In reality, those calculators don't do a very good job with arrow weight, or DL changes.
Originally Posted by MLN1963
Your B-I-L's bow is shooting about 3 F.P.S. slower than the calculator says it should be.
Okay punched numbers and i added 6.4 gr for d loop 6.5 for meta peep and 31.55 grains for cat whiskers 70# 27" draw its saying 285.66 which is really close it took off 10 fps for the whiskers wow!! if i took the whiskers off and grained my arrow out to 350 it showed 301.13 which would be real close to ibo at 10 fps per inch on draw then take off for peep and d loop....
The whiskers don't rob as much as the calculator says they will.
Originally Posted by sway
I have hard data of a 70# NOS B Cougar, shooting a 380 grain arrow at 305 F.P.S. at 28" of DL.
That was with 14" limbs and a 6.25" brace height. With 13" limbs, a 27" DL and a 5.25" brace height, it would be the same speed.
@mln just punched ur b.i.l numbers in and with nothing on the string it showed 280. Im shooting blazer vanes by the way. Ur also only talking about 2fps faster on my bow. And as far as the whiskers taking that much off i have no idea just what it shows but comes out about right with where im at..
Last edited by sway; 01-16-2011 at 09:35 PM.
I suddenly don't care about your problem.
Originally Posted by sway
I sudddenly realize i didnt ask u to care...
Short draw lengths doomed
Having rattled off. Any IBO listed for a bow can be math-ed to get a close idea of what you'll really have. See following.
General rule of thumb;
2 fps / 1 # of Draw Weight
10 fps / 1" of Draw Length
1 fps / 3 grains of arrow weight
1 fps / 3 grains of weight on the string
There are "tweak" procedures that can add a bit to figures for the older Firecats and should work for the 400. Search ArcheryTalk. Fine tuning (center shot off can cause 10 fps loss), arrow to poundage, speed buttons, center serving to be no longer than necessary (4" max), string stop adjusted for best results and of course stay within one arrow length of the chronograph when adjusting buttons and stuff. Yes, a chronograph can be used to set center shot.
All said and done, some rigs perform outstandingly for some reason. Build, tolerances held, I don't know.
Beyond all doubt there are some fast bows, but then there ain't enough salt to take for some speeds given for how the bow setup is....
Just to get this out in the open, I'm not pushing the Assassin, it's just that I have hard numbers for it. My local Martin dealer doesn't have a chronograph so I like to play with the calculators.
If I use the B.I.L. numbers it gives the numbers his came with, 279 fps. I got 279 with 20 grains on the string and 285 without anything on the string. These are just numbers and the page even says it will be close to what the chrono says. They are fun to play with while trying different combos to see how it affects your arrow speed.
At the top of that page it says try our new calc. Here is the link.
Last edited by MLN1963; 01-17-2011 at 07:04 AM.
BTW this discussion is great because I am a lot learning things from you guys. My learning curve is going straight up with all the help around here. Thanks!
Last edited by MLN1963; 01-17-2011 at 09:08 AM.
I got 2 bows that will hit the 300fps+ mark at less than 60 lbs and a 26.5 draw lenght. A Hoyt Ultratec with Spirals and a Matthews Prestige. The Shadowcat with the Cat Cams wan't even come close. But, boys and girls, neither the Hoyt or the Mathews are as forgiving as the Martin. I with Sonny on this, forgivest is way more important than a few fps. My son in his first year shooting ASA (known distance) took his indoor bow and smoked everything he shot, at a whooping 215 fps. So speed ain't everything, a miss is still a miss. Anyway, I would like to see these bow people start using real life numbers on their bows. And BTW, it's always a little funny when you go into a archery shop and they start telling you that you can shoot such and such brand X bow at 320fps at 50 lbs draw and I tell them WHY the speed limit is 280 everywhere I shoot.