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Message started by The Celestial Paladin on Oct 16th, 2019 at 4:44pm

Title: I got to thinking:
Post by The Celestial Paladin on Oct 16th, 2019 at 4:44pm
Now obviously a whip is very different. I wonder though if our science guys could use a similar approach to better understand sling mechanics?

https://youtu.be/AnaASTBn_K4

Title: Re: I got to thinking:
Post by NooneOfConsequence on Oct 16th, 2019 at 8:08pm
Yeah, Iíve watched that video about a dozen times so far, and it still fascinates me. Iím still waiting for the academic paper on this, but I donít think it translates to slinging. That video is really focused on the transition of a knot on a whip as it breaks the sound barrier. In that respect the mechanics of a sling crack are identical but thatís has little to do with the actual slinging part.

Title: Re: I got to thinking:
Post by NooneOfConsequence on Oct 16th, 2019 at 8:15pm
I do have some Mocap data from a few slinging motions, but Iím missing the speed of the ball, because it didnít have a reflective marker.
6D607229-FFCD-481C-ACC4-E334C63FE6DB.gif (168 KB | 15 )

Title: Re: I got to thinking:
Post by Teg on Oct 17th, 2019 at 5:35am

NooneOfConsequence wrote on Oct 16th, 2019 at 8:15pm:
I do have some Mocap data from a few slinging motions, but Iím missing the speed of the ball, because it didnít have a reflective marker.


(With the danger of repeating your thoughts ::) )
There should be a synchronized, timestamped video recording available for this MOCAP?
Two options:
a) Requirement: video from several known positions.
rewrite the code to do pattern recognition of the video to do triangulation onto the ball.
appropriate color channel separation, edge detection and centroiding should give a decent result for marker position for each camera channel. Then feed it as an additional marker point to the triangulation routine of the software. But I'm not sure if you have that deep access to the software  ::).

b) Requirement: video feed from single position with timestamp.
get the release time. approximate ball speed =  pouch speed at release time. This will yield an upper limit for the ball speed.

Title: Re: I got to thinking:
Post by Curious Aardvark on Oct 17th, 2019 at 6:28am
Cool byzantine capture :-)

did you do any other styles ?

Title: Re: I got to thinking:
Post by vetryan15 on Oct 17th, 2019 at 6:55am
I am not technology inclined,  but what is Mocap? That is sweet. I vaguely remember seeing something liliklilike this before.

Title: Re: I got to thinking:
Post by Teg on Oct 17th, 2019 at 7:27am

vetryan15 wrote on Oct 17th, 2019 at 6:55am:
what is Mocap?


Motion capture. The tracking of movement in space. This allows to create a "digital image" of some real-world action in your computer and then do analysis and further processing on it (e.g. animations in films and computer games).

https://en.wikipedia.org/wiki/Motion_capture

Title: Re: I got to thinking:
Post by NooneOfConsequence on Oct 17th, 2019 at 7:50am

Curious Aardvark wrote on Oct 17th, 2019 at 6:28am:
Cool byzantine capture :-)

did you do any other styles ?


If I could do it again today, I would have better form, but here are the other variations.
I was also confined to an enclosed lab and was only allowed to throw a very lightweight plastic ball.

B4CC69D0-35B1-4098-B5E5-38C2295DB12E.gif (173 KB | 12 )
79023502-E8A7-427C-891E-40CFC7E378D9.gif (261 KB | 11 )
88D825AA-FAED-4293-AD55-0A7965ABB6CD.gif (299 KB | 16 )

Title: Re: I got to thinking:
Post by NooneOfConsequence on Oct 21st, 2019 at 11:34am
Ok CP... Iíve been thinking about this, and I think I wanna was wrong when I said it doesnít relate to slinging. The whip crack starts as a traveling wave, and heavier whip handles mean there is more momentum and thus itís easier to get a good crack. There is a similar transfer of momentum from the ammo in the pouch to the pouch and release cord as the pouch is opening. Iíve noticed that heavy ammo tends to crack better... probably for the same reason that heavy whips crack easily.

Title: Re: I got to thinking:
Post by Kick on Oct 21st, 2019 at 12:21pm

NooneOfConsequence wrote on Oct 21st, 2019 at 11:34am:
Ok CP... Iíve been thinking about this, and I think I wanna was wrong when I said it doesnít relate to slinging. The whip crack starts as a traveling wave, and heavier whip handles mean there is more momentum and thus itís easier to get a good crack. There is a similar transfer of momentum from the ammo in the pouch to the pouch and release cord as the pouch is opening. Iíve noticed that heavy ammo tends to crack better... probably for the same reason that heavy whips crack easily.


I've found this too. It still depends a lot on the whip but the extra momentum the larger ammo brings helps with cracking. Whether that really means a faster release/positive effect of the "performance" of the sling, I'm not sure. Cracking a whip and slinging are related but I'm not sure how closely.

Title: Re: I got to thinking:
Post by The Celestial Paladin on Oct 22nd, 2019 at 5:12pm
I figured, I thought it was something like that, but I just didnít have the scientific vocabulary or the know-how to express it.

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