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General >> General Slinging Discussion >> Sling Speed????????????????????
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Message started by Gan Banor on Jul 6th, 2008 at 4:48pm

Title: Sling Speed????????????????????
Post by Gan Banor on Jul 6th, 2008 at 4:48pm
I found an interesting fact..... no one has yet measured the speed on an object thrown from a sling and therefor how effective it is. we know that it can kill but how deadly it is over distance and on someone like Goliath. Do you need a head shot to have a fatal wound or will one to the chest kill or to the arm break a bone...... all in my opinion vital facts to understand how a sling preforms in an engament.

I agree they were a common force in armies but was this due to its scattering effect and relitive cheapness to arm herders who were a fair shot with one


Any comments on how to establish this will be welcome and hopefully someday we can find out these facts

Title: Re: Sling Speed????????????????????
Post by dork on Jul 6th, 2008 at 5:54pm
This topic has come up so many times it isn't funny. If you loook through some old posts I'm sure you could find some info.

Title: Re: Sling Speed????????????????????
Post by wanderer on Jul 6th, 2008 at 5:57pm

Gan Banor wrote on Jul 6th, 2008 at 4:48pm:
I found an interesting fact..... no one has yet measured the speed on an object thrown from a sling and therefor how effective it is. we know that it can kill but how deadly it is over distance and on someone like Goliath. Do you need a head shot to have a fatal wound or will one to the chest kill or to the arm break a bone...... all in my opinion vital facts to understand how a sling preforms in an engament.

I agree they were a common force in armies but was this due to its scattering effect and relitive cheapness to arm herders who were a fair shot with one


Any comments on how to establish this will be welcome and hopefully someday we can find out these facts


No idea where you found your interesting fact ;). Do a search on 'speed'. What we don't really have any idea of is how much better ancient slingers might have been than the best of current times.

http://slinging.org/forum/YaBB.pl?num=1067904262/0
http://slinging.org/forum/YaBB.pl?num=1195572094/0
http://slinging.org/forum/YaBB.pl?num=1129613270/0
http://slinging.org/forum/YaBB.pl?num=1162715332/0

Those of us who are interested have several times posted methods to measure speed, and have measured our own. The main trouble is that the fact that I can sling at a particular speed is of very little interest to you, particularly since I might not be a particularly strong slinger. Most slingers here are not that interested in measuring such things.

It is possible to make estimates from sling distances also, and I think these all lead to similar figures, of somewhere around 50m/s upwards for those of us who have used the sling for a reasonable time.

Matthias posted his ideas of general sling speeds among contemporary slingers, the figures are in the threads above. I agree with his figures.

I realise there is a lot of information around here, and it is not arranged in to some 'convenient' digest - but we kind of expect people to spend some time looking :).

Title: Re: Sling Speed????????????????????
Post by dork on Jul 6th, 2008 at 6:09pm
Damn wanderer you do have good computer speed. I suck at finding and organizing threads.

Title: Re: Sling Speed????????????????????
Post by wanderer on Jul 6th, 2008 at 7:09pm

dork wrote on Jul 6th, 2008 at 6:09pm:
Damn wanderer you do have good computer speed. I suck at finding and organizing threads.

Well, I just got there first ;) - and I bet I missed lots ;D

Title: Re: Sling Speed????????????????????
Post by curious_aardvark on Jul 7th, 2008 at 7:12am
Also check out the balearic-sling initiated david and goliath thread over on the project goliath section.

Balearic-slinger is a balearic slinging champion who took part in a recent discovery channel program where they measured his slinging and also the force of impact it had on a goliath head shaped target.
http://slinging.org/forum/YaBB.pl?num=1208522774
We're all waiting for the program to air to see just how much info they'll be broadcasting.

But, it's definitely been measured. ALso look up some of aussieslingers posts on measuring projectile speed using a simple stopwatch and sound recording program.
:-)

There is an outside chance that you might alight on a slinging related subject that has not been so far discussed in the 5 years the forum has been running - but it's unlikely :-)

Title: Re: Sling Speed????????????????????
Post by wanderer on Jul 7th, 2008 at 7:51am
Just as an addendum to this.

