Main Discussion Area > Flight Bows
Virtual Mass revisited
sleek:
--- Quote from: DC on September 29, 2020, 12:52:56 pm ---It is strange. I've run the test twice and even with the the readings from the second chrono being different that hump for the 548 one is there. If your wave theory is right wouldn't you think that the 556 one would show some improvement?
The 501,548 and 556 are all the same Tiger shafts. the 501 and 556 are both 60# spine and the 548 is 55#. Could that one be getting a cleaner launch?
I think I'll sand down the 556 to 55# spine. I'll take 5 shots before and 5 shots after.
--- End quote ---
Certainly a cleaner launch is a very good possibility and could completely explain this. I assumed you had all the arrows spined for the bow so similar flight would be hoped for. If you can try different spines all in the same weight range that would be an interesting test. Are they arrows all hitting the target fairly straight?
I wouldn't expect the 556 to show much if any improvement, because i don't know where the harmonic range on this, or any, bow is. and chances are, its a narrow range. The difference from 548 to 556 is 8 grains, and thats enough to make a noticeable difference in flight distance.
Id like to see the speed differences as the grains go up one at a time, then down from 548 one at a time. That would help you dial right in and you may even be able to plot the results of the wave as a wave. You should be able to if my theory is correct.
DC:
Foiled! I started scraping down the shaft and realised that I was removing weight as well as spine. I took off 10 grains of arrow and lost 2.5-3# of spine. I gained about one or two fps which 10 grains of weight could explain so that's a bust. I've never really worried about spine as it didn't seem to have that much effect in the speed and it's a PITA to have to make equal spined arrows in every weight. This is where the mathematical method would shine because you can change one thing(I think). I think where the cleaner launch would help is in equalising the two chronos readings.
The arrows are hitting the target pretty straight.
With a real arrow you can't change the weight without changing the spine and vice versa. Maybe you could increase the weight by wrapping tape around the middle of the arrow so it wouldn't change the spine but then you'd have to wonder if the bumpy surface going across the bow would have any effect. More thinking required :D
sleek:
--- Quote from: DC on September 29, 2020, 01:29:09 pm ---Foiled! I started scraping down the shaft and realised that I was removing weight as well as spine. I took off 10 grains of arrow and lost 2.5-3# of spine. I gained about one or two fps which 10 grains of weight could explain so that's a bust. I've never really worried about spine as it didn't seem to have that much effect in the speed and it's a PITA to have to make equal spined arrows in every weight. This is where the mathematical method would shine because you can change one thing(I think). I think where the cleaner launch would help is in equalising the two chronos readings.
The arrows are hitting the target pretty straight.
With a real arrow you can't change the weight without changing the spine and vice versa. Maybe you could increase the weight by wrapping tape around the middle of the arrow so it wouldn't change the spine but then you'd have to wonder if the bumpy surface going across the bow would have any effect. More thinking required :D
--- End quote ---
Wrap tape around the nock end. If you can do ALL your weight adjustments back there, spine won't be an issue.
DC:
It takes a lot of tape. Half the length of the arrow is just a few grains and I'm not so sure that putting the weight on the back doesn't increase the spine. If weight on the front decreases it, I dunno.
sleek:
--- Quote from: DC on September 29, 2020, 01:40:01 pm ---It takes a lot of tape. Half the length of the arrow is just a few grains and I'm not so sure that putting the weight on the back doesn't increase the spine. If weight on the front decreases it, I dunno.
--- End quote ---
We are over thinking this. The arrow doesn't care how much it weighs. So, don't add weight to the arrow, add it to the string right at the nock area using split shot fishing weights. The bow will handle it fine, just a little hand shock, but it will force the bow to push the correct weight, and you won't have a variable in spine to worry about.
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