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.


Jörg

6 comments:

  1. i think the theraband tan should be able to propel a small steel ball very fast. and when i say small steel ball im talking about like a 6mm steel ball. you may also want to check out torsten's video about his bands because he uses theraband blue green and black. thanks for posting the results of your theory!
    Daniel

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  2. To properly switch the new cannon to the Thera Band Tan you would need what? A half mile of it? Sounds like expensive fun...

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  3. is this theory also the same for surgical tubeing thicknesses?

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  4. can you describe what are those measurements of band?21 cm * 7 cm * 20 cm do you mean 7 cm wide and split it half?double layer?and lenght 21 or 20 cm?????what? just got thera black and dont know how to cut it properly.. :(

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  5. ahhh..feel so stupid...i got it now...happy hunting ahead :)

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  6. The trade-off is, as bands get thinner they dissipate heat faster, so the only way to gain significant speed is to shoot intuitively.

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