Trebuchet Projectile Optimisation
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- เผยแพร่เมื่อ 26 ก.ค. 2018
- I've spent quite a bit of time trying to optimise my trebuchet for the highest velocity tennis ball possible, but how can I modify a ball to go further?
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Film at night, put LEDs in a ball of some sort so it glows or whatever. EZPZ
Take a photo with the shutter time of the flight duration would potentially make for a good curve.
glow in the dark paint and a laser pointer to make it GLOW
actually a good idea holy fuck
fire
Trebuchet tracer rounds.
You get cricket balls in 113g, 136g and 156g like you had... They make lighter easier grip ones for junior cricket. Definitely recommend you try one of them and they'll be easy to get hold of...
Also the marginally smaller size will improve it's air resistance...
Also they don't have the hairy texture that most tennis balls have, which should even further improve air resistance.
golf ball dimples do help them travel further, weigh about 46 grams
a 1+1/16 standard steel pinball weighs about 80 grams... look out!
1+3/16 steel ball, about 112.9 grams, 1+1/4 about 131.5 grams (bingo!)
1+5/16 gets over 150 grams so no. 1+3/16 like a near 4oz bullet, lot of force!
The tennis ball wasn't dropping straight down at the end. Remember that your camera isn't directly overhead the ball for the hole trajectory, and that it's just at a point. Think of a triangle with the ball falling along one of the legs.
Great video, I'm glad someone is out living life and having fun 😉
+2MAz Bit late to the party, but: Veritasium proved in one of his videos that making something spin requires a lot less energy compared to what's used for accelerating it. So little in fact that shooting a wooden block in the middle or to the side (to make it spin) made practically no difference in the upwards velocity. The energy going into making this tennis ball spin is probably going to be in the 0.1% of its velocity, which would not be noticeable on a camera.
@@Excludos the backward spin allows it to stay airborn longer too due to the magnus effect, so it should be beneficial to have the ball spin
Cashy 1 It is. You gain height exactly because of the magnus effect, but you don't lose a lot of velocity, which increases distance by quite a bit
There are a lot of smart people here
@@dp4advanced234 😂😂😂😂
I think you should remake your trebuchet to be... 3 times bigger?
In length, area or volume?
Since we exist in a 3D universe, as far as we know, I would assume volume.
So the trebuchet should only be about 1.44 times higher?
at least 3 times bigger so not only tiny people can fit inside it..
NB. x2 scale would be quite large... coconut launcher...
(punkin chunking trebuchet record is around 864 metres.)
I have 5 scales of Rolling Whippers. 16 inches to 22 feet tall.
Being a maths nerd I love these videos! Just a quick point, just because a graph is curved, doesn't make it exponential. Keep up the great work!
1:12 What a catch
Best catch ever! You single handedly saved bretts gopro
You could try to stabilize that footage. It would be interesting. :)
Tom Stanton
To your question on how the acceleration should be faster, the outward acceleration shouldn't be that much different ( there is a bit of a difference because the weight difference of the balls should impact the end velocity, more weight=lower end velocity). If you actually mean the forward acceleration of the ball, the ball with the lower weight should have a higher acceleration due to it having less potential energy and more kinetic energy and of course having a lower mass inertia.
Of course, this is just a mere assumption, so take it with a grain of salt ;D.
too low fps to stabilize, you are simply missing the information
I had a random idea actually, in a future series do a video on reaction wheels, and build a small one then hook up camera to it and throw it with the trebuchet to demonstrate how it stays stable. Like it could be programmed to always point the camera a certain direction. Not sure how realistic that is though or if a reaction wheel setup small enough would even have enough power to stabilize.
Magnus effect.
Try a release mecanism that uses a pivot and a screw to adjust easely on field. Turning the screw modifies the angle., and the system is quite robust.
You might want to try a ball with dimpled texture on it, like golf bals... This will help it to travrl further... And you might be able to modify travel direction if you dimple it with different paterns (just a dimple band and non dimpled sides)
Good luck!
I found a couple of interesting videos ... This might give you an idea for optimizing the projectile, and there are videos that talk about trebuchet angle of release.
Physics of golf balls 1 : th-cam.com/video/fcjaxC-e8oY/w-d-xo.html
Physics of golf balls 2 : th-cam.com/video/zZsvpw-JOO0/w-d-xo.html
Physics of golf balls 3 : th-cam.com/video/iBrwwYm7As0/w-d-xo.html
Magnus effect : th-cam.com/video/23f1jvGUWJs/w-d-xo.html
Thanks for your videos and efforts... they are incredible!
