Trajectory or Weight on the Tail

[Chain2]

With all this EFOC and UFOC and all the other FOCs we all buy into, what does this do to the trajectory? Aren't we shooting very nose heavy projectiles  ? If our nose is down at or near impact what happens to lethal penetration ? Would we be better served with the same weight projectile for penetration purposes but with the weight closer to normal FOC? Just some random thoughts. Thanks guys

[Michael Arnette]

[McDave]

Given the same bow and tuned arrows, trajectory depends solely on arrow weight. EFOC arrows are no more nose down than any other arrow. The feathers trail behind: nose up as the arrow arcs up, nose down as the arrow arcs down.

It is just a total weight thing, however, it is quite often possible to get a  quicker recovering  wood arrow with a lighter point, lighter spine and more feather surface.  which can help to get an arrow through the sticks at times.  Personally, I go for a heavier point, so I can use a stiffer and heavier wood shaft and then slow it all down with a lot of feather.  completely wrong, but I on a rather long shot this year, I snapped a rib going in, a rib going out and the arrow broke in half skipping off a sampling ten feet beyond the deer.  That was with a 50 pound longbow and 26" draw, pushing a heavy for its spine cedar with an older file sharpened single bevel Hill that had seen its better days.  I was shocked how such a narrow broad head could cause so much bleeding and bring a deer down so fast.  Just some random thoughts from me, I believe that I over think things at times.

[damascusdave]

I am just going to keep hunting with what I am using

DDave

[Doc Nock]

Indeed... too much thinking pisses off the Gods of Trad me thinks...

Don't ask me how I come to that conclusion...   :rolleyes:        

Build a good arrow, practice with it till you know YOUR effective range for "good enough to kill" and then go forth and hunt!

I LIKE higher FOC cause I shoot lower draw weight as  I got older and Uncle Arty came to visit and stayed...took a room in both shoulders...

I believe in the science that it enhances penetration, so with lower draw, I like the confidence it gives me...

No substitute for practice and then go and kill something...

[CEO]

Technically speaking - Trajectory depends on speed not weight. A 500 gn arrow or a 5000 gn arrow, each going 200 fps, would have identical flight paths. Good luck getting a 5000 gn arrow up to 200 fps.

[Chain2]

I guess I do have too much time on my hands now that my arrows are flying well. You guys that reload will recognize the disease, trying to put five shots in one hole at amazing distances has kept me up in my room many winter nights. I was thinking that with the weight being proportioned more over the entire arrow that the arrow itself would stay flatter in flight. It would still be affected by gravity the same because of the same weight and duper but it's overall disposition would be more parallel to level.
See you can tell I reload. I also golf.

[woodchucker]

Ok!!! So you Golf... A 9 Iron is heavier the a 5 Iron... Heavier head = Longer Ball... I think  

(Me don'ts do Golf... Or Reload...)

[Chain2]

My 9 150 yds My 5 190. Launch angle and spin rate.
I'm talking about two arrows weighing the same. One arrow with substantially more FOC than the other.  If would seem that the less FOX arrow would have a better flight path for penetration. Not a flatter trajectory but a flatter posture upon impact

[old_goat2]

More weight up front increases the FOC, which in turn gives the fletching a longer lever arm, increases leverage which gives them more control, that's in my opinion ONE of the things that keeps them from tipping over. I hear over and over, guys and a few gal's say that increasing the tip weight caused their arrows to fly tip down, in reality they just increased their arrow weight which caused more of a rainbow trajectory. Longer lever arm helping the feathers stabilize flight is in my opinion the biggest single advantage to higher FOC numbers!

[Chain2]

Well Chief that helps me understand it a little.

[Charlie Lamb]

Gravity affects all things equally. The point is no more affected than the nock.

[Chain2]

Correct but I still picture the heavier FOC arrow falling more point first. The leverage explanation helped some.

