Any science behind offset degree vs arrow weight or FOC?

[sacklunch]

Build a set of arrows after years of paying custom arrow makers.

Had some great help from some folks on here getting weight dialed it, bare shaft and nock tuning, shooting bullet holes and bare shafts are grouping about an inch at 20.

I'm ready to fletch. My bow spins shafts left. So I guess a left offset? My question is, as advanced as arrow building has become, is there any science between arrow weight, length, FOC, etc as it relates to offset in a 3 fletch? I'd like to keep these fast, leaning towards a 2.5 or 3 deg. I've got a short draw at 27", pulling 75# on a 452gr arrow with 175 up front and no wraps. Carbon to carbon is 26"...assuming longer arrows can get away with less offset but since mine are pretty short is it best to lean towards that 3 deg (or more?)

I'd like to not have to fletch multiple times, but can if that's the best suggestions. Maybe fletch 3 or each? I'm shooting tac driver 2.75s and planned to fletch them 1" from end of carbon.

Any inputs, suggestions based on experiences?

 

[Insomnia]

You are so overthinking it

 

[sacklunch]

You are so overthinking it

Devils advocate only...then why do they make variable offset jigs?

 

[S.Clancy]

Devils advocate only...then why do they make variable offset jigs?

The same reason they keep making new rifle calibers....they sell.

 

[Beendare]

I did a test years ago in my compound [back when I could really shoot well]

I tested Helical blazers [AZ Eze fletcher] against my clamps at about 1.5 degree offset at 50y.
Zero difference...both shot identical groups.

RH/LH is a pick em...I like RH.

FOC is what it is...massive FOC creates problems

The keys to making you own arrows is;
1) Don't be under spined...over spined still tunes well and makes for a durable hunting arrow
2) mill the ends of the shafts perfectly square- they ain't square right off the saw
3) alight the components perfect- and spin check on a jig- no BH wobble

 

[sacklunch]

The same reason they keep making new rifle calibers....they sell.

Sounds nice, in theory. But the hole in your arguement is that different caliber rifles (to an extent) can serve a different purpose.

 

[MattB]

Fletch your arrows and go shoot your bow. Time spent mentally masturbating about whether 2.5 degrees or 3 degrees of offset would be better will not improve your success in the field.

 

[sacklunch]

Fletch your arrows and go shoot your bow. Time spent mentally masturbating about whether 2.5 degrees or 3 degrees of offset would be better will not improve your success in the field.

But it can/could improve arrow flight. Some things matter more to others. I prep brass for my rifles in the same steps most BR shooters do. Some may not worry about perfection, some do. Some are happy with some off the shelf shop built arrows/ammo. I got into handloading because I was not. Same reason I decided to build my own arrows. No reason not to invest time in an offset if it matters. Same reason behind 3 vs 4 fletch, some claim 4 steers broadheads better, some don't. The question was if any actually science supported claims like that. If you don't care then move along...or mentally masterbate, as you put it, over how much better you'll be in the field because you didn't care what your fletched offset was? Whatever floats your boat.

 

[S.Clancy]

I fletch my own arrows because, in order:

1. I save $$$
2. It actually saves time not having to drive to and from shop
3. It saves aggravation not having to deal with a shop.

Form, tuned bow and properly spined arrows are 99.9%+ of shooting a bow accurately. Anything beyond that is really just guys thinking they can buy their way to the 12 ring.

 

[MattB]

But it can/could improve arrow flight. Some things matter more to others. I prep brass for my rifles in the same steps most BR shooters do. Some may not worry about perfection, some do. Some are happy with some off the shelf shop built arrows/ammo. I got into handloading because I was not. Same reason I decided to build my own arrows. No reason not to invest time in an offset if it matters. Same reason behind 3 vs 4 fletch, some claim 4 steers broadheads better, some don't. The question was if any actually science supported claims like that. If you don't care then move along...or mentally masterbate, as you put it, over how much better you'll be in the field because you didn't care what your fletched offset was? Whatever floats your boat.

