I'm asking mainly about total weight. Everything I seem to find on the topic is in terms of grains/# of draw weight which is a measure that I reject. I can take a "light" arrow from a 70# bow and shoot it from a 50# bow and all of a sudden it's a "heavy" arrow? No, it's the same arrow and still weighs the same, except now it's traveling slower. Maybe I'm missing a key point in how the grains/# draw weigh figures into the equation. If so, please educate me. Share your thoughts. What is a heavy arrow?
I look at a heavy arrow by how many GPI (grains per Inch). But you could call a heavy spine a heavy arrow. If your shoot a proper spined arrow out of a 70 lbs bow, that same arrow most likely wont be the proper spine for a 50 lbs bow.
the minimum weight of an arrow is by grains per inch and changes as the poundage changes. I use the same yardstick for heavy arrows. meaning as the weight goes up what I consider a heavy arrow goes up. But that's just me. personally I say figure it anyway that best suits your purposes.
It's somewhat relative...what is fast? Where it really plays into the, ahem, equations is the physics. KE or momentum both affected (in fact directly proportional) by mass of the arrow-strictly based on the math. But the arrow mass also had an effect on the arrow speed (eventually) in other words if I have a bow shooting and arrow (maybe 400gr) at 300fps and I were to add weight (like 100gr more per test), I should quickly see the arrow speed off the bow slow...draw weight not changed simply the arrow weight. Ignoring all else (foc, fletching, etc) probably not ideal. Similarly, if I have 1 bow and I alter the draw weight only, there will almost guaranteed be some impact on speed of the arrow. The same bow shooting 70# just won't give the same results (speed) as 40#. Make it, as much of a science as you'd like. Experiment to find what works best for you YMMV. Tfox used to have a ton of threads on these topics hit the archives...
Based off IBO standards a lite weight arrow is 5 grains per pound of draw weight. Bow manufactures will not warranty a bow if it is damaged shooting an arrow under 5 grains per pound. Determining whether an arrow is lite or heavy directly relates to the bow that it is being shot from. A 40 pound bow shooting a lite weight arrow at 5 grains per pound would be a 200 grain arrow. That same arrow could cause a 70 pound bow catastrophic damage.
A step further, a bows efficiency really determines what is the top end of a heavy arrow. There is a point where adding more arrow weight will cause a loss of KE, not just speed. Take the weight of your arrow in grains and multiply it by the speed of your arrow squared. Then divide it by 420240. This will give you your KE. Now add weight to your arrow maybe 20 grains at a time and redo the formula each time. Soon you will stop seeing your KE rise by adding more arrow weight and it will actually decrease. Generally a heavy arrow is 6.5 grains per pound or heavier. Using the steps above will tell you when you have reached an arrow to heavy for your bows efficiency.
A heavy arrow is relative. I shoot a 496 grain arrow which a lot of people would consider heavy for my specs but a lot also shoot a lot heavier arrow. I shoot for whatever arrow weight gets me around 275 fps
About 7 to 8 times your draw weight would be considered heavy. I don't base that on anything other than my experimentation with arrow weights.
