Wheels on a trebuchet?
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- čas přidán 26. 08. 2024
- NOTE: the efficiencies I mention are actually the MOMENTUM efficiencies of the trebuchet. The actual energy efficiency of this final design on wheels is 46.7%. The actual energy efficiency of the fixed frame was 37.4%.
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A friend of mine made a trebucket (it is when he's made it). I think he got about everything wrong then he saw your vid with the whip trebuchet. How could something so wrong go even "wronger". The trebucket is now precisely balanced and set up to launch a cricket ball nearly a foot straight down into the ground.
XDXD This made me laugh my ass off! I need to see this!
@@ericolens3 Hes calling it a trebucket probably because he used a bucket for the counterweight.
😂
Some poor farmer's going to be incredibly confused when they find a bunch of tennis balls in their field.
12:41
Snaily and craters from wherever they landed
@David It makes more sense to compare efficiency. He could jack up the weight and it would go a lot farther.
It would be worse if he found only one and then got pelted by 5 supersonic tennis balls though. Then he would run to yell at tom, and have a heart attack thinking he was a time traveler. Imagine that video.
@@wheelslifts851 The balls were no where near supersonic speeds though. The speed of sound is 343 m/s and the balls were launched at roughly 55 m/s but I bet that farmer would be yelling of pain anyway and come after Tom anyway lol
Any truth to the rumor that this will be available from IKEA sold in a flat-pack? Will they call it Flingå?
IKEA names is not random. Beds are named after places in Norway, outdoor furniture after Scandinavian islands etc. Though some things that doesn't fit nicely in one of the categories are named after some Swedish word that is somehow related to it's function. So unless trebuchets is considered garden furniture, it could be called "kasta" (throw) or "skjuta" (shoot).
I don't think "flingå" is a word in Swedish, but "å" is a word for river in Scandinavian so it could hypothetically be a river.
@@SteinGauslaaStrindhaug r/ whoosh
@@burkhardtniec3653 No, I know it's a joke. I'm just being needlessly pedantic
@halnywiatr made me laugh
@Stein Gauslaa Strindhaug floored me with knowledge. Well done.
Stein Gauslaa Strindhaug. Doesn’t pedantic inherently mean “needlessly pedantic?”
You should enter the "Pumpkin Chunkin'" contest. I'm not sure if they have international contests though. They have trebuchets and pneumatic cannons and spinning arm pumpkin tossing competitions. All these seem right squarely in your field of study!
Oh hell yes!
I always thought those were really cool
Last I checked, that event had been cancelled. I'm not sure they'll be coming back. There was a personal injury lawsuit after someone was hurt.
Evan M. Jones rip
The worst part is the guy who sued was hurt riding a quad bike and it had nothing to do with chunkin punkins. What an asshat.
I've been teaching people about synchronizing the stall points for years. Nice to see it quantified.
Me Too!
I was waiting for your best English pronunciation... and it didn't even happened!
Well done Tom, you truly know how to explain things.
Oh yes pronouncing words is hard 🍄
Can you please optimise it a little more so it's 69% efficient... that is all.
Matthew Evans 69% efficient is not shoddy.
68% is shoddy, 69% is perfect, 70% is too much :)
Add just enough weight to the frame to increase it to 69%. Reduce the little bunny hop it does, thatll get it to 69% haha
Spencer Coleman cast iron wheels
This is where 6 9 started
Your video should be required viewing for Physics 101 classes. The presentation is great and your enthusiasm is infectious. It also makes dry concepts much more exciting.
might as well, modern "scientists" don't seem to be learning anything anyway..
Amazing work, dude! Really nice! 😀
Thanks man!
A lot of maker videos are no longer explaining things, but instead show montages, etc. I love that you’re videos actually still dive into a subject. Loving this. BTW, Winston Moy has nice videos on CNC; in one of the previous videos you struggled with frizzy edges-you might want to look at his upcut, downcut, compression end mill video. Love the sound of the trebuchet. 👍
you still need the frame weights with the wheels, supposed to roll, not jump in the air
Jusb1066 noticed that too
This is a test I'd be interested to see. Will a weighted, wheeled frame break 70% efficiency? Can we get the tennis ball to 140?
