Minimum energy for mechanical broadheads??
09-26-2005, 11:31 AM
#11
Join Date: Sep 2005
Location: Senatobia ms
Posts: 153
RE: Minimum energy for mechanical broadheads??
ORIGINAL: Jeff K
Actually that is 128 Lbs of KE, but I mean come on I don't think you are flinging a 570gr arrow at 318fps that is a bit ridiculous, a IBO rating for your bow is 326-334, remeber IBO system uses a 350gr arrow at 30" draw and 70lbs pull. Ok your arrow is 220gr more than that and 30gr more than the AMO rating which is 540gr at 30" and 60lbs pull. Mathematically I don't think that 2 lbs pull difference from the IBO testing is going to catapault you to 318fps, not to mention you lose speed when you decrease your draw length. If I had to guess a speed, it would be about 265fps-290fps, no more because of your outstanding arrow weight, which would put you at 99 lbs of KE. You lose speed at 29" draw, you lose speed because of the arrow weight, and you gain a little back at 72lbs pull.
ORIGINAL: PatriotDually
I am shooting 72#'s with 29" draw and 570 grainarrows, so i am producing about 120lbs of KE. But yea i hear you need about 55lbs to shoot the Nap spitfires.
I am shooting 72#'s with 29" draw and 570 grainarrows, so i am producing about 120lbs of KE. But yea i hear you need about 55lbs to shoot the Nap spitfires.
09-26-2005, 07:09 PM
#12
Join Date: Nov 2003
Location: Yorkville, IL
Posts: 423
RE: Minimum energy for mechanical broadheads??
ORIGINAL: PatriotDually
Hmmmm i guess you are right Jeff, being im pretty new to this my bow was chrono'ed when i first bought it, only had a peep site and i was shooting his arrows at that time. They were carbon extremes not axis, so they were lighter, but the only thing that has changed since then is i added a loop and the heavier arrows so i did prolly loose about 20 feet or so. Im headed over there today to get my arrows re-fletched, ill get him to shoot it thru the chrono today and see what she is doing
ORIGINAL: Jeff K
Actually that is 128 Lbs of KE, but I mean come on I don't think you are flinging a 570gr arrow at 318fps that is a bit ridiculous, a IBO rating for your bow is 326-334, remeber IBO system uses a 350gr arrow at 30" draw and 70lbs pull. Ok your arrow is 220gr more than that and 30gr more than the AMO rating which is 540gr at 30" and 60lbs pull. Mathematically I don't think that 2 lbs pull difference from the IBO testing is going to catapault you to 318fps, not to mention you lose speed when you decrease your draw length. If I had to guess a speed, it would be about 265fps-290fps, no more because of your outstanding arrow weight, which would put you at 99 lbs of KE. You lose speed at 29" draw, you lose speed because of the arrow weight, and you gain a little back at 72lbs pull.
ORIGINAL: PatriotDually
I am shooting 72#'s with 29" draw and 570 grainarrows, so i am producing about 120lbs of KE. But yea i hear you need about 55lbs to shoot the Nap spitfires.
I am shooting 72#'s with 29" draw and 570 grainarrows, so i am producing about 120lbs of KE. But yea i hear you need about 55lbs to shoot the Nap spitfires.
Using my best judgement, I am guessing you are shooting a 30" arrow at 9.5gpi, guessing your insert and nock add about 28gr, and your fletchings add about 23gr, my guess would be with a 100gr spitfire you are looking at a total arrow weight of 436gr, which will probably mean you are near the 290fps range, which is fast as he**, so don't be disappointed with that if it was your getting, still puts you at 81 lbs of KE with those weights and at 290 fps, which is plenty enough to kill a deer!
Let me know what you are shooting!
09-26-2005, 07:24 PM
#13
Typical Buck
Join Date: Aug 2005
Posts: 774
RE: Minimum energy for mechanical broadheads??
Yeah,you would need to be shooting 308fps with a 570gr arrow to achieve 120 ft lbs.I was going to ask you about your speed until I read the other posts.
When you get your speed you can go to jacksons archery and use the KE calculator.
www.bowjackson.com
Anybody want to place bets on his actual speed?I would guess around 280,..Are you sure you mean a 570gr axis?[&:]I mean it would take a 32.5" axis 300(the longest length,and biggest sized shaft they make),and a 175gr tip to make an axis arrow weigh 570gr.[8D]
There is also an Arrow weight calculator there with axis figures.Hope I helped.
Sorry for the excessive use of smilies,but I wanted to show a friendly post,and didn't want you to think I was giving you a hard time.
When you get your speed you can go to jacksons archery and use the KE calculator.
www.bowjackson.com
Anybody want to place bets on his actual speed?I would guess around 280,..Are you sure you mean a 570gr axis?[&:]I mean it would take a 32.5" axis 300(the longest length,and biggest sized shaft they make),and a 175gr tip to make an axis arrow weigh 570gr.[8D]
There is also an Arrow weight calculator there with axis figures.Hope I helped.
Sorry for the excessive use of smilies,but I wanted to show a friendly post,and didn't want you to think I was giving you a hard time.
09-27-2005, 09:09 AM
#15
Join Date: Sep 2005
Location: Senatobia ms
Posts: 153
RE: Minimum energy for mechanical broadheads??
Damn Jeff lol.. you know ur bows and setups..
I apologize for my ignorance, my arrows are 30.5" long and yes they are 340's that weigh around 430grains.We shot 3 arrows thru the chrono my best was 291fps , slowest was 289.8.He said that puts me around 80lbs of KE. Ty was telling me if i went with a lighter arrow i could get back to 300fps, but i would loose KE, so im gonna stick with these arrows, they hit hard as hell, and its still the fastest bow in his shop. And really the only reason i wanted this much speed was so i could shoot one pin out to 30yrds. It really makes it easier to judge distance, plus i have been shooting out to 65yrds all summer, i am dialed in, and aint changin nothin now lol....Man only 4 more days!!!!! Gawd im so freakin pumped i cant sleep at night! lol....thanks for yalls input Jeff and Ranchand99
I apologize for my ignorance, my arrows are 30.5" long and yes they are 340's that weigh around 430grains.We shot 3 arrows thru the chrono my best was 291fps , slowest was 289.8.He said that puts me around 80lbs of KE. Ty was telling me if i went with a lighter arrow i could get back to 300fps, but i would loose KE, so im gonna stick with these arrows, they hit hard as hell, and its still the fastest bow in his shop. And really the only reason i wanted this much speed was so i could shoot one pin out to 30yrds. It really makes it easier to judge distance, plus i have been shooting out to 65yrds all summer, i am dialed in, and aint changin nothin now lol....Man only 4 more days!!!!! Gawd im so freakin pumped i cant sleep at night! lol....thanks for yalls input Jeff and Ranchand99
09-27-2005, 08:05 PM
#16
Typical Buck
Join Date: Aug 2005
Posts: 774
RE: Minimum energy for mechanical broadheads??
OK OK I lost!![8D]I wasn't sure of the arrow weight.I gaurantee It will shoot 280fps with a 570gr arrow!Well,PD you are still shooting very fast,and still haveboo koo..KE.Good Luck!!
Well,PD you are still shooting very fast,and still haveboo koo..KE.Good Luck!!
