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Sling Speed???????????????????? (Read 37403 times)
Rockman
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Re: Sling Speed????????????????????
Reply #30 - Apr 23rd, 2009 at 2:21pm
 
Hey Thomas, you can always use a sound recorder, since it´s the snap and the hit that counts.
I have easily calculated speed with audacity.
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Re: Sling Speed????????????????????
Reply #31 - Apr 23rd, 2009 at 3:12pm
 
Hallo Tom,

normaly you can find the frame count in the instruction manual. When you have a better programm for cutting videos, the frame count is shown.

Greetings Michel

Ps: Tough enough Wink
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Thomas
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Re: Sling Speed????????????????????
Reply #32 - Apr 24th, 2009 at 5:53pm
 
Rockman

See post #16 for one of the Audacity tests. I have been using this program since Aussie suggested it last year and it has good resolution for even some you tube takes. Judgment is needed for measuring sling speed without some form of audible noise maker attached to the sling. I don’t mean the release cord snapping that some people think is entertaining. I use those novelty poppers that have a short length of string attached to each end. When the pouch tips up those things give a sharp report. The tiny Sansa recorder is placed midway between the two events. So far my results have been uninspiring in the limited space of my back yard. At the short and dangerous distance of 15ft. my baseball result was only about 85mph. At this speed the ball will only travel around 300ft. I’m currently launching them on a ball field as far as 450ft. in crummy conditions. This activity has to be continued at a near by safe location, against a solid backstop, weather permitting.


Fx 2000

I don’t mean the frame rate. How do you arrive at the number of frames between release and impact? Does the software allow you to view one frame at a time or do you select the start and finish frames and the program tallies them up?

tom  
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Re: Sling Speed????????????????????
Reply #33 - Apr 24th, 2009 at 6:16pm
 
Hallo Thomas,

sorry for the mistake. Yes my software allow me to show me each frame after the other. I`m sticking colouerd staffs in the ground, each 50cm, red and green alternately, so it`s easily to see the range.

Greetings Michel
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Re: Sling Speed????????????????????
Reply #34 - Apr 24th, 2009 at 6:49pm
 
Fx 2000

Thanks for the reply about the frame count.

tom  
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jlasud
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Re: Sling Speed????????????????????
Reply #35 - Oct 26th, 2009 at 11:29am
 
I've done some shooting at 30 m(measured) and filmed them. I watched the vid in windows movie maker because it has milisecond counter and counted the time.I get a 60 m\s with an 85g stone resulting in 153 J kinetic energy and a lead gland of 57g at 65m\s resulting in 120j.The lead gland was shot with a long sling and i couldn't put all my energy in it..i'm not used to that sling. I say for ancient slingers 70-80m\s with lead was normal..I'm sure that i ccould get 75 m\s sec with a lead gland if i train a little bit.I must mention that my measurements of time aren't precise..i don't have the professional equipment to do it so i say a 5% difference could easily be ..10% the most.We should send the Mythbusters some homework! they have the equipment and everything necesary to reveal some facts.Maybe they could bring  that balearic champion slinger and make some measuring tests.Someone should write a letter in the name of this site asking them to make an episode of testing a myth saying for example:A sling bullet as powerfull as a 9mm pistol round..or something like this.
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Burner
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Re: Sling Speed????????????????????
Reply #36 - Oct 26th, 2009 at 11:34am
 
Mr.Boss,your moment has arrived!He's been saying this for ages,and although he does generate some incredible velocity from his pirouette cast with the 6' sling,we've yet to see him hit anything(except the broad side of a barn Grin).
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Re: Sling Speed????????????????????
Reply #37 - Oct 26th, 2009 at 12:56pm
 
jlasud wrote on Oct 26th, 2009 at 11:29am:
I've done some shooting at 30 m(measured) and filmed them. I watched the vid in windows movie maker because it has milisecond counter and counted the time.I get a 60 m\s with an 85g stone resulting in 153 J kinetic energy and a lead gland of 57g at 65m\s resulting in 120j.The lead gland was shot with a long sling and i couldn't put all my energy in it..i'm not used to that sling. I say for ancient slingers 70-80m\s with lead was normal..I'm sure that i ccould get 75 m\s sec with a lead gland if i train a little bit.I must mention that my measurements of time aren't precise..i don't have the professional equipment to do it so i say a 5% difference could easily be ..10% the most.We should send the Mythbusters some homework! they have the equipment and everything necesary to reveal some facts.Maybe they could bring  that balearic champion slinger and make some measuring tests.Someone should write a letter in the name of this site asking them to make an episode of testing a myth saying for example:A sling bullet as powerfull as a 9mm pistol round..or something like this.


