O.K..heres the deal......My bow shoots reasonably flat from 15 out to about 30 yards...Gaps are pretty decent for a bow shooting 176 f.p.s....After 30 yards, the arrow really dive off.....Bareshafts are showing a bit weak at 5 to 10 yards, but I know that I need to trim the arrows down in length a bit, and possible tweek centershot, and plunger button..Grouping is still good at 35-45 yards(For me, that is,,I'm not a good shot), but those arrows really drop off fast...Can anyone help solve this puzzle??..I'll await the responses...Thanks in advance......Jim
Arrow flight riddle
Harperman
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O.K..heres the deal......My bow shoots reasonably flat from 15 out to about 30 yards...Gaps are pretty decent for a bow shooting 176 f.p.s....After 30 yards, the arrow really dive off.....Bareshafts are showing a bit weak at 5 to 10 yards, but I know that I need to trim the arrows down in length a bit, and possible tweek centershot, and plunger button..Grouping is still good at 35-45 yards(For me, that is,,I'm not a good shot), but those arrows really drop off fast...Can anyone help solve this puzzle??..I'll await the responses...Thanks in advance......Jim
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Jim...yep...think i can help...just recently?...like this past month?..i had some 31" full length beman ICS Bowhunter 500's tipped with 100gr points making a 350gr carbon fiber arrow...with 4" full helix feathers...and they are screamers off my 42# Bob Lee..but the problem with subscribing to the lighter='s faster='s flatter='s more accurate thing is...those 350gr arrows run out of gas quick once past 25yds...and just fer giggles?..i tipped some 28 1/2" GT5575's with 175gr points for a 450gr arrow..and guess what?...they carry a stronger flight than the lighter arrows do with a far more predictable line of flight...sorta amazed me at first cause i was hitting like 6-8"s higher at 30yds with the heavier arrow where the lighter arrows had quite a dramatic drop to them the last 5yds of that same distance.
Chop one down and toss some weight on up front and see if you don't experience the same...bet ya do!
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Interesting point jinx!
Several with 2" Blazers, and one experimentally fletched with 3 2.5" Parabolic feathers.....Jim
Bender.....Could be??....Full length Radial X-Weave 100's, (.520 spine), 6.6 G.P.I...12 grain insert, 100 grain field tip....27.5" draw length, 39# at the Clicker...Maybe just too much arrow sticking out front,adding to the F.O.C......Experiments, experiments.....
........Jim
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While adding weight to the tip may cause more curvature in trajectory due to slower speeds, I am really not convinced that higher foc causes a different trajectory in itself. Doesn't jive with really basic physics. Gravitational acceleration is independent of mass or center of gravity. Bare shafting arrows with low foc will glide a bit for awhile, because they are not steering into the path of the arrow (i.e. downward curvature), until they eventually porpoise down, but usually into target before that. Think that was covered by easton. but with arrows with fletching, nope. If the arrow is dropping faster vs. Distance, it's because it's going slower horizontally. If it is slowing down faster, it has more drag for a given amount of mass. Dropping an arrow sideways is a bogus example for foc, because what you're seeing is the arrow going through air sideways, and higher foc will correct faster because steering force is farther out from center of gravity, there is less rotational inertia with less mass in the shaft, etc. I can see some effect at high speeds with broadheads, perhaps, but, anyway, happy to hear of contradictory evidence, but in the very least, it the effect sounds exagerated, and anything that does happen given equal weight and velocity would have to be a matter of aerodynamics, and as said, i would think that any reasonably fletched arrow would go through the air pretty straight, which should minimize glade...
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Arrows will drop in my estimation for one of two reasons.... most likely is a too forward cg. As speed bleeds off the dynamics of the arrow start to change and the lighter the arrow the more noticeable the dive. If the cg is neutral or aft, I'm thinking it will fall flat to the ground.
