Too late for this season, but I'm going to be changing arrows fairly soon. I have narrower my choices to a couple choices. What I want to know is, is there a way to calculate the speed to would be shooting with new arrow weight given old data? I'm currently shooting CX pile drivers @ 490 grains in the 260/270 fps range. Is it possible to guess what the fps rating would be at around 400 grains?
Bing or Google(if your old school lol) archery calculator.It will bring your to site where you can click Arrow Weight/Speed calculator.I use that and found it very accurate.Then take your fps reading and go to Gold Tip and use their KE/Momentum/FOC Calc that's what I do....Im going out on a limb and say maybe 290ish just a guess...
I was curious as well for your setup,so I ran the info myself....Not familiar with Hoyt's but I put an ibo or ata in this case, rating of 335(Not sure how close that is),29/70,400 grain arrow,with 20 grains on string and got 301FPS.
Very much appreciated, captain clutch. Your post told me what to search for. Ran the numbers myself and the results are as follows. Hoyt Vector turbo-70 pounds, 29", ibo 340 Arrow- 400/410 grains total weight. Estimated speed- 306 @ 400/301 @ 410
Kinetic energy was around 89 foot pounds. Not to sound snippy, but I don't think momentum will be a huge issue. I'd have to see how penetration is on the block at home for sure, though.
Just make sure if you drop weight, you keep enough spine to tolerate the torque of that bow... I shoot a 62# Alphaburner, and have to put a 100gr tip on the end of a 29" .340 rated arrow or it shows weak spine. So trying to drop weight, you're gonna need to look for a very stiff .300 spine likely to keep enough FOC to make your arrow fly well. With that set-up, something in the 475gr range will actually optimize your energy usage of your bow, keeping it quiet but moderately fast as well... Remember that a bow has "stored" energy when drawn, when you release it that energy is let go, the more noise you hear, the more energy is being wasted and let off as sound. I'm shooting a 420gr arrow out of my 62# Alphaburner, similar spec to the Turbo you shoot, and it's relatively quiet, and hit like a ton of bricks for a 60# bow. If I remember correctly I think it was sending them out at about 279-282 when I chrono'd it, which is getting 73 ish ft/# of KE. And that is enough to kill nearly any animal in North America with a well placed arrow and dependable broadhead. In comparison, one of my old 70# bows shot the same arrow and tip combination at 265fps, and yielded only 65ft/# but it was only 310 IBO being shot at 70#.
I belive it's 1 fps for every 2.5 grains, approximately. Also, momentum = penetration. Kinetic energy only vaguely applies to archery, if at all (more suited for the gun world). I'm not saying don't go to a lighter arrow. Mine are right at about 400 grains.
Just bought 6 Easton Bowfires. From the specs, I'm gonna be in the neighborhood of 440 grains. So I dropped about 50 grains.
Yes. Think of it this way, would you rather get hit in the stomach by a 10 lb bowling ball going 15 fps or a 15 lb ball gowing 10 fps?
