Contributors to this thread:
FOC or Total Arrow Weight
What’s better and why:
I shoot a 523 Gr Easton Axis 300. 10.7 GPI. 25 Gr insert. 10 Gr impact collar. 125 Gr head. Nocturnal nock, wrap and three Q2iarchery fletches. 286 fps. They shoot pretty well.
I can build a stiffer 250 RIP TKO. 8.9 GPI. 75 Gr insert. All other components the same. 523 Gr total weight.
What is better or more effective, since one is light on FOC and the other is heavy on FOC…..Or does it matter since they’re the same weight flying at the same fps? Thanks all you physics gurus in advance.
I'd shoot which ever one groups better.
The second one if it flys well.
I know since I’ve switched to more weight up front it seems my broadheads tune a lot easier.
The first because the shaft is likely more durable. Ashby says arrow integrity is #1 but in the internet age some guys try to split atoms and go with high FOC which is way down the list, That can result in a weaker shaft which can result in arrow failure.
what does randy ulmer say
What's the FOC (percentage) of the first arrow? And the second? As long as the first meets the 7-10% minimum recommended, it's fine. If the second flies better, great.
Does anyone think giving up accuracy for more FOC is a *good* idea?
I think I got a little over 10% when I did the measurements on the first one. I haven’t made the TKO arrow yet….so I don’t know what the FOC is…..but obviously it’s much more…..maybe “extreme FOC” as they say now.
Matt, the 250 is a stiffer arrow, what do you mean the Axis is more durable? Thanks!
If you load the front of that stiffer arrow up, you are indeed making the arrow weaker. That’s what he meant.
There is zero reason to excessively front load an arrow setup out of a modern compound bow. None.
Both are important when it comes to penetration. IMO a heavy arrow with high FOC is the ultimate shaft for penetration. Try each setup and see which flies best.
The arrow does not become weaker. Weight upfront does not change the fiber structure of the arrow. What it does do is that it changes the axis of rotation (end over end) more forward which changes the dynamic spine that could result in too much "tail-whipping" if the draw weight it too high for the arrow setup. This will concentrate the compressive/tensile stress along the axis of the shaft to a shorter length magnifying them further back toward the fletching and the new axis of rotation.
A stiffer shaft is better for penetration regardless of FOC. Shoot the stiffest shaft possible (within reason) that doesn't degrade accuracy.
Adding tip weight does weaken the spine of the arrow. Spend time bare shaft tuning instead of just putting components on that guys tell you to. Most guys on here will move the rest out of center shot to tune the bow, instead of taking the time to tune the arrow instead. If you want to see which flies better, spend time bare shaft tuning. You're gonna find you'll need more the another 50 grains tip weight to get the VAP 250 to tune.
As long as the arrow is flying straight, I can't imagine there would be a perceptible difference in penetration.
Buglmin, I have a Hoyt Carbon Spyder Turbo at 73lbs, so I can yoke tune this bow pretty easily. I paper tune too, walk back tune, broad head tune, etc. I know to keep the rest centered and move all other variables respectively.
I guess what I was hoping to do, going down this rabbit hole, was see if anyone has experience moving to lighter, stiffer shaft, loading up the FOC and see a MEASURABLE difference shooting these two scenarios.
I can very accurately shoot the Axis out to 80-90 yards on the practice range. I have zero complaints……but what if the other arrow offers some advantages??
I wish TBM was still here :)
I would shoot the one made in the USA and never even consider the TKO. I shoot Axis 300 50gr insert.
No, the spine of the shaft is a set property reflective of the diameter, wall thickness, and content makeup whether it's aluminum or carbon fiber.
What varies is the dynamic spine dependent on all the input variables of the applied forces to the shaft.
I cut, add my insert, screw in my point & have no idea what my FOC is. I shoot Aluminum shafts for everything. A 2216 or 2219 hunting & 1716 or 1913 out door targets. No tuning problems, fly awesome & like bullets. I did Carbons 2 years & was "never" satisfied & yes, I do know how to tune..
"...high FOC which is way down the list, That can result in a weaker shaft which can result in arrow failure."
