Speed, or Weight
08-26-2003, 07:30 AM
#11
Giant Nontypical
Join Date: Feb 2003
Posts: 9,175
RE: Speed, or Weight
Now wait a second. Arthur posted a good two-three paragraph reply and I did not see the word " momentum" mentioned once.
You feeling ok Art?
You feeling ok Art?
The way I see things, the lower your draw weight -and/or- the shorter your draw length -and/or- the less efficient your bow is, the higher your arrow weight to draw weight ratio should be. Especially, as Bees so eloquently pointed out
, when you' re after a large or thick skinned critter.I have to admit to hunting with arrows at 6 grains per pound back in the 80' s. And I was using them with a longbow, of all things. However, the arrows were 720 grains.
08-26-2003, 07:39 AM
#12
Boone & Crockett
Join Date: Feb 2003
Location: Lehigh County PA USA
Posts: 12,157
RE: Speed, or Weight
SOME people can use light arrows. 5-6 grains per pound, at high speeds and do well. I think most people would do much better to set 7 grains per pound as a minimum for a hunting arrow.
The way I see things, the lower your draw weight -and/or- the shorter your draw length -and/or- the less efficient your bow is, the higher your arrow weight to draw weight ratio should be.
...Bubba shooting a Bowtech Pro 40 at a 30 inch draw length and a 70 lb draw weight can probably get away with shooting a 375-425 grain arrow and still expect very good KE and penetration in general on just about anything he would normally shoot. While on the other hand, his cousin, T-bone, might not get very good performance in terms of KE or penetration if he is shooting a PSE Nova with Vector wheels set at 50 lbs with a 27 inch draw length and an arrow weighing in around 250- 300 grains. Right?
Same 5-6 grains per pound ratio but the bow, draw length and draw weight all factor into it.
Excellent post Arthur.
08-27-2003, 02:18 AM
#14
Join Date: Aug 2003
Posts: 174
RE: Speed, or Weight
The KE vs. Momentum vs. Speed debate will never be agreed upon as long as we all shal live.
You can find 100 guys that will tell you FROM EXPERIANCE that lighter is better, and they get nothing but pass throughs on Moose with 50gn mech heads, and you can get another 100 that will tell you the only way to get a pass through on anything bigger than a balloon is to go with 1000gn arrows flying at 100fps...they will tell you this from experiance.
You can also find several semi-scientific tests showing that heavy and slow is better...and light and fast is better....and still other tests that say it' s all the same.
The best tests I have read, and my own tests have shown ME, that it pretty much IS all the same...within reason.
1 thing I have found that is reasonably constant. the slower the arrow, the better to have a cut on impact head. The faster the head, the better you are with a head that has less surface area (Slick Tricks...and similar...and even mech heads).
Match your head to your arrow, and you' ll do fine.
You can find 100 guys that will tell you FROM EXPERIANCE that lighter is better, and they get nothing but pass throughs on Moose with 50gn mech heads, and you can get another 100 that will tell you the only way to get a pass through on anything bigger than a balloon is to go with 1000gn arrows flying at 100fps...they will tell you this from experiance.
You can also find several semi-scientific tests showing that heavy and slow is better...and light and fast is better....and still other tests that say it' s all the same.
The best tests I have read, and my own tests have shown ME, that it pretty much IS all the same...within reason.
1 thing I have found that is reasonably constant. the slower the arrow, the better to have a cut on impact head. The faster the head, the better you are with a head that has less surface area (Slick Tricks...and similar...and even mech heads).
Match your head to your arrow, and you' ll do fine.
08-27-2003, 06:33 AM
#15
Boone & Crockett
Join Date: Feb 2003
Location: Lehigh County PA USA
Posts: 12,157
RE: Speed, or Weight
Dan,
Explaining momentum is more of Arthur' s cup of tea than mine. As with most equipment related issues I always take the road of " moderation" . I realize that both KE and momentum play a large part in penetration but do not place excessive stock in either. I prefer to have enough of both so that my setup can be sufficient for either side of the argument.
For example, my arrows are roughly 6-6.5 grains per pound of my draw weight. This provides reasonably flat trajectory, very good speed (considering my draw length and draw weight) and yet at the same time I have enough mass weight to satisfy those who prefer to use momentum as the primary indicator of penetration.
In essence, I believe you need a healthy dose of both to cover all of your bases.
Explaining momentum is more of Arthur' s cup of tea than mine. As with most equipment related issues I always take the road of " moderation" . I realize that both KE and momentum play a large part in penetration but do not place excessive stock in either. I prefer to have enough of both so that my setup can be sufficient for either side of the argument.
For example, my arrows are roughly 6-6.5 grains per pound of my draw weight. This provides reasonably flat trajectory, very good speed (considering my draw length and draw weight) and yet at the same time I have enough mass weight to satisfy those who prefer to use momentum as the primary indicator of penetration.
In essence, I believe you need a healthy dose of both to cover all of your bases.
