# Straight Vs Offset



## StarDog (Feb 17, 2007)

For years now I have just done what both my coaches (past and present) have recommended with plastic vanes or XS wings.

1 degree offset. so that's what I've been doing.

I still don't know why that is. Can someone enlighten me? Is there an advantage? Does it make a difference?

All I think I know is that one of you kind folks advised that the more offset the wonkier arrows behave at distance.

For low poundage (32# DW) XS wings, what's the deal?

Before I do this again on new arrows for reasons I don't understand.....

Thanks as always.


----------



## damiaan (Feb 17, 2014)

its just to make the arrow spin, wether you do it with a spin wing type vane of a hard plastic one. the angle sort of determines drag and spin rate. for what its worth, use plastic vanes at an angle, spinnies do the same job when fletched straight.
in your case, take 40 or 50 mm XS wings (preferably 40 since they are smaller, given that your DL is sub 28"-ish), make sure there is enough clearance and you're good to go.

in regard to the size of the vane and angle, shoot groups at all distances and check if your grouping is 'consistent' I.E. a 4" group at 20y means a 8" group at 40 etc, if the group opens up at longer distances, get a smaller vane. if your group at close distance is worse, get a bigger vane.

then again, will you see a difference? not really


----------



## Kim Jong Skill (Dec 19, 2014)

When you shoot an arrow you're trying to apply as much force in the "forward" direction as possible. By offsetting arrows and using spin vanes, you're letting the wind catch the vanes and rotate the arrow. The amount of energy being put into the arrow is constant so if you fletch with too much offset / helical, you're using more of that energy essentially spinning the arrow than moving it forward hence more offset = wonkier at a distance because your arrow slows down a lot faster.

The reason you want your arrows to spin is because it corrects imperfections in flight. Imagine a spinning top. While its spinning fast its difficult to make it spin "wonky". Even if you start with a bad spin, if the rotational speed is correct, the top will correct itself and spin straight. You want something similar with your arrows except your arrow is traveling in 2 directions: forward and spinning. The energy being applied to the arrow is constant so there is a trade off, more spin = less forward force, less spin = more forward force.

I fletch my xs wings straight because I find that the vane shape already applies plenty of spin. Our mutual friend fletches his vanes with a slight offset. Its up to you how much helical / offset you want but at a certain point, how fast your arrow spins no longer corrects arrow flight any faster / better.


----------



## StarDog (Feb 17, 2007)

Kim Jong Skill said:


> When you shoot an arrow you're trying to apply as much force in the "forward" direction as possible. By offsetting arrows and using spin vanes, you're letting the wind catch the vanes and rotate the arrow. The amount of energy being put into the arrow is constant so if you fletch with too much offset / helical, you're using more of that energy essentially spinning the arrow than moving it forward hence more offset = wonkier at a distance because your arrow slows down a lot faster.
> 
> The reason you want your arrows to spin is because it corrects imperfections in flight. Imagine a spinning top. While its spinning fast its difficult to make it spin "wonky". Even if you start with a bad spin, if the rotational speed is correct, the top will correct itself and spin straight. You want something similar with your arrows except your arrow is traveling in 2 directions: forward and spinning. The energy being applied to the arrow is constant so there is a trade off, more spin = less forward force, less spin = more forward force.
> 
> I fletch my xs wings straight because I find that the vane shape already applies plenty of spin. Our mutual friend fletches his vanes with a slight offset. Its up to you how much helical / offset you want but at a certain point, how fast your arrow spins no longer corrects arrow flight any faster / better.


I borrowed a set of McKinney's from a nice person who uses a straight fletch so that's what made me wonder. Plus I think the ACC's I'm using from one of your fellow coaches is a straight fletch.....so that's why I was curious.