If the frame has more weight, it would take more energy to move it the same distance forward, which is the distance required so the counterweight falls directly down the whole time
But there's already wasted energy in the jumping around of the frame. The weights may damp that. Or not.
Yeah but if the frame is weighted to resist jumping, it might end up being less wasted energy. I think it's worth a test.
Launch a gopro!
Bill Codey Yes!
Good idea, even though in practice it'll end up a little complicated. This will require a lot of stabilisation if we want to see a smooth image rather than a shaking hell
It d be epic. Just add a spherical frame and fins to make it stable.. Otherwise a gyroscope inside the spherical frame
And add a parachute.
And fins to stabilize it.
A old NOVA special covers this in great detail.
The wheels are originally intended for a fixed weight arm. The basket arm does most of what the wheeled fixed arm accomplished.
On a fixed arm, the weight falls in an arc like a pendulum. The wheels allow the frame to move forward, allowing the fixed arm weight to fall in a vertical line, taking out the arc of the pendulum. The vertical drop gathers more force than the arc.. it’s not the trebuchet moving forward... it’s the weight falling “faster.”
This is the video that introduced me to the Tracker software, and I've gone and introduced it to my team when developing the Mars helicopters. Thanks!
I really like your work on this. Thank you. I wanted to add something. I heard that wheels were added to medieval trebuchets to reduce the strain on the support frame, aka 'the crushing lurch.' Fewer repairs, greater lifespan, etcetera. Of course, they were working on a much larger scale, under very different circumstances, but it's still worth mentioning. Thanks again for all your great videos and careful, skillful work!!
Time for a castle siege, I think we're ready.
the wheels also increase the hight, so unless the cross bars get in the way, that means you should be able to increase the length of the arm as well.
I hope that's a cup of tea you are drinking at 5:46. Tea has powered British ingenuity for centuries.
You introduced that tracker software to me, and it's changed the way I analyze my PhD research! Thank You
Did you succeed in getting that PhD? 🍄
@@davidbergmann8948 I quit with a masters because my boss was an insufferable narcissist!
Gotta make one with my daughter for a yr 7 project/competition in Australia.
Very glad to have come across your work!.
Very impressive!.
I agree with a comment you received about showing the full journey of the payload for a bit of action.
Love it!.
Thanks mate!.
Amazing video dude! I have been trying to find videos on youtube about the physics of trebuchets and couldn't find a good insightful infomation about the specifics of how to build an efficent trebuchet until you started the trebuchet project. KEEP UP THE GOOD WORK!😄
The really good trebuchet vids that I’ve seen (MIT) use a stationary frame, but only the axle of the arm is on wheels. This allows the weight to drop nearly vertical. If the weight had no horizontal speed, then the potential is transferred more efficiently. You don’t have the mass of the frame being accelerated.
For the wheels, the suggestion probably comes from people who saw the PBS special on trebuchets and they got a great improvement from adding wheels - in that case it was more critical due to the massive size and risk of damage if wheels don't help dampen the rocking of the machine.
The entire arm from sling pouch to counterweight is a lever. At the ideal launch moment, the counterweight is behaving like a fulcrum. With a fully extended arm (moment of synchronized stalls), mark the counterweight as “A”, the arm’s pivot on the frame as “B”, and the pouch as “C”.
Take the wheeled frame’s speed of 1.2 m/s, divide it by distance AB, and multiply it by the distance AC. It should come close to your total speed improvement.
Build a set of rails for the wheels to roll on. That'll greatly reduce your rolling resistance and should allow the frame to accelerate faster. Also, maybe bearings on the wheels?
We need more Trebuchet stuff! Your videos are great!
Hi Tom, I watch all your videos the day they come out...and today I joined your patreon. No idea why I haven't joined earlier. Keep the fantastic work up. I absolutely love your calm and analytical way of beeing fascinated.
Greetings from Switzerland
it looked so clean! no bouncing or anything. you can really see that its really important to sync up the stall points of the arm and the counterweight and the release of the ball.
5:45 tea. He needs his cup of Tea.
thank you for the technical bits, facinating
Holy crap, dude! This is a brilliant series! And I am new to your channel! And I did subscribe/all! I am... like since yesterday you popped from “never heard of him” to “Top 3 CZcams channels”. Seriously.
This has been WICKED cool... thank you for making my weekend better.
