In the clocked speeds thread Yurek analyzed one of his videos and got a figure of 167fps which is ~200km/h. It wasnt extremely precise but seems reasonable.

I think someone has tested with better high speed camera equipment but I dont remember the results.

Been raining here for the last few days so havent been able to go out slinging ;-(

I was reading on another website that slung stones can usually go about 90 mph, as fast as a major league baseball pitch. This is confusing though. I thought slung stones would go much faster than a thrown baseball because they are heavy enough to gain momentum, small and aerodynamic, and have the obvious (i don't like the word obvious  :-/ but) physical advantage. Any reasons for this?

Sorry I can't help you cratercaster.

I am wondering how would I measure the speed of my rock?

Quick answer: The folks that say a slung stone can go no faster than 60 miles/hour (or 90, or whatever) read that figure somewhere, and didn't think about it.

The sling has a significant mechanical advantage over a bare arm: if a baseball pitcher can zing one over the plate at 90, a slinger should be able to do better.  Much better.

This is borne out by Thomas, who has claimed over 500 feet distance slinging a baseball (farther than any recorded home run hit that I know of ... any baseball fanatics out there?  Give me some REAL figures).

I tend to believe a higher estimate that I have read, of around 200 miles/hour for a slung stone.  I can't do the math right now, but the Guinness world record for a slung stone is 1,434 feet.  What velocity would be needed to reach that distance, in air? Assume a launch angle of 30 degrees above horizontal.

There is some interesting information on the following page, http://www.baseball-almanac.com/feats/art_hr.shtml

I think 502 feet is the longest homerun hit they talk about. I dont know much about baseball but I would assume you can hit one a lot further than you can throw one.

A few sites I looked at suggested a hit ball can travel up to 160mph but they were just approximations. The world record pitch was listed at 100.9 mph.

I didnt look much at golf stats but the longest drive I could find was ~626m and the highest speeds quoted were ~200mph for Tiger Woods.

Me and gard have analyzed one of Yurek's projectiles to 120 km/h. On the home site of slinging.org it stands that the slingers are availebale to get the stone up to 400km/h???? how could that happen?? ???

  Well, I'm thinking that if you're good you could have a large plywood board as a target around 10m away or any other interval of ten [it's just easier and I'm lazy] then have someone [who knows exactly when the projectile is released] use a stopwatch and time how long it takes to leave the sling and hit the target. Then you could just do the math from there ie:

  30m/2sec=15m/sec

  I think that you would need a person on the stop watch who has really fast reaction time and some quick fingers...

I believe TechStuf has recorded speeds upwards of 200 - 250 mph. He was using ball bearings and a special sling with a trigger release.

The 400 kph claim on the front page is my estimation of the sling's upper velocity limit.  

Larry Bray though he might have been able to surpass the 2000 ft mark with lead projectiles.  That would require some pretty significant "muzzle" velocity.  

Chris

wrote on Oct 31^st, 2005 at 10:35am:

me and gard have analyzed one of yurek's projectiles to 120 km/h. On the home site of slinging.org it stands that the slingers are availebale to get the stone up to 400km/h???? how could that happen?? ???

How did you do the analysis? That number seems _very_ low: 33 m/s. My estimates for average slinger speed based on confirmed ranges that members have posted are usually in the 45 to 60 range, with exceptional slingers going much higher. Once you break 60, it seems like you are "over the hump" to opening up truly long distance cast based on the aerodynamics of the projectile.

Fast reaction times and lucky! We're talking about flight time of less than a 1/4 of a second over 10m. I haven't had a chance to try out the "blowgun soundcard chrony" we talked about in another thread yet, but I bet those numbers would at least be a little more repeatable ;)

Matthias

We all use different units on this board, depending on where we're from and our experience/education/jobs. A very useful tool for quick conversion of units is to type the desired conversion into google.

Example: "60m/s in mph" returns "60 (meters / second) = 134.216178 mph"

Much handier than loading up a java calculator every time.

Matthias

That's it.....I may just have to finally get off my increasingly fat @$$ and put this baby to bed once and for all.   So much for hoping an inspired young pup would grab the torch from my fatigued, burnt out hand.  Perhaps I should not have waved it so vigorously and then hung on so tight.....


At any rate,  I will endeavor to post some video by week's end.


Peace,


TS

Alright, Techstuff!!!  Don't break the sound barrier!

Stein Vegard,

How did you and gard figure out the 120 km/h on yurek's shot?  That's really slow!  Did you mean 120 miles/hour?  Even that would be slow for a sling projectile.

There was a thread recently, I think the one where Yurek posted his video hitting the tyre, where some people analyzed the video by calculating the distance of the shot and working out the time expired from examining the movie frame by frame and knowing the fps of the video.

I dont think it was a full powered shot if its the video I'm thinking of.

Tint, I believed I'd heard somewhere that the distance was 20 metres, so if that's wrong...
The stone uses 0,57 second from release to when it hits the white thing.
20 meters divided on 0,57= 35,0877193 meters/second =126,315789 km/h
But, as I said, I'm not sure the distance is right.

