Egg Trebuchet 2. Can I do better?

A more refined version of the trebuchet. This is the one I actually entered into the competition after trying to fix the recoil issue.
You can see the livestream of the event and highlight videos on the Fieldhouse engineering channel: @fieldhouseengineering4943
Livestream (recorded on 1/7/23): • FEng Challenge - 009 -...
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[@andagaintv8756]

I really like the sounds effect you added! 😆😆

[@nutwiss]

I'm barely a third of the way through the video and already rooting for you!

[@ipadize]

you should call it Treggbuchet!

[@spacerst9341]

Trebuchegg 👍🏼

[@alvarotorijano]

Make another one! I think...: - Legs should be long enough to prevent the hole thing to lift at all. - Counteweight could be a magnet as you proposed.

[@archiefieldhouse]

Egg-cellent entry Andy! We really enjoyed setting it off

[@AndysMachines]

I enjoyed building it and I was really impressed by all the other entries! Thanks for organising the competition and I look forward to hearing what the next challenge is going to be!

[@traitorouskin7492]

this is the 3rd vid I've watched this evening. I learnt something from the first 2 and a ton from this 1. its been a good day 😀.cheers.ta.

[@AndysMachines]

😊 I always prefer KZbin videos I can learn something from!

[@DFEUERMAN]

Two observations: (1) Might have greater stability and energy transfer if weight never strikes the ground and is more centered; (2) biomechanics similar to a tennis serve or baseball pitcher: centripetal force and conservation of energy: with a smaller radius (eg wrist) for final launch, a greater velocity is created (acceleration = velocity^2 / radius)

[@AndysMachines]

Yes, there are so many variables, and having now seen the other entries, if I were to do this again I would probably do it completely differently.

[@seanburnett7760]

Great work! I always look forward to your videos

[@AndysMachines]

Thanks, I'm glad you like them!

[@eveningecho5334]

Fantastic work, watching my own mind bend on something so trivial, classic

[@SuicideNeil]

That is a brilliant piece of engineering no matter how the contest goes. I swear though, if you put wheels on that thing it would look like a Battlebots competitor...

[@AndysMachines]

Thanks! Perhaps over engineered! There were some entries literally taped together that outperformed mine! I was wandering what to do with it after the competition! 😁

[@GenericAnimeBoy]

Now that you're converting the energy to a different form, there's no reason the arc of the counterweight has to go in the same direction as the arm. Having the weight behind the fulcrum when the arm fires should improve stability and reduce the tendency for the machine to tip forward. Ideas for next year I guess.

[@AndysMachines]

Yes, in hindsight that may have been better and I did build the first version with the weight hinged to the back. But I probably should have gone with a different trebuchet design altogether, I discounted the Murlin as it seems hard to release the projectile consistently, a floating arm type might have been better (the winner actually used this design), but I thought the frame might be heavier.

[@Smallathe]

Awesome design. Very impressive eggsling.. :)

[@szeredaiakos]

Who said that you have to release the spring when the weight hits the floor? Anywho, your machine was the coolest.

[@stefanguiton]

Excellent

[@Ben-Dixey]

Brilliant videos, I wasn't very interested in an egg trebuchet but so glad I watched. You're a very clever guy.

[@AndysMachines]

Thanks! I actually learnt a lot about trebuchets I didn't know before doing this.

[@Ben-Dixey]

@@AndysMachinesI'm sure, it's always surprising what can be learnt from a seemingly simple project. It's as much about the process as the outcome, skills and knowledge can be applied to other projects as well.

[@Hiksan5]

I have enjoyed these videoes a lot. Rare to see so much of a enginering developement process, thank you for sharing with us! A thought: It looks like there is some energy lost at the end of the swing arm travel as the spring approach the dead low point. Could a solution be where the spring pull on a cable that goes around a sort of pulley, shaped a bit like a Logarithmic spiral? That would make the last energy transfer to the arm and probably make take the point of release above 45degrees (hope that makes sense?) Come to thik of it, a sort of kidney shaped profile for the pulley is perhaps better in order to provide the largest pull at the point where the torque is highest (and hopefully delay the point where the arm will tend to bounce)

[@garrattfan]

12:36 “in the egg-tual competition” 😆

[@AndysMachines]

Yes, I was avoiding making jokes like that!😁

[@garrattfan]

@@AndysMachines 😆

[@EliasFakenami]

Nice. Can't wait for you to do some work on your Terminator. Great work overall ✌

[@AndysMachines]

Terminator is continuously ongoing and there'll be an update soon, I promise!

[@GameBacardi]

14:40 I think also, some are using crazy strong magnets. It's trend in past year.

[@GameBacardi]

07:24 @Abom79 :D

[@bschwand]

Spiral shaped pulley on the arm Like on Nautilus fitness machines. Or modern bows with pulleys. To modulate spring tension applied to arm as function of angle and time. Model, then solve for optimum pulley shape.

[@AndysMachines]

I did consider this for the previous design (see first trebuchet video), I think it would be less effective with the spring though compared to the weight acting directly. Murlin and sliding-beam trebuchets achieve a similar gearing effect as the weight falls.

[@bschwand]

@@AndysMachines possible but it's got to be suboptimal. Bows and crossbows use it for a reason. I think it's a given that the tension curve is not linear, but maybe it's negligible. Just saying there is an optimum that can be defined and solved mathematically.

[@azinfidel6461]

Well done. It occurred to me that the weight reaching the end of its travel, being closer to the egg itself is it possible to give the egg A little nudge with the remaining energy in the weight? Perhaps with a block of rigid foam where the weight and the arm meet.

[@AndysMachines]

Thanks! Yes, there is a little energy left in the weight, it needs some to carry it past the point where the spring could pull it back up again. I was actually careful to avoid the weight nudging the egg (it does get close) in case it broke it and also because it would make the strings go slack which could either cause the loop to fall off the peg, or cause a large jerk when the arm takes up the slack. I tore two pouches in testing because the strings became slack.

[@captainjerk]

Eggbuchet

[@shahrilismail6899]

did u stop making terminator?

[@AndysMachines]

No, Terminator is still ongoing, I've got to the stage where there's a lot of fiddly work putting some of the previous parts I've made together, and it's not very interesting video material. There will be an update soon, here's the last video: kzbin.info/www/bejne/aV7TlHqqnLmHf5I

[@genemcintyre5352]

Who won and what distance

[@AndysMachines]

‘Smashed It’ from Simon Jelly and Mark Mellors won, with I think around 17 metres, impressive! The livestream cut off suddenly and the video doesn't seem to be available, but I'm sure there'll be an update from the Fieldhouse team soon.

[@genemcintyre5352]

Thank you

[@AndysMachines]

The video of the whole live stream is up now, but it's unlisted on KZbin and only available with this link: kzbin.info/www/bejne/iKmahoWOmNl3oJY

[@travismiller5548]

But is a spring not a battery? 😂

[@AndysMachines]

Yes, you could think about it like that, but it is only 'charged' by the weight, it has no stored energy to start with.