There is just as much science behind the optimal degrees of helical as there is the optimal weight distribution on stabilizers if that helps. Similarly, there are just too many variables to distill it down to a nice, clean answer of "x degrees" that applies to every possible combination of vane length, vane height, vane stiffness, point type, dynamic spine/reaction, bow, shooter form, etc. If you really want to nerd out, trial and error is the only way to determine if a specific offset works better than others for your set-up.

But if you want to arrive at a quantitatively supportable, highly scientific answer, consider that you can purchase jigs that will vary from 0 - 6 degrees of offset.

((0+6)/2) = 3. So, 3 is the answer.

 

[sacklunch]

There is just as much science behind the optimal degrees of helical as there is the optimal weight distribution on stabilizers if that helps. Similarly, there are just too many variables to distill it down to a nice, clean answer of "x degrees" that applies to every possible combination of vane length, vane height, vane stiffness, point type, dynamic spine/reaction, bow, shooter form, etc. If you really want to nerd out, trial and error is the only way to determine if a specific offset works better than others for your set-up.

But if you want to arrive at a quantitatively supportable, highly scientific answer, consider that you can purchase jigs that will vary from 0 - 6 degrees of offset.

((0+6)/2) = 3. So, 3 is the answer.

I stopped listening when you said mentally masterbate.

 

[Billy Goat]

Most of it is a matter of having enough, usually more isn't really better.


You need enough drag on the back to counter what you have on the front. The bigger wings you have on the front, the more drag you need on the back.

Drag can be from vane height, or offset/helical, to some extent length but height seems to do a lot more than does length. Of course more vanes give more drag for same vane versus same vane.



I guess it's like twist in a barrel, for the most part if you have enough to stabilize, that's all you need.

 

[sacklunch]

Most of it is a matter of having enough, usually more isn't really better.


You need enough drag on the back to counter what you have on the front. The bigger wings you have on the front, the more drag you need on the back.

Drag can be from vane height, or offset/helical, to some extent length but height seems to do a lot more than does length. Of course more vanes give more drag for same vane versus same vane.



I guess it's like twist in a barrel, for the most part if you have enough to stabilize, that's all you need.

Thanks, makes sense. Shooting short little tac driver 2.75s...might lean towards slightly more offset to start and see how they do with BHs.

 

[Fisherhahn]

I guarantee that you, me, and 99% of other people on this site are not good enough shots to be able to tell the difference. The time spent overthinking this would be better spent shooting arrows, working on your form, broadhead tuning, e-scouting, etc.

 

[sacklunch]

I guarantee that you, me, and 99% of other people on this site are not good enough shots to be able to tell the difference. The time spent overthinking this would be better spent shooting arrows, working on your form, broadhead tuning, e-scouting, etc.

For some, arguably you, mediocre is acceptable. For some it's not. Great inputs though, thanks for sharing.

So form and tune are important but the right helical or vane # is not? what about nock tuning or spine aligning? Also a waste of time because you don't shoot well enough to see a difference?

Shitty handloads with a massive ES/SD are going to shoot like shit, even in the hands of the most capable/fundamentaly sound shooter...it would be naive to assume the same isn't true with arrows.

 

[Mighty Mouse]

If I handed you an arrow fletched at 2.5° and another at 3°, you wouldn't be able to tell the difference by visual inspection or by shooting them. A greater offset/helical angle gives the fletching more steering ability but also slows the arrow down (slightly) more rapidly due to increased drag. The "optimal" angle would be that which steers your arrow just enough to keep it on target at your max range in non-ideal conditions (e.g., windy, poor shot execution). As you can imagine, finding that optimal angle would be very difficult, and I'm unaware of any controlled studies attempting to hone in on it. Steering ability is more important than a little bit of extra downrange speed, so it's best to err on the high side of fletching angle. I use approximately 3° because that's the most I can get out of my Bitzenburger jig with straight clamp while maintaining full contact between the vane and shaft.

If you think you might want to shoot a single bevel broadhead someday, fletch to the right because right bevel is more common and it's a good idea to match fletching orientation with bevel orientation. If not, choose whichever direction you want. Fletching with or against natural/bareshaft rotation direction won't amount to a hill of beans worth of difference. The arrow will be spinning in the direction determined by the fletching within a few feet of launch either way.