Gard

Gard,

Thanks!  

You mean 20meters / 0.57 seconds = 35.08 meters/second

which is

35.08 x 3600 = 126.3 km/hour

Make perfect sense there. 8)

Thanks Gard... I seriously had a problem to answer that...

wrote on Nov 1^st, 2005 at 9:16am:

Tint, I believed I'd heard somewhere that the distance was 20 metres, so if that's wrong... The stone uses 0,57 second from release to when it hits the white thing. 20 meters divided on 0,57= 35,0877193 mph =126,315789 km/t But, as I said, I'm not sure the distance is right. Gard

Gard I'm curious how you got that time. Could you explain your way?

The mentioned calculations are here:

http://www.slinging.org/forum2/yabb/YaBB.cgi?board=1;action=display;num=1124289190;start=6#6

I estimated the time at the 0.4 s (1/15 * 6 frames), what gives:

20m/0.4s = 50 m/s = 180 km/h = 111.8/h

of the averange velocity, not the muzzle velocity.

Jurek

I did like you, but I got the time 0,57 seconds.
20 m / 0,57 = 35,0877193 meters/second = 126,315789 kilometers/hour
I don't know how I could done it different, when I got the time 0,57 second.
But, if you got the time 0,40, it'll be 20 / 0,40= 50 meter /second = 180 km/h.
I'm not sure who's time is right, but I got the time 0,57 seconds :-/
A friend of me got 0,6 seconds when he measured.

Gard :-[

I thought movies were at least 24 frames per second ???  Was it just 15 frames/sec?

I will be using a camera at 30fps this weekend.....and we will have a definitive speed averaged from flight time.

Of course it certainly won't be pretty watching me try to replicate the days of yore....

At least I'll have a visual record for the insurance agent.


TS

seems to me every body needs a freind and a stop watch
i think if we could get several sets of results from several people at a set distance say 20m we could come up with a true range or average
possibley a standard ammo such as a 3ounce lead egg sinker or a golf ball

I am in! 8)

Same here! Just list the projectile type, weight and distance and i'll see if i can get a vid that has me getting somewhere near the target.

[quote author=Gard link=1129613270/10#18 date=1130966807]I did like you, but I got the time 0,57 seconds.
20 m / 0,57 = 35,0877193 meters/second = 126,315789 kilometers/hour
I don't know how I could done it different, when I got the time 0,57 second.
But, if you got the time 0,40, it'll be 20 / 0,40= 50 meter /second = 180 km/h.
I'm not sure who's time is right, but I got the time 0,57 seconds :-/
A friend of me got 0,6 seconds when he measured.

Gard :-[/quote]

Gard,

I know you got the 0.57 from your previous post :) But, my question was: how did you get that time? What way of measure did you use? I was just curious. Doesn't matter if I got the 120 or 180 km/h, either if my estimation is exact or not. Could you exactly explain your measure? Anyway, I'm glad you like me :)

Tint,

I used a Canon's digital camera for still images, it gives only the 15 frames per sec. It is not a typical camcoder, so movies made by it are not the best. You can see, that the frame period is somewhat inregular, the 15 frms/s is an averange rate.

lobohunter

That is a good idea, but I think a stop watch is very unacurate tool at the 20 m. The time is too short, no body is able to cath a reliable measure.

Anyway, I'm also in 8)

Jurek

First I measured how much time the whole video used, and then I divided it on how many pictures there is, so that I knew how long time one picture was. Then I counted how many pictures there was from release to when it hits, x how long time one picture was.

Gard

you maybe right yurek sop watchs are common.
my be the distance should be increased I think a hundred yards is to far. worried about deceleration. not sure if fifty meters would be much differnt than 20 meters. What Does everybody say to golf balls at 75 meters at some thing large such as a barn

Is it necessary that we put a restriction on the distance?  Couldn't everyone just use whatever range they want, as long as they can explain how the speed was calculated?

I am thinking of using a radar speed gun!

Being a wannabe scientist and to up hold what I learn in Chemistry ;) I think that we must have the same projectile, weight, and distance as a control then we can throw in other things to experiment. So do we have any agreed on variables like what brand or type of golf ball to use?

Tumakas;
ty those are my points excactly

What about putting up a net, and have the camera behind it, and shoot at the net while the camera records? It would make it easy to see release, and when the stone hits.
Just be careful with using small stones... :-*

Gard

I would do the camera thing if I could get my shot within the same 180º of the target! ;D

But personally, I wouldn't place the camera right behind my target because it would be hard to spot exactly when the projectile left the pouch and when it hit the target and also due to the fact that it's headed straight at the camera. The only difference in movement that you'd be able to detect in that short amount of time is movement on the X and Y axises but not anything significant on the Z axis (to and from the camera). I think that a place directly to the left or right of the whole experiment would be more suitable but I guess we'll have to try and see.

