Author Topic: interesting.. .  (Read 599 times)

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Offline jeffp51

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interesting.. .
« on: March 11, 2018, 06:35:28 pm »
I recently saw this video:
https://www.youtube.com/watch?v=pDCzZXnp7bY

it's in German, but that shouldn't matter.  the guy shoots light and heavy arrows at the same target.  it seems that the common wisdom is that heavy arrows drop over distance more than light ones.  The interesting thing is that the further back he shot, the more the light arrows dropped relative to the heavy arrows.  Is this because the heavy arrows have more momentum and are affected by drag less than the light ones, or is there possibly something else that accounts for the difference?  He doesn't seem to have any sights on his bow, so it is difficult to tell if any error is creeping into his experiment--perhaps he is unconsciously aiming higer with the heavy arrows.  He seems equally surprized by his results as I was

Offline Hawkdancer

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Re: interesting.. .
« Reply #1 on: March 11, 2018, 07:43:52 pm »
Is he using the same bow for both?  If so, I would expect the heavier arrows to drop more at least out to about 25-30 yards, but I haven't been doing a lot of shooting lately, too cold and windy!
Hawkdancer
Life is far too serious to be taken that way!
Jerry

Offline jeffp51

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Re: interesting.. .
« Reply #2 on: March 11, 2018, 08:12:15 pm »
same bow.  he shoots all arrows back to back, starting at 20meters, and then backing up progressively to about 45 meters.

Offline TSA

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Re: interesting.. .
« Reply #3 on: March 13, 2018, 04:25:09 pm »
ok heres what i think is happening, based on not being there at the time of the experiment ;) and of course my german not being that fluent  )P(

so with the arrow builds,  did he use the same weight points for both arrows- must have, i assume.
so one set of arrows wre physically lighter in mass due to differences in shaft weight.

even though its negligible, but the  lighter  mass arrows will have had a higher FOC.- due to the steering arm of the arrow being lighter in weight, so improving the foc.

Now FOC works , for its intended purpose, we all know that,  however it does have its shortcomings.

as the velocity starts to bleed off the projectile, the higher foc  arrow starts to  adopt a downwards attitude- simple aerodynamics, being that the balance point is further forward,
this forces the arrow to adopt a different ( downward angle ) flight path bringing it to earth sooner, not because there was a greater loss in velocity, but rather a change in flight attitude- due, inadvertently to the higher FOC.

flight arrows, where distance is critical, will perform better with lower FOC's, the closer to a zero  FOC will allow the arrow to come back to earth still kinda parallel to the ground, where as the higher foc will come back to earth sooner in a more downwards attitude.
now for flight archery,  this also comes at a bit of a compromise, lower FOC take longer to stabilize and that equates to a loss of efficiency, which robs distance.
 but i think its an easy trade off, the extra distance gained due to a flatter flight attitude outweighs the minimal efficiency lost, assuming of course all the test arrows are well tuned.

so in closing, shoot two arrows the same weight out of the same bow, same velocity!
 but one with a higher foc than the other, the higher foc will cover less distance.

But to be honest , we all know how this works  in theory, i just would not have belived it was so evident, over such a short distance, with such an unintentional and negligible difference in FOC %.

If i  am correct, this just goes to prove just how important it is to well tune , and well match your arrows.

this is a great topic, anybody else have any thoughts and ideas?
« Last Edit: March 13, 2018, 09:07:36 pm by TSA »