----------



## theminoritydude (Feb 11, 2013)

3 years ago, there was a discussion in AF about arrow spin and its advantages (if any). One gentleman drew our attention to the difference between longitudinal stability due to rotational rigidity, and "finning". Rotational rigidity is a physical property imparted to a body of distributed mass that is spinning. The axis of the body's rotation tends to maintain its orientation to space. This property is actively employed in firearm ballistics, to maintain a certain rigidity in the round when it travels across vast distances, without tumbling. Finning on the other hand, is the process by which a long body maintains minimal form drag through the use of tail surfaces coupled with a forward located center of mass. A spinning arrow was initially thought to take advantage of both these properties.

But that is not entirely true.

You see, as a long body, finning alone is sufficient to most efficiently maintain the lowest level of form drag. Rotational rigidity either adds little advantage, or is in extreme cases, detrimental to the smooth flight of the long body through a medium (air), by way of rigidly maintaining a predetermined orientation, with no regards to the flight path.

If so, why do we spin the arrow? 

Two reasons really. The first has something loosely to do with the law of probability. Imagine that during release, one accidentally introduces an error in a particular lateral/vertical direction. OR, a single fin out of three was improperly attached. If the arrow is allowed to fly without any rotation, the single dimensional error is then allowed to be factored by the distance travelled, translating into a larger error on the target. Conversely, if the arrow had rotated, the error would then be evenly distributed in a circular fashion, constantly added and deleted during the flight, translating to nothing more than a constant error that was introduced at release. 

The second reason has to do with spin direction. "You gotta choose one". How straight could you attach the fletches to guarantee zero offset(pitch), such the the arrow does not spin in either directions, at all? What if one wanted to go clockwise, the other wanted to go anti-clockwise, and the third just wanted to watch the TV? This then results in a situation where additional drag is ironically introduced. 

How much pitch is too much? Interestingly, we conducted an experiment 3 years ago to investigate the effects of a 5 deg pitch. Turns out that other than a magnificent spin that was observed as a "puffy" figure (the massive centrifugal acceleration derived from the high spin rate kinda stretched the spin vanes outward, further encouraging the spin due to nett increased airflow over the larger aggregate wing area) eerily floating to the center of the target, the height of the arrow was not reduced at 70m. 

We do not know why.

For those who maintain that a larger pitch will significantly reduce the speed of the arrow, that is only true in the initial potion of gaining rotational velocity. After the correct rotational velocity is matched to the pitch of the vanes with respect to the forward velocity of the arrow (equilibrium), minimal drag is achieved. Furthermore, due to the extreme drag/damping effect of the high pitch, some release errors were surprisingly taken out.


----------



## Stash (Jun 1, 2002)

This topic has been discussed over and over, but curiously there have been very few people who have done a practical test. Easy enough to do yourself and settle the issue. Just fletch up half a dozen straight and half a dozen offset and see if one set groups better than the other.

I did test this one time years ago and found no difference, so I just locked my jigs down tight and keep the same angle all the time.


----------



## aread (Dec 25, 2009)

Offset - all fletching will have a right or left bias. The fletching may be exactly the same angle, but they often vary +/- a small fraction of a degree. 

Straight - you are attempting to get all fletching exactly in line with the longitudinal axis of the arrow. But again they will often vary +/- a small fraction of a degree. So this vane will be slightly off and trying for a left spin, but the next vane will be trying for a right spin. As you can imagine, accuracy will suffer. 

Or at least this is the theory I was taught. My guess is that the variation that you get with straight fletching is not noticeable for most archers. But most of us are trying to get better and these little things accumulate.

Allen


----------



## Viper1 (Aug 21, 2003)

Guys - 
All fletching does is give the arrow more air resistance at the tail than at the point. 
The ballistic spin thing is a factor, but small since we're talking spear ballistics here, not projectile (bullet) ballistics. 
Even a perfectly straight fletch (which I think is impossible to physically do by humans) will increase air resistance to some degree.

The question becomes: how much air resistance do you need to stabilize the arrow? 

Theories abound. 

