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sling revolution speed clocking (Read 1339 times)
big_sling_gland
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sling revolution speed clocking
Jan 1st, 2008 at 6:12pm
 
     I found a cool way to clock slings revlution speed.
What you will need:
A 12-hour clock with a second hand
A calculator
Sling 
Weight for the sling pouch like a rock


This method is quite easy to use.

1:Measure the folded lenth of the sling this will be the radias of the revolutions measure in inches X this by 2 that will be the diameter. Then X the diameter by pie (3.14) you will then get the circumference of one revolution Ie:how far the pouch travels in one revolution.
2:Get your sling and put the weight in the pouch and get the clock.
Wait for the second hand to land on the 12 standing in the ready position. When the hand reaches the 12 spin the sling in a over head style as fast as you can and count how many revolutions you can get in 30 seconds until the second hand reaches the 6.
3:Devide how ever many revolutions you got in the 30 seconds by 30 this will give you how many revolutions you get in 1 second use exact numbers this will give you more acurate readings and take how many revolutions you get in 1 second and X that by the slings revolution circumference and you get the revolution in feet per second


I would like to give my readings

My sling is 2.2 feet long X 2 = 4.4 feet long X pie (3.14) = sling revolution circumference 13.816 feet.
I got 71 revolutions in 30 seconds divided by 30 = 2.366666667revolutions a second
2.366666667 X 13.816 = 32.69786667 feet per second.

Feel free to give criticizm. Wink
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big_sling_gland
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Re: sling revolution speed clocking
Reply #1 - Jan 1st, 2008 at 6:16pm
 
ExclaimSorry where there is this smiley  Cheesy  I said devide. Exclaim
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Aussie
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Re: sling revolution speed clocking
Reply #2 - Jan 1st, 2008 at 7:11pm
 
B-S-G young friend,

I assume that you are attempting to work out how fast the stone leaves your sling when you throw. The figure you calculated  works out to be about 22 mph and I'll bet you actually sling much faster than that. Such a low speed would barely get you 20 yards cast.

Your arithmetic is fine but it's based on the assumption that you sling just goes round and round in circles at a constant speed, with your hand at the centre of the circle. The reality is far more complex. When you do your final thrust just before release your hand speeds up enormously. The sling which is just string ie. not rigid cannot keep up with the sudden increase in rotational speed and initially lags behind the hand. This causes the sling's effective radius to tighten and then attempt to catch up with the hand so at the instant of release the sling is actually rotating faster than the hand, which gives additional speed over that caused by the sling's already being longer than your hand.  

Try to have a look at frame by frame video of someone slinging. You will see that at release there is a large angle, often as much as 90 degrees, between the sling and the slinger' arm. Have you ever noticed how a long sling is much harder to suddenly accelerate than a short one. Slinging is one of those supposedly simple things like riding a bike. You do it automatically by feel and have no idea how complex is the physics involved.
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Cranks are little things that make revolutions.&&
 
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Curious Aardvark
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Re: sling revolution speed clocking
Reply #3 - Jan 2nd, 2008 at 7:20am
 
plus swinging it round your head is a fairly slow process compared to the actual explosive throw.
But hey - you're thinking, that's always a good thing - keep it up :-)
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Do All things with Honour and Generosity: Regret Nothing, Envy None, Apologise Seldom and Bow your head to No One  - works for me Smiley
 
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big_sling_gland
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Re: sling revolution speed clocking
Reply #4 - Jan 4th, 2008 at 6:51pm
 
still cool to find out Tongue
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CanDo
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Re: sling revolution speed clocking
Reply #5 - Jan 4th, 2008 at 9:26pm
 
big_sling_gland,

Please check your private messages.
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WWW  
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big_sling_gland
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Re: sling revolution speed clocking
Reply #6 - Jan 5th, 2008 at 4:35pm
 
just did sorry about that
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