How does that result in a weaker shaft? Higher FOC might require a stronger shaft.
What most fail to consider is that there are two dynamic spine components; one at launch and one at impact, that are opposite. The higher the FOC, the stiffer the dynamic spine at impact, resulting in less arrow flexion and more efficient transfer of energy through the arrow point. That results in better penetration. A higher FOC arrow properly spined for good arrow launch will necessarily require a stiffer/stronger/heavier shaft, a more stable arrow in flight, and better penetration at impact. What's not to like?
So how much penetration are you looking for? On whitetails or something bigger?
“I'd shoot which ever one groups better.”
“There is zero reason to excessively front load an arrow setup out of a modern compound bow. None.”
I couldn’t agree more with with both those observations. With your arrow weight and speed, there’s zero need to sweat the minutiae. Pick whichever tunes best out of your bow and go kill things.
My current arrows weigh around 441 gr with an FOC around 14%.
I already pass thru on whitetails, no issues. I also hunt elk. I’ve passed thru on them with a lesser arrow. I just like the idea that I have confidence in penetration, arrow flight and efficiency. And now the gears are turning on this much higher FOC arrow. It’s a lighter, stiffer shaft with A lot up front. It will be interesting to see and play around with.
Ziek, that was the only thing I was thinking of, driving that new arrow thru my target. I’ll have to see if I can find one 250 RIP TKO and buy just one, set it up and figure it out.
Question - do high-FOC arrows tune as easily?
There is another consideration. Virtually every impact on an animal results in some deflection. If there is any crosswind the arrow is not aligned with its direction of travel. If the hit is not perfectly broadside, some blades engage first. Different blades may impact different types of tissue (ie rib on one blade, soft tissue between ribs on others. Use your imagination). Animal moving on impact. Again think about every and any scenario. ANY deflection at impact is made worse by less FOC. The more weight behind the point, and the greater that distance that weight is, the more force there is to continue that deflection. Vanes stop steering the arrow at impact. At that point the BH is steering based on how far out of alignment the shaft is, and it can be quite significant. FOC and type of BH can make a difference.
Is it THAT important? I guess that depends on each individual hit. But if there's no downside to improving your odds of turning a bad outcome into a good one, even a little, why wouldn't you?
Ziek that was a great post. Outstanding.
I can’t disagree with a thing that Ziek posted, but in why flip side I have a hard time thinking back to any of my ~100 bow kills where I think it could have made a difference.
If I had a 32” DL, I wouldn’t give FOC a second thought. That long a power strike can cure a lot of ills.
Check out the Ranch Fairy on YouTube, he’s done lots of experiments with high foc and has some good video’s about it.
With a compound the advantages aren’t nearly as noticeable and about impossible to quantify at typical hunting ranges (<30yds). Longer distances will better illustrate advantages, but obviously within the limitations of the archer. Bottom line, physics says the higher foc projectile will be more stable in flight… if you can prove it otherwise get the hell off Bowsite and go cure cancer.
How would wind factor in? A higher FOC will be weighted more in front, so wouldn't the wind impact the lighter tail more than a more evenly weighted arrow? I don't think about wind much because I am a short range whitetail hunter, but just trying to wrap my head around it.
Very high FOC is pushed by a small group of “ Look at me” internet influencers….where on the contrary its worth noting;
1) Easton recommends avg FOC (8-16%)
2) Every single experienced bowhunter I know places low to no priority on FOC.
3) every single pro in every single archery discipline shoots an avg FOC- not one single legit pro shoots uber FOC
Who are you going to believe? Grin
The “heavier” tip, weight foc will maintain its path of trajectory. The more weight distributed to the front the less influential the rest of the projectile becomes. Higher foc will result in less deflection from its intended path.
12yards, Here are my thoughts on wind impact. The greater the FOC the more forward the center of gravity is and the more leverage the fletching has to steer the arrow over the broad head. Wind blowing on the side of the arrow may make that a bad thing because the higher surface area of the fletching would have a greater impact on the back of the arrow than on the front. However at the speed that arrows travel today the greater leverage that the drag from the fletching gets from the increases leverage trumps the impact of a side wind. If wind is a big concern a greater twist of angle to the fletching will provide added drag which really helps to straighten out the arrow in wind.
