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11 July 2010

8 Comments

Posted by ZDP-189

I've just signed up a Youtube account (ZDP189HK) to share videos. I'm not competing with Jörg; I'll just post maker tutorials and technical videos there.

Here are three videos to kick off. They were shot in high speed motion capture to illustrate and measure slingshot action and band acceleration.

This is one of Perry's with natural rubber bands filmed at 420 frames per second.

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ZDP-189

11 July 2010 - 02:05 PM

This is recorded at 1,000 fps. You can see that the ball doesn't leave the pouch until the pouch is at its furthest forward position, being about 18" forward of the fork. You can also see that the pouch goes through the fork (so the depth and spacing is important. The pouch and bands also descend after the flip but the ball flight path after departure is straight along the line of the forearm.

This is also at 1,000fps, but is reframed to show the entire acceleration from release. It's interesting to see my hand twist to the outside. I didn't know I did that.

ZDP-189

11 July 2010 - 02:31 PM

I am learning a lot from these high speed video shots, both about my technique and the physics of the shot.

The camera is a Casio Exilim EX-FS10. The board behind the slingshot is calibrated at 4" between leading edges of the black bands which are almost 2" wide. I can use this to both check the alignment of the bands perpendicular to vertical and to measure speed and acceleration.

A+ Slingshots

11 July 2010 - 05:13 PM

That is very interesting Dan!!!! Thanks for the videos. It's great to learn new things about our sport.http://slingshotforum.com/public/style_emoticons/default/smile.gif

Skit Slunga

11 July 2010 - 05:42 PM

Veddy Intevesting! InDeeed! I've seen the same wrist rotation in my own shooting occasionally - especially when focusing on form and follow through shots. Seems as when I try to correct it (re: fight natural follow through) my shooting suffers. You can tweak it if you're willing to completely alter your existing shot cycle. If I understand your natural tendency to make things right...at the moment you're designing a new fork to resist that rotation without altering your shot cycle. Carry On Sir!

Dayhiker

13 July 2010 - 04:42 PM

But it looks like your hand doesn't twist until the ball is gone from the pouch? If so, no reason for concern, is there? :iono:

ZDP-189

22 July 2010 - 07:54 PM

Here's more:

Flatband's Single Slotted Pocket Plinker

http://www.l2i.org/s...cketPlinker.jpg

There's a link to my review of Gary's excellent service and slingshot here: (link)

Stats:
10.2g (.36oz) shot.
Temp: 31C (89F)
Humidity 90%
Altitude 150ft MSL

48.2m/s
52.1m/s
43.6m/s
40.4m/s
38.5m/s
44.3m/s
43.3m/s

Mean 43.9m/s (144fps)
Median of 43.6m/s (143fps)

Bunny Buster's Rosewood and Red Oak Laminate

http://www.l2i.org/s...nnyBuster01.jpg

Stats:
10.2g (.36oz) shot.
Temp: 31C (89F)
Humidity 90%
Altitude 150ft MSL

74.4m/s
38.9m/s
63.1m/s
33.8m/s
31.5m/s
31.8m/s
50.6m/s

Mean 46.3m/s (152fps)
Median of 38.9m/s (128fps)

ZDP-189

22 July 2010 - 07:54 PM

USASlingshot's Pine Boardcut

http://www.l2i.org/s...lingshots01.jpg

I posted a detailed review of this slingshot here: (link)

Stats:
10.2g (.36oz) shot.
Temp: 30C (86F)
Humidity 90%
Altitude 150ft MSL

38.8m/s
47.5m/s
38.0m/s
42.2m/s
44.3m/s
42.9m/s
45.5m/s

Mean 42.7m/s (140fps)
Median 44.3m/s (145fps)

A traditional Filipino slingshot bought in the Philippines with original (new) bands

http://www.l2i.org/s...hilippino01.jpg

Stats:
10.2g (.36oz) shot.
Temp: 31C (89F)
Humidity 90%
Altitude 150ft MSL

31.3m/s
20.2m/s
28.2m/s
28.1m/s
25.3m/s
25.4m/s
21.6m/s

Mean 26.6m/s (87fps)
Median 26.2m/s (86fps)

Sam

22 July 2010 - 08:49 PM

Intriguing stuff! It's improved my understanding of why the 'over-the-top' design is so popular, especially with flat-bands - from my observations this method of attachment seems to give the pouch a much smoother trajectory, which surely results in higher accuracy and velocity? http://slingshotforu...default/huh.gif

PS: I think your blog is great, a real service to the community! http://slingshotforu...default/wub.gif

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