08-27-2003, 07:02 AM
#16
Giant Nontypical
Join Date: Feb 2003
Posts: 9,175
RE: Speed, or Weight
With a 70 pound hard cam compound and 30" draw with a 350 grain arrow, the fabled ' IBO standard' , shooting 300 fps, you get 70 ft lbs of energy and .4655 lb secs of momentum. That arrow will pass through a deer on a good broadside hit, according to all reports. I would not shoot such a rig at an animal, so I wouldn' t know from my experience.
What I do know is that my 580 grain arrows from a longbow at 182 fps gives me 42 ft lbs of energy, exactly the same momentum as the light arrow, .4655 lb secs, and will pass through a deer on a good broadside hit using Magnus heads. It will also pass through feral hogs in the 300-350 pound class. Using blunts, it will flat knock the stuffings out of rabbits and squirrels with a solid thump on the noggin.
Now, this raises a problem for those that claim KE is the best determinant of how much penetration you get. I get the same passthru as the high KE bow does with 28 ft lbs LESS energy. The common factor between the two setups is momentum. Of course, when confronted with that problem the KE crowd ignores it.
Like I said above, the lower KE your bow gives you (lighter draw weights, shorter draw lengths, less efficient bow designs), the higher your arrow weight to draw weight ratio should be. That is because you have to rely more on momentum when you don' t get gobs of KE.
What I do know is that my 580 grain arrows from a longbow at 182 fps gives me 42 ft lbs of energy, exactly the same momentum as the light arrow, .4655 lb secs, and will pass through a deer on a good broadside hit using Magnus heads. It will also pass through feral hogs in the 300-350 pound class. Using blunts, it will flat knock the stuffings out of rabbits and squirrels with a solid thump on the noggin.
Now, this raises a problem for those that claim KE is the best determinant of how much penetration you get. I get the same passthru as the high KE bow does with 28 ft lbs LESS energy. The common factor between the two setups is momentum. Of course, when confronted with that problem the KE crowd ignores it.
Like I said above, the lower KE your bow gives you (lighter draw weights, shorter draw lengths, less efficient bow designs), the higher your arrow weight to draw weight ratio should be. That is because you have to rely more on momentum when you don' t get gobs of KE.
08-27-2003, 07:31 AM
#18
Giant Nontypical
Join Date: Feb 2003
Posts: 9,175
RE: Speed, or Weight
One goes over to Jackson' s site and plugs his numbers into the ballistics program. 
At least, that' s how I do it. I used to know the formula but when I found that program, I promptly forgot it. The good thing about the ballistics program is you can also see what kind of performance you can expect downrange, where the animal is. Also, there' s a link to a graphing trajectory calculator so you can see what various arrow weights and speeds do to your trajectory. Great stuff!
www.bowjackson.com
At least, that' s how I do it. I used to know the formula but when I found that program, I promptly forgot it. The good thing about the ballistics program is you can also see what kind of performance you can expect downrange, where the animal is. Also, there' s a link to a graphing trajectory calculator so you can see what various arrow weights and speeds do to your trajectory. Great stuff!
www.bowjackson.com
08-27-2003, 07:47 AM
#19
Nontypical Buck
Join Date: Feb 2003
Location:
Posts: 2,994
RE: Speed, or Weight
Wow, I was just telling my youngest daughter this a.m. that you learn something new everyday if you pay attention, and I' ll be damned...
As many times as I' ve been on the site, I' ve never been to that part. Thanks for the kick in the seat
As many times as I' ve been on the site, I' ve never been to that part. Thanks for the kick in the seat
08-27-2003, 11:00 AM
#20
Boone & Crockett
Join Date: Feb 2003
Location: Lehigh County PA USA
Posts: 12,157
RE: Speed, or Weight
Despite the risk in sounding like I am firmly in the KE crowd...
...Yeah, but Arthur, that 180 fps arrow will arc more than a rainbow.
Sorry, had to say it.
Seriously though, I guess that we could say that many of our current equipment beliefs are based one upon the other....and this KE/momentum issue is a perfect example....
....in order to flatten our trajectories to somewhat compensate for poor yardage estimation skills the bowhunting fraternity had turned their heads towards faster arrows. Those faster arrows are primarily obtained by lightening their overall weight. Since we lightened the overall weight of the arrows we also greatly decreased the momentum that each arrow carries with it. So, in order to justify our choice of light arrows and their ability to continue to penetrate well with certain setups we have turned to using KE as a basis for comparison.
Would that be somewhat along your line of thinking Arthur?
...Yeah, but Arthur, that 180 fps arrow will arc more than a rainbow.
Sorry, had to say it.
Seriously though, I guess that we could say that many of our current equipment beliefs are based one upon the other....and this KE/momentum issue is a perfect example....
....in order to flatten our trajectories to somewhat compensate for poor yardage estimation skills the bowhunting fraternity had turned their heads towards faster arrows. Those faster arrows are primarily obtained by lightening their overall weight. Since we lightened the overall weight of the arrows we also greatly decreased the momentum that each arrow carries with it. So, in order to justify our choice of light arrows and their ability to continue to penetrate well with certain setups we have turned to using KE as a basis for comparison.
Would that be somewhat along your line of thinking Arthur?