Trajectory or Weight on the Tail

[**DONOTDELETE**]

Well i'm no aerodynamics engineer bro, and i don't really know how to explain it....But it sounds like you got it right.

Watching arrows of the same weight, side by side come out of the same bow shooting exactly the same speed was an eye opener at long dstance..... I was shooting two different set ups on a 3D course to check out this EFOC theory.  Where i could really see the difference is shooting long distances. I shot 180 yards at the same reference point in the trees with two different radically different FOC one at 12%  the other at 30%. The 12% had std helical 4" fletch, and the 30%  with two inch straight fletching....

Now common sense tells you the 30% arrow with less fletching drag is going to shoot further at the same degree angle of release than the 12% foc arrow with helical fletching and more drag. but that wasn't the case at all....

The only explanation i have is as the arrow slows down to a certain point, the 12% foc arrow is better balanced and coasts, or planes flatter for a longer distance before the tip weight tips it downward.... Is what you referred to as steepness of the parabolic curve? If so the EFOC arrow was definitely steeper & fell short of the 12% foc arrow....... It was noticeable at 40 yards too just looking at the arrows sticking out of the target. EFOC arrows were tail high.

The only logical explanation i can see is that the helical fletching that spins the arrow mitigates the extra drag and helps stabilize the arrow in flight for a longer distance.

[McDave]

I can see two possible explanations for what you observed, Kirk.  If you were shooting broadheads, the EFOC broadhead is probably bigger than the 12% FOC  broadhead and therefore would have more wind resistance, so would decelerate faster.

If you were shooting field points, which would have negligible wind resistance, then it is possible that the EFOC arrow was not tuned to the bow, so may have wobbled in flight.  This wobble would not be controlled by the 2" straight fletching.  To get by with 2" straight fletching, you have to have a perfectly tuned arrow.  Or, perhaps neither of the arrows was very well tuned to the bow, but the wobble of the 12% FOC arrow was controlled by the helical 4" fletch.  The helical 4" fletch has more wind resistance than the 2" straight fletch, but the wind resistance of either one would not have as much effect on trajectory as wobble of the arrow itself.

[screamin]

a 30% foc arrow also requires a much lower knocking point or you are going to get tail high, tip low flight causing the arrow to hit the dirt sooner rather than later.

The reason I asked is that i have a dozen tapered carbons, I have some that are fletched minimally and some with large feathers.  On longer practice shots the ones with small feathers are not as accurate as the ones with the larger fletch, vertically.  Also, I have some very heavy tapered cedars with 5.5" feathers that are nearly as heavy as the carbons (watco oil) and shoot out of the same bow, they seem to be more predictable over 40 yards than the tapered carbons, even though from my perspective they both seem to have perfect arrow flight.   My son tells me that the carbons fall from the sky like a lead ballon.  I have a feeling the longer the nose heavy arrow is in the air and the slower that it is moving the more effect the tugging of the nose will effect the attitude.  It would be an interesting test for someone with a bow site or a bow that shoots good out of a Hooter shooter that does not have an agenda to push.  My secondary sighting method is not conclusive enough to make a claim one way or the other,but my point on distance is shorter with high efoc than it is with wood arrows or aluminum arrows.

[Chain2]

That's what I was talking about Kirk. My thought was a tail high EFOC arrow even though being EFOC it will penetrate more, will actually be penetrating down and not more horizontal thru the target. Probably in small detail though. But if it hits something my thought would be that it would glance even more downward. Sort of like a ricochet only not as pronounced. Worse for killing penetration.

[**DONOTDELETE**]

Well i certainly don't have any agenda. i'm just another obsessed archer interested in getting the best possible combo for my hunting and 3D rigs..... and... i'm not afraid to experiment with different set ups.... In my long distance tests, EFOC arrows were bare shaft tuned nicely, and the same spine arrow was used on the 12% FOC shafts. Both arrows flew nicely at close ranges.... BUT... the EFOC arrows were much less forgiving to a pluck or imperfect release..... i got a lot of tail waggers playing with that.....But strangely enough ....it didn't seem to effect my point of impact so much, but it did effect the angle the arrow was at upon impact..... Now that right there is going to effect your penetration. IMO


The EFOC arrows are without question getting better penetration. But there is a trade off with stabilized arrow flight using the tiny fletching prescribed...... So that led me to testing a 27% EFOC arrow with 4" helical fletching. My thoughts were that the heavy EFOC is going to help penetration without sacrificing the flight stability you get with a helical fletch.....

Results were much less tail wag, but they still had a steeper parabolic curve coming back to earth as they slowed down at longer distances..... I think if a guy really likes his EFOC arrows he could get the best of both worlds using decent fletching on the tail end.

The one thing i didn't touch on was wind drift. Shooting in a heavy cross wind, the EFOC arrows would still tail wag a bit, but the wind didn't effect the point of impact near as much as a 12% FOC balanced shaft.  It seemed to me the whole arrow would drift more with the larger fletching on the low FOC shaft..... In that side wind test i don't think you can beat a tiny fletched EFOC shaft at close rage.....


Its all real interesting stuff, and everything seems to have a trade off. Same thing is true when designing limbs for a bow. There is always a trade off...

