Jump to content

Close
--Click to Remove Ads--




* * * * * 3 votes

Analysis of Shooting Form

Posted by ZDP-189, 24 November 2011 · 6,473 views


I have done some further analysis of Jörg's high speed video. It shows Tobias shooting full butterfly, a style which he mastered. I was impressed and intrigued by his form and chose to look at it in more detail.

Here he is at the start of the draw.

Posted Image

Here he is at the end of the draw.

Posted Image

When I over lay the two images together, you can see how little he moves over the course of the release.

Posted Image

I have also overlaid the position of the projectile on a frame by frame basis.

Some surprising phenomena can be seen. Please note I am not criticising; he shoots far better than I.

The frame is a hammer grip style with low tips. It appears to have a pivot, or at least it may pivot in the hand. The fork is a little cocked in the hand throughout the release; I believe it is straight with respect to his arm, but not with respect to the bands at full draw. As a result, the top band is a little less taught than the bottom band. Yet, the projectile is not pulled downwards towards the taughter band. It's path is not straight. There is a slight upward movement at the beginning and then it tracks straighter, eventually passing close to the top fork.

I can offer no explanation for the ball's surprising path.

Next, as pop shot already noted, the bands noticeably bow due to aerodynamic drag. I would say that there should be negligible difference between a wide bands and doubled narrower bands, but that's only a gut feel.
Posted Image

Jörg noted that the bands ripple at the end of the impulse.

Posted Image
In my own high speed video, I never see any ripples, because I flip the slingshot. I see the ball pass over the forks and the bands follow. I think ripples happen on non-flipped slingshots for the same reason and I can't see how either would affect the flight. Indeed, in the case of the flip, the bands cease to have any effect on the projectile path and that allows for just a little inconsistency on the wrist action. I'd conclude that there should be no difference whether the wrist is flipped as long as the action is correct for the design of the slingshot.




Great explained. Thanks. Only one thing: 30 cm band lenght looks too short for me for butterfly style. How exactly could I mesure the right lenght for full butterfly?

Great explained. Thanks. Only one thing: 30 cm band lenght looks too short for me for butterfly style. How exactly could I mesure the right lenght for full butterfly?


Scale the length proportionally. If you have a 150cm draw and you want a 400% elongation, then divide by five for 30cm. More than 400% is possible and bands get faster as you reach the limit. If in doubt, start a little long and tie shorter till you find the sweet spot.
Let's take a look at the various methods of aiming:
Posted Image
  • The solid black line and arrow marked (1) is the flight path of the projectile once stabilised.
  • Blue dashed line (2) is the line from the eye past the top fork tip
  • Red dashed line (3) is the line following and projecting from the top band
  • Green dashed line (4) is the line from pouch to the centre of the forks
  • Yellow dashed line (5) is the line from shoulder socket along arm and coincidentally the line perpendicular to the fork.
What we want to achieve is an aim point that produces a consistent elevation and traverse angle with respect to the aim path.

An obvious comment is that the grip of the pouch and fork should be changed to eliminate the pop-up of the projectile path then 1 lines up with 4, but as long as the flight path is consistent, then we need only worry about a consistent aimpoint offset.

(5) is never going to work; there are too many variables.

(2) and (4) come remarkably close to (1) in terms of elevation and (3) is perfectly in line with horizontal traversing and offers an intuitive shot. I use a combination of this (for traversing) and gap aiming based on the top tip.

I have seen Chinese gangsta shooters, who use very short tubes aim with the pouch under he eye and gap aiming relative to the top tip. That makes sense.

It would seem for butterfly that it would make sense to draw the arms level with the bands below the eye across the clavicles/ base of the throat and use an elevated peep sight above the top fork to aim. I am not sure about the safety of shooting a projectile across the throat when it will already have picked up substantial velocity by the time it passes your neck, especially if combined with a flip action, but I have never heard of a related injury.
Dan, thank you much for doing this!
i´m glad for all the analysis you have done with this video, very good!

Tobias

Dan, thank you much for doing this!i´m glad for all the analysis you have done with this video, very good!Tobias


Thank you Tobias. Thank you for your contribution to the sport via this video and your support of the analysis and observations.

I am also super grateful to Jörg for filming this and agreeing to let me write about it.

I am also thankful for Jörg's sending his readers here. I hope they can comment and contribute to the discussion as you did. Here is a reciprocal link to his blog:

http://slingshotchan...ds-science.html
thanks a lot again
I guess you would have to use single bands to allow the long stretch. I may try that sometime. You would lose draw weight but could gain on the time the projectile is under acceleration. It would take a lot of practice as the hand that draws back will be difficult to lock in the same place each time for accuracy!!
Very interesting, I really liked.
Thank you
I wonder what would happen to "Line 1" if the fork was square to the pouch, and the bands were drawn to exactly the same distance. I wonder if Line 1 and Line 4 would have been identical. If they were, that would be a good case for a swiveling fork.

I wonder what would happen to "Line 1" if the fork was square to the pouch, and the bands were drawn to exactly the same distance. I wonder if Line 1 and Line 4 would have been identical. If they were, that would be a good case for a swiveling fork.


I also wonder. I think the design and grip used here approximates to a swivel, although not effectively. I think that the strange track of the ball (line 1) is due to the pouch grip and release. I grip like this with my wrist cocked forward:

Posted Image

I'm not saying it's better, but we need to look for better ways to grip.
dan, you need to know that this is not my typical shooting style! i shot only like tihs because the camera can see the lines on the bands! i think i can hit noting with this style! was only for the Video. and a one off shot. i shot not sideway.

I was wondering why you did not already have the other video taken with the non-tapered bands, that's a good shot, you can see how straight the flight phat with this grip is.
my fistgrip are very good for very strong bands! Destin test this bands with the normal thumb index finger grip, he can´t draw it full.

the fork was not swiveling! it was a fix fork. wie have no rotating fork slingshot this Day.

the grip you test there is not good for bands up to 15kg draw weight in Butterfly.
maybe this work for weak bands.

Tobias

My Picture

user(s) viewing

members, guests, anonymous users

March 2017

S M T W T F S
   1234
567891011
12131415161718
192021222324 25
262728293031 

Search My Blog

--Click to Remove Ads--