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.