The published velocities, in Thom Richardson's article and in Korfmann's Sci Am article are most certainly hopelessly under the real values. In the first case the problems probably came about because it's not easy to sling full speed through a tight space as needed for a chronograph.

Always worth remembering that 90mph = 40m/s is a decent bare-handed 'throw' in baseball pitching or cricket bowling.

I'd second C_A's pointer to Balearic Slinger. He is part of a tradition dating back at least to Roman times. Have a look at him, and ask yourself whether a 200g stone hurled by him needs to hit you in the head to hurt you really bad ;)

Title: Re: Sling Speed????????????????????
Post by aussieslinger on Jul 7th, 2008 at 9:16am
One of our long time members, TechStuf, has made a demonstrational video of himself slinging at a plywood cutout of a Goliath figure. You will be able to see the stones deeply imbedded into the 3/4" thick timber. Of course not all of us are as strong or comptent as TechStuf but this video proves beyond all doubt that in the hands of a good exponent the sling is potentially lethal with shots that hit the body as well as the head.

As I recall using the sound track to measure the elapsed time the stone speed was around 135 fps.


http://video.google.com/videoplay?docid=5648598808576881556&hl=en

Title: Re: Sling Speed????????????????????
Post by HurlinThom on Jul 7th, 2008 at 1:09pm
If a radar gun can pick up a thrown baseball, couldn't one also pick up a slingstone of moderate size? Accuracy wouldn't be as great as with a chronograph, but should be sufficient. Heck, you could just sling a baseball, though those may be a tad heavy (5+ ounces). Maybe a handball or racquetball?  

Title: Re: Sling Speed????????????????????
Post by Thomas on Jul 7th, 2008 at 6:43pm
Bear with me because I have illuminated this before. So far the only sling speed testing Iíve done was in the early 1990ís using a standard baseball. The radar measurements were done in a large indoor area by a professional who stood behind a hanging net about 10m away. My sling was about 1.3m long folded and of standard 3mm braided nylon. The pouch was integral with the sling cords (split), similar to a ladder pouch but the lateral connectors did not form coils. My best time was 128mph (about 57m/s). It takes at least 49m/s to drive a baseball to 122m (400ft).    

I imagine the experienced slingers we have can easily beat this speed using ordinary stones which are more massive and have less air resistance.

Title: Re: Sling Speed????????????????????
Post by Gan Banor on Jul 8th, 2008 at 5:05am
hmmmmm thats very true.

Thanks for the comments on this.
Why i posted this was that i found a site with balistics of bows etc but no sling and i searched the internet for it. i couldnt find any data recorded that related

Title: Re: Sling Speed????????????????????
Post by curious_aardvark on Jul 8th, 2008 at 5:33am
lmao - well bear in mind the greatest repository for information on slings is here at slinging.org.

Whether or not it's anywhere else on the internet, the odds are good it's round here somewhere :-)

Title: Re: Sling Speed????????????????????
Post by wanderer on Jul 8th, 2008 at 8:49am

Gan Banor wrote on Jul 8th, 2008 at 5:05am:
hmmmmm thats very true.

Thanks for the comments on this.
Why i posted this was that i found a site with balistics of bows etc but no sling and i searched the internet for it. i couldnt find any data recorded that related

I think the specific ballistics of slings is much harder than for bows and arrows. It depends what kind of questions you want to answer, and in what kind of detail. There are a few of us who think about this, but it rapidly becomes far more complex than most people want to know about, particularly since it involves math.

The sling has received nothing like the attention which the bow has, so it's hardly surprising you can't find anything much. You can find discussions on a number of these matters (look up dangerous words like 'physics' ;) ) on the threads, but these are mostly quite old. Actually they often give you an idea of how much people on this forum were rediscovering the possibilities, which is interesting of itself.

The kind of thing you are looking for may eventually appear in the WIKI, but don't hold your breath ;D.


