SEW, please read this and give me your input

[Boo]

https://www.ezfletch.com/why-true-helical/

[ThunderXB]

It was an interesting read and if all is true, I'm glad you guys talked me into an EZ-Fletch Bolt with Right True Helical.

Looking forward to that jet jockey's feedback.

[Boo]

Looking forward to that jet jockey's feedback.

[SEW]

Preliminary thoughts. A vbow's arrow needs to be stabilized ASAP after launch. A xbow's arrow is already virtually stabilized immediately after launch. Imparting and maintaining spin takes some energy(creating drag). A stabilized arrow has less drag than a less stabilized arrow (minute lateral drag). However, helical has more drag than offset which has more than straight fletch.
What's true for vbows does not always translate directly to xbows. Not sure this does as the initial premise is that the trajectory difference is primarily due to energy loss differences between offset and helical orientations due to length of time to stabilize.
Fortunately, I have identical Zombies except for slight offset and helical. I plan to test in Thurs or Fri at the latest. Yes, I still work

[Boo]

Never thought about the energy loss from being unstable Steve. Good thinking!

[ThunderXB]

I'm learning more and more as I shoot these stiff little arrows and appreciate more now why they call them "bolts", especially the Zombies which are extra stiff.

It would be interesting to see a crossbow bolt shot in slow motion like they have done with some of the V-bow arrows to see how much archers paradox (undulations/bending) occurs, if any.

I don't think it could be anywhere as much as it is on a V-bow arrow.

Watching those arrows bending back and forth in slo mo, makes you realize how unstable they are and how much energy they must be bleeding off. (also makes you wonder how you ever put two arrows in the same spot which speaks to why spine matching is important there)

Truthfully I've thought that the factory offset used on factory Zombies was sufficient enough until I started adding weight on the back end of the arrow with lighted nocks. As I use some fixed blade broadheads for bear, etc., the helical will have even more value for longer range stability, althought I do agree with SEW that all the extra spin imparted has to be driven by something and that likely uses up some energy AND the helical adds some drag, hence all the feedback we see from others on this forum who see a small drop in trajectory and POI.

All good stuff, sometimes we overthink things and sometimes it pays off.

I learned in competitive shotgun shooting that once I understood all the leads, speeds and ballistic stuff, I was better off just shooting and not thinking about it anymore.

[SEW]

I've had a little more time to reflect on this and have come up with some thoughts.

An arrow flying straight thru the air has virtually no lateral drag while one with any wobble that would have some side drag.

Vanes in helical have more drag than offset, offset have more drag than straight.
Crossbow arrows are virtually stabilized upon launch so there's little to no stabilization going on immediately after launch since its already stabilized. So there is virtually no initial slowing of the arrow due to stabilization drag.

Arrows that are already stabilized upon launch, WILL be slowed least by straight fletch, next by offset, and most by helical.

So after launch, the arrow with the least drag will drop the least IF it remains stabilized.

A field point is easiest to stabilize, followed by expandibles, followed by fixed Broadheads.

Slight offset (very low drag) will stabilize a fieldpoint to 100 yards, moderate offset will stabilize an FOC or Schwackers (very low profile expandibles) to 100 yards, whereas helical will be needed to give best accuracy with the vast majority of fixed broadheads.

There's not just "one" correct answer even for a crossbow.

Likely, a fieldpoint tipped Xbow arrow will have the least drop with a slight offset configured arrow, while a fixed broadhead may be flatter flying due to better stabilization and will be more accurate with helical vane configuration. The expandible broadheads will be somewhat in between .

The entire article's premise is based on initial stabilization by helical vane configuration outweighs all else on trajectory . Maybe that's correct with the much longer arrows of vbows. I don't feel this article applies to xbow arrows.
However, I do believe that that the Arizona E. Bolt is the best overall fletcher for the vast majority of Xbow users' arrows: but, not for trajectory;rather, for accuracy.

[MTBighorn]

Isn't there quite a difference between the physics of "deflection" and "lift"??

Seems to me that a true curved helical vane is actually creating, and being spun by lift. Each curved vane is actually a little wing. With the ability to create a low pressure in top of the vain and high pressure across the bottom plain.