[**DONOTDELETE**]

Originally posted by Chain2:
That's what I was talking about Kirk. My thought was a tail high EFOC arrow even though being EFOC it will penetrate more, will actually be penetrating down and not more horizontal thru the target. Probably in small detail though. But if it hits something my thought would be that it would glance even more downward. Sort of like a ricochet only not as pronounced. Worse for killing penetration.

I have no doubt you are correct bro... even shooting 3D there was a noticeable difference on the penetration with an EFOC arrow with good arrow flight.... but..... those tiny fletching aren't very forgiving coming of the string less than perfect..... If your arrow is still tail waging on impact, that effects the penetration BIG time.  

So why not hedge your bets and put some 3" helical fletching on your EFOC arrows?

[Chain2]

This is really something. I love it. But I actually started shooting a longbow to simplify everything. Hah. My biggest issue with the EFOC arrows is us long draw guys. Everything needs to be perfect for good arrow flight. After I've been in a tree for a couple hrs with the temp in the teens, I'm not sure that perfect is attainable. But that's another point to ponder.

As I posted somewhere before, we met a fellow with a long draw with his recurve.  He lost quite a lot of his draw when shooting down from a tree stand, for him it greatly affected his arrow flight and his penetration.  I am not a long draw person, but using a rather normal tapered cedar arrow and a Hill head, on a rather long shot, my arrow hit a rib square on entry just behind the shoulder and broke a rib on exit.  the little ash tree beyond the buck was more than my arrow could take, it snapped it in half.  The buck ran for 80 yards and went down hard.  Of course ribs on an Iowa whitetail are not ribs on a moose.

[Chain2]

I wish I could find wood arrows long enough. I raise bow arm then draw then I bend from the waist or left leg. Ateadt I try to remember to do that

[ChuckC]

The arrow is following the head, if it is flying well ( tuned).  

Whether that is straight forward, or on that "downward trajectory", it is still following the head and flying straight behind it.  If you hit a deer from a tree stand, does the arrow penetrate less than if you hit a deer from the ground ( because of angle ) ?

CHuckC

[**DONOTDELETE**]

Originally posted by ChuckC:
The arrow is following the head, if it is flying well ( tuned).  

Whether that is straight forward, or on that "downward trajectory", it is still following the head and flying straight behind it.  If you hit a deer from a tree stand, does the arrow penetrate less than if you hit a deer from the ground ( because of angle ) ?

CHuckC

Absolutely no difference whether shooting from the ground or a tree stand.... "IF" the arrow flight is good....

If you come off the string poorly, or don't reach full draw because you are lowering your bow arm instead of bending at the waist, and that arrow is tail high or tail wagging on impact... your penetration is going to be poor.

The point i was trying to make is that a good helical fletching can & will stabilize that arrow a lot quicker than using tiny straight fletch arrows designed for less drag and more FOC. I've watched those tiny straight fletch arrows wag their tails for 30 yards just from a bad release.


There are so many human error factors that can cause poor arrow flight even with well tuned arrows. Why not hedge your bets with good fletching? You can still have a decent EFOC arrow AND good stabilized arrow flight. Win / Win

[Chain2]

My thoughts weren't that it would penetrate less. I was thinking that it would penetrate in a downward angle. The angle would seem to steepen after impact.

[LookMomNoSights]

For me,  its not worth the time and mental anguish..... Shoot 10 (ish) gpp in a properly tuned arrow,  with the correct brace height on your bow....and spend lots of time shooting,  so that you can actually shoot and put them where they need to go, every time.....SHOT PLACEMENT!!! I didn't carry the EFOC, UFOC baggage very far....and lots of dead critters cant argue.  I shoot a straight, silent, fast arrow with a sharp broadhead and the job gets done in the woods.  Tons of POINT WEIGHT is a "what if" I refuse to concern myself with.

[Fletcher]

Originally posted by Kirkll:
 
There are so many human error factors that can cause poor arrow flight even with well tuned arrows. Why not hedge your bets with good fletching? You can still have a decent EFOC arrow AND good stabilized arrow flight. Win / Win

I agree.  I'm a big fan of higher FOC's and heavy points, but my arrows are helical fletched with four four inch feathers.

I find heavy points no different to tune than a lighter point, it just takes more spine.  What I do find is that the heavy points fly and perform better for me.

[Fletcher]

Originally posted by ChuckC:
 If you hit a deer from a tree stand, does the arrow penetrate less than if you hit a deer from the ground ( because of angle ) ?

CHuckC

Lots of ifs and maybes in this question/ answer.  All other things being equal, I would say no.  I shot a doe from a treestand a few weeks back.  It was a fairly close and pretty quartered shot.  I hit her high about mid way back and the arrow exited between the chest and front shoulder.  In this case I had more deer to shoot through but what affected penetration was the ribs being closer and heavier up high.  I cut two ribs going in, one of them pretty deep.  Still, the arrow almost made it all the way thru, breaking just in front of the fletch.

You can barely see the entry in this pic, the exit is clear.  My form on the shot was good and the arrow well tuned.  I don't regret my choice of a 235 gr Grizzly Kodiak and 620 grains of arrow for 50 lbs.