Personally, for my own shooting - it's a lot less than most people think.








60 yards, 1.75" straight vanes (sight offset) vs 5" helical feathers.
All arrows weighed the same (that part is critical). 

I don't claim to be an Olympic level shooter, but these results reproduced, and it's enough for me. 

Viper1 out.


----------



## StarDog (Feb 17, 2007)

I believe I will experiment when my new arrows show up and see what happens. Thanks for your input.


----------



## baller (Oct 4, 2006)

I use straight lines for Mylar vanes (spin wings, x's wings etc) since they are engineered with their own curl for drag. 

If I use glued on rubber vanes like vanetec swifts or aae Wavs I use ~3 degrees of helical to creat some drag with a straight vane.


----------



## lksseven (Mar 21, 2010)

Rick McKinney said he got better results with spin wings with 'no offset'.


----------



## theminoritydude (Feb 11, 2013)

I propose we use "pitch" in place of "offset". Offset could very well be misconstrued as the angular displacement between adjacent vanes, which in this case is 60deg.


----------



## StarDog (Feb 17, 2007)

I need all the speed and distance I an squeeze out of an arrow so I think I'll give the straight line on the xs wings this time around.


----------



## theminoritydude (Feb 11, 2013)

Correction: 120deg


----------



## Mika Savola (Sep 2, 2008)

Plastic vanes require as much "pitch" as you can apply :wink: (meaning that both vane ends are still glued on the shaft)


----------



## chrstphr (Nov 23, 2005)

Actually it would be yaw. Pitch is up and down, roll is balance from side to side and yaw is the left and right movement on the horizontal plane.


The fletching would yaw 3 degrees. 

Chris


----------



## theminoritydude (Feb 11, 2013)

http://www.pddnet.com/sites/pddnet.com/files/legacyimages/NabtescoDiagram.jpg

http://www.gregorie.org/freeflight/wind_turbine/pitch.jpg


----------



## StarDog (Feb 17, 2007)

chrstphr said:


> Actually it would be yaw. Pitch is up and down, roll is balance from side to side and yaw is the left and right movement on the horizontal plane.
> 
> 
> The fletching would yaw 3 degrees.
> ...



which, the straight or the 1 degree offset?


----------



## theminoritydude (Feb 11, 2013)

NOooo~.........


----------



## chrstphr (Nov 23, 2005)

theminoritydude said:


> http://www.pddnet.com/sites/pddnet.com/files/legacyimages/NabtescoDiagram.jpg


you are dealing with an arrow and flight characteristics. Just like an airplane. 



theminoritydude said:


> url]http://www.gregorie.org/freeflight/wind_turbine/pitch.jpg[/url]


yes, that is pitch, the wing is pushed UP and wind flow goes under it. This is not pushing the wing to the side. 

Here are photos that show the correct terms and movement. 

View attachment 4295457


View attachment 4295465


the fletching rotation on the arrow shaft is yaw. If it were pitch, you would angle the fletching on a slope slanting up or down on the shaft. The profile of the vane has a downward pitch toward point. 


this should make it easy, 

nodding head Yes is pitch, nodding head NO is yaw, and tilting head to side like I'm thinking is roll. 


View attachment 4295473


the fletching is moved as if to say NO. 

Chris


----------



## Stash (Jun 1, 2002)

Although it is not correct to compare arrows which are projectiles in free ballistic flight to airplanes which are flying objects, if you must, then the vanes on an arrow are more like ailerons in that they induce roll. In the case of arrows, the roll is simply continued over 360 degrees.


----------



## theminoritydude (Feb 11, 2013)

Yessss~......


----------



## chrstphr (Nov 23, 2005)

Stash said:


> Although it is not correct to compare arrows which are projectiles in free ballistic flight to airplanes which are flying objects, if you must, then the vanes on an arrow are more like ailerons in that they induce roll. In the case of arrows, the roll is simply continued over 360 degrees.


arrow vanes INDUCE roll, but the placement on the arrow shaft in reference to straight or offset is yaw. 