A normal CG, that is one slightly forward, will have the arrow fly an arc into the ground and bury itself... but too far... and they will dive and cartwheel... that is my story anyways... :grin:
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Well, the arrow described isn't a ridiculously light soda straw, nor with 112 grains up front does it really have EFOC. So some easy obvious explanations don't cut it.
Probably a stupid question but Harperman, have you in the past shot a bow that you KNOW (no guessing) was significantly faster than your current 176 fps? Did you shoot it at 40 yards like you are now? What I'm getting at is what is your basis of comparison that you feel your arrows are falling out too quickly at longer distances? We often forget that arrow flight is not a true parabola due to drag, no matter how slight that drag may be.
Probably a stupid question but Harperman, have you in the past shot a bow that you KNOW (no guessing) was significantly faster than your current 176 fps? Did you shoot it at 40 yards like you are now? What I'm getting at is what is your basis of comparison that you feel your arrows are falling out too quickly at longer distances? We often forget that arrow flight is not a true parabola due to drag, no matter how slight that drag may be.
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What are you trying to achieve? A long distance target arrow? Or do you shoot mainly under 40 yds anyway? Did you watch any of the olympics? Those arrows are shot from very high performance bows with small fletchings and small diameter shafts and still lob like crazy. Gravity, Time and Drag are the three things working against you, not going to do much about the first one, but the other two have some room to work.
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Jim -
Can't help ya with the drop, it's just part of the game.
The change in tune may be normal as well, and you may have to resort to walk-back tuning, if you current rig will allow it (requires a plunger). Still may not get a "perfect" tune all all distances.
Viper1 out.
Can't help ya with the drop, it's just part of the game.
The change in tune may be normal as well, and you may have to resort to walk-back tuning, if you current rig will allow it (requires a plunger). Still may not get a "perfect" tune all all distances.
Viper1 out.
Thanks for the posts, guys!...I think what I'm seeing is the effects of a badly tuned arrow, that is just using up too much of it's own energy trying to correct it's self on the way to the target....I'm planning a real tuning session this evening.....Fletching some arrows as I type this...Maybe the arrows arent dropping off as hard as I think, but here's something ....I can aim and group arrows pretty much in or around the Dot at 30 yards, on the top row of Dots on a large Range bag...At 40 yards, using the same aiming method, same sight picture, at same top row of Dots, arrows end up darn near the bottom of the bag...Same/Same at 50 yards, I'll shoot well under the bag...maybe I've been away from the single string bows for too long, and I am just conditioned to the flatter trajectory of the Compounds...But, I'd think that a bow that shoots reasonably flat from 15-25 yards and still close to same out to 30 yards, that drops the arrows somewhere in the range of 2 feet lower at another 10 yards seems excessive...I'll try to get a reasonable tune on this rig, and see how things go from there.....Thanks again, fella's!..........Jim
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My stats have some similarity to yours.... 6.9 gpi, 100 grain tip for a 316 grain arrow with 39-40# OTF. My three-under PO is in excess of 80m though.Bender.....Could be??....Full length Radial X-Weave 100's, (.520 spine), 6.6 G.P.I...12 grain insert, 100 grain field tip....27.5" draw length, 39# at the Clicker...Maybe just too much arrow sticking out front,adding to the F.O.C......Experiments, experiments.....
I attribute it to a number of things.
A fast set of limbs- Border HEX 6 H.
A low anchor point. My forefinger tip at anchor lies on top of my jaw bone, about a fingers width under the corner of my mouth and worth about 15-20m (?).
I've a 29.75" DL with a 7 7/8" BH. So the arrow is longer on the string receiving propulsion.
As I SW, my NH is a compromise. Too high for long crawls and low for under the nock. This may be increasing my PO too.
An arrow verging on the too-short. 28" BOP.
Of these things the only variable you have is arrow length. You could probably, safely go down to 28" but you'd have to go up in poundage if you stay with those arrows.
Using a shorter weaker spined, and therefore lighter, arrow will aid your PO in two ways.
Compromising a little on spine (going for an intermediate spine in the shorter length) and compensating with a slightly heavier point to increase FOC may well help grouping at distance.
