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 1 
 on: Today at 11:31:54 AM 
Started by John Buechele - Last post by ta0
I guess I was really hoping for ta0 to notice the color!
Marbled black and white? Like the Worlds logo?  :-\
Sorry, I didn't notice.

Did you notice the color of the medal ribbons? I chose it white and blue because of the ice and water of Iceland. I guess I missed the red of the volcanoes fire, which is on the flag.

 2 
 on: Today at 11:24:58 AM 
Started by jmadrigal - Last post by ta0
Jakub: it sounds like an unforgettable trip! It's great that you could share the experience with Lada and your family.

Top Men with Medals:



 :)

 3 
 on: Today at 09:57:16 AM 
Started by jmadrigal - Last post by Hroch
I arrived from Iceland yesterday evening. It was really awesome trip including renting a car, hitchhiking, camping in a tent, treking and TOP SPINNING. I've met many old friends and many new players who I had seen just in the videos.

We tried many different tops made by Jon, Jose and others. We also played classic games with target. I've learned a new stuff like spinning a small whip top from ta0 or "left hand regens" from Jon and I also tried to teach some tricks  :)

Competition was good. Daniel was probably pretty close to win. Before awards I was giving him better chance of winning. Jose also did very well. Jon is a legend.  It's good we have new players like Futoshi. Marco lost lots of points by winding up the top  :( but he is a very good player. Mike's fresstyle was a big fun. It's a pitty he tangled a string.

I tried to post some photos soon  ;)

Big thanks goes to ITSA for support of our trip and get spinning medals. Thanks ta0 for bringing the raffle price. Thanks Jose for a top which is awesome and I'm going to make video soon  ;) Thanks Marco for t-shirt and other stuff. Thanks to others for being there and having fun playing tops!

Thanks Jim for making very nice corkscrew trophy. It's a pitty you couldn't be there. Now I'm looking for the bottle of wine and I'll make an opening video  ;)

And thanks for all congratulations!

 4 
 on: Today at 08:38:31 AM 
Started by John Buechele - Last post by the Earl of Whirl
I guess I was really hoping for ta0 to notice the color!

 5 
 on: August 16, 2017, 01:13:14 PM 
Started by ta0 - Last post by ta0
After more delays, I finally got home at 3AM. I have been reading (not even answering) emails the whole morning, so I don't have time to upload photos. But I just want to thank you and your wife for letting me stay in your beautiful home and for showing me what can be done in tops with LEGOs, including black light and strobe shows. And also thank you a lot for all the LEGO tops and spare parts that you provided me (and kept adding to the bag as the day went on.)

You already had a solid throw on the ground, what helped a lot. You made very good progress on the tricks I showed you and you can now say that you are not only a maker of LEGO tops but also a spintop trick player!  8)

It was a great finale to a wonderful trip. Thanks Jeremy!

 6 
 on: August 16, 2017, 08:59:27 AM 
Started by the Earl of Whirl - Last post by mailman
Yes, David and I will be.  We wouldn't miss it!  It's a major highlight of our trip....

 7 
 on: August 16, 2017, 07:22:40 AM 
Started by ta0 - Last post by the Earl of Whirl
Go Jeremy!!!  Sounds like a terrific visit.

 8 
 on: August 16, 2017, 04:10:20 AM 
Started by Iacopo - Last post by Iacopo
As for separating the aerodynamic and frictional braking torques by varying air pressure, be aware of two things: (i) The density of the air will be proportional to the pressure inside the vacuum chamber. (ii) The viscosity of the air will probably remain constant over the entire range of pressures you can actually achieve.

I remember, you made me aware of this issue.
 
The minimal residual pressure in my vacuum chamber is 68 millibar, so there is still a bit of air drag, but, how much drag exactly ?

In my wooden top Nr. 5, RPMs drop from 600 to 440 after one minute of spinning.
So 140 RPMs are lost in one minute at 520 RPMs as average speed.
In the same top, in the vacuum chamber, at 68 millibar, RPMs drop from 547 to 496 after one minute of spinning.  So 51 RPMs (instead of 140) are lost in one minute at 520 RPMs average speed, at 68 millibar.  How many RPMs would be lost after one minute of spinning at 0 millibar ?

Millibar      RPMs lost in one minute       from RPMs   to RPMs
   68                     51                                547          496
   91                     60                                550          490
  114                    63                                555          492
  123                    70                                554          484
  132                    66                                553          487
  148                    71                                554          483
  320                    93                                569          476
  574                    121                              581          460
 1011                   160                              600          440

I plotted the data in this graph:



Prolonging the curve at the left until 0 millibar, a point can be found which seems to correspond to 35 - 40 RPMs lost at 0 millibar.




 9 
 on: August 16, 2017, 03:46:47 AM 
Started by Iacopo - Last post by Iacopo
Q: At what speed did the top fall over?

The top fall over at less than 32 RPM, (deeply recessed tip).
The complete sequence is,(minute:RPM):
0:2150 - 1:1971 - 2:1816 - 3:1674 - 4:1548 - 5:1431 - 6:1333 - 7:1240 - 8:1151 - 9:1075 - 11:936 - 12:876 - 13:816 - 14:764 - 15:715 - 16:667 - 17:629 - 18:590 - 19:550 - 20:515 - 21:--- - 22:450 - 23:423 - 24:394 - 25:366 - 26:342 - 27:318 - 28:295 - 29:274 - 30:253 - 31:233 - 32:212 - 33:--- - 34:177 - 35:160 - 36:--- - 37:125 - 38:109 - 39:94 - 40:79 - 41:61 - 42:47 - 43:32


 10 
 on: August 16, 2017, 01:55:16 AM 
Started by Iacopo - Last post by Jeremy McCreary
I'll analyze and plot that data set in a spreadsheet and then get back to you on a reasonable way to extract a single representative time constant from it. The calculations are the easy part.

Q: At what speed did the top fall over?

As for separating the aerodynamic and frictional braking torques by varying air pressure, be aware of two things: (i) The density of the air will be proportional to the pressure inside the vacuum chamber. (ii) The viscosity of the air will probably remain constant over the entire range of pressures you can actually achieve.

Since drag depends on both density and viscosity, and the latter probably in nonlinear ways, you could still have significant drag at the lowest pressures.


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