Thomas,
I just didn't pick up your thread on speed measurement in my quick 'grab' of threads - I hadn't forgotten ;)

Title: Re: Sling Speed????????????????????
Post by IronGoober on Jul 9th, 2008 at 9:39am
Well, if you know the distance of the projectile and the angle at which it was released you can calculate the speed.

The formula is
Velocity=sqrt(a*d/(2*cosx*sinx))   x is the angle of release, a is the gravitational constant (9.8 m/s^2), d is the distance

This is assuming that there is no air resistance

I was messing around with some distances from the "Sling Ranges" page on this site and calculated Mr. Engvall's throw to be around 73 m/s, assuming a 30 degree release angle.  This means it had an energy of about 167 Joules, which is about a quarter of a .45 colt(~630 joules).

But looking at Mr. Gaylor's throw, which was a much heavier object, the energy of it comes out to be 364 joules (assuming a 45degree angle, the energy is even greater if the angle was less!). According to a few websites I checked, this is more energy than a .38 special round!!!(~200 joules).  Now that packs some punch!

Title: Re: Sling Speed????????????????????
Post by wanderer on Jul 9th, 2008 at 11:37am
The achievements of the long distance slingers are all the more impressive when the effects of air resistance are taken into account. This post is, I think, the earliest to deal with this matter.

http://slinging.org/forum/YaBB.pl?num=1091676756/6#6

The post also gives a very good idea of the uncertainties in the calculations. It's difficult to say with any certainty, but I think Larry Bray probably exceeded Engvall's 'muzzle velocity' by a significant amount in making his throw. Whatever the effective drag coefficient for his stone, it was likely rather higher than Engvall's dart.

Title: Re: Sling Speed????????????????????
Post by HurlinThom on Jul 9th, 2008 at 7:46pm
[quote author=IronGoober link=1215377301/0#13 date=1215610770]
This is assuming that there is no air resistance

I'd be willing to bet that very little slinging takes place where there is no air resistance. Sorry if I sound nit-picky, but I'm hyper-aware of what effect air resistance can have on a hurled object. Said objects can lose so much forward velocity that they seem to fall straight down. (They don't, but it seems that way.) Ruins that nice parabolic path.

Title: Re: Sling Speed????????????????????
Post by Thomas on Jul 10th, 2008 at 12:40am
I used the Audacity program to speed check the following film clip of Yurek hitting a tire. An allowance was made for the speed of sound at the slinging distance of 20m. The camera to slinger distance was not used for the sound adjustment. This sound recording was complicated with all the various events, but the key peaks are discernible.

The adjusted interval is .336 sec. and average speed over 20m is 59.5m/s. (133mph).
Compare this to Yurekís film analysis on his post #6.

http://www.kajakowe.com.pl/sling/hit1.avi

http://slinging.org/forum/YaBB.pl?num=1124289190/0#0


tom    

Title: Re: Sling Speed????????????????????
Post by Aussie on Apr 15th, 2009 at 6:09pm
Working my way through removing that blasted spam but at least it's brought this thread to the top. In light of some of the speed questions of late, very timely ;D

Click on the link in the previous post and see one of the best of our slingers getting a genuine 60 m/s, and that is average over the distance, release velocity would be considerably higher.

Title: Re: Sling Speed????????????????????
Post by Thearos on Apr 20th, 2009 at 7:25pm
On sound measurement: I've seen some vids on YouTube-- but wouldn't the 'crack' of the sling tassel come after the stone has already left the pouch ?

What's the muzzle velocity of a black powder rifle ? I ask this, because of T. Rihll's claim that slung lead really can't go fast enough to penetrate human skin-- and hence that lead bullets in ancient med. literature isn't from hand slings, but small catapults. Can slung lead go as fast and hard as a bullet fired from e.g. an arquebus or a wheellock pistol or a flintlock /fusil/ or musket ?

On a completely different matter, a friend has just returned from her Easter vacation on Ibiza-- and I just heard that she's bringing me a woven esparto grass sling that she bought (+video on the making of it). I hope it's not a tourist knock off, but a working balearic sling. Will report on Wed. !