Also I think that wind drift is dependent on arrow profile area and speed and is pretty much independent of FOC.
1.75 long 1/2” high fletch, proper spine for 250 grains up front and length of arrow. Draw weight. 26% FOC
This is a 30” arrow
1.75 long 1/2” high fletch, proper spine for 250 grains up front and length of arrow. Draw weight. 26% FOC
This is a 30” arrow
Goyt, it’s actually the opposite. The more FOC the less fletching is needed. Excessive fletching is wasted energy.
The best analogy for FOC is how a passenger jet is designed versus a fighter jet
fighter jets need to maneuver and change direction quickly so the center of gravity is more in the middle to pivot on
passenger jets are built with a high FOC and can almost fly themselves and are harder to change course quickly
All things equal, except weight distribution, the projectile with the most weight forward will be more resistant to deviation.
The jet analogy isn’t perfect by any means. And may not even be relevant :>))) Because a jet is propelled from the center and has to land on wheels so isn’t much like an arrow at all I guess.
Who has played jarts? Make your own with arrows and tell us which weight distribution you prefer.
AS, I bet them arrows fly like a thing of beauty. I love the feeling of a nicely weighted arrow launched via stick n string.. the feed back and trajectory is just… aaaaah
Ohio, I have slo Mo video of the arrow flight. It recovers from the initial flex quicker and your right. It flys like a laser. And the penetration is impressive
Altitude Sickness, I think that we are saying the same thing. I certainly agree that the higher the FOC the easier it is for the fletching to control the arrow. My point was that with a larger FOC the wind has an increased advantage to push the fletching end of the arrow more than the front but that IMO the advantage gained by the drag on the fletching from a larger FOC is more significant so even in wind a higher FOC is better which is also consistent with your statement.
"Very high FOC is pushed by a small group of 'Look at me' internet influencers….where on the contrary its worth noting;"
Well, crap. I just found out that I'm not an experienced bowhunter. By the way, the influencers and experienced bowhunters that don't push the "look at me" on FOC push the "look at me" in the opposite direction. I wouldn't follow an experienced bowhunter or archer pro off a cliff either...
Sometimes we discuss what is necessary when asked what is better. I have some arrows that are not as good in theory and probably not in practice either that I use because they are still extremely effective, and I have them.
Its no wonder that we cannot discuss emotional issues, when we cannot even agree if weaker arrows are more flexible or more likely to break.
If you add weight, then why would you not want it in the part that does the killing?
FOC is an emotional topic.
Feelings bout to get hurt… I guarantee every Olympic archer, or their coach, makes sure they’re heavy up front.. calculated or not I bet it’s over 15%. More likely around 20%
"...thinking back to any of my ~100 bow kills where I think it could have made a difference."
Matt, respectfully, those are irrelevant. It's the ones you hit and didn't recover you should be considering. Of course those are all conjecture. All you can say is 'maybe only if I did this in my seat-up'. Since it's usually impossible to really know what went wrong, I look to the physics to give me ANY possible advantage, no matter how small.
And to be clear, I don't use or promote ridiculously high FOC. The more the better, within reason. It's just too hard to assemble a balanced arrow for the higher speeds of compounds. I try for about 9 gr/# of draw weight for total arrow weight, and 15% or more FOC. And the lower the power of the bow, the more important it becomes. My wife's grains/# and FOC are a bit higher than mine. With other aspects of my choices, mostly BH, both my wife and I get excellent results.
"Matt, respectfully, those are irrelevant. It's the ones you hit and didn't recover you should be considering. Of course those are all conjecture. All you can say is 'maybe only if I did this in my seat-up'. Since it's usually impossible to really know what went wrong, I look to the physics to give me ANY possible advantage, no matter how small.":
Understood and I should have clarified, I don't have any of those I can think of. Every animal I have hit and lost has been either shot placement or scapula-related. Not one deflection or head scratcher that I can recall. Even the couple of "failures" I have experienced have been BH-related (folded ferrules) but thankfully resulted in recovered animals.
