# Speed Nocks **myth Buster??**



## JAVI (Jun 19, 2003)

Depends on the bow... and string... I've seen any thing from no gain to 7-8 fps... 

is it worth it? to some people who wat the absolute max speed I say Yep...

For me with a 29" draw.... I don't bother...

P.S. even nock fit can affect the speed...


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## bowman78 (Oct 21, 2005)

*free speed ?*

since when is 4 fps of speed with no extra draw weight or length not worth it? it is free speed , why wouldn't you want it if you have a chrono and the time. i have added 4-5 fps average on my bows anyways and it is well worth it to me and i also have 29 in. draw but i am not the greatest at judging dist....tim weesner


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## JAVI (Jun 19, 2003)

1. I'm limited to 280 feet per second....

2. have you ever calulated the difference in drop between 280 fps and 300 fps at 40-50 yards...


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## hoyt275 (Mar 17, 2005)

Try 2 nocks about 2 inches away from cam... 2 near top, 2 near bottom...
on spirals this usually gave me about 8 fps...

Keep adding nocks until you lose speed or make no difference... 

For me it was 2 nocks always close to cam..

Besides speed gain it cuts down on side to side string oscillation:wink: , which is not as much a factor with the short string Hoyts as compared to th longer solo cams...


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## bowman78 (Oct 21, 2005)

*drop?*

though i have never calculated the drop with the speed difference, my concern is not just speed for 3-d but also free k.e. which gives that little bit more penetration. i am also sure the drop difference is probably in the range of 1-1 1/2 inches which in 3-d is a mile if you misjudge yardage......tim weesner


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## JAVI (Jun 19, 2003)

bowman78 said:


> though i have never calculated the drop with the speed difference, my concern is not just speed for 3-d but also free k.e. which gives that little bit more penetration. i am also sure the drop difference is probably in the range of 1-1 1/2 inches which in 3-d is a mile if you misjudge yardage......tim weesner


Just as an informational post... with my 3-D rig.... the difference at 50 yards is 0.16 inches... 

Example: If I judge a 50 yard target as 49 yards.... at 280 I'll be 1.13" low... 

At 301 I'll be 0.97" low.... 

Sorry guys I can't shoot that good at 50 yards... If y'all can I bow to your superior abilities....

One more... if I'm off by 4 yards short, the difference is 0.63"



The best thing about speed nocks is they will quite a string twang a bit, and they do help with string oscillation which may improve accuracy… The speed thing is secondary to me… 

Ok... one more... If I'm off by 10 yards.... I'd miss belly meat by 1.55" lessukey:


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## bowhuntrrl (Oct 9, 2004)

JAVI said:


> Just as an informational post... with my 3-D rig.... the difference at 50 yards is 0.16 inches...
> 
> Example: If I judge a 50 yard target as 49 yards.... at 280 I'll be 1.13" low...
> 
> ...



It's all nice to use software to calculate drop and trajectory, but I bet in the real world the difference is more significant than that. I bet 20 fps is good for 2" or more. I've used ballistic software for years. You have to remember something, it's all based on theoretical calculations and physics. It doesn't take real world effects into account. I found this out many times in the past sighting in rifles.


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## ursonvs (Sep 19, 2003)

another reason to use some kind of speed nock is to make sure the string tracks the cams groove better right after release. at that split second moment, everything is really loose and having something to help track a string better to me is a added safety precaution IMO. I have witnessed several brands with no type of speed nock or eliminator button near the cam become unguided and the string ends up on the axle.


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## Miles Gloriosus (Feb 11, 2006)

bowhuntrrl said:


> It's all nice to use software to calculate drop and trajectory, but I bet in the real world the difference is more significant than that. I bet 20 fps is good for 2" or more. I've used ballistic software for years. You have to remember something, it's all based on theoretical calculations and physics. It doesn't take real world effects into account. I found this out many times in the past sighting in rifles.


So, professor, what kind of real world effects are we talking about here? Sunshine beating down on your arrow, causing it to fall lower? It seems interesting that you'd dismiss Javi's calculations *without doing any of your own (I HOPE I'M MAKING IT CLEAR THAT YOU DIDN'T DO ANY MATH OF YOUR OWN!)*.