Yes somone should send mythbusters some info. Plus mythbusters would need the best slinger for the job... Im not saying its me but still. Roll Eyes
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Re: Sling Speed????????????????????
Reply #38 - Jan 31st, 2010 at 6:49pm
 
Found a YouTube clip of someone using the Audacity sound recording method to measure the speed of a slingshot.

The film clip maker uses a "double screen" method with a distance of only 2 metres between them and shoots so the projectile passes through both targets. For an actual sling I think the double screen method is too complicated as it requires quite accurate shooting to hit both screens. I found it much easier to just shoot at my garage wall from a distance of 8 metres and simply record the swishing sound of the release and the whack of the ball hitting the garage wall. I would suggest a minimum of 5 metres from firing line to target as the ball may have already moved some distance towards the target when the "swish" of the release occurs, so too short a distance may introduce an error.

He also places the recording microphone midway between the slingshot and the target. For slinging you may want to move the microphone/laptop further back if there is any risk of it being damaged. Even if it is not equidistant from both the error will be very small.

So the way you record, the distance and times you get will vary from those on the video but the actual data analysis method is the same and clearly explained.

BTW I have also used the same single target method to measure blowgun speed with very satisfactory results. It would probably even work for airguns if set up carefully.

(Ironically for a method involving sound I suggest watching the clip with the sound off as the background 'alleged music' is atrocious.)

http://www.youtube.com/watch?v=fjeQbDMzAak
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wanderer
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Re: Sling Speed????????????????????
Reply #39 - Feb 5th, 2010 at 7:38am
 
Hmm.. well, I think we got there first Wink I mentioned the 'two pieces of paper' here and Aussie found Audacity some years ago. I still think the two bits of paper are worth it on principle(!)

With two bits of paper and the microphone between them the traces of the two impacts should look very similar except that one is the negative of the other - you can see that on the video. The similarity of the shapes means that you can fit the two curves and thus get a more precise value for the time interval. However, the result seems more than good enough just picking a peak, and I agree that it's much easier to just time with picking the sound of release and striking of a target.

- I couldn't hear the sound track - no sound on my work computer Grin
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Re: Sling Speed????????????????????
Reply #40 - Feb 8th, 2010 at 1:00am
 
Back to the Mythbusters thing. I've read from a few sources on the net, that the maximum range of a sling (quoted by some authors) is around 500m. I would really, really like to see that. And this is apparently with normal ammunition, not a dart like Mr. Engvall had.  But, I agree, a Mythbusters sling episode would be very welcome, as I like slings and I like Mythbusters.
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Re: Sling Speed????????????????????
Reply #41 - Feb 8th, 2010 at 11:47pm
 
Could be very good, but also could be very bad. If they went to the trouble of finding David Engvall, Larry Bray or Yurek, preferrably all three, it could be fantastic. Mythbusters is an extremely popular show and the budgets they have are phenomenal so if they wanted to, they could do it wonderfully well. However just about everything on the show is done with an eye to TV ratings, ie. if it blows up or smashes they love it; rigorous scientific testing ain't really what they're about. Throwing stones a long way with a sling probably won't be spectacular enough for them.
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Thearos
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Re: Sling Speed????????????????????
Reply #42 - Feb 9th, 2010 at 8:57am
 
I'd like to see if they can sling a lead bullet into something simulating a human body...
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Re: Sling Speed????????????????????
Reply #43 - Feb 9th, 2010 at 9:04am
 
They'd like to see a TNT bullet go through a ring of fire. Roll Eyes I love mythbusters, but how many myths don't go "boom" at the end?
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Pikåru wrote on Nov 19th, 2013 at 6:59pm:
Massi - WTF? It's called a sling. You use it to throw rocks farther and faster than you could otherwise. That's all. 
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Thearos
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Re: Sling Speed????????????????????
Reply #44 - Feb 9th, 2010 at 10:59am
 
Heck, somebody write to them
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