Cheers!
Bump
and thats how you do real science.. calculate some theory..trial and error.. gather the info.. tweak the components.. and try to figure it out mathematically later....well done
Earth is flat tho
@Algren Nonymi
Flat Earthers are full of sphere! 😆
I love that you have both the curiosity and competence to follow your exploration of this wonderful machine. It's a fascinating journey!
Nice way to science things up!! Really nice job with the testing and consistency doing so.
I think this is my favorite of all your projects yet. I will never build one but your process of investigation is great and your results have been really surprising, like I would never have thought wheels would increase efficiency! This is better than anything on Netflix. You're a legend!
Love the video! Great graphs and analysis, very interesting to watch. Always love me a good trebuchet video
The drone shots of launches are just so satisfying. Nice one!
Love your vidoes! That ending was great! Keep doing what you're doing! Your great at it!
Hey Tom, I am loving your work. Keep it up!
great work with the data analysis and optimisation. now you ahve the weight pinned down, now its time to optimise for release angle
That's awesome that you have that big field right there! Makes it more convenient for these kinds of experiments haha. Great video.
I discovered the channel yesterday and ended up spending most of my Sunday watching your videos. Fantastic work on the airpowered engines btw... and today i ended up here. at the trebuchet videos. I'm still in the middle of watching them all, but a thought that i had was. Maybe you can get even further by making your own prejectile in the style of a golf.... and i reached the end of the video and you mention exactly that idea. And here i thought i waited long enough to share that idea :D
This is a really cool series thanks for doing it!!
You can actually see the weighted tennis ball with backspin rise slightly from the backspin.
@@Teklectic you can tell by its leather jacket and it's smoking a cigarette. FUCKING cool!
Awesome stuff ! love ever bit of this! Thank you for all that data!
I love this series! Great videos 👍🏻
great new advance. love these vids i always learn something new. cheers Tom!
This is such a cool project. I love optimization
I've subscribed because of these trebuchet experiments. The cricket ball was the decisive factor! ;-D Thanks Tom.
Great channel you have👍
When we hit the golf balls on the driverange, we hit with topspin, to make the balls float on the air, when the balls are hit just right, there is a pretty decent gain. Good luck
Tom, I look forward to seeing you run out of variables to test, and the only option is to double the size and weights so you can compare the two data sets! Thanks for making these videos.
excellent as always - cheers mate!
That is really awesome. This video should be on trending.
Tom, awesome! thanks for taking time to try out the cricket ball, too bad it ended being a bit heavy! Staying on the sporting theme, can you possibly aim the trebuchet such that it "serves" a tennis ball on a court or bowls a heav-ish tennis ball at a cricket pitch, thereby building a either a serving machine or a bowling machine! Again great stuff!
I really enjoy your videos
Enjoyed the juggling at the end way more than I should have done
Getting there Tom keep at it 🖒
I am glad to see that you're not done with the trebuchet as I'm really enjoying it. I would be interested to know what your efficiency came out to be with the last ball that you were using.
It makes sense that the Ke change wouldn't be exponential, I mean, the larger ball is being accelerated for about 10-20% longer by the same force. The speed won't be quite as high, but it won't be solely based on that kinetic energy equation, since that can't account for the change in inertia of the rotating body, which is now significantly greater.
Also, I'd love to see this thing launch a fin-stabilized projectile. Maybe a go-pro embeded into a nerf football?
Hell yeah, I was hoping you'd be back with this thing...
What a wonderful juggling outro!
Experiments like this are the best way to figure stuff out... or at least the most interesting. But I'm pretty sure research is goes just as far!
that drone shots around the 6 minute mark are awesome and I would love to see more.
And for a projectile, just 3D print one and add some metal weights in the center. Maybe a "2 part shell screw together design" with even spots for steel marbles to customize weight?
Barnson that’s a great idea, he could also add the ”golf-ball-like” texture to it to increase the Magnus effect!
simply brilliant
Ohey we have the same scales!
You've taught me so much about this :D I'm modifying my own according to these findings and I've nearly doubled the range (though it's tiny so it's nowhere near the range of yours)
Trebuchet cricket. Want
1 per run, 6 for boundary and win the game if you can hit the trebochet on the full
the winner is the person who survives batting
Wow! That's impressive! 😮
nothing better then some classic catches with a trebuchet on a saturday
I think this is maybe one of your best projects
great job ! keep going !
