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Main Boards => PowWow => Topic started by: RC on November 30, 2010, 11:46:00 PM

Title: really crazy question....
Post by: RC on November 30, 2010, 11:46:00 PM
If you have two arrows of the exact same weight . One has say ...a 100 grain point and the other has a 300 grain point but both arrows total weight are the same.Will they both have the same trajectory or will the heavy in the nose one drop more? Told you it was crazy.RC
Title: Re: really crazy question....
Post by: sweeney3 on December 01, 2010, 12:09:00 AM
I dunno about trajectory, as in the arc of the arrow, or flight path, but the spine and therefor the flight characteristics will likely be very different.  That might affect the final trajectory.  Trajectory is the sum of internal and external ballistics and nonstandard conditions, for you artilerists out there.   ;)   Kinda similar with arras, but a lot less math.
Title: Re: really crazy question....
Post by: Encino Man on December 01, 2010, 12:59:00 AM
My guess is that in theory, two arrows weighing the same would have the same trajectory. But in reality the arrow with the greater FOC would have better flight which means less resistance and that equates to a flatter trajectory. Just my humble guess.
Title: Re: really crazy question....
Post by: S.C. Hunter on December 01, 2010, 01:03:00 AM
My belief is if the ratio for FOC is not exceeded for stability. The arrows in short distances may not differ much. We are only talking about flight and not penetration correct?

 The arrow that has the weight distributed more evenly will give better flight characteristics at distance. In windy conditions this would probably be seen more. Some say a heavy head pulls the arrow along for the ride? If this is so I guess the lighter head arrow is driven by the launch of the bow and the feathers help to steer the arrow.

 My point is at some point an increase in head weight will have a negative influence on flight. If the back end doesn't have a offset in weight or a bigger rudder, that being larger or more feathers. Just my thoughts. When I shoot my heavier head arrows I see a flight difference in the wind or at distance. I have wood arrows that weigh 550 grains with the 125 grain heads included. My carbons have the same weight overall but have 175 grain heads and I see a difference in the wind past 20 yds. My woods are more stable both may drift but my carbons will move more at the back end.
Title: Re: really crazy question....
Post by: Bjorn on December 01, 2010, 01:14:00 AM
We are assuming perfect flight-right? If they weigh the same they will hit the ground at the same time.
Title: Re: really crazy question....
Post by: RC on December 01, 2010, 09:53:00 AM
Let me clear it up. I don`t care about penetration. I just was wondering if the arrow with the high foc would drop faster being nose heavy. Both arrows fly like bullets.
 not being a smart axx but I have killed over 100 deer and more than twice that in pigs. I have never had any penetration issue and I have always shot under 60 lbs usually around 50. I can`t understand all the issue on penetration. Of course I`ve never hunted elk or cape buffalo but I have killed some BIG Boars.I think the reality of it is sometimes we hit shoulder blade and we just plain out made a bad shot. Superduper broadheads and arrows don`t make up for that ...better shooting does.RC
Title: Re: really crazy question....
Post by: BobCo 1965 on December 01, 2010, 09:59:00 AM
I believe that OL Adcock won distance records with very high FOC arrows.

I would assume that the higher FOC arrows would have a flatter trajectory.
Title: Re: really crazy question....
Post by: Apex Predator on December 01, 2010, 10:08:00 AM
I haven't done the experimenting on this particular set-up choice Robert, but I've read lots on it.  The general consensus is that the higher FOC arrow flies flatter and is affected less by the wind.  That's contrary to what "common sense" tells us.  Most would figure the heavier point would cause a nose dive eventually.
Title: Re: really crazy question....
Post by: pronghorn23 on December 01, 2010, 10:12:00 AM
Interesting question. I would think (just my guess based on nothing) that the one with the heavier front would sink faster. I guess I think this because it's like the arrow is pushing the extra weight up front and therefore would lose more energy vs having the arrow evenly weighted throughout or with less weight up front.

This reminds me too much of math class story problems.
Title: Re: really crazy question....
Post by: Ryan Rothhaar on December 01, 2010, 10:14:00 AM
Gravity is gravity.  Unless the air resistance of the two projectiles is significantly different they'll both "drop" the same, regardless of how the weight is distributed.  (See, I DID learn something in Physics class!)

And RC, I'm right with you on the penetration thing, bud!  What carbons with heavy points have done for me has more to do with increasing the spine range of arrows I can shoot out of my bow than penetration.  Of course I'm back to shooting XX75's now!

