Band Size

[irtrogdor]

Hi, I just wanted to clarify some things about bands. If I remember correctly the formula for band size is

[([Distance from muzzle hole to shaft notch x2] - Wishbone Length) / ratio of 3-4]

I was wondering if this applies to all sizes of bands. I.E. if I have 16mm rubber and it turns out my band needs to be 24 inches long, will a band made of 19mm rubber need to be the same length?

Also, is there a formula you can use to predict the increase in power you get by adding extra bands? And how does that extra power translate into range? (obviously if you double the power you don't double the range. Right?)

 

[Bill McIntyre]

That's the formula I used, with a divisor of 3.5, and I use the same formula no matter the thickness of the band. Its a matter of the optimum stretch before the band starts to bleed off power because its beyond its elastic limit (or some such thing as that), so it applies to any thickness.

I have a recollection that a 9/16" band produces about 80 pounds of force, and a 5/8" band produces about 100 pounds, but I may be wrong. I think some sources list a bit more force than that.


Extra power does produce more range, but certainly not in proportion to the increase in power, and of course it can cause accuracy problems if it causes muzzle flip or shaft whip.