[McDave]

Picture a rock with a string tied on it, and a small ball of cotton tied on the end of the string.  That's about as EFOC as you can get.  When you throw the rock, the string and cotton ball just follow along behind the rock, with the string at a tangent to the arc of the rock, i.e. as the rock is rising, the string and cotton ball are angled up, and as the rock falls, the string and cotton ball are angled down.  Clearly, a lot can happen to move the flight path of the string and cotton ball off tangent, but the relative weight of the rock and cotton ball isn't one of them.

To avoid flight problems when shooting a real arrow, it is necessary that it be tuned to the bow, which means that as you increase point weight, you have to also increase arrow spine.  If these things aren't done, you can get all sorts of squirrelly flight characteristics, including some that might appear to be nose down (or as we prefer to say in arrow tuning, nock high).

[Chain2]

That's right but when the rock is coming nose down and hits something like an animal isn't it going to track or want to track down steeper where as if the shaft was more level ( less FOC) the arc would be more gradual the change in course after impact would be less.

[McDave]

Two things of major importance that affect penetration are arrow weight and arrow flight.

The first factor is arrow weight.  More weight = more penetration.  As to your question, Dr. Ashby did studies a few years ago where he concluded that weight forward resulted in greater penetration than a more even distribution of weight.  It is interesting to speculate on the physics of arrow flight, but he did exhaustive tests, and until we have better evidence, most bowhunters rely on his results.

The second question has to do with arrow flight.  If an arrow hits an animal and the nock isn't directly in the line of force, if the arrow is porpoising or fishtailing, for example, the shaft will deflect away from the line of force, dissipating energy away from penetration.  Optimal arrow flight and penetration are achieved when the arrows are properly tuned to the bow and archer.  If an arrow is properly tuned so that a bare shaft flies true, then weight distribution for that particular arrow is irrelevant: tuned is tuned.  I think some people have problems with EFOC because they try to get heavy heads to fly straight with weak shafts, but that is no different from anyone who tries to get mismatched equipment to work as they wish it would.

As far as the angle of attack that an arrow hits an animal, if one arrow hits an animal at a 45 degree angle, and another arrow hits an animal at a 90 degree angle, penetration will be unaffected by those angles as long as the arrows are properly tuned and the direction of force is the same as the angle of attack.

What people do worry about, validly in my opinion, is the tradeoff between using a heavy arrow and a lighter arrow, since the trajectory of any heavy arrow, EFOC or not, will be more curved than a lighter arrow shot from the same bow.  This makes it easier to miss or wound an animal.  Other people would say that the flatter trajectory of a lighter arrow makes it more likely that longer shots will be taken, leading to just as many missed or wounded animals.  We're not likely to settle that argument here.

The shape of the broadhead can also play a part if the angle of the hit is more severe.  It is also a large variable and difficult to predict, depending on what it hits no matter how good the arrow is flying and on the angle of the blade at impact.  i like the statement that I got from a fellow with a very nice takedown recurve and very long efoc arrows, 'I don't get pass through, so you don't either.'  He was referring to my shorter draw and tapered wood shafts with Grizzly and single bevel Hill heads.  My answer was simply, 'sorry, but I usually do.'  After some back and forth debate and theorizing, a couple of shots from my ladder stand reveled his problem.  He had a two inch shorter draw when shooting from a tree stand than he had standing and stretching out his draw from the ground.  His arrows flew terrible with the shorter draw.  one can put al the fundamentals into a setup, but if the execution varies in a real hunting situation, the outcome can be completely different.

[**DONOTDELETE**]

At standard hunting distances being 15-20 yards, trajectory isn't a huge factor when your target is wide open.... where flat trajectory really makes a difference is shooting through small windows through branches, or at longer distances....

Arrow speed determines trajectory, but down range when the arrow starts running out of gas, the heavy EFOC arrows with tiny fletching will nose dive at a steeper angle than a more balanced FOC shaft with a helical fletch..... That is simple aerodynamics....btw ...it IS rocket science...

The efoc and penetration thing has been debated for years and proven that more weight up front does penetrate better.

So Kirk, do you think that a heavy efoc has a low speed point where the attitude of the flight angle is nose down or is it that the flight line has a steeper parabolic curve, but the fletching is still behind the head weight?