Title: Re: Sling Speed????????????????????
Post by wanderer on Apr 20th, 2009 at 8:19pm

Thearos wrote on Apr 20th, 2009 at 7:25pm:
On sound measurement: I've seen some vids on YouTube-- but wouldn't the 'crack' of the sling tassel come after the stone has already left the pouch ?

What's the muzzle velocity of a black powder rifle ? I ask this, because of T. Rihll's claim that slung lead really can't go fast enough to penetrate human skin-- and hence that lead bullets in ancient med. literature isn't from hand slings, but small catapults. Can slung lead go as fast and hard as a bullet fired from e.g. an arquebus or a wheellock pistol or a flintlock /fusil/ or musket ?

On a completely different matter, a friend has just returned from her Easter vacation on Ibiza-- and I just heard that she's bringing me a woven esparto grass sling that she bought (+video on the making of it). I hope it's not a tourist knock off, but a working balearic sling. Will report on Wed. !

A quick look around the internet seems to suggest muzzle velocities of the order of 800fps upwards for these firearms. I would not be at all surprised that these greatly exceed the velocities for the sling.

I'm currently reading Rihil's book, and her selectivity with respect to her sources strikes me as a little troubling. To quote her book (p100):
"To penetrate human skin, a blunt projectile must hit at 49 metres per second or more (111mph, or 163fps). To break bone it must hit at 65m/s or more (145mph,213fps)."  I think these numbers are probably about right, although lead glandes are decidedly 'pointy'!

On the next page she writes
"..a good slinger can consistently reach a velocity of 30-31m/s (about 68mph or 100fps), with best performance of 32m/s, and worst of 29m/s."

This is quite ludicrous, despite being in the academic literature. Such velocities are entirely inconsistent with observed ranges (ancient and modern!). I would guess many of the experienced slingers here exceed 50m/s without recourse to ultra-long slings etc. She does reference this web site, but somewhat selectively.

She asserts that Baatz's work must refer to catapults rather than hand slings simply because his figures are significantly higher than the 30m/s or so. Note that such velocities imply a maximum projectile range of less than 100m. This is not rocket science, it's basic physics.

I agree with you about the crack of the sling. This does occur significantly after the departure of the sling from the pocket. The projectile can be of the order of 1m downrange at the time of the whip crack.

Perhaps it is about time to get some realistic measurements from hand slinging into the 'respectable' academic literature before this gets too silly. Any suggestions about how to go about doing this?!

Enjoy your new sling!

Title: Re: Sling Speed????????????????????
Post by Thearos on Apr 20th, 2009 at 8:34pm
Yes, you're right about the surprising "pointiness" of lead bullets (which I posted about in the Goliath forum)-- so that the figures about blunt penetration are not relevant-- we must be dealing with lower penetration thresholds !

If you want to get the figure into academic literature: you have to write a short note, with good evidence (not YouTube measurements, etc), but real measured experimental evidence, and clear argument-- and send it off to a refereed ancient history journal. The piece will be sent anonymously to two specialists (military historians of the ancient world), who read it and make a recommendation.

The catch here is real experimental (not "speed gun by the side of the road") + referenced (not "I read somewhere on the internet") evidence-- not because of academic snootiness, but just so that the results are checkable...

For what it's worth.

Title: Re: Sling Speed????????????????????
Post by Thearos on Apr 20th, 2009 at 8:35pm
PS If you post it here, I'll read it first.

Title: Re: Sling Speed????????????????????
Post by Thearos on Apr 21st, 2009 at 8:46am
One possible outlet would be the Journal of Roman Military Equipment Studies (they had a good piece on sling bullets from Frisia a while back, and are very receptive to experimental archaeology)-- but I have no idea if they're still going.

Ancient History Bulletin might be a good bet. Military History Quarterly ?