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It's a play off between Kinetic Energy and Momentum.
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As with any “missile” it’s all about the CG .... too nose heavy drops the nose at distance , tail-heavy drops the tail ... With the right CG the arrow should fly pretty “flat" in the horizontal (pitch) plane ...the trick is adjusting the tip weight/balance while not affecting the spine ... (Yaw)
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Oh yeah i would've! :laugh: albeit i held a lot of things back and at times even kissed his butt a lil in the name of diplomacy. :laugh:
but...i did have a lil penetration test of my own almost prepared to video that does show the opposite of shapies results..and by a fair margin i might add...but instead of using some arrows with weight tubes and others yet with wood grain wrapping over the carbon fiber?..i'm using all carbon fiber...and instead of a phone book for target media?...i just had gotten a couple sheets of virgin ethafoam from the shop last week to prove it out using the very arrows specified above.
Very good Greysides!...i like it...as..
While "Momentum": determines how energy is delivered?..."Kinetic Energy": is how much energy a moving body can carry.
and since it's friday?..and i just got home from work with my first cup of coffee and it's raining out?...here we go. :laugh:
"missiles"?..."projectiles"?..how about bullets?...anybody ever wonder why a 150gr .30-30 round can come out of a muzzle at velocities rivaling that of an AK47 round yet while the AK has the ability to keep'em all in a dinner plate at 200yds you'd be lucky to hit a fridge at that distance with the 30-30 round?...enter "Frontal Area" and "Drag Coefficient"...30-30 rounds (like any other round produced that are chambered in calibers that can be used in "tubular magazine" fed rifles) are flat on the front...as if they were pointed like a spitzer/speer type bullet?..the point could act as a firing pin during recoil and blow the rifle up in the shooters hand by initiating primers of the leading rounds in the tubular magazine..so 30-30's, 35rem, .444marlin, .45-70...all blunt point rounds..and once they leave the muzzle?...they shed velocity and drop out of the sky like nobodys business..but the bullets used for these chamberings are usually of high mass weight bore for bore as compared to other popular box fed chamberings...what's this got to do with archery?...not a whole lot except..the "Drag Coefficient" part...but we don't induce DC with blunt points...we do it from the other end of our projectile..with fletching..and really?..missiles or bullets are not to be compared with arrows...two very different beasts...speaking of which?...let's break down "The Arrow"...and with me exercising a bit of poetic license here?...allow me to suggest we look at the arrow this way...
The Point?...is "The Bullet"
The Fletching?: is "The Drag Coefficient"
The Shaft?: is the wet noodle linking the two together.
And we need that noodle to be wet as it gives us archers the much needed "Paradox"...how wet?..depends on how stiff or weak of a spine your draw weight and length demand..that said?...a percentage of the bows stored energy gets eaten up by this necessary evil of paradox..as when the bows stored energy is released?..the energy is transmitted through the nock...into the shaft..and finally into the point..and as the now flying arrow cycles through it's numerous shaft oscillations?...what helps it to "recover" from that sudden jolt of stored energy is two fold...as while the energy moves forward through the arrow amassing itself in the point?..that energy in the densely weighted point begins "PULLING" the arrow shaft straight while the opposing force?...the fletchings (aka "Drag Coefficient")..is "DRAGING" the tail end of the shaft straight from the rear as the arrow reaches a state of "Full Recovery" and the energy then balances out throughout the arrow...somewhat...as the tailend is still inducing drag.
and this is where i believe i've made a mistake using 4" full helix feathers on my 350gr full length bemans..as while they are screamers up front and flat as sin out to 20-25yds?..they drop off dramatically due to too much drag...as i've come to the conclusion that they suffer an "Over-Fletched" condition.
Bet if i put some 2" RaZrs on those babies they'd be right uptown! :laugh:
and no..i wouldn't have posted all that had sharpy still been here! :laugh:
L8R, Bill. :cool2:
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