Flywheel Trebuchet First Test
Added 2020-09-17 18:02:23 +0000 UTCHope everyone is well! This project has been on my list for a long time and I've finally built it!! The flywheel is 0.8m in diameter and weighs 1.9kg. Including the weight of all the arms, the total moment of inertia is about 1.1kgm ² . I've carried out a few physics simulations and think I can launch the tennis ball at 200mph (89m/s) with it spinning at 270rpm. I can only spin it up to about 120rpm directly by hand, so I will add a belt and pulley ratio to get it going faster!
Comments
I can see you coming from where I’m coming from and you want to see that projectile make it across the channel also don’t you? ;)
Gary Benninger
2020-09-18 20:03:35 +0000 UTCWith respect to complexity vs simplicity, I totally get it. However, it sounds like you're thinking of engaging the clutch at the moment you fire: "it would be difficult to time the clutch engagement so quickly". I don't think that's what Gary is suggesting. If you have a heavy flywheel in addition to the existing flywheel + arm assembly, you could 1) spin up the heavy wheel, 2) engage the clutch, 3) until the launch assembly is at speed, 4) then disengage the clutch, 5) and fire. So the heavy flywheel would just be a stored energy device, not part of the actual firing mechanism.
Ethan
2020-09-18 19:39:16 +0000 UTCI'm wondering if you'll need to install some kind of automated engagement mechanism to guarantee proper timing of the release though... Can't quite see how you did that there, but it looks like careful manual timing.
Jonathan Charnas
2020-09-18 10:30:33 +0000 UTCReading this answer was almost as good as watching your videos and listen to you talk about physics. :)
Gary Benninger
2020-09-17 23:05:15 +0000 UTCI have considered a clutch mechansim, but comparing a complex mechansim vs an efficient launcher, the efficient/simple trebuchet won. Having a clutch mechansim introduces inefficiencies/complexity and it would be difficult to time the clutch engagement so quickly (would need to be within 160ms). According to my physics simulations, the trebuchet mechanism should work consistently across the rpm range, however that's yet to be tested!
Tom Stanton
2020-09-17 23:02:22 +0000 UTCAttach your e-bike wheel to the shaft of the trebuchet and have at! Wheeeee!
Sean Guzek
2020-09-17 21:56:22 +0000 UTCCould you have a heavy fly wheel spinning up with a ton of mass and inertia and then a clutch that would spin up the trebuchet arm? And of course my question is does getting that thing to spin faster work with the trebuchet mechanism?
Gary Benninger
2020-09-17 18:12:21 +0000 UTC