R
Title: Re: really crazy question....
Post by: lpcjon2 on December 01, 2010, 11:21:00 AM
A pound of bricks and a pound of feathers are dropped of the Empire State building which lands first?

I would think that all weight being the same would not matter,as the heavier weight in front would cause it to drop faster due to wind resistance on the head. the heavy head once met with the resistance should allow gravity to take it down faster than an all balanced arrow of the same weight. The equally balanced arrow should drop at an even pull to gravity and the heavy front arrow will have more pull on the front lifting the rear and causing a faster drop.This is my un-educated hypothosis on the matter further testing will not be done by me.   :goldtooth:   JMHO
Title: Re: really crazy question....
Post by: Jeff Strubberg on December 01, 2010, 11:23:00 AM
They will have exactly the same trajectory.  The arrow shaft doesn't provide enough wind resistance to matter, so mose up/nose down is pretty much irrelevant.
Title: Re: really crazy question....
Post by: Guru on December 01, 2010, 11:27:00 AM
Robert, The only think I've noticed it they(lighter pointed arrows) seem to come out of my bows higher. In other words they seem to hit higher at close range...not sure why, and I may be crazy...but thats what it seems like to me. At long distance, not really sure.

I will say this thou...I really like the way a heavier point shoots compared to the lighter point weight arrow.

If choosing between the two, I wouldn't hesitate, my choice would be the heavier point     :thumbsup:
Title: Re: really crazy question....
Post by: straitera on December 01, 2010, 12:44:00 PM
One thing I do know is I can learn from anyone who's killed 100 deer & 200 pigs w/50# setup. Can't help you w/your question; but, I have questions of my own you can help me with. Worthwhile stuff Robert. Much obliged.
Title: Re: really crazy question....
Post by: Jim now in Kentucky on December 01, 2010, 12:46:00 PM
Better to turn to science than philosophy for the answer. It's not what we think that makes a difference. It's what can be demonstrated and has been measured.

Paul Klopsteg did some extensive tests on the effect of center of mass for arrows back in the 1930s. It's all available in "Archery, the Technical Side."

I realize these forums would wilt without the flow of unsupported opinions, but if anyone really wants answers that can be trusted, they should consider a little research into Klopsteg's work and the field of flight shooting.

jm .02
Title: Re: really crazy question....
Post by: SveinD on December 01, 2010, 06:03:00 PM
If FOC objects fly flatter than objects of equally distributed weight, wouldn't aeroplanes be FOC-heavy?

Of course, this would imply that arrows should have two larger feathers at center, or FOC-Zero, and two (3?) feathers at the back for optimal flight, at least while at low FOC values^^

Hm, I know it's getting late here, but ranting is more fun in dozy states of mind!  :)  

Zzz...
Title: Re: really crazy question....
Post by: Hot Hap on December 01, 2010, 06:09:00 PM
My head hurts. Hap
Title: Re: really crazy question....
Post by: Chris Shelton on December 01, 2010, 06:16:00 PM
Hmmmmmm . . . arrows begin to drop as soon as they leave the string! The non-FOC arrow will not fly as smoothly as a FOC arrow.

Foc arrows have a more off-balanced placement of mass. Its like a water bottle filled halfway with water, if you push it that second wave of energy will push it again. With a fully filled bottle of water it only moves once.

The whole point of increasing FOC is to increase penetration. That penetration increase is due to the slower decrease in energy.

The higher FOC arrow will loose energy much slower than a lower FOC arrow . . . to me that says the higher FOC arrow will go further and drop slower . . .
Title: Re: really crazy question....
Post by: Rob DiStefano on December 01, 2010, 07:02:00 PM
QuoteOriginally posted by Chris Shelton:
... The whole point of increasing FOC is to increase penetration. ...
um, nope, not for me - higher foc arras just fly and track better, for me.  

dunno or care that much about the penetration factor 'cause all i'm interested in is an arrow that's about 10gpp and has good straight flight.  that equates to better accuracy for me, and as we all know too well, it's accurate shots with sharp coc broadheads that down the game best, not foc, gpp, lmnop or whatever.  so for me, it's consistent accuracy with straight flight that matters most.