Great work and research Tom.
The amazing fact to me is that the original designer of this machine achieved all this without the aid of modern day computers to analyse the performace. They would have had wheels to transport and manouver the machine into the attacking position. You certainly wouldn't want to be standing behind one when it was loosed....
This is bloody good work mate, keep it up!
Wow, this is actually amazing. I don’t think research of this kind has been done on CZcams, and it’s a mind blower. Keep up the fantastic work!!
That was all jolly interested and clearly explained. It's good to see the proper detail in the way you went about designing and improving this trebuchet. I was actually sceptical that the wheels would help but I was wrong. It's always interesting to be wrong.
You have earned yourself a subscription.
This hurts my brain, but I can't stop watching your videos! Good stuff!
Awesome! Addressed questions I had myself after watching the first video
6 shots within 4 meters? That is some tight grouping, amazing accuracy!
this is legendary research. I'm using it in my middle school tech class.
This is awesome! Real science and craftsmanship in practice. I gotta build me one eventually.
Very well done, I enjoyed the journey through these videos. Your reveal of the result with the wheels was great. Thanks.
Great additional research and presentation!
This video was worth watching to behold the extreme tidiness of that workshop, alone.
What a cool series on mechanical optimization!
Tom Stanton the reason why the wheels increase efficiency is not due to the velocity of the trebuchet moving forward, but what the moving forward allows the counter weight to do. Without the wheels the counterweight does more rotation, but with wheels the counterweight drops directly down decreasing the amount of energy lost due to it rotating back upward like a pendulum. It is the same reason why having the counterweight fixed to the arm is less efficient then having the small piece of wood as a go between. I drew a picture to illustrate the idea i.imgur.com/NjUtqmM.jpg track the weight with the aplet you are using to see the differences in the actual counterweight.
So it's similar to a floating-arm treb?
exactly my thought too. I was suprised nobpdy Else commented on the same
I hope he sees this comment because other people have comented other things that makes no sense. This is the true explanation
@@caracaes but he explained it quite well in the video. As he puts it the stall point of the weight and the arm are synchronized.
There are many ways to explain the same thing. All you want is as little energy left as possible.
This encompasses both explanations. Synchronizing the stall points means that at some point neither the arm nor the weight as much kinetic energy left. Having the weight drop straight down (as oppose to swing that wide circle) also means the weight has less kinetic energy left (otherwise it'd keep swinging).
See, in a way the video's explanation encompasses more than the one you so want him to see.
Coming in very late on this, I first came across the wheels-on-a-trebuchet issue many years ago in a Scrapyard Wars-type programme where the challenge was to throw a Mini. The reasoning given then was that with a simple trebuchet for best efficiency the weight needs to be able to drop vertically, hence the frame need to be able to move.
tenacity patience and thoroughness
I endorsed - wheels and weights- or wheels restrained in channels to prevent frame lift
Great video, as always. I catch myself looking forward to the weekly video on Friday, by far my favorite channel. I should probably sign up with Patreon so you don't run out of tennis balls. Thank you for another high quality and proper engineering video.
So, your main source of inefficiency here seems to be that your frame has horizontal kinetic energy at the release point. Your wheels make the weight move more or less straight down. So now you could gain efficiency by making your weight and your "tennis ball" more massive. If you increased the weights to the max amount the frame can handle, you'd have something pretty impressive on your hands. ;-)
Very cool videos, Tom!
The frame moving forward is not loosing energy, compared to not moving you are just not moving the planet as much. With regards efficiency of the device with wheels, the counterweight does move backwards as part of the rotational path, if instead of the weight moving backwards the fulcrum moved forward the lighter end of the arm gains more forward momentum. ie by adding wheels you are effectively changing the rotation point of the whole arm, moving the effective fulcrum closer to the counterweight and increasing the throw arm length just as it approaches the release. (see moving fulcrum trebuchets)
If you put markers on the arm you will see that the arm no longer rotates precisely around the axle but slightly closer to the counterweight as the frame moves forward.
To get even more energy out, try getting just the axle to move rather than the whole frame by putting it on a track on top of the frame.
Try building a fixed frame with the central Axle/arm assembly on a wheel - If the wheel is scaled well, then as the counter weight falls the whole thing will roll forward as the arm raises, and you waste less energy shifting the counterweight backwards before the arm reaches release point. You can bulk up the supporting frame to keep things stable without having to put any energy into moving said frame forward when firing.
