Testing

[DC]

I have not found a place to shoot yet so my testing is limited to chrono testing in the shop.  I've always tested at 10 gpp but with this 35#@24" bow I've been messing with a lot lighter, down to 6.1gpp. Is there any point in this other that seeing big numbers on the chrono?

[PatM]

Sure.   Checking for clean arrow flight as you drop  gpp and it will tell you what distance you could potentially reach.

[willie]

lighter arrows don't let the bow shoot as efficiently as heavier arrows, so if you are building for lighter arrows you need to test with lighter arrows.

you could keep velocity and weight notes and calculate kinetic energy of the various arrows weights.  curves on a graph plotting arrow weights vs kinetic energy could be useful to compare bows

[DC]

Do you know if there's a site where I can just plug in the numbers and click a mouse Like the Metric conversion sites.

[willie]

http://www.1728.org/energy.htm

[DC]

Thank you

[avcase]

It has been commonly stated that the bow which is fast with a heavy arrow will also be fast with a light arrow, so why bother testing with anything other than a standard 10ggp arrow?  But I have found that I would have missed some important insights if I hadn’t tested flight bows to conditions that match how the bow is intended to be used.

With light arrows, some small changes to the bow or how the bow is setup are greatly magnified on the chronograph. These trends may be difficult to detect with a heavy arrow, where it may only register a 1 fps difference and go completely unnoticed. With a light arrow, the difference can be much amplified. Add up a few of these discoveries, and it can add up to make a significant difference.

For example, I may find I do pretty well with a 165-175 grain 24” long flight arrow for a 50# bow.  Then this is what I would use to test my bow.  The bow would be drawn around 26”, depending on how you measure your draw length, and I’d use a few carbon test arrows so I’m not wrecking my flight arrows. I’d may even use something like a 150 grain, 175 grain, and 200 grain arrow test arrows to test all my 50 pound flight bows.

Alan

[DC]

Thanks Alan, now I have to make light arrows. the best I have done is 236 grains and I'd hate to think what the spine is. It doesn't hit the target very straight.
What kind of changes are we talking about? I've reduced tip weight and cut the arrow pass a little deeper. I was playing with BH but found that 6" seemed to work across the board. Maybe I should look at that harder.

[loefflerchuck]

I made a bow this year about 49# @ 27" that shot a 460 grain broadhead arrow 216 yards. With what should have been proper spine flight arrows 240 grains I was getting 240 yards. I've had other bows like this that are okay for broadheads but hardly any better with flight arrows that should in theory shoot 100 yards further. I think the dry fire speed comes into play here for the bows that shoot flight arrows far, but not as important with broadheads and heavier arrows.