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## CoppertoneSPF15 (Mar 14, 2006)

Miles Gloriosus said:


> So, professor, what kind of real world effects are we talking about here? Sunshine beating down on your arrow, causing it to fall lower? It seems interesting that you'd dismiss Javi's calculations *without doing any of your own (I HOPE I'M MAKING IT CLEAR THAT YOU DIDN'T DO ANY MATH OF YOUR OWN!)*.



Induced drag (Varies depending on geometry of field tip/broadhead, vanes, and maybe nock depending on if it's internal or external)

Form drag (Varies depending largely on how clean your arrow is aerodynamically speaking. Very likely a minimal effect on arrows as they don't come anywhere near tran-sonic speeds. However, there's still an effect, minimal or not.)

Skin friction (Residue, manufacture labels, scratches, nicks, left over glue... many different skin friction properties, extremely difficult to calculate precisely)

Interference drag (Feathers? Duravanes? Blazers? Parabolic shaped vanes or shield cut? These will all generate varying quality vortices. Some negligible, others not so much.)

Wind

Humidity

I'm not saying Javi's approximations weren't a close reflection of reality. I got the impression he quoted measurements he made from actual tests. What Javi got with his bow/arrow setup might be different from someone else. A bow with straight and level nock travel will fling that arrow differently than one that maybe has high travel. Oscillations in the arrow can change alot things. Moreover, there's many different kinds of tips, fletchings, arrow shafts, and nocks out there. They are not all balanced the same and can shoot very differently.

Realize that bowhuntrrl brought up a valid concern. Even in aeronautical engineering, the math we use to design aircraft flight behavior is only an approximation. There are such equations and computer simulations that will produce highly accurate reflections of reality but infinite precision is near impossible. That's why designs go through live test phases, then back to redesign, then test, then redesign, then test... etc... There's always factors that can be and are overlooked/underestimated by calculations and computer simulations. 

Run a search on google under: engineering factor of safety. Mayhaps wikipedia has something on that. Just about anything, if not everything that is engineered to product has a factor of safety built in.


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## JAVI (Jun 19, 2003)

bowhuntrrl said:


> It's all nice to use software to calculate drop and trajectory, but I bet in the real world the difference is more significant than that. I bet 20 fps is good for 2" or more. I've used ballistic software for years. You have to remember something, it's all based on theoretical calculations and physics. It doesn't take real world effects into account. I found this out many times in the past sighting in rifles.


And I'll bet that with a bow.... you can't shoot well enough to know the difference at 50 yards.... But it's nice to think you can...:wink:

By the way.... I actually test this stuff in the "REAL world".... The same as I did when shootin' benchrest and High Power...:wink:


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## JAVI (Jun 19, 2003)

As I sit here at my desk this morning, supposedly designing the latest and greatest thingamabob; I thought I might interject this as well…

Each arrow and bow setup will behave differently; the numbers I quoted are from my setup; yours will vary. Even the difference in the vanes or feathers you use and how you fletch will have an impact on the results. The diameter and the length of the shaft, the humidity, air temperature, barometric pressure, wind direction, elevation and many other things will vary the results. 

But rest assured that I have tested my setup right down to the “REAL” chronographed speed of my arrow at 50 (for my 3-D setup) and 80 yards for my field rig… and I have found the best arrow combinations for me…

My numbers are not based on supposition nor guess work but real world work, and I do use OnTarget for many of my preliminary calculations, I find that if you impute correct real world data into the fields it is surprisingly accurate. I don’t assume the weight of my vanes, raw arrow shaft, points, wraps, nock or pin bushings, "I know" and enter the data. "I know" the difference in down range velocity for my arrows with 1.75” mini FITA vanes vs. 2.3” Super Spines and the drop associated with the difference. 

I eat this stuff up… it’s how I relax and it ain’t bad practice either….

Finally….

I don’t blindly take someone’s word for what will work for “ME” I test it… There are way too many internet experts who read or see that someone or other shoots this or that and immediately assumes it to be the best for them as well.

If I write that something works for me, it does…. Because I tested it and found it to work… not because ______________ told me it was the best. And because it works for me, will not and cannot guarantee that your results will coincide.


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## Miles Gloriosus (Feb 11, 2006)

The point was that Bowhunter basically said, "no ur wrong." Not, "No, I disagree, my set up drops this much at this distance, and here's the equation I've figured out. I call it, 'Bowhunter's Law of How Quickly Arrows Fall to the Ground'."