Title: Re: Sling Speed????????????????????
Post by Thearos on Apr 21st, 2009 at 9:01am
Aussie: I mean no offence by what I wrote, and take none at what you wrote. But whoever Wanderer is, he asked a question; as one who has sat on the readers committee for several peer reviewed Classics and ancient history journals, and as one who's had peer reviewed papers accepted, and rejected, I thought I had the expertise to offer a reaction.



Title: Re: Sling Speed????????????????????
Post by wanderer on Apr 21st, 2009 at 2:58pm

Thearos wrote on Apr 21st, 2009 at 9:01am:
Aussie: I mean no offence by what I wrote, and take none at what you wrote. But whoever Wanderer is, he asked a question; as one who has sat on the readers committee for several peer reviewed Classics and ancient history journals, and as one who's had peer reviewed papers accepted, and rejected, I thought I had the expertise to offer a reaction.


Thearos, no problem. I did ask! I'm quite familiar with academic practise. There also seems to be a journal which had 'scientific archaeology' in the title - the work of Brown-Vega which we discussed here a few weeks ago was published there.

At any rate, it seems to me that a clear up of these figures is long overdue. I'll think about it - bearing in mind that I am well past my 'sell by' date I'm not convinced I'm a good experimental subject.

Title: Re: Sling Speed????????????????????
Post by Thearos on Apr 21st, 2009 at 5:24pm
Wanderer: I guess I can hear a dry chuckle, and I deserve it. But my suggestion still holds: organize a real bit of  experimental archaeo, and publish it in a journal. Journal of Roman Military Equipment Studies had plenty of those in the day (e.g. guys timing how long it took to make a Dacian-war scythe, then photographing the impac of the war-scythe on reconstructed Roman armour, etc).

What's the guy's name, who does a lot of Roman experimental archaeology ? Not Baatz-- Marcus junkermann, who reconstructed a Roman cav unit. It might interest him.



Title: Re: Sling Speed????????????????????
Post by Thearos on Apr 22nd, 2009 at 4:14am
http://junkelmann.de/

Title: Re: Sling Speed????????????????????
Post by wanderer on Apr 22nd, 2009 at 8:08am

Thearos wrote on Apr 22nd, 2009 at 4:14am:
http://junkelmann.de/

Thearos,
Thanks for the suggestions and the above link. I will have to spare some time to trawl a little in the current archaeology literature and get a sense for the style. Rihil's book quotes a number of sources to which I have no access. and I would like to read them if possible also.

Title: Re: Sling Speed????????????????????
Post by Fx 2000 on Apr 23rd, 2009 at 8:41am
Hallo,

I use the videocam with 25pics/sec, so each picture is 0,04sec. Today I sling a stone 225gramm, 10,5m ins 6 pictures (0,24s).

10,5m/0,24s = 43,7m/s †

E= 0,5 x m x V x V
E= 0,5 x 0,225kg x 43,7m/s x 43,7m/s = 215 Joule ore 161ftlbs

It is not so exact, but the rate of mistake is less 5%

Greetings Michel

Title: Re: Sling Speed????????????????????
Post by Thomas on Apr 23rd, 2009 at 10:51am

Quote:
Fx 2000

     
Re: Weavers figure 8 videos
Reply #4 - Today at 9:06am Quote
A littel tipp for people like me, who have there problems with a right figure 8. When I tested it, I ever loos my tennisball. So I take a 3 feet long naylon rope, at the end I make a ball build of two old socks, tough guys can use a tennisball Grin Grin Grin. With this constuction I learn it verry fast.

Greetings Michel


Fx 2000

With 225 gr. you are with out doubt a tough guy! I donít own a video cam. How do you determine the frame count?

tom † † † † † † † † †

Title: Re: Sling Speed????????????????????
Post by Rockman on Apr 23rd, 2009 at 2:21pm
Hey Thomas, you can always use a sound recorder, since itīs the snap and the hit that counts.
I have easily calculated speed with audacity.

