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.

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  

Fx 2000

Thanks for the reply about the frame count.

tom  

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 ).

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

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.

I'd like to see if they can sling a lead bullet into something simulating a human body...

Heck, somebody write to them