so cool to see you do more.

The design optimization study is great to see and the musings on the creakines of wood just wonderful, thank you for this magnificent video and design, it is inspiring to say the least.

Amazing how modern engineering allows you to do extraordinary things without using modern materials. It seems to me that something almost as good as this could be built with Renaissance technology, if they'd only known how to design it

I would never even have thought of including design difficulty in optimizing the trebuchet, this is exteremely interesting super cool video, thank you

Exactly one video on RU-vid. 1.2 million views. Excellent work sir

It's a hybrid of a trebuchet and a catapult Trebuchets are usually powered by a falling weight Catapults by tension springs ( Rope Timber or rubber in modern times ) It's way cool thought

This is absolutely amazing, nice work on everything and I have no doubt you'll have a lot of interest. I commend you on this project I really do personally I'm thinking how amazing it would be scaled up lol.

Incredible you converted something seemingly arbitrary like difficulty of manufacture into min and maxes in useful equations. Wonderful engineering.

Awesome. I would love to see a larger trebuchet throwing heavier projectiles. Insanely cool!

For your next assignment, please design a larger version that can cast an object into stationary orbit. We've already seen the big spin, but it's way too expensive. 🙂

That's insane. I would expect a mechanical device to barely break the sound barrier, not going nearly 100m/s over the speed of sound. Your work is truly impressive.

man and I thought Tom Stanton was doing the Lord's work. you are the king my friend. I've subbed and liked. Gonna share this on FB too!

That is some PROPER engineering. Fantastic job.. That's pretty amazing.

David's done one video and it's absolute gold. More, please, if you have the time and the interest!

I achieved mach2 with nothing but a car inner tube back in 1988. Cut the whole thing into a 1 inch wide strip, tied one end to a power pole and walked the other end about 400m up the road. It was shocking. Less than half a second to get well past the pole. It touched a parked cars wing mirror about 50m past the pole, which exploded into tiny fragments of glass and metal. A hard grade of nylon monofilament works better than rubber as a tension spring. More energy storage per mass, and less hysteresis.

One of the best videos on RU-vid.

Great video, it’s content like this that still makes RU-vid No 1 for thinkers and learners 👍

This is absolutely fantastic. A much needed and well done explanation of a rigorous design process

That was epic, loved it. With a larger budget I'd love to know what the maximum speed possible would be given the current limitations of material science.

First video I'm watching of yours. Love it !

This is soo cool! I can't wait for Dustin to put his high speed camera to work.

This truly fantastic. I too have re-engineered ancient devices (conceptually) to increase efficiency and effect, but what you have created is awe inspiring. I have a couple of suggests/ideas that would make it more powerful and efficient, and I'd be more than happy to share with you if you're interested.

Just found your video yesterday. Very well done. Took almost a year for RU-vid to recommend it to me (an engineer). If this only took you 3 weeks, your channel can rivel that of similar content.

Amazing. So very well explained and boy, how well articulated. Props for that and thank you!

I have a personal rule not to subscribe to a channel unless I have seen more than 1 video from that channel and enjoyed both. Any man who can build a supersomic trebuchet easily is worth breaking that rule.

How is this your only video? It feels like a well established channel that has tons of uploads and really good videos

Reminds me of the old "Fibonacci 540" chunker design (540 for the range of motion in the throw). I think they found it too unpredictable an later returned to a sub-180 degree arm stroke. Very nice job on the engineering!

The echo of the sonic boom is very satisfying.

Wow! Great project, and great explanation of how & what... smart fella here! I had an idea, a $20 boat wench from walmart would make cranking a bit easier * if you plan to use often.