I think you've got a glimmer of enlightenment, but have yet to step into the full blaze of illumination there, mobo.

Ever heard of flu-flu fletching? It's used for aerial shooting, to severely cut the distance an arrow will travel when shot into the air. Where a normally fletched arrow would fly a couple hundred yards, a flu-flu will only go about 45-50 yards before the fletching robs the arrow of all it's energy and makes it fall out of the air. There are several ways to make a flu-flu, but one is to use a long, uncut feather and spiral it tightly around the shaft.



That is an extreme example of how too much helical causes the arrow to lose energy faster. A flu-flu arrow is stable and accurate. It straightens out quickly when it leaves the bow. It uses up energy so fast that it can't stay in the air very long, but that's the whole idea behind it.

You're correct that an arrow won't lose as much energy within 30 yards as it would at longer distances, but that's not really the point. You can reach a point with helical where any more doesn't increase the spin of the arrow. Instead, it begins acting like a flu-flu and causes the arrow to lose speed and energy faster than need be.

The trick with helical, or even offset, is to figure out how much will give you the best stability and accuracy while limiting how much speed and energy the fletching will bleed off the arrow downrange.

There is some good info on fletching styles at www.trueflightfeathers.com