Arrow Clocking

[Marcus]

So the latest thing on social media arrow tuning is "Arrow Clocking"
This is where you mark a bare shaft (doesn't actually matter if its bare but anyway) and shoot at a few feet away and see which way it naturally spins out of the bow.
You then offset your vanes accordingly to match.
The reason given is that if you fletch it the incorrect way the arrows will change their spin direction part way to the target (which is assumed to be bad)

I thought I would shoot some high speed video to test
Which way the arrow spins out of the bow
Which way it spins for LH fletches
Which way for RH fletches.

In my first test ALL arrows spun left out of the bow. This made me thing it was pointless.
I then shot another video with the focus changed down range and you can make out the RH fletches stop spinning left and start spinning right.

Still don't know if it matters.

[Brenton]

Interesting...
What causes the initial spin from the bow do you think?
Could it be... Nock bias, nock point torque due to release style or hand pressure, string pressure on face???

[Marcus]

Interesting...
What causes the initial spin from the bow do you think?

dunno as yet.

Could it be...
Nock bias - possible. I have only tested with Beiter nocks
nock point torque due to release style - Could be, I use am open hook Incredible release on my Hooter Shooter as it's the closed thing to my hinge.
hand pressure - I don't think so.
string pressure on face - No. This video was shot from a Hooter Shooter, so no face contact.

[craigr]

Contact with blade rest?

Whatever it is its weird..love to know.

[dcgold]

What angle are the fletches?
James Parkes' experiments (Archery Technology, Chapter) talks of a 1 degree angle providing about 1 rotation each 3m.
The arrow point seems to point to the right near the end of the flight...

[Ozzy]

Seems well worthy of consideration. No point in fighting against the arrow's natural spin tendency if it's just as easy to set up the fletching jig to suit.
Worth noting though, that there is no rule for this amongst top pro archers shooting amazing scores either way.

Would be very interesting to test a variety of arrows.

[Andy!]

The rotation is an artifact caused by the force of the power stroke bending the arrow, and the arrow unbending in flight.
Imagine you are looking down the flight path of the arrow from the back.
What are the chances that the axis of the arrow is going to precisely line up with the force the bow puts on it during the power stroke?
Pretty much none.
You'll get the force applied off center, so the arrow will want to bend in two directions.

Now, go and look at all the good quality high speed video you can find of arrows on the rest during the power stroke of a compound.
You'll see that as the arrow is under power, it has a standing wave, going back and forth incredibly fast.

Be aware that some of what you see on high speed video is the same as what you can see on low speed video. You've very likely have seen the video of the helicopter flying around with it's rotors not moving because the speed of rotation matches a perfect fraction of the frame rate?
Just be constantly aware of that possibility. Particularly if the movement matches the direction of any mechanical shutter or electronic shutter effect caused by the reading of the sensor.

So, when the arrow leaves the string, it will have a bend to the side, and either up or down from the true flight path of the Center of Mass of the arrow. It will instantly try to straighten out.
The biggest motion will obviously be the first one once the string isn't holding the arrow, so the initial movement will have the most effect.

Here's the fun part. That motion will either assist the intended direction of the arrow rotating, or resist it. You've got at least 50/50 in up and down, and 50/50 in left and right.

Depending on the direction of force on the arrow and how misaligned it is, it would be logical that you can have a crap release that is going to change the direction of the forces.
Moving your rest up and down, torquing the bow, string contact.. Anything at all that you can do to change minutely the forces on that arrow prior to it leaving the string is going to have an effect.

Accuracy is predictability. You can predict an arrow will land where you want, because it is consistent. Therefore, if something is consistent, it WILL be accurately predictable.
We spin arrows to average out the effect of their inconsistencies. We absolutely know this to be the case and we also know that this is important because arrows that are not straight enough WILL cost you points. Eventually, if the arrows are too inconsistent, their variation will exceed the size of the smallest scoring zone.

Does the change in rotation of the arrow contribute to a significant factor? Possibly sometimes. Possibly not other times.

Will a slight change in tune, or technique totally change the forces that influence the direction of initial rotation that the arrow wants to go? Hell yes.
Will you always be able to detect it? Doubtful without a lot of money in equipment.
Could it be a factor that explains weird things happening when bow tuning? Yes, possibly.
Should you worry about it? Personally, I wouldn't. There's a long history of people shooting brilliant scores without having to know about it.
Can I use this an an excuse to why I am not performing. Yes. Go right ahead. In fact, the laws of archery insist that you add it to your excuses as it is new and mysterious.

So you could go to a huge amount of effort, fletching your vanes to ensure that your initial rotation matches the intended rotation.. and then move your centershot a fraction.. and your arrows now rotate initially the opposite direction again.
Or change release aids.
Or move your rest down.

[Andy!]

Here's a reference article.
Notice that there is absolutely no mention of "I checked to see if my arrow rotation changed direction with any adjustment to my bow."

But there is this statement "I believe if you fletch your arrows with the direction they naturally want to spin, you will create an arrow that is more forgiving."

Here's another statement. "Gwyneth Paltrow's old business, Goop, recommends jamming jade eggs up your cooch to control hormonal imbalances"

What do both of these statements have in common? They both rely on coming from an appealing person so that people want their statement to be true and accept that it is.
Neither of them have any level of actual testing rigour.

http://lastchancearchery.com/article...donnie-thacker

[Marcus]

That was the point of the video. The conversation was going around and someone said that by shooting every foot they tracked their arrow spin changing direction. I thought that would be
a) not likely
b) good to see if it did
And that's what the video showed. That
a) I was wrong
b) it was good to see
c) that it may have changed the way the arrow was flying as the tail kicked left.

Next stap is to film at the same depth my LH fletched arrows and see what they do at that distance.

I also want to see if I have a bow with it's string twisted RH to see if that impacts it. (as some believe it will)

I'll do a few other things as well, like try twisting the release the opposite way.

[Andy!]

Are your LH fletched arrows the same shaft and other properties as the RH ones?

I have lots of high speed video that I've been asked not to publish online, but I've been looking at the release phase. Now I'm going to concentrate on initial flight to see how often this happens.
Outside, full zoom, as small aperture as possible and manual focus about five to ten meters ahead should have a wide enough depth of field to show arrow rotation changes
.

[Marcus]

Are your LH fletched arrows the same shaft and other properties as the RH ones?
.

Same Arrows. Except the LH ones have ICE vanes and the RH ones AAE.
My LH feathers stay spinning left and group fantastic!



Sent from my iPhone using Tapatalk

[Andy!]

Is there any chance you can tweak your rest a bit left or right and see if the RH fletched ones don't reverse?

[bimble]

or could how you tie your d-loop one also be a culprit? For instance, mine are tied with the top knot to the right, bottom knot to the left, so at full draw there could be a slight twist to the string, which once at bracing height will have straightened out... (spitballing admittedly) suppose it depends on how much time you're willing to spend on playing...

[Ozzy]

Is there any chance you can tweak your rest a bit left or right and see if the RH fletched ones don't reverse?

Surely adjusting a rest out of centre would defeat the exercise ?

Interesting discussion.

[Andy!]

Surely adjusting a rest out of centre would defeat the exercise ?

Interesting discussion.

It will change the line of force along the arrow axis. If there's enough change, it might change the rotational cast put on the arrow.