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## CoppertoneSPF15 (Mar 14, 2006)

Miles Gloriosus said:


> The point was that Bowhunter basically said, "no ur wrong." Not, "No, I disagree, my set up drops this much at this distance, and here's the equation I've figured out. I call it, 'Bowhunter's Law of How Quickly Arrows Fall to the Ground'."



I would say I got a different impression from what bowhuntrrl had posted. It seemed to me that he was saying from his personal experience with ballistics software and rifle sighting, trajectory calculations can't always be relied on for accuracy. There's too many variables that come in to play. 

Like I mentioned earlier, I believed Javi's post to be based on his live test results. Which in turn means that what bowhuntrrl had posted about ballistics software isn't entirely applicable anymore. I think the point of confusion came when Javi had asked, "Have you ever *calculated* the difference in drop ....." At first what I got from that was probably very similar to what bowhuntrrl seemed to get out of it, that Javi was indicating that a drop could be hand/computer calculated (not to say it can't be). Then after reading his post on the effects of 20 fps at 50-60 yards, I was fairly certain he was referring to his results from live testing. 

Seems more a mis-communications as Javi himself even pointed out that there are varying degrees in everyone's setup. His results are not going to be someone elses results. You can't calculate everyone's arrow drop the same. Javi uses smaller, target type vanes. Swap those for some 5" feathers at 3 degree helical and I bet bowhuntrrl wouldn't have been far off when he assumed a 2" drop at 50-60 yards when losing 20 fps. 

Back to the topic at hand, 4-5 fps might be worth the trouble if you shoot long range and outdoors. Or, if you use longer vanes, feathers, heavy shaft, etc... you'd would want to squeeze as much fps out of that rig as possible. I shoot mostly indoor 20 yards. Whether it's 200 fps or 300 fps, as long as that arrow is delivered to the target the same way everytime, it makes no difference. An X at 200 fps is as good as an X at 10000000 fps. Except you'd have a baseball size hole in your backstop with the later case.


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## silverback (Jan 20, 2005)

CoppertoneSPF15 said:


> Induced drag (Varies depending on geometry of field tip/broadhead, vanes, and maybe nock depending on if it's internal or external)
> 
> Form drag (Varies depending largely on how clean your arrow is aerodynamically speaking. Very likely a minimal effect on arrows as they don't come anywhere near tran-sonic speeds. However, there's still an effect, minimal or not.)
> 
> ...


How do any of those things change by adding speed nocks???
The arrow still has the same vanes, the same nicks, the same label.
Drag is proportional to speed, but we are only talking about an approximate 2.5% difference in speed in the extreme case. That won't increase the drag a noticable amount.

Also, I would think arrows are not going fast enough to generate very much skin drag, and the difference a manufacturer's label adds is going to be insignificant.


I would guess that the theoretical (calculated difference) is very accurate.
If you are using the measured speed before and after speed nocks, you are calculating the exact KE. Same as if you measure how fast a car goes in a certain amount of time-- you can calculate the exact speed.

Even if the calculated difference is off, the actual difference should be smaller.
We can calculate how much the faster arrow will drop in a vacuum (which I think is Javi's number; if he is saying he can't shoot good enough to measure a .97 inch difference at 50 yds, then I assume it is a calculation.)
Assume the increase in drag is significant, it means the faster arrow has more drag. So it will hit below what the theoretical calculation is.
It will hit closer to the slower arrow, so the difference between the faster arrow and the slower one could be less than the calculated difference. 

Add speed nocks and increase the speed by so many FPS,


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## CoppertoneSPF15 (Mar 14, 2006)

silverback said:


> How do any of those things change by adding speed nocks???
> The arrow still has the same vanes, the same nicks, the same label.
> Drag is proportional to speed, but we are only talking about an approximate 2.5% difference in speed in the extreme case. That won't increase the drag a noticable amount.
> 
> ...



Think you mis understood the point of my post. Point wasn't that adding/removing speed nocks changes the above mentioned attributes. Point was that due to the above mentioned qualities, calculating precise arrow drop due to decrease fps is very difficult. 

Yes, drag on the label is minimal by itself. Add many minimal variables together and you get something that ends up being not so minimal. 