Title: Re: Sling Speed????????????????????
Post by Fx 2000 on 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 ;)

Title: Re: Sling Speed????????????????????
Post by Thomas on 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 donít 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. Iím 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 donít 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 †

Title: Re: Sling Speed????????????????????
Post by Fx 2000 on 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

Title: Re: Sling Speed????????????????????
Post by Thomas on Apr 24th, 2009 at 6:49pm
Fx 2000

Thanks for the reply about the frame count.

tom †

Title: Re: Sling Speed????????????????????
Post by jlasud 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.

Title: Re: Sling Speed????????????????????
Post by jax on 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 ;D).

Title: Re: Sling Speed????????????????????
Post by mrboss on 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. ::)

Title: Re: Sling Speed????????????????????
Post by Aussie on 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

Title: Re: Sling Speed????????????????????
Post by wanderer on Feb 5th, 2010 at 7:38am
Hmm.. well, I think we got there first ;) 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 ;D

Title: Re: Sling Speed????????????????????
Post by IronGoober on 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.

Title: Re: Sling Speed????????????????????
Post by Aussie on 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.

Title: Re: Sling Speed????????????????????
Post by Thearos on Feb 9th, 2010 at 8:57am
I'd like to see if they can sling a lead bullet into something simulating a human body...

Title: Re: Sling Speed????????????????????
Post by Masiakasaurus on Feb 9th, 2010 at 9:04am
They'd like to see a TNT bullet go through a ring of fire. ::) I love mythbusters, but how many myths don't go "boom" at the end?

Title: Re: Sling Speed????????????????????
Post by Thearos on Feb 9th, 2010 at 10:59am
Heck, somebody write to them

Title: Re: Sling Speed????????????????????
Post by Et Cetera on Feb 9th, 2010 at 4:01pm
Lets all write to them! The more the merrier.

Title: Re: Sling Speed????????????????????
Post by Aussie on Feb 9th, 2010 at 10:29pm
My initial reaction was to suggest, "Nah, they wouldn't be interested." But then perhaps they would! However they like to "Bust Myths" ie. investigate some controversy or other. What better controversy than whether a slinger could in fact take out a skilled warrior with a shot to the head? In other words a dispassionate secular look at the DvG controversy. That subject often gets people hot under the collar even on this site where we generally know about a sling's capabilities. It's been done before but usually by religiously motivated groups who like to put their own spin on it which may not be generally acceptable.

Title: Re: Sling Speed????????????????????
Post by Et Cetera on Feb 10th, 2010 at 7:32am
Also do they televise everything they do? It'd be interesting even if they didn't televise it but still tried it, and shared the results.

Title: Re: Sling Speed????????????????????
Post by MitchInTheGlatrix on Aug 5th, 2020 at 9:37pm
Playing cards are moving well, maybe it's time to dust off the slinging gear...
Card_Speed_Test__forum.jpg (98 KB | 67 )

Title: Re: Sling Speed????????????????????
Post by IronGoober on Aug 5th, 2020 at 11:43pm
Holy moly! This is the first thread I ever posted to!

Mitch, what are the units on that thing? is that 20.4 or 204?

If you do get some confirmed speeds, please post them in the "Chronographs" thread in "Here be Maths" as well. It would be much appreciated since we are trying to track them there.

Title: Re: Sling Speed????????????????????
Post by MitchInTheGlatrix on Aug 6th, 2020 at 4:32am
204fps (139mph). Sling speeds can get considerably more 'out of hand'.

Title: Re: Sling Speed????????????????????
Post by NooneOfConsequence on Aug 6th, 2020 at 1:54pm
Is that tracking the leading edge of a rotating playing card? 

Title: Re: Sling Speed????????????????????
Post by MitchInTheGlatrix on Aug 6th, 2020 at 2:24pm
It works via light sensors exactly one foot apart. You get a LOT of errors unless the card passes level over the sensors.† It actually works best when just the advancing or retreating edges catch the sensors.† High speed video from a cell phone camera can also be used to verify speeds.