The roll is each arrow vane at end is placed 120 degrees in roll around the shaft. Two different things. and neither of those things are PITCH.


Chris


----------



## baller (Oct 4, 2006)

Pretty simple guys. It's either straight or it's not. Set your jig to your preference and go. As long as all of your arrows are the same you're good. Everyone is different so some experimentation might be needed to find you're preference. 

MOST (read not everyone) fletch taped on curled Mylar vanes straight to prevent too much drag. 

MOST (again not everyone) fletch glued on rubber vanes (that have no natural curl) angled on the shaft to create more drag.


----------



## bobnikon (Jun 10, 2012)

I think, though I am not sure how much deeper down the rabbit hole we can get...

We are trying to induce roll to try and reduce pitch AND yaw as we want the arrow to travel as straight as possible.


----------



## Stash (Jun 1, 2002)

chrstphr said:


> ... but the placement on the arrow shaft in reference to straight or offset is yaw.
> 
> The roll is each arrow vane at end is placed 120 degrees in roll around the shaft. Two different things. and neither of those things are PITCH.
> 
> ...


This is all gibberish. 

Pitch, roll and yaw in this reference are all nouns that describe a type of motion. Conventionally attached vanes all with the same direction offset (all right or all left) induce roll, either clockwise or counterclockwise. If you put only 2 offset vanes on an arrow, one left, one right, and have the arrow oriented with the vanes horizontal, you induce pitch, either up or down. If you orient that arrow with the vanes vertical, you induce yaw, either left or right.

Pitch with reference to a propeller (which vanes are not, and are not remotely similar) is a different use of the term.


----------



## theminoritydude (Feb 11, 2013)

So how do we differentiate between the offset angle between individual vanes (120 degrees) and the "twist" of the vanes? Anyone?


----------



## Ar-Pe-Lo (Oct 16, 2011)

baller said:


> Pretty simple guys. It's either straight or it's not. Set your jig to your preference and go. As long as all of your arrows are the same you're good. Everyone is different so some experimentation might be needed to find you're preference.
> 
> MOST (read not everyone) fletch taped on curled Mylar vanes straight to prevent too much drag.
> 
> MOST (again not everyone) fletch glued on rubber vanes (that have no natural curl) angled on the shaft to create more drag.


THIS is the answer for archers. Tinkerers will continue of course


----------



## Stash (Jun 1, 2002)

theminoritydude said:


> So how do we differentiate between the offset angle between individual vanes (120 degrees) and the "twist" of the vanes? Anyone?


Offset is the angle of the vane with respect to the center line of the shaft. Spacing is the ...well... spacing around the shaft, as in 3x120 degrees, or 4x90 degrees.


----------



## theminoritydude (Feb 11, 2013)

So vanes on a small diameter carbon shaft have the same spacing between them as the vanes on a Fat Boy?


----------



## Stash (Jun 1, 2002)

In degrees, yes.


----------



## bobnikon (Jun 10, 2012)

theminoritydude said:


> So vanes on a small diameter carbon shaft have the same spacing between them as the vanes on a Fat Boy?


Would you put 6 vanes on a Fat Boy???

Never mind... you might :wink:


----------



## theminoritydude (Feb 11, 2013)

bobnikon said:


> Would you put 6 vanes on a Fat Boy???


I see you thought about that.


----------



## Bender (Dec 6, 2006)

Doing some research and ran across this thread. In reference to what is commonly called "offset" when using fletching/vanes, call it pitch if you must call it something other than offset. It is as if the arrow were a screw. Or a sloped roof. The word can be either a noun or a verb.

Really though, when talking about fletchings/ vanes, say "offset" and it seems that most people take it for the angle that it applied at on the shaft. I have never seen it confused with the number of degrees of separation between adjacent vanes.


----------

