Monday, December 5, 2011

Two new videos

Yes, I made two new vids this weekend!

First, I always wanted to know how deep various ammo types penetrate into ballistic gel.


Then, it was high time for a review about Flippinout's slingshots.


Enjoy!

25 comments:

  1. Lovely videos! I love those slingshots!

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  2. YAY punch that gelatine on the nose!

    Nice video's.

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  3. Jörg, I would really appreciate some chrony numbers of those projectile-slingshot combinations so I can verify my slingshot round ball terminal ballistics model.

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  4. Dan, I have stated the chrony results for each shot in the video.

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  6. How to punch a block of gelatin LIKE A BOSS...

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  7. awesome videos.how is your hand man . aren't you petrified to use heavy ammo and strong slingshot after the accident?
    question: what is the most accurate slingshot you have beside the metal x bow ,with the scope mounted?

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  8. very nice design on the impossible slingshot

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  9. I liked the ballistics gel video. Now we know the best ammo! XD

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  10. Sorry, Jörg, I must have played that video pack 5 times and never spotted the numbers in big bold type!

    BTW, for 25mm steel, I calculate 80J.

    If you still have the gelatin block of truth, I would try reshooting the 8mm and 38mm balls; I consider them to be outliers. They lie far below the Penetration/Diameter vs Velocity regression line. My model predicts penetration of 28cm and 32cm respectively.

    Anticipating your blog readers will suggest that it is the model is incorrect and that the relationship should be fit to a curve, generally accepted terminal ballistics theory says that this should be a straight line and all the other points lie close to a straight line.

    I will work up my analysis of your video into a blog entry that will be published later in the week.

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  11. Zombie Rooftop Slingshot Vs Ballistics Gelatine?

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  12. ^^^
    ballistic gelatine imitates the characteristics of flesh. And he has already tried that

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  13. LOL, Andreas! Well said and all too true! Hopefully he won't do that again anytime soon. :)
    Those were some of the best looking sling-shots I've ever seen.

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  14. alirafy, don't forget that we are no pussies here at The Slingshot Channel :)

    Dan, it may well be that the 38 mm and the 8 mm were outliers. I still have the block, it is on my compost heap. I have no idea if it has deterriorated too much already for another try (it is fairly cold, so chances are it is still OK), so I will check this weekend.

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  15. My small sling-shots have an approximate, tested range of 250 yards if fired for maximum distance. Since I have a smaller back yard than you do, I use a hanging blanket for a back stop for safety's sake in back of my catch box. Since 'Myth Busters' just misfired a cannon ball into a neighborhood causing rather serious damage ( http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2011/12/06/BA1D1M99V5.DTL ), I wondered how you deal with major misses. I do realize you are very safety concious and accurate but I wonder how much space and protection there is for the neighbors.(especially for the bigger,more powerful ammo)

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  16. Jörg, I am no longer entirely convinced that they are outliers, but if you have the opportunity, there are a few data points I'd like to check:

    > Any different combinations of velocity and ball size, so that I can test my new model with out of sample data.

    > An estimation of the velocity that the projectiles travelled before impact in the Schweinebacke video.

    Jörg, in case you're wondering why I am flip-flopping about whether the datapoints are outliers, you may wish to refer to my blog entry on number crunching your video:

    http://slingshotforum.com/blog/11/entry-416-terminal-ballistics-a-model-to-predict-penetration-depth/

    One particular chart is quite telling. You may use it in your blog/forum if you wish:

    http://www.l2i.org/slingshot/Sub_03/TBallisticsGBOTRegress3.jpg

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  17. @Lord Robere - He has a cat that stands behind the backstop and swats balls away with his paws.

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  18. LOL, I would easily believe that as frequently as Joerg has stated,'We are no pussys here at the Slingshot Channel.' Those have to be some tough cats! :)

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  19. Dan, great Blog entry.

    From my experience and gut feelings, I don't think that the questionable results are outliers. I have shot so many different rounds from different slingshots that I pretty much know my outliers BEFORE they hit their target.

    What needs to be figured out is the pressure per square millimeter of the half spheres. I guess that this pressure probably peaks for the 20 mm ammo.

    I think the smaller ammo does not have enough momentum to penetrate any deeper, and the big balls simply have too much surface for their speed.

    In terms of shattering harder objects such as bricks, PC monitors and junk, the 38 mm ammo does one heck of a job. Just devastating.

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  20. I'd recommend shooting some exploding targets in a future episode. Perhaps a few two liter soda bottles pressurized to 100 psi?

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