I shoot a 27" fmj with 100gr tips. I don't have a scale that does grain. How do I figure out my kinetic energy. I shoot a Matthews z7 at just shy of 70# with a 28" draw. Can Ke be figured with this info or do I need to shoot it threw a chronograph? Sent from my iPad using Tapatalk HD
You can estimate the KE from this information. 1. Multiply the grains per inch weight of the arrow with the length of the arrow. 2. Add the tip weight (100), vanes (19.6), nock (11) and insert (11), that will get your total arrow weight 3. The ibo of a z7 is 333, subtract 10 fps for every inch less than 30, so 313 fps 4. Take your arrow weight and subtract the 350 grain arrow to get the difference of your arrow and the ibo arrow 5. Your bow will loose speed at 1 fps for ever 2.5 grains. So take the difference and divide by 2.5 6. Take the answer to #5 and subtract it from the 313, that will give you a new estimated speed in fps Now that you have your new esticmated speed, you can go online and find an arrow KE calculator. lastly, don't put too much stock in the KE of a setup, it's only a very little piece of the puzzle.
There are special calculators that do the calculations for you... Some are better than others. For example, some want you to know your arrow speed while others ask you the IBO rating and then what your draw length and poundage - fill in the blanks on the rest and it gives you an estimate.... I like the bottom one... Here are a couple of examples: GT Calc Archery Calculators-Calculate Arrow Speed, Kinectic Energy,Front of Center %
If you want the correct info, you need to shoot through a chrono and weigh your arrows. Anything else is an estimate and ke changes quickly with the wrong info. Sent from my SAMSUNG-SGH-I317 using Tapatalk 2
So I shot my bow threw a chronograph yesterday and was a bit disappointed. I am shooting at 266fps. I shoot a matthews z7 with a 28" draw drawing 70#. I shoot 27 inch fmj arrows with 100 grain tips. I was expecting more than 266 I was expecting closer to 300. Anyway what can I do to get that faster. Sent from my iPad using Tapatalk HD
Why do you think you need faster? More poundage assuming spine can handle it or lighter arrows are your options. Looks like you mught be maxed out on poundage so that leaves lighter arrows. But there is nothing wrong with your setup. Sent from my SAMSUNG-SGH-I317 using Tapatalk 2