Tim257, right there with you, I said the above but know of a couple of instances where guys tried to get high FOC and keep the total arrow weight down and had shaft failures on impact (presumably due to side force cause by a deflection). One resulted in a really long afternoon but a successful hunt after a follow-up shot (antelope), but a couple resulted in lost animals (elk). Ashby has FOC quite a ways down the list compared to structural integrity (#1) for a reason.
9 grains per pound of draw weight?! That would mean I would need a 720 grain arrow. C’mon now…
Definitely need details regarding these shaft failures at impact. I think everyone could use this info.
One was a Carbontech Cheetah and I am not sure about the other 2.
How did they fail? I can’t imagine a shaft failing under its own momentum.
Hit a bone at an angle and the shaft sheared behind the insert if memory serves. When you start pushing 7.0 gr/", my sense is that you lose a lot of margin for error.
Anything can happen when you hit bone, I don’t care if you have foc, fda, cod, or fha. We all know hunting is like real estate.. location location location… in more ways than one.
Matt - noted your comment on losses related to scapula hits - to me that’s the reason to shoot a heavier setup with higher FOC. If I hit them in the ribs every time I wouldn’t even think about it as about anybodies setup will put the arrow in the dirt on the other side. I always plan for the worst. If I screw up the shot I want that arrow to not fail on the scapula.
Just my .02. Lee
Just shoot a reasonable weight arrow and forget about it. In bowhunting there is only about 100 other things we should be worried about over FOC.
Lee, I believe that if my friend had the same arrow weight but a higher GPI, more durable shaft (and less FOC), he likely would not have broken the shaft on that hit. Would he have penetrated the scapula? Who knows. The point is that FOC in a vacuum can hurt more than help.
Getting into this conversation late... Didn't read all of the posts... Here's what science tells us for certain...
We already know that shot placement and a durable sharp head are crucial. After that, use enough weight to achieve good momentum for the game hunted. Tune your setup so the arrow travels without wobble & fishtailing. Now for the science part... it matters not where the weight is throughout the arrow as long as the aforementioned items are good. Picture in your mind an arrow falling straight down from above. That arrow will penetrate the same with 10% FOC as it will with 30% FOC. Honest...
^^^ A free falling object at terminal velocity relative to it's own mass is not the same dynamic as when additional force is applied for forward motion and impact of a projectile...
You cannot replace a vector with a scalar.
I’m not sure why this is such an emotional topic, but I stand by my comments.
A lawn dart comparison, really?
What the very high FOC folks forget is the law of Physics rule of equal and opposite reactions. An arrow is launched under extreme tension. The additional mass on the tip can be a benefit once in flight but its a big destabilizing force on the launch. Put a lawn dart….or one of the soda straws Ashby uses to trick his followers in a bow and see what happens.
I look at it like this; If Ashbys original criteria of 30% + FOC…(edited, 39% was a typo, Ashby original paper on FOC was a “Threshold of 30% plus) or even over 20%FOC was better, every single pro would be using it…and Easton would be all over it. Nope, not a one.
If you think it works for you, then great.
Here's trivia.... granted not a broad head application...
Frank Pearson my occasional mentor was a champion back some time ago. (His wife Becky was also).They call it NFAA or something, not 3D. He got arrows by the case from Easton, a sponsor.
Anyway he'd just got back from South Africa where he won a 100 meter special contest. He was showing me the trophy. We were in his shop at his home in Vail, Arizona. I think Ulmer was there also.
Anyway (ramble, ramble)..I asked him what his FOC was on his arrows. He had never checked them, he just tuned for good flight.
We checked them out of curiosity and ....... they were a little less than 2.5%. Truth.
I think over the years my hunting arrows ran from 6.5% to 11% depending on my setup. 3D likely 4% to 6%
No point in post, just felt like rambling. ;)
Thanks for the responses. I think we’re all missing something in translation. I’m not taking the same arrow and adding more weight upfront……
I guess I was more interested to see if the two arrows would react the same……..since one is 300 spine and the the other is a 250 spine with 50 Gr more upfront…..effectively creating a similar effect…..but I was hoping a physics guy would chime in. :)
I’m seeing it as the arrows will react similarly. But the 250 might be more effective at lots of the stuff already mentioned. But I have to find a place I can buy one 250……and that’s more difficult than one can believe.