"Ground effect" may even be involved with a spinning curved helical because of the close quarters of the 3 vains???..this would really reduce drag if it is present.

A straight vane, set at an angle to the axis of the shaft, is inducing spin through deflection and angle of attack. Right?

[Boo]

Isn't there quite a difference between the physics of "deflection" and "lift"??

Seems to me that a true curved helical vane is actually creating, and being spun by lift. Each curved vane is actually a little wing. With the ability to create a low pressure in top of the vain and high pressure across the bottom plain.

"Ground effect" may even be involved with a spinning curved helical because of the close quarters of the 3 vains???..this would really reduce drag if it is present.

A straight vane, set at an angle to the axis of the shaft, is inducing spin through deflection and angle of attack. Right?

I believe that both create lift like an airfoil. The offset still has high pressure on one side and negative pressure on the other side like a rear spoiler on a car. The curvature of the helical has a better airfoil profile creating more lift.


But what do I know? I'm a lowly mechanic

[SEW]

I believe that both create lift like an airfoil. The offset still has high pressure on one side and negative pressure on the other side like a rear spoiler on a car. The curvature of the helical has a better airfoil profile creating more lift.


But what do I know? I'm a lowly mechanic

See all those lift vector arrows? Lift isn't free. There is just as much drag created as there is lift. In an airplane, thrust overcomes that drag. With an arrow, momentum (kinetic energy) moves the arrow forward but is being dissipated from the minute drag of the arrow itself and the greater drag of the vanes. It's a well known fact that helical vanes act like weight in the back of the arrow which causes helical vaned arrows to require more FOC than offset or straight vaned arrows. This in and of itself should give credence that helical orientation has more drag. The "lift" just spins the arrow faster which requires energy which eats away at the energy imparted to the arrow.
Lift isn't free. No force is free: all forces are opposed by an equal force.
And to address Boo's next to final statement, more lift, more drag, more slowing of arrow, increased arrow drop.
To address Boo's final statement, great mechanics are among the smartest people in the world. This doesn't include "parts replacers".

[MTBighorn]

It's a well known fact that helical vanes act like weight in the back of the arrow which causes helical vaned arrows to require more FOC than offset or straight vaned arrows. This in and of itself should give credence that helical orientation has more drag. The "lift" just spins the arrow faster which requires energy which eats away at the energy imparted to the arrow.
Lift isn't free. No force is free: all forces are opposed by an equal force.

Good stuff!!

Trying to pair this w/things I have seen on the target.
Here is a scenario...
Factory arrow..
Arrow= 18" BEE, factory fletched (offset?)
92gr insert
100gr ST BH
Plastic nock

These shot fairly well to 100 yards w/ the factory fletch..( a few flyers, probly from un-checked wobble of the BH's)

Then I added a 30gr Lighted nock...there-by reducing my FOC ...and I lost all control of my arrows with the Slick-Tricks.

I sliced off the factory vanes and re-fletched with the helical Bolt, and my arrows came back into the bulls-eye at 100 yards.

So if the helical shifted the FOC back even further....the helical overcame the FOC shift and still stablilized the arrows.

[Boo]

The helical and subsequent added rotation of the arrow will also over come the effects of a poorly aligned broadhead and shaft runout.

[Hi5]

Interesting conversation to be able to eavesdrop.......

[SEW]

This afternoon, windy!!, I did a trajectory test.

I shot identical arrows, except offset on one and helical on the other, to 90 yards just now. Recorded the 5yd speed of each and impacts of each, side by side to show the vertical difference. Shot at 20,40,60,80,90 yards off of a #13 Protector bag with my wonderful Dr Stirrup rest on top of the bag. M405, Optimizer, Duralyt 2-8. C/W of 10-15 mph. No sweat - little offset needed for these arrows with field points. It'd been an entirely different situation with broadheads. My 405 is shooting Grizz Tricks, BD400 is shooting FOCs and goes when it's really windy.

Anyway, I'll post ASAP after I upload to PB.

Want to make some guesses as to which dropped the most or least?

[Boo]

You da man Steve! I'm impressed at your shooting!! I will never get you mad!
However, I'm far less impressed at the difference!
I'll let you explain Steve since you delt with the real thing up close and personal