Saturday, November 14, 2009
Are thinner bands more powerful?
As you may know. my slingshots are much, much more powerful than the ones (most of us) used as a kid.
The main reason is the far better rubber we can use today, no longer are we limited to inner tubes and surgical tubing.
I have used the Thera Band Gold flat bands so far, which is the thickest (but still thin) stuff you can get.
Recently, a fellow slingshooter in a German forum posted that multiple layers of thin flat bands are faster than the same amount of rubber in thicker material.
The eternal hunt for power goes on! A great new frontier.
I have bought Thera Band Black, which is a lot thinner than Thera Band Gold. The manufacturer says the draw force is 0.43 in comparison with Thera Band Gold.
So I converted my favorite Gold setup (9cm * 6 cm * 20 cm) to 21 cm * 7 cm * 20 cm of Black. Have to use two layers as the roll is only 14 cm wide. It is true, same resistance.
Compared to the Thera Tube Black, the flat band has the same draw force in 14 cm width, so compared to Thera Tube Black my band set is 1.25 times harder to draw out. That works.
OK here is the result.
.75 l = 19 mm lead ball, 36 gramms, 576 grains
.60 s = 15 mm steel ball, 12 gramms, 192 grains
.38 s = 9.5 mm steel ball, 4 gramms, 64 grains
TBG = Thera Band gold, 9 x 6 x 20 cm
TBS = Thera Band black, 21 x 7 x 20 cm
TBG .38 s 78 m/s, 255 fps
TBG .60 s 73 m/s, 239 fps
TBG .75 l 54 m/s, 177 fps
TBS .38 s 90 m/s, 295 fps
TBS .60 s 79 m/s, 259 fps
TBS .75 l 63 m/s, 206 fps
Max. Energy TBG = 52 Joule = 38 fpe
Max. Energy TBS = 71 Joule = 52 fpe
The black bands did not tear throughout the tests.
Temperature was 14 degrees celsius, 57 degrees Fahrenheit.
The theory works! Now let's see what will happen if my thiiiiin Thera Band Tan band arrives. This is the thinnest material you can get. I guess to get to the same force, I will have to use ten layers per side.
Posted by The Slingshot Channel at 11:36 AM