Tom, did you know there is a trebuchet simulator website. You can enter in all of the variables, and it calculates everything for you. It even animates the model! Good luck, and keep up the good work!
Hey Tom, love these videos!
I recently observed a full scale reconstruction of a medieval trebuchet in action, and the engineers operating it said that the ideal counterweight/projectile mass ratio is 100-1. So for a 5kg payload, a 500kg counterweight would be rigged. I'm not sure if this is optimal, merely anecdotal, or simply the manner in which the machines were configured historically, but I thought it would be worth mentioning.
I believe your counterweight is 15kg? If so that would put your 156g Cricket ball slightly over the (alleged) optimal mass (which would be 150g) for your current counterweight. I assume though that the optimal mass ratio would vary based on the other parameters of the machine, though it seems not by a great deal, given the results you've shown here.
Also of note: the trebuchet I observed was fixed (as I imagine most historical examples would have been). Perhaps as the mass of your projectile and counterweight approach the optimal ratio, the benefit of the wheels is reversed and becomes a detriment? IIRC the wheels altered the stall angle of the main arm, and you said in this video that raising the mass of the projectile changes the release angle as a result of a faster transfer of energy into the projectile.
Maybe you could try the Cricket ball without the wheels, as the plateau you observed at ~130g could be a result of the wheels stealing away some of the energy from the projectile.
If you can juggle those dissimilar weights so well you should be easily capable of Mill's mess. Great video. I am currently working on a UK legal sea fishing bait launcher, and your videos are of real practical interest (mainly because they rule out trebuchets as too bulky given the range and weight of projectile). So thanks!
To make tuning the angle of release less tedious, you could erect a large net to catch the balls as they leave the sling. That way, you could reload and shoot within seconds, and still get some accurate slow-motion footage of the angle of release.
3d print a projectile!
Adjust the infill accordingly. I don't know if the density is high enough though
Dööörk was about to comment I see a 3D printed projectile coming on
Totally could work. Maybe something that opens up and has a bolt going through and he can thread small weights inside. Like actual nuts/washers. Idealy want to try to keep the weight in the centre.
But would it survive repeated impact for testing purposes?
I use 3-D printed models to make silicone molds.
Maybe if printed with flexible filament it would
Looks like a sick FPV meetup!
Still VERY interesting Tom, style as well as content!.... and juggling too!
10 and 12 ounce pitching baseballs without dimples, and rubber, dimpled baseballs and softballs, from SKILZ
So impressed by your adherence to the scientific method. I have watched four of your videos and you sir, deserve the subscription.
You are a really lucky man with the British weather this year.
Hi Tom ! To understand the influence of spin on the trajectory, you could try the experiment with a ping pong ball shot in different styles with a bat.
"flat" spins should give a parabola that's steeper in the end (because of drag)
Back spins should give an almost linear trajectory in the beginning, and then vertical drop (like the one you experienced)
Top spins make the ball want to go downwards with a trajectory that is more curved
Once again it is very easy to try this yourself with a ping pong ball, and there are many simulators out there!
Comparing the ranges of the three in your next trebuchet video would be awesome! Keep up the great content!!
... and he juggles!! This is now the best channel on youtube
What i am interested in now is how the shape/weight/movement of the frame impacts efficiency. My instinct says that allowing the pivot to move vertically would help, but i don't know how to do that. Installing wheels for horizontal movement is simple, but vertical is trickier, especially since you'd want it adjustable to allow for some experimentation. Maybe some sort of suspension could work.
Fascinating project!
I have built my own trebuchet copying your design and having fun. It started as a lockdown project during our New Zeland level 4 lockdown. I am trying a tapered arm made of radiata pine rather than an arm of constant rectangular cross section to reduce inertia moment. I am considering making the sling itself from thin cord as well as the using the same thin cord for the fixed and release strings. And then
making the pin as light as possible-maybe from nylon. All this to reduce the inertia of the arm so that more energy goes into the projectile. Going further a tapered carbon fibre arm might be better for better strength to weight ratio.
Welp, time to go to bed it's like 2am BAH GAWD, NOW HE'S OPTIMIZING THE PROJECTILE
In electrical engineering we understand maximum energy transfer with matched impedance (Load). Your experiment here parallels this axiom in mechanical Physics as well. Thank you and well done
Hi Tom, just a thought. You did one video explaining how efficient the Trebuchet is, and the result was lower than you expected. As a cyclist this reminded me of the marginal gains of cycling adding up to a huge efficiency difference between an old bike drivetrain and a new drivetrain with sealed bearings, often ceramic and in general a very watt efficient transfer of energy with the same input. What if you did a video replacing all the pivot points with sealed bearings, and similarly looking at other materials for the sling and other contact points. This could be very interesting to see how much different these reductions in friction can make and effect projectile velocity. Thanks For the great videos.
