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Author Topic: Flywheels and fairings and spokes, oh my!  (Read 7281 times)

Jeremy McCreary

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Re: Flywheels and fairings and spokes, oh my!
« Reply #60 on: March 02, 2021, 04:40:44 PM »

Jeremy, so you say by this I should really go for the 0.04 mm fishing line instead of the 0.3 mm line I am currently using?

Test, test, test!
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Playing with the physical world through LEGO

ortwin

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Re: Flywheels and fairings and spokes, oh my!
« Reply #61 on: March 02, 2021, 05:39:15 PM »

Jeremy, so you say by this I should really go for the 0.04 mm fishing line instead of the 0.3 mm line I am currently using?
Test, test, test!
Alright, I am preparing for the test!
Ordered 10 m of this one:

0.04 mm and 3 kg sounds good.  The one I used in the CRTs so far read 0.3 mm an 4 kg.


Actually you could also use thin nylon strings instead of your spokes, right? Or do you have some kind of contract with LEGO that does not allow for this kind of mixing something else into the system?
« Last Edit: March 02, 2021, 05:47:54 PM by ortwin »
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Jeremy McCreary

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Re: Flywheels and fairings and spokes, oh my!
« Reply #62 on: March 02, 2021, 06:57:02 PM »

Yes, planning to try more "suspension tops" with cables instead of spokes. Some interesting engineering challenges there.

Or do you have some kind of contract with LEGO that does not allow for this kind of mixing something else into the system?

Surprisingly touchy subject. The "purists" among adult fans of LEGO use only official, unadulterated parts. They look down on some of the ways legitimate parts can be joined and might get physically ill if forced to watch me alter one. Some view anyone who doesn't build this way as a heretic. Every hobby has zealots. No contract. They do it to themselves.

Personally, I'm a selective impurist, as are many who build working gizmos. Once I have a functional goal, I do my best to get acceptable performance as purely as possible. That's part of the challenge. But if the laws of physics insist, I'm off to the hardware store. Among my many sins...
o Parts of parts, like most of my top tips
o Non-LEGO functional stuff -- springs, elastics, strings, pneumatic tubing, electricals, boat propellers, etc.
o Rarely, metal axles and supports
o And a few times, (gulp) glue -- mainly for centrifugal safety.

There's a bounty on my head.
« Last Edit: March 02, 2021, 07:05:01 PM by Jeremy McCreary »
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ortwin

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Re: Flywheels and fairings and spokes, oh my!
« Reply #63 on: March 03, 2021, 03:41:07 AM »

.... Some interesting engineering challenges there.



If these ones really do what I think they should, I do not see the challenges even if you want to stay a purist. You could do the balancing by ear and you would call it tuning!
« Last Edit: March 03, 2021, 04:09:04 AM by ortwin »
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Jeremy McCreary

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Re: Flywheels and fairings and spokes, oh my!
« Reply #64 on: March 03, 2021, 10:02:27 AM »

Yes, tuning the centering would be one issue, and there I think I'd want no-stretch cables with secure but adjustable cable mounts (for the same reason you want balancing screws). Your idea of guitar tuning screws might be just the thing for a big non-LEGO version.

Use your audible tuning method to even out the tensions in the return elastics below. Otherwise, you get unbalance wobble from uneven expansion/contraction. Seems like no 2 rubber bands have exactly the same tension vs. stretch curve.

https://youtu.be/jEMUGFQTux0

In flexible tops like these, you can also get nasty wobbles from structural oscillations excited during spin-up. A suspension top would be subject to that. Don't mind short spin times when necessary, but I really don't like wobble. I tolerate it above only for the cool mechanical effect.



« Last Edit: March 03, 2021, 10:08:58 AM by Jeremy McCreary »
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ortwin

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Re: Flywheels and fairings and spokes, oh my!
« Reply #65 on: March 04, 2021, 01:47:02 AM »

Your idea of guitar tuning screws might be just the thing for a big non-LEGO version.


Non-LEGO version?? The picture in my last post here shows LEGO guitars. They offer a Fender Stratocaster set, I read. Does it not have strings and tuning screws?

https://www.nme.com/en_asia/news/music/lego-to-release-fan-created-fender-stratocaster-brick-set-2781950
« Last Edit: March 04, 2021, 10:19:50 AM by ta0 »
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Jeremy McCreary

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Re: Flywheels and fairings and spokes, oh my!
« Reply #66 on: March 04, 2021, 05:18:02 AM »

Non-LEGO version?? The picture in my last post here shows LEGO guitars. They offer a Fender Stratocaster set, I read. Does it not have strings and tuning screws?