Gotta love that golden spiral the projectile makes.
This is one of my favorite channels. He actually thinks about how he does his projects and learns things.
I really enjoyed watching this video, great work!
That was really interesting! I'd watch more of these analysis videos. Still interested in watching more air pressure machines, but I'd also be interested in watching you throw some heavier items, like fruit or pumpkins.
This is my favourite CZcams vid for a long time. Bloody well done!
Great work, Tom 🍄🍄🍄
I've seen designs where instead of having the main arm attached with a fixed axle, you add wheels to that as well, and let it roll on a track on top of the frame. That way more energy is transferred.
THIS IS AMAZING! GREAT WORK!!! Adam Savage and Jamie Hyneman would be proud! Great experimenting and controlling the variables to make your trebuchet more efficient!! I really enjoyed watching this!
A couple of years ago me and some friends got to the same conclusion after a weekend of fun tests, but we had no idea why. Basically we noted the counterweight swung less affter firing on a wheeled trebuchet. This did explain it so much better though. :D
Truly excellent video and project. A hearty thumbs up for doing replications and showing some data!!
I've always thought it was because it let the counter weight fall straight down instead of in an arch which to me makes sense since the shortest distance between two points is a straight line your counter weight is using the same amount of energy over a shorter amount of time thus it would go faster.
By moving the frame forward you actually move the point of rotation of the arm as well. Look at the footage, the point of the rotation now closer to the weight which means you have a longer leaver to throw the projectile. +1 ms at the frame multiplies to +5 ms at the tip of the arm
a single experiment is worth 1000 expert opinions.
Brilliant Video! Fantastic work!
Tom, awesome videos. But since its summer and cricket season is on, can you do a launch of a cricket ball and see if you can thow it a 90mph, or thow it back in from the boundry line?
Plausible
very well-done. thank for your work.
Excellent investigation. The stall point of the counterweight is lower with wheels. The difference in height of the counterweight stall point between the fixed and wheels version gives rise to the additional transfer of potential to kinetic, partially offset by the loss from the weight of the trebuchet moving forward. Maybe....
This was the best and most inspiring mechanics lesson I ever watched.
This is just awesome! I realy enjoyed that.
That's very interesting! Great work!
I do hope physics and math teachers around the world will use you material to make their bone dry lessons a lot better.
The wheels are also moving the fulcrum (the hinge that the throwing arm spins around) forward which simulates a longer throwing arm. You could add the distance between where the hinge starts and where the hinge is when the projectile releases and I would guess that would be close to the distance between the end of the arm when stationary release and when its rolling release. Still awesome work Tom!
I love your dedication to the scientific method, really great video!
It's to do with having the counterweight drop as vertically as possible, any drop that's not vertical is transferring excess energy into the frame that kicks it requiring it to be secured down. Allowing it to roll with the counterweight incresses the efficiency of the drop and the rolling effect takes less energy that what is wasted when the frame kicks.
Adding the wheels doesn't delay the stall point of the counterweight, it increases the speed of the throwing arm so that it is in the vertical position when the counterweight stalls. Like a hoola-hooper has to rock back and forth at the right time to add speed to the hoop, the rocking of the trebuchet adds energy and speed to the arm.
Really been enjoying the trebuchet vids, cheers!
Great set of videos! Trebuchets rocks. You may try a launch with the counterweight fixed to the arm, as the wheels will make the counterweight do a vertical fall instead of a circular movement.
Tom, your analysis of the stall points was very clever, and I do believe that their synchronization is what allows your trebuchet to throw faster. However, I do think that your idea that allowing the trebuchet to move causes a loss of energy is flawed. If there is one thing I have learned about physics, it is that every action has an equal and opposite reaction. Regardless of the presence of wheels, the same amount of energy should be lost. With the wheels that energy is utilized to move the frame of the trebuchet forward, and when it is anchored that same energy goes into changing the earth's rotation which, due to it huge mass, is altered an imperceptible amount.
Limitation of current construction is that here is only one full turn of the shaft with projectile available. What if we add some circle spring (like a mechanical arm watch has) to be able increase the power of launch due to additional rotation energy. It will also require stopper to prevent the spring from premature release and also synchronization of pin unlocking the projectile sling with the cycle of rotation. It must be unlocked when last circle of rotation almost finished.