That is a pretty cool drone course. I wish we had an active drone racing group around me.
Love Love Love Love Love this, you, your video. Your resources really put my channel to shame, but I have been researching Whippers intensively for several years. I'm very proud of you! You're doing a Great job! I wanna come play with you So Bad I can't stand it. I could show you So much and you could bring the hard science!
When optimizing something (such as projectile mass) you have to actually try values of range high enough so that there's an extremum point. For example in your projectile weight vs distance graph it just increases which means that you could have further increased projectile mass and got even longer shots before you actually reached maximum. So instead of monotonously increasing/decreasing curves, all of them actually have minimums and maximums if you plot them on wide enough range of input values.
Neat videos!
One variable worth considering would be the launch arm length; if you increased the length you’d increase the rotational moment of inertia of the launch arm, which would delay the stall and compensate for the tennis balls’ low weight. Would make life easier not having to procure specialty projectiles.
Alternatively, you could try adding incremental amounts of weight to the tip of the launch arm as this would have the same effect of increasing the launch arm’s rotational moment of inertia.
You can either 3D print or CNC the right projectile. That way you can make any combination you want.
Maybe even add something to it so it's better visible on the drone shot?
I use 3-D printed models to make silicone molds for casting dimpled projectiles in several sizes and weights.
Awesome, you build a trebuchet that can shoot around corners!
Oh lord!.....and the devil is in the details!
Kudos from the "Colonies" and loving this series! Found them a bit late, but WELL worth the time spent viewing them.
Nice work ! You could use a phosphorescent juggling ball and do a long exposure or just film it as you did. I would love to see golf balls also (discovering your channel, maybe it has been done since).
Engineer AND a juggler. Well done!
I think it would be cool if you could try to find the optimal release angle (or better yet, initial projectile trajectory angle) between 30 and 45 degrees with backspin. Then once you know the best release angle hold that constant and optimize on the ball weight.
RE: Dimples: The only point of dimples is to trip the boundary layer so it becomes turbulent and the flow can maintain attachment reducing pressure drag caused be the wake. The dimples increase viscous surface drag, but for the right Reynold's number the decrease in pressure drag is greater than the increase in viscous surface drag. If the larger tennis ball (relative to a golf ball) and fast speeds of the trebuchet can put a smooth ball into the regime (i.e. high enough Reynolds number) where the BL has transitioned to turbulence and remains attached (for longer) then the drag coefficient will be much lower. See the plot for C_d on the right hand side at en.wikipedia.org/wiki/Drag_coefficient. (Link to image: en.wikipedia.org/wiki/Drag_coefficient#/media/File:Drag_coefficient_on_a_sphere_vs._Reynolds_number_-_main_trends.svg)
correct
"The back spin didn't change the range much", but as Barnes Wallace found out (or rather already knew), inducing back spin on the bouncing bombs enabled them to be released in time for the Lancasters to get clear of the dams before they came to a stop and sank to the base of the dams before exploding.
In junior school we used 133g cricket balls, that is right in he money I would say. I am sure they will be easy enough to find. I love these videos, keep up the good work 👌
1. E=mv^2 is a second degree polynomial in the velocity, also called a quadratic form. Functions that have the variable in the exponent are called exponentials.
2. At 9:19 and 8:07 it looks like that the arm is flexing quite much under the force, perhaps try for a more stiff arm? I would guess that the flex is messing up the projectile release.
3. At 8:07 you state that that the arm is moving far less with a heavier projectile, that should be due to the higher energy transfer efficiency of a heavier projectile. It is simply less remaining energy in the system. Edit: your trebuchet is also a double pendulum which is a chaotic system which means that very small deviations in initial values (starting position of the projectile, skewness or give in the machine construction e.t.c.) will affect the behaviour dramatically. Therefore the behaviour is very hard to predict.
.
Very nice comment, thanks for the information :)
I like how the GoPro is spinning faster than a complete scan so you can see the sky twice in some of the frames.
What about rigging some sort of electrical switch to the sling release pin? You could have some high-intensity LEDs mounted to the lever arm flash when the string slips off and that will give a pretty clear visual of release angle. Plus you could do some neat photogrammetry with long exposures.
At 10:30 that doesn't look like backspin. It looks like topspin!
It's back...