Yes, but...
1. The tuning screws are too bulky for a LEGO top of reasonable size.
2. Don't even want to think about the aerodynamics.
3. I'm sure the screws have a lot of backlash (as all LEGO gears do), and that could make precise tuning of a top suspension cable quite difficult.


All that said, the guitar and amp are very cool builds. Thanks for sharing!
« Last Edit: March 04, 2021, 05:21:23 AM by Jeremy McCreary »
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ortwin

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Re: Flywheels and fairings and spokes, oh my!
« Reply #67 on: March 04, 2021, 06:21:30 AM »


All that said, the guitar and amp are very cool builds. Thanks for sharing!


Sharing? Seriously? I would NEVER have thought I could show something that is new to YOU in the LEGO world!
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ta0

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Re: Flywheels and fairings and spokes, oh my!
« Reply #68 on: March 04, 2021, 12:07:30 PM »

Ordered 10 m of this one:
0.04 mm and 3 kg sounds good.  The one I used in the CRTs so far read 0.3 mm an 4 kg.
That's really thin, specially considering that is braided!  :o Each strand must not be more than 10 microns! If black they would be perfect for magic tricks  >:D
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Jeremy McCreary

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Re: Flywheels and fairings and spokes, oh my!
« Reply #69 on: March 04, 2021, 03:23:03 PM »

Up to this point all results made some kind of sense at first glance: bottom covered better than bare top, upper side covered a bit worse than with a covered bottom but better than the bare top, both sides covered gave the best results.

- I ripped both covers off and did another measurement on the bare top
This curve ended up somewhere between the others! Which means the whole measurement as I performed it so far can not tell us much.There must be some different effects involved here so that we can not see the aerodynamic effect by the fairings clearly.

Just now looking over your nice experiment here. Before the 2nd bare run, my corrected results and yours pointed toward the same conclusions regarding the value of fairings WRT spin time.

Despite the confounding 2nd bare run, I think the value of 2 fairings seems likely to be a reliable finding.
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ortwin

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Re: Flywheels and fairings and spokes, oh my!
« Reply #70 on: March 04, 2021, 04:40:40 PM »


Despite the confounding 2nd bare run, I think the value of 2 fairings seems likely to be a reliable finding.
Nevertheless I took further steps today towards the building of a more serious top than the Curtain-Ring-Series with thinnnnn spokes. They can be covered later anyways to test the difference.
I contacted my man with the golden hand at the lathe and proposed this little project. He is willing to help so I am very happy about that.About most parts of the spinning top  we are going to build I have a clear picture in my head. Once I have put it to some kind of constructive sketch I will show it, so we can discuss it before it is actually being build. I think the contour of the flywheel has the most potential for discussion. Below is a rough picture of the evolutionary stage the flywheel has in my head at the moment.


« Last Edit: March 04, 2021, 04:58:38 PM by ortwin »
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Jeremy McCreary

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Re: Flywheels and fairings and spokes, oh my!
« Reply #71 on: March 04, 2021, 05:56:00 PM »

Below is a rough picture of the evolutionary stage the flywheel has in my head at the moment.

Ooooh, interesting!
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ortwin

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Re: Flywheels and fairings and spokes, oh my!
« Reply #72 on: March 05, 2021, 05:29:24 AM »

Below is a rough picture of the evolutionary stage the flywheel has in my head at the moment.

Ooooh, interesting!


Once evolution took a few further steps in the right direction and the flywheel provides good results ( spin times), I might get T-shirt with something corresponding to this one:
« Last Edit: March 05, 2021, 12:13:42 PM by ta0 »
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Jeremy McCreary

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Re: Flywheels and fairings and spokes, oh my!
« Reply #73 on: March 05, 2021, 12:27:20 PM »

Osmium is the densest metal. Just sayin'.

PS: But maybe not the best choice for a finger top, as the inevitable oxide coating would be quite poisonous. I'd go with irridium instead.

Osmium a noble metal with beastly properties
« Last Edit: March 05, 2021, 02:14:40 PM by ta0 »
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Jeremy McCreary

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Re: Flywheels and fairings and spokes, oh my!
« Reply #74 on: March 05, 2021, 12:59:35 PM »

Once evolution took a few further steps in the right direction and the flywheel provides good results ( spin times), I might get T-shirt with something corresponding to this one:

Please order an extra for me!

My wife sometimes thinks I'm an evolutionary throwback. Now that I see that last step in posture, she could be right. Just this once.
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