QuoteOriginally posted by RC:
If you have two arrows of the exact same weight . One has say ...a 100 grain point and the other has a 300 grain point but both arrows total weight are the same.Will they both have the same trajectory or will the heavy in the nose one drop more? Told you it was crazy.RC
dunno for sure, but if i shot both arras i'd probably see the high foc track better and that's what i'd wanna take hunting.
Title: Re: really crazy question....
Post by: lpcjon2 on December 01, 2010, 07:06:00 PM
Now Rob, I would have thought you would have already tested this theory.   :goldtooth:   I didn't think there was much you haven't tested or researched.
Title: Re: really crazy question....
Post by: Rob DiStefano on December 01, 2010, 07:12:00 PM
QuoteOriginally posted by lpcjon2:
Now Rob, I would have thought you would have already tested this theory.    :goldtooth:    I didn't think there was much you haven't tested or researched.
in reality, and as alluded to above, i have no interest in this matter.

i'll leave the formal testing and research to the rocket scientists, and we'll get a bunch chiming in on this thread  ;)  ... i never graduated MIT, but did get decent marks in street smarts.  :D
Title: Re: really crazy question....
Post by: wapitimike1 on December 01, 2010, 07:27:00 PM
The heavy nose drops like a rock when I've done it!
Title: Re: really crazy question....
Post by: Ben Maher on December 01, 2010, 07:36:00 PM
QuoteSuperduper broadheads and arrows don`t make up for that ...better shooting does.RC  
I am with you Robert . I have taken a lot of pigs over the years , some rather big and mainly with moderate poundage bows , medium weight arrows and straight limbed bows . Shot placement is forever the key .
I load my arrows up with 200gns up front ... but that is spine and arrow weight consideration with my alloys . My woodies shoot 190's ... again this is to get them up to 10/11gns pp
I did notice that the few carbons i have played with shot very well with high FOC ... as did the arrows woth moderate FOC lol ...
Title: Re: really crazy question....
Post by: xtrema312 on December 01, 2010, 07:50:00 PM
RC,  If you have both arrows why not just go out and shoot them to see for yourself?  OH, that wouldn't be as much fun would it.  ;)  

QuoteOriginally posted by lpcjon2:
A pound of bricks and a pound of feathers are dropped of the Empire State building which lands first?
The brick because a pound of feathers would be a much larger mass with more air resistance.  That is unless we are in a vacuum of the feathers have been super compressed into a density and mass equal to the brick and somehow don't expand or are packed into some other contain thus not being really just a pound of feathers.................

QuoteOriginally posted by Chris Shelton:
The non-FOC arrow will not fly as smoothly as a FOC arrow.  
That is a generalization.  I have found that not to be true at times.  I found out by shooting paper at all different distances.  I have seen HFOC arrow fly most of 25 yd. 1-2" out of line.  To the eye they look very smooth and wobble free, but they never fully correct over the distance most of us shoot.  They look fine and shoot consistent with good bare shaft POI readings, but being out of line has to cause more drag due to more feather and shaft area exposed.  I have seen a different arrow set-up with basically standard FOC correct quick and stay that way shooting bullet holes 15' to 25 yd.
Title: Re: really crazy question....
Post by: Ragnarok Forge on December 01, 2010, 07:53:00 PM
It is always fun to discuss the issues like this and yes we should all look to science for an answer.  The same weight of feathers will not hit the ground as fast as the same weight of lead.  That only works in a vaccum.  Resistance over the larger surface area will slow the feathers more than the lead.

If the arrows weigh the same, have the same  surface area, and same fletching sizes the arrows will hit the ground at the same time.  The interesting part of this is that the EFOC arrow will recover from paradox more quickly, giving cleaner flight and less drag.  So I guess the real question may be....wait for it....... will the EFOC arrow fly further in the same time of travel when fired at the same speed as the non EFOC arrow?  I have noticed that an arrow with a lighter head at the same weight has a higher arc to it's trajectory to hit the same point of impact.
Title: Re: really crazy question....
Post by: RC on December 01, 2010, 07:58:00 PM
Told ya`ll it was a crazy question...but an interesting one.RC
Title: Re: really crazy question....
Post by: Mike Vines on December 01, 2010, 08:16:00 PM
QuoteOriginally posted by Bjorn:
If they weigh the same they will hit the ground at the same time.
X2
Title: Re: really crazy question....
Post by: Jason R. Wesbrock on December 01, 2010, 08:28:00 PM
QuoteOriginally posted by RC:
 
 not being a smart axx but I have killed over 100 deer and more than twice that in pigs. I have never had any penetration issue and I have always shot under 60 lbs usually around 50. I can`t understand all the issue on penetration. Of course I`ve never hunted elk or cape buffalo but I have killed some BIG Boars.I think the reality of it is sometimes we hit shoulder blade and we just plain out made a bad shot. Superduper broadheads and arrows don`t make up for that ...better shooting does.RC
I couldn't possibly agree more!
Title: Re: really crazy question....
Post by: Sixby on December 01, 2010, 08:35:00 PM
Ballistic co-efficiency is important with arrows just as it is with bullets. The arrow with the best ballistic co-efficiency will travel the furthest even though they are the same weight. For instance you could have one arrow with a shield cut and one with flu flus and both shot from same bow and both weigh exactly the same the Shield cut arrow has less drag and will go further. There is more resistance to the air. I believe that the balance of the arrow would definately enter into the ballistic propertys of the arrow.

