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Post by BT on Dec 5, 2009 20:05:10 GMT -5
I think, after April's hunt, I will be done with the Ashby experiment. 
The momentum arguement is just not logical and is full of flaws. Why does almost the entire archery industry rely on Kinetic Energy? Some might argue that fast bows sell, and there's truth to that. But, let's give those engineers and bow designers some credit, they have some sort of grasp on physics. I think a lot of bowhunters intuitively deduce that because heavier arrows penetrate better, it must be because of momentum. Never occurs to them that a heavier arrow better conserves kinetic energy. Or the effects of friction on arrow penetration. What did I do when I went to skinny Axis arrows and a 2 blade head? Reduced the amount of friction working against the arrow, that's what.
I'm not saying that heavier arrows don't have their place. Saving wear and tear on a bow, quieting a bow down, making a bow easier to tune and shoot, and maximizing downrange KE are all good reasons to bump up the arrow weight. But there is such thing as too much of a good thing. Ashby's recommendation of a minimum of 650grains is just ridiculous for most compound setups and for most situations.
Plus, this is getting really expensive. Luckily some of the components, like the zwickeys, can be used with my recurve. But what the heck am I going to do Axis FMJ 340's cut to 26.25"? You know, about $140.00 a dozen. Plant stakes I guess. I guess I'm bitter because I've realized I'm just chasing windmills....  6.0 GPP 75gr. head weight 4 fletch 2.5" low profile feathers _____________ 45# 25" Draw Spec. 250 fps (IBO for bow @ current draw length & weight) 75% let off _____________ Objective285+ fps 25 yards flat flight ________________________________ I believe that I can get this rig to 300fps...but not sure if it is safe to shoot at that speed  We will soon see  |
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Post by oldfarmsblueman on Dec 6, 2009 9:18:17 GMT -5
Thats me 26"@50# I will be keeping my eye on this  |
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Post by BT on Dec 7, 2009 16:44:21 GMT -5
First run specs:
222fps @ 42# & 26" w/309gr. arrow
Estimate end run (stock) on stripped string @ 50# = 240fps
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Estimated advancement @ IBO = 253fps
Estimated advancement w/ string change = 258fps
Estimated advancement w/ latent cam cycle reduction = 288
Estimated advancement w/ forward cam cycle advance = 293
Estimated advancement w/ push forward grip = 303
* Custom broadheads/field point may be required. |
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Post by BT on Dec 7, 2009 17:33:27 GMT -5
 This is a potential 65gr. commercial head choice for this rig |
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SPIKER
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Post by SPIKER on Dec 7, 2009 17:57:53 GMT -5
Yeah, I'll be watching too. I need to get my dad a rig close to this one for next season.  |
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Post by oldfarmsblueman on Dec 7, 2009 17:58:11 GMT -5
I'm getting lost here BT ;D Is that arrow 4.9 gpi ???Sounds like pasta ;D.Almost dangerous 8-)The little head looks interesting |
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Post by BT on Dec 7, 2009 18:26:09 GMT -5
Copied from BT's Journal....
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For every 5 grains deducted, 1fps must be added on a baseline of 400grns @ 285fps w/ 2"X 2.5 resistance.
This would mean (in a perfect world) that the current project bow would have to spec out at
322fps - 250grn. w/ 2">3 forward resistance.
Reduce the forward resistance by 50% ( forward 1>3 ) and we will require the target speed (corrected) of 300fps.
With a further corrected forward resistance value of 1>2....we could achieve more leverage than MrX.
That said...we are not (at this time) looking to exceed based on penetration alone and would rather seek to achieve a higher contact value within the scope of our initial plan.
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Post by BT on Dec 7, 2009 18:33:04 GMT -5
I'm getting lost here BT ;D Is that arrow 4.9 gpi ???Sounds like pasta ;D.Almost dangerous 8-)The little head looks interesting 4.9 is starting and we may not be able to perfect it...but we must try. I perfected the same shaft at 345fps...so it's worth going through discovery. 5grn. is IBO standard and I have (long ago) shot 3.5 up to 1500 rounds before the limbs failed. I am confident in this set up....on paper anyway |
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Post by BT on Dec 9, 2009 20:38:40 GMT -5
   Second round goodies Third round is going to get retarded! ;D |
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Post by BT on Dec 10, 2009 7:35:49 GMT -5
The Kobalt is reported to have an excessive amount of hand shock. This (excessive) really just doesn't happen unless cams are out of time or some other similar type of malfunction is at hand. A call was all it took to find a potential problem that could be remedied quickly. When the pro at the shop (I use the term Pro loosely) measured the ATA...he only checked one side of the bow. On a split limb design (even a 3/4 split) both sides of the bow must be measured due to the fact that the 4 limb sections can and will have different rebound rates. The left side of the bow was found to be out 1/8" (over extended) which would indeed cause shock. Doegirl will be headed back to that shop soon. Hopefully, once this is resolved....the hand shock will be reduced to manageable. I cant wait to get this bow on my bench....provided the Bass No Pro team doesn't destroy it before that happens  |
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