Here's some backyard science showing downrange speed vs. fletching angle and direction. The observed speed differences are negligible.

 

[PurpleDriver]

It seems you are like most of us gear heads in that you are searching for perfection. You’re tuning your arrows for most efficient flight. No fault there. But to the point of overthinking it, you likely are doing just that. I went down this rabbit hole but with 3-, 4-, 6-fletch to increase FOC with my BH. But I had a great time and learned a little, so go for it!

Whatever BH you use is the key. Too little spin and BH flies like crap. Too much and you’re giving up performance due to drag. In my 30+ years of shooting archery I’ve never seen anything but trial and error for the type of tuning you’re attempting.

 

[Billy Goat]

I'm not convinced you want your arrow fletched the same as a bareshaft. The whole point of fletching is to create drag. Having it force the shaft counter to the way it comes off the bow creates more drag.

Many target shooters actually shoot with their bow slightly out of tune, because it ensures the exact same reaction leaving the bow.



Keep in mind that anything you might find that is the ultimate in accuracy, is likely target related and just because it works there doesn't mean it applies to broadheads.

 

[Eastonsgrandpa]

I've gone down the rabbit hole with building arrows like I do with just about everything. I've done the super high FOC. The hard helical. The worrying about how the arrow clocks and fletching that way. Super heavy weight. Super light weight. The "best" broadheads (as evidenced by their price). I always fletched 4 vanes.And all the other stuff one can obsess about.

I finally said enough.
I have stopped worrying about it. I cut my arrows at home, taking half the cut from the front, half from the back. I do obsess about squaring the ends, but that is extremely important. I want arrows that are now kind of middle of the road. Decent weight up front. Strong components. And a finished arrow somewhere in the 450 grain arena. I am at 458 on my latest build.


I don't care what way my bow clocks the arrow off the rest. I fletch right. I don't like the left twist as it has a tendency to loosen the head on impact. While I've never had one come off completely, that is a concern. And I find zero accuracy change either way. I use 3 vanes and see better results than with 4. Too much drag out at long distances with four. I'm using the DCA Custom Arrow vanes this year and really liking them.


Hard helical was great, up to about fifty yards where you could actually watch the arrow start to parachute. Now I fletch a 3 degree offset and it's fixed that.
I use a 50 grain brass hit, a 25 grain impact collar, and a 100 grain head. I'm sure I have good FOC, but I don't know what that is.
The idea of a heavy arrow is good, until you need your arrow to get there or slip through a tight lane. Animals move. Branches grab. I want a hard hitting arrow that is flying a minimum of 280 fps.
So yeah, don't overthink it. Build a good arrow you are accurate with and that gives you the best mix of hard impact and speed. But accuracy trumps it all. Spend the time obsessing over everything spinning true and coming off your bow straight.

 

[5MilesBack]

Same reason behind 3 vs 4 fletch, some claim 4 steers broadheads better, some don't.

This totally depends on what vanes you're using in a 3-fletch and/or 4-fletch. IMO the best reason to use a 4-fletch is to be able to use lower profile vanes (i.e. vane clearance) and still get the same drag as with 3 high profile vanes.

I use 2" QS Speed Hunter vanes a lot (high profile vane). They have a "kicker" on them that initiates rotation even when fletched straight. The only difference between straight and higher degree of offset is the trajectory. I prefer to use as little offset as possible and still get good BH flight/tuning out to 60-80 yards. So my 2" QS's are fletched pretty straight. My 4-fletch lower profile Q2i Fusion Xii 2.1's are fletched with a little more offset, and they impact very similarly with the QS's out to 80.

I would shoot for the least amount of drag that gets you to where you want or need to be. For reference I shoot 500gr RIP TKO's with 200gr up front, but I also shoot 520 grain GT Kinetic XT 200's with 141gr up front. Same fletching profiles work just as well with these. I also have some 441gr RIP TKO's with 141gr up front that use the same fletching as well. They all shoot well with FP's and BH's.