U can also try adding a second frame which contains the rails for the first, triangular frame. This would probably lower the energy losses due to terrain being not entirely flat and the fact that you didn't use bearings for the wheels.
Some trebuchets have a sliding axel, so that the the net motion of the counterweight is essentially vertical.
Wheels also would make moving a seige weapon easier. You would still fill the rock box locally. It would also make aiming easier. I could see merit in having it on two wheels and moving it around like an artillary piece.
Great video! I appreciate all the effort you put in this project.
I think you may have slightly missed one point. The remaining energy in the system after ball release is lower with the wheels because you have less angular velocity of the counterweight, the wheels on the frame allow it to fall straighter.
The wheels allow the weight to fall in a more vertical direction which increases the energy transfer efficiency. It likely has a greater effect on the more traditional treb design as the weight would not be forced around the central pivot.
on a traditional trebuchet with a single arm the wheels allow the weight to fall vertically instead of in an arc. this allows for greater acceleration of the weight downwards and more force to the projectile.
this channel is a yt-gem
I’ve been following your channel for a while, I’ve never felt compelled to comment before this video. It is both informational and entertaining… I was thinking he better do a slow-motion shot... Then there it was :-)! Cheers!
Adding the wheels allows more distance for the counterweight to drop (mostly) entirely vertically by moving the main axle forward, hence a gain of gravitational potential energy. The syncronization of the stall points is just in a different location due to the movement. I bet if you look at your footage you will see a difference in the height before the counterweight begins to move horizontally.
This was awesome! Perfect blend of engineering and fun.
The added efficiency of the wheel version may come from the concept that with the wheels and move vertical stall location of the counterweight, the counterweight ends up stalling at a lower elevation relative to the ground than the non wheel versions. The results in more gravitational potential energy being delivered to the arm/ball. In the case of non-wheels, the ball is released and the counterweight still has another few inches to drop and that energy goes into the swinging of the arm post release of the ball.
I loved this series. My first building project was a trebuchet so it strikes a soft spot
Now, for efficiency, lots of energy is used to accelerate the different frame parts, so is you can lighten/thin especially the rotating parts it should be faster. :)
1. You store energy in the arm when it's raised.
2. The frame is stationary because it's not being acted upon by any extra forces inside your frame.
3. When you release the weight, part of that force acts on the frame making it move because the frame does not have enough mass to oppose that force, therefore it no longer remains at rest ;)
4. Either make the base heavier OR pretend the whole earth is it's base by attaching the base to it with something so it becomes one masivelly solid object. Then you transfer as much energy as you can to the ball rather than sharing it with the rocking of the frame. (Minus the friction in the sistem of course, but that should be negligible)
5. The tunning is in the ratios of the arms amongst themselves and also with the sling.
Wheels add efficiency because it allows the weight to fall in a straighter line. Measure the horizontal motion of your weight with and without wheels. This is especially pronounced for fixed-weight trebuchets. Forcing the weight to move in a curve takes up a lot of kinetic energy.
Wow. That's awesome. Thanks for your work
Great explanation despite its complexity... Kind of Trump during a press conference with the French president Macron:When Macron finished giving a statement in French, Trump quickly
responded to tell the French leader he enjoyed listening despite not
actually having any idea what was being said.“It sounded beautiful,” Trump joked. “I have no idea what he said, but it sounded great.”I have no idea what you said but it sounded great.... Of course it's a joke... Your videos are as entertaining as instructive. Thanks Tom! Happy that the UK still has dynamic young engineers like you.
Dang, that's pretty sick. It feels like a scratch I can't itch when you don't show how far the ball goes but this series was pretty great non the less.
If you use off center wheels, the forward motion will make the frame raise, and add more kinetic energi to the weights.
Another way of looking at the wheel advantage is that when weighed down you are effectively transmitting the waste energy into the ground which rotates planet earth an unmeasureably tiny amount (no really!). By adding the wheels that energy moved the frame enabling you to work out the necessary adjustments. I wonder if further improvements can be made with a few more tweaks? Great video!
Physics is awesome! Very well done Tom, and i hope to see more like this :)