O.k we did the stop watch thing golf ball 75yds
i made ten tosses at the side of a brick wall with every thing I had I am glad it was a large building  because i almost missed a couple of times. I have not done the math but the average came out 1.34 seconds this was with a digital stop watch sorry about it being yards instead of meters but that was the tape I had.and measure may be of a bit. because it was only a 75 yd tape also a couple of times i beleave I threw before mark by maybe a foot
so take this for what you will and probaly a grain of salt lol

So... 168fps? I think that's right, correct me if I'm wrong. Does that seem like a reasonable speed?


(168 feet per second * 60 seconds)60 minutes= 604,800 feet per hour

604,800 feet per hour / 5,280 feet per mile = 114 mph

168 fps = 114 mph = 183 kph = 50.8 m/s

I think that's right...

Hello,

After reading this thread on measuring velocity, I have to suggest an easier/better way. A shooting chronograph has two light gates and measures an objects velocity with extreme accuracy. Here is a link, http://www.eabco.com/chronyshooting.htm.

All you have to do is cut a 10 inch diameter hole in a piece of plywood, then mount the chronograph on the backside so it will be protected from the throw. Then hope your accurate enough to throw through the hole.
The closer you are to the chronograph the more it will reflect the true max velocity, and the easier it will be to hit your target.

-erin

hmm good idea
just not worth the money for me to no lol

Time for me to chime in.

We could reverse engineer the speed of any projectile if we have given factors such as mass of the projectile, the angle at which it was thrown (trajectory) and the distance it flew until it hit the ground.
R = MxV@T: Range equals Mass times Velocity at trajectory.

For instance, a ten pound round projectile needs to fly at just over 120 MPH to reach 1,000 feet.
(Am I the only one here who hurls pumpkins?)
http://www.slinging.org/images/walker/1.jpg


If you really want to find out the velocity of your projectile, I suggest asking for help from a local math or science teacher.  ::)

If I read what was stated correctly, then 117 MPH for a lead sinker or a golf ball is not unreasonable but fairly good.

Physics rule: a short sling swings faster than a long one.

My rules:
Accuracy beats speed.
Range requires speed and mass.
Hitting your target at any range, priceless.

i'm no expert and you sound like you know what you're talking about, but are you sure the equation accounts for air? a lot of equations only work in vacuums  ???

Can pounds be substituted for grams and feet for meters? And say that we used your example:

1000 ft.=10 lbs.*120 mph @ T

What's the "@ T" used for? Can you do a sample problem, this is interesting and I want to learn how to do this.

Has anyone measured their shooting velocity accurately?

ArizonaSlinger

The plywood won't protect the chronograph.  I've seen a rock go through two pieces of 5/8 inch plywood.


wrote on Jan 6^th, 2006 at 12:44pm:

Hello, After reading this thread on measuring velocity, I have to suggest an easier/better way. A shooting chronograph has two light gates and measures an objects velocity with extreme accuracy. Here is a link, http://www.eabco.com/chronyshooting.htm. All you have to do is cut a 10 inch diameter hole in a piece of plywood, then mount the chronograph on the backside so it will be protected from the throw. Then hope your accurate enough to throw through the hole. The closer you are to the chronograph the more it will reflect the true max velocity, and the easier it will be to hit your target. -erin

I always want to know what is the highest speed achievable with a sling in feet-per-second.....(my maths is poor) I'm more familiar with fps.

The best speed a rubber-powered slingshot can achieve is 300fps. I just want to compare this to the sling with heavier projectile. :P Sorry if this is out of topic. ::)

ish? 200 fps, but keep in mind that the projectile is much heavier...

Only 200fps with much heavier projectile?? :-? :o Then, how could this reach distance of more than 200 metres? :-? I expect more than 500 fps! ::)

What's that in mph or kmph?

I think I can do up to 150 mph and bigger stronger guys can do much better than me. :-?

I think 200 fps is pretty slow, even a compound crossbow can shoot more than 300fps and a sling shot from a skillful hand should beat that..... If it's only 200 fps, then how could the shots from the ancient romans go through flesh??  :o

200fps is just over 136mph.

Tint, you don't surprise me that you could sling over 150mph (220fps) - but I think Matthias was giving a
figure for us reasonably athletic but not gifted individuals!

My more modest aim is to reach 50m/s consistently - that's a mere 112mph.

I think that is more than enough to put a hole into living flesh!

Oops - I missed the fastest possible bit and went with "pretty darn good" - round number:

American Baseball pitcher: 40 m/s, 130 fps, 90 mph
Practiced slinger: 45-50 m/s, 165 fps, 110 mph
Strong Slinger: 60 m/s, 200 fps ,130 mph
Tint: 70 m/s, 220fps, 150 mph  
Jurek and the record setters: 90m/s+, 300fps, 200 mph

60 m/s should comfortably put a rock over 200m.

200 fps, although not particularily fast by rifle or compound crossbow standards, is still pretty darned fast.

If you figure the energy of the glans moving 200fps (100g) you end up with 140 foot-pounds energy, not far off what a .50 cal black-powder pistol would have made, and almost triple the energy delivered by a modern bow. By the time you are throwing in the upper end of our range the energy is starting to push .45 ACP levels. The shock of impact is very high.

So be careful.

Matthias