God bless and Merry Christmas to you all, Steve
Title: Re: really crazy question....
Post by: Sixby on December 01, 2010, 08:37:00 PM
An Addendum here. Even though the two arrows hit the ground at the same time , one of them will hit it much , much further away from the point of origon than the other one.
Title: Re: really crazy question....
Post by: S.C. Hunter on December 01, 2010, 08:56:00 PM
Guru, just to back up what you said about the arrows with a lite head hitting higher at short distance. I went out today after my post last night. I shot my wood arrows at 550 grains with 125 grains up front and 3-5" feathers. And my carbons of the same weight and feathers but with 175 grain point and 50 grain insert up front for 225 grains up front. From 20 yds my woods hit about 4-5 inches higher than the carbons. From 25 yds it was about almost the same. when I moved to 30 yds it was about a foot of difference.


  What I did notice was when the wind would gust the arrow that was heavy up front would get a fish tail type of action going, on the way to the target. The arrow with the 125 grains up front would drift just a little but the flight did not fish tail. I would not say I saw a nose dive but the trajectory was different.
Title: Re: really crazy question....
Post by: AdamH on December 01, 2010, 09:25:00 PM
Working for "Budweiser" here in Pa. I had a guy ask me once, does a 1/2 of Bud weigh as much as a 1/2 of Bud Light .............
Title: Re: really crazy question....
Post by: Ryan Sanpei on December 01, 2010, 09:42:00 PM
RC,
PM me if you are interested in my findings past 30 yards.  It was done with a compound so I don't think that I should post it here.  I used the compound because I cant group a trad bow well enough past 30 to know if the arrow's shooting high or low or if it's just me.

With a trad bow, 30 yards and under, I have found no difference in impact point between two well tuned arrows of the same total weight.  I've gone with tip weights from 100 gr all the way to 300 gr upfront.  I've even bareshafted with the same results (if anything would dive I would think the bareshaft would).  Keep in mind that these are my informal results.  

After trying all of this, I've found that a 200gr tip plus my standard insert and sleeve(227gr upfront) performs the best for my set up.
Title: Re: really crazy question....
Post by: RC on December 01, 2010, 09:49:00 PM
Thanks S2, I have a bunch of each arrow and I`m gonna shoot stuff with each till I run out then buy some more God Willing. I was just sitting by the fire trying to stir some friendly conversation on an interesting subject...it worked.Thanks for your input guys.RC
Title: Re: really crazy question....
Post by: Friend on December 01, 2010, 09:57:00 PM
I believe the arrow with the much higher FOC will have a flatter trajectory. The higher FOC arrow will correct itself quicker,thus wasting less energy. Don't believe you will notice the difference until they are well down range.
Title: Re: really crazy question....
Post by: xtrema312 on December 01, 2010, 10:09:00 PM
QuoteOriginally posted by AdamH:
Working for "Budweiser" here in Pa. I had a guy ask me once, does a 1/2 of Bud weigh as much as a 1/2 of Bud Light .............
And?  :dunno:
Title: Re: really crazy question....
Post by: Don Stokes on December 02, 2010, 06:33:00 AM
The higher alcohol content Bud would be lighter... alcohol has a lower specific gravity than water.

RC, is there nothing to hunt in GA now?    :)
Title: Re: really crazy question....
Post by: hvyhitter on December 02, 2010, 09:06:00 AM
What FOC do they shoot out of Olympic bows out to 70 meters or more in competition? I see alot of their target points are rated in FOC (7%-9%)They couldnt care less about penetration just perfect arrow flight. Much money and science has been thown at target archery at that level so they pretty much have tried all combinations and are going to use the best one. For a hunting arrow at real hunting distances I dont think it matters all that much.
Title: Re: really crazy question....
Post by: leatherneck on December 02, 2010, 10:26:00 AM
Cabin fever has hit early. I'm going back to the woods.  :bigsmyl: