ORIGINAL: bigbulls
If you calculate the numbers on the arrows that I posted you can see that my numbers agree with MeanV's findings. All three arrows were shot three times each through the same chronograph, out of the same bow, at the same draw length, at the same draw weight.
For poops and giggles I just shot a 397 grain arrow too.
397 grain arrow... 315 fps ......... 87# KE
443 grain arrow... 302 fps ......... 90# KE
502 grain arrow... 283 fps ......... 89# KE
625 grain arrow... 256 fps ......... 91# KE
Aparantly the 82nd, and probably the 101st, are less efficient with certain weight arrows.
Very interesting. I only hope that 435 grains is close to that sweet spot.
Alright, this is going to be hard for me to explain because I do not have a lot experience in testing arrow masses and their efficiency, but I'll do my best. Is it possible that the marginal gain in KE peaks. Think about it. Look at the following HYPOTHETICAL data:
365 grain arrow — 1# KE — _ Marginal KE
370 grain arrow — 2# KE — 1 Marginal KE
375 grain arrow — 3# KE — 1 Marginal KE
380 grain arrow — 4# KE — 1 Marginal KE
385 grain arrow — 6# KE — 2 Marginal KE
390 grain arrow — 8# KE — 2 Marginal KE
395 grain arrow — 10# KE — 2 Marginal KE
400 grain arrow — 13# KE — 3 Marginal KE
405 grain arrow — 16# KE — 3 Marginal KE
410 grain arrow — 19# KE — 3 Marginal KE
415 grain arrow — 23# KE — 4 Marginal KE
420 grain arrow — 27# KE — 4 Marginal KE
425 grain arrow — 31# KE — 4 Marginal KE
430 grain arrow — 35# KE — 4 Marginal KE
435 grain arrow — 40# KE — 5 Marginal KE*
440 grain arrow — 44# KE — 4 Marginal KE
445 grain arrow — 48# KE — 4 Marginal KE
450 grain arrow — 52# KE — 4 Marginal KE
It's like combining economics and physics into one very complicated question.