Should try it, it's a real hoot.† It's a fun but laborious way to chop vegetables for the stew pot. lol


Title: Re: Sling Speed????????????????????
Post by Mersa on Aug 6th, 2020 at 9:37pm
Love to see your numbers with the sling

Title: Re: Sling Speed????????????????????
Post by IronGoober on Oct 1st, 2020 at 1:44am

MitchInTheGlatrix wrote on Aug 6th, 2020 at 2:24pm:
It works via light sensors exactly one foot apart. You get a LOT of errors unless the card passes level over the sensors.† It actually works best when just the advancing or retreating edges catch the sensors.† High speed video from a cell phone camera can also be used to verify speeds.

Should try it, it's a real hoot.† It's a fun but laborious way to chop vegetables for the stew pot. lol

Is that a thrown speed? How are you getting a card to 139mph?

Title: Re: Sling Speed????????????????????
Post by NooneOfConsequence on Oct 2nd, 2020 at 8:22am
If you think about how a playing card moves in the direction of a throw, one edge of the card is moving faster than the other because of the rotation. I expect you would see a lot of variation in speed measurements with a break-beam system because of this. 139mph is not the average speed of the center of mass on the playing card. Itís a combination of the card speed and the linear speed of the rotating edge of the card.

Title: Re: Sling Speed????????????????????
Post by IronGoober on Oct 2nd, 2020 at 11:55am
The card would have to be as big as the distance between the sensors for that to be picked up.  Since it uses sensor separated much by several card lengths, any spin would be averaged out to some degree. If it were a radar gun and just picking up all of the doppler shifts that occur from reflected waves, then maybe it would see the spinning as increased (and decrease) velocity, though I doubt the cross-section is big enough for the card edges for this to happen.

Title: Re: Sling Speed????????????????????
Post by NooneOfConsequence on Oct 2nd, 2020 at 12:08pm
Not quite.    A chrony works on the assumption that the shape and geometry of the thing it is measuring don't change, and that's not true with a playing card.  Try throwing a circular playing card and see if that gives the same speed reading.

Title: Re: Sling Speed????????????????????
Post by IronGoober on Oct 2nd, 2020 at 1:51pm
I believe your reasoning is incorrect, but without a chronometer to test, I can't know for sure. If I had a chronometer, I'd certainly run this test to make sure I understood its limitations.

Title: Re: Sling Speed????????????????????
Post by Sarosh on Oct 2nd, 2020 at 2:50pm
the card length difference length-width is 2.5cm if the sensor gap is 30cm then the error will be +/-8.3%

the card was going super fast for a card or the error was bigger . those sensors seem to get a lot of errors but if there were many such readings then yes it was super fast

Title: Re: Sling Speed????????????????????
Post by IronGoober on Oct 2nd, 2020 at 3:13pm
Sarosh, that was the exact analysis I just did and was about to post, I got ~4% for a 24" sensor distance(~61cm).  I agree that the card speed is extremely fast for a throw, from what I've seen elsewhere, around 60mph is the "world record".

Title: Re: Sling Speed????????????????????
Post by Albion Slinger on Oct 30th, 2020 at 2:11pm
Short clip of a stone flying towards the camera.
I used my 18" Lahun-style sling
I calculated the average velocity over 40m to be ~50m/s.
https://www.youtube.com/watch?v=becjp8sMm_M&feature=youtu.be

Title: Re: Sling Speed????????????????????
Post by IronGoober on Oct 30th, 2020 at 11:01pm

Archaic Arms wrote on Oct 30th, 2020 at 2:11pm:
Short clip of a stone flying towards the camera.
I used my 18" Lahun-style sling
I calculated the average velocity over 40m to be ~50m/s.
https://www.youtube.com/watch?v=becjp8sMm_M&feature=youtu.be


Daaang!  What was the approximate weight of your ammo?

Title: Re: Sling Speed????????????????????
Post by Albion Slinger on Oct 30th, 2020 at 11:23pm

IronGoober wrote on Oct 30th, 2020 at 11:01pm:
What was the approximate weight of your ammo?

I don't know exactly, but I remember it was vaguely similar in size and shape to a 120g stone I picked up at the same time. Not more than 150g.

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