You’re looking at it wrong. At this point you are only conversing with yourself as NO ONE, I’ll repeat slower.. NO ONE is advocating for extreme foc. So no need to attempt to derail the topic any further. The op asked a specific question, choice A or B, which is the better option? If anything you’re the emotional person in the room.
Beendare - you might want to go back and edit your most recent post...
Blood (OP) - "physics guys" have chimed in, take it for what it's worth.
Shoot a properly spined fmj and your good, you want foc add a 125gr bh, there u go
Thanks Carcus. But at 11.5 - 12 GPI on the FMJ’s you’ll need ALOT more than adding a 125 Gr broadhead to give you heavier FOC on those. Great arrows however.
FMJ's and chasing FOC are mutually exclusive.
"FMJ's and chasing FOC are mutually exclusive."
I shoot FMJ 300, 28 1/4" with 14.9 % FOC without even trying very hard. 150 gr. BH + 16 gr. outsert.
My wife shoots FMJ 500, 25 1/4" with 16.8 % FOC with 125 gr. BH + 20 gr. outsert.
125 gr. up front is really pretty light if you're shooting over 60#.
I shoot FMJ 400 with either 150 gr or 175 gr. head and I have a great FOC and a strong arrow.
"125 gr. up front is really pretty light if you're shooting over 60#."
Based on sales across the industry, 125 gr. is on the heavy side regardless of draw weight. Looking at Lancaster Archery as one example, they list 63 125 gr. BH's, 61 100's, and only 12 150's. Volumes by SKU would only further demonstrate that.
Shooting a 150 gr, head essentially means you are trying hard just be virtue of deviation from the mean/mode in terms of head weight.
^^^ customer preference due to marketing is irrelevant with flight dynamics. Doesn't mean a thing...
"Shooting a 150 gr, head essentially means you are trying hard just be virtue of deviation from the mean/mode in terms of head weight."
Maybe some people just like a little more steel in their broadheads. Not a bad strategy.
Lancaster Sales?? blahahahaha… I think Biden could conjure up a better argument about cockroaches and his blond leg hair.
Tuned is tuned. Center shot and the race of the arrow to stabilize in relation to where weight is applied, is a mute point if the arrow is tuned. Regardless of foc.
I like a heavier broadhead for the extra steel in it. I don’t think it does anything for penetration out of a modern compound. Because of my reasoning in my first paragraph.
However, I do believe it helps penetration with finger shot trad bows. Because fingers do funky things versus a release on a compound. But, in my opinion, there is a point that shows no benefit to extra upfront weight.
One of the better traditional bow shooters ever born is Rick Barbee. He’s tinkered with this stuff long before Ashby put out his “report”. He’s got a long draw and shoots 65-70 pound trad bows even at close to 70 or more years old. His findings were in contradiction to Ashby’s extreme foc.
Rick claims anything over 18-19% is no benefit for penetration. Or accuracy. I see no reason to doubt him. Especially after watching him shoot out candles at 60 yards in the dark. Or, tennis balls at 90 yards during daylight practice. Since most sponsored bow shooters I know in the compound world are looking for the 13-14% foc, I’m guessing there’s merit to the idea that it has its place for both. I just don’t think it’s a huge issue in the realm of modern compounds.
Am I right? I do not know. But, after shooting quite a bit of stuff with both trad bows and compounds, it’d take a lot to convince me I’m not. Or, I’d have to want to research it more then watching this paint dry. That’s about how important I think it is for a modern compound setup.
Ok. Here’s an update. I was able to find the RIP TKO 250’s and had to buy a dozen shafts. Just made up 6 arrows like I described. Nock tuned them and fletched them. They are almost 17% FOC. They all come in at 526Gr. and are all 286-287 FPS. I’ll shoot them for the next week and compare them. Right now, I’m liking the way they came out and paper tuned very nicely. We’ll see….