Definitely looks like a forward spin. might just be aliasing, but at 0.25x speed it looks too smooth for that...
It would depend on wind direction. If you have a headwind, you'd want topspin, tailwind, go for backspin.
You never want topspin. You must control the amount of backspin. It's actually pretty much impossible to get topspin. You can however get side spin, as you can see in Tom's video. I'm going to see if I can launch a spiral with a football.
It could be the camera shutter making it look like forward spin. Same reason why the popular no spin helicopter vids are possible.
thank you for correcting the previous KE calculation error, and for good science in this video.
The tennis ball is quite furry which may have caused significantly more drag
Many good ideas in comments if you have the time. I was thinking of adding weights inside the tennis balls free moving and fixed to see the different effects. The smoke and leds sound great!
This is very close to my feild of hobbie physics im an air rifle nerd but more a pellet nerd i was designing pellets as a kid to now and ive made some intresting finds and rounds over the years i specifically make great hollow point ammo that can work from as low as 3ftlb just do a ftlb calculation on the projectile get a speed and weight its all very simple from that you can work out range distance ect but you may need to get drag coefficient calculations too to be as precise as possible from that you could be quite accurate with consistent ammunition weight i also make slingshots that can and do drive. 44lead balls at 30ftlb lol
Tom. If you 3d printed a ball ie two half spheres and then installed two bright leds or purchased a led poi ball you could film a launch at night and capture its angle of launch using long exposure or bulb mode photography @tomstanton
What was your Major again?
P.S.: I just love the way you explore stuff and am very interested in your videos. Eager to see what you found out next!
you should try one of those dimpled hard rubber baseballs that are made for pitching machines. i'm not sure how much they weigh, but i bet you could reduce the weight a little if needed. it'd be interesting to see if the dimples help it fly further like a golf ball.
I use them. I used them to make silicone molds for casting cement projectiles too.
I built a trebuchet as a high school project for my daughter and then couldn't leave it alone. I also found that tennis balls weren't ideal due to wind resistance and weight. Problem solved by cutting a small slit in the ball and inserting pea gravel. Weighing each ball on the scale for consistency. The gravel in the ball reduced bouncing and rolling on impact which helped recovery. Pink is easier to find in the grass than green. Changing the length of the sling also alters release time so heavier projectiles need to be tuned to the sling.
Love what you are doing Tom, how about replacing two things, the arm and string, just put a flexible arm and a longer strin/rope, like a fly rod but on asteroids , anyway thank you for the time to share and work , you are in my top 5 best you tubers!!!
You can use the knowledge to adjust your aim. Tilting the ball left or right, you can aim about 6 degrees left or right. For a huge war trebuchet that can,t be moved, that would be quite handy.
What you've discovered is what electrical engineers call impedance matching. The sling length, counterweight mass and lever geometry all affect the ideal mass of projectile. If they are matched, you get a newton's cradle kind of effect where all energy is transferred from one moving object to the other. Alternatively, have you seen a newton's cradle with unequal balls?
Tom the Ginger Warrior with the Trebuchet. God I am chilling. The blow of the Winter wind is coming. Good Job 😵 😵 😵 💝
You could add this to your trebuchet playlist
Pay very close attention to the stitching on the balls that have it. The stitching can interact with the spin on the ball and affect trajectory.
Hej... This is great fun! Any news on your trebuchet... would love to see much more. Maybe try heavier weights counterweights???
also, have you considered a steel ballbearing. heavy and small
Glen M also deadly if you get hit haha
And a job to find out in the field
Somebody is going to lose an eye. lol.
Or a head :o
I launch 2", 1.4375# bearings. They go good, but no magnus.
Wonderful experimentation!! Can adjusting the length of the sling make it work better?
If you decide to use a baseball, keep in mind that the placement of the seams can make a big difference in where the ball will go. This is how pitchers can throw fastballs, curveballs, sliders, etc. Search for curveball and you will find a lot more information on this.
Nice juggling, bro!
Nice juggling !
keep the fuzz on the ball, believe it or not but it actually decreases drag, look at the workings of a golfball. to increase distance you can increase weigt of the counter balance, increase the arm of the trebuchet, change the release angle of the projectile and maybe give the projectile a spin to generate a bit of a magnus effect. maybe you can also make a stop for the counterweight so that it remains extended while upright.
I think it would be very interesting to try and launch a winged projectile like a glider from it and see how far it can go with the extra lift. would be tricky to get it flying straight though
I love this trebuchets and tennis, mostly trebuchets