Like I mentioned previously, it depends largely on the arrow. Take 2 of the same shafts, fletch one with 1.3 inch straight vanes and the other with 5 inch helical feathers. It won't take a rocket scientist (pun intented :wink: ) to tell you that regardless of how fast those arrows are going, drag makes a noticible impact.

Although many of the aircraft I work on are high altitude, tran-sonic fliers, I still do come across low altitude low speed vehicles once inawhile. You are correct in stating that lower speeds minimized drag effects. But it seems you are forgeting that arrow balance, weight, oscillation plays a big role in just how much you get hit by drag, even if you're slinging them at 250 fps or lower.


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## silverback (Jan 20, 2005)

CoppertoneSPF15 said:


> Yes, drag on the label is minimal by itself. Add many minimal variables together and you get something that ends up being not so minimal.


Yes, but I would think even the sum will be very small, even for a fast 300 fps bow.



CoppertoneSPF15 said:


> Like I mentioned previously, it depends largely on the arrow. Take 2 of the same shafts, fletch one with 1.3 inch straight vanes and the other with 5 inch helical feathers. It won't take a rocket scientist (pun intented :wink: ) to tell you that regardless of how fast those arrows are going, drag makes a noticible impact.


Comparing helical vanes to straight vanes is a very different thing.
The drag calculation should only matter if you are trying to calculate the drop for 1 arrow.
I would think it makes no difference when you are calculating the* difference in drop *between 2 arrows.

My point is this:
Take the same shaft, measure the speed before and after.
The difference is less than 10 feet per second.
Calculate the drop for the first arrow. We know it won't be accurate because of drag and friction, etc.
It doesn't matter.
Calculate the drop for the second arrow, it will have the same errors.
Make the assumtion that 7 fps does not increase the drag significantly (which is pretty fair). Both arrows have the same drag (same difference between theoretical and actual results).
When you take the difference, those errors cancel out.
So, the difference in drop is still a valid calculation, even if the base calculation is not.

Ok, now remove the assumption and say 7 fps significantly increases the drag.
Well, you have a faster arrow that should drop less. But it has more drag, so the gap between the two arrows will not increase in proportion to the increased kinetic energy.
So, the difference between the two arrows would be less than the theoretical difference.
The utility of the calculation would be to establish the upper bound of the drop between the arrows.


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## JAVI (Jun 19, 2003)

silverback said:


> How do any of those things change by adding speed nocks???
> 
> *They don't... I said it wasn't worth the trouble to gain 5-7 fps... and asked if they...??? had ever caculated the difference in impact at 50 yards between 280 and 300 fps...*
> 
> ...


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## CoppertoneSPF15 (Mar 14, 2006)

It would matter. Form and interference type drag varies greatly with speed. 300 fps, the drop difference with an arrow that has high helical and long vanes will be much different than one with little to no helical and short vanes. The drag function in relation to speed is exponential. You cannot compare it linearly like in your example. 

Also makes a difference between a well tuned bow and one that slings an arrow with oscillation. Vibration will be different depending on fps and consequently, how much momentum is lost in transit. 

Assuming a well tuned bow, the complications are much simplified but if not, any erratic behavior is quickly compounded unless you shoot with perfect form/technique.


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## CoppertoneSPF15 (Mar 14, 2006)

Just as clarification, the above post was adressing:



silverback said:


> The drag calculation should only matter if you are trying to calculate the drop for 1 arrow.
> I would think it makes no difference when you are calculating the difference in drop between 2 arrows.


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## MNmike (Dec 27, 2003)

*I believe what Silverback was saying is...*

if shooting the same bow and same arrow twice.

One W/O speed turds on and one with. All the same with the one exception.

IMO at 40 or 50 yards with a moderatly fast bow, you wouldn't notice the drop much at all.


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## CoppertoneSPF15 (Mar 14, 2006)

Mike Ryan said:


> if shooting the same bow and same arrow twice.
> 
> One W/O speed turds on and one with. All the same with the one exception.
> 
> IMO at 40 or 50 yards with a moderatly fast bow, you wouldn't notice the drop much at all.



If that's all he was addressing, it holds little bearing on what I was talking about in my original post as those were in response to Mike Gloriosus' post. Read back a bit to the beginning and you'll see that is the case. 

However, my previous responses can be extrapolated to relate to the original topic, which I also briefly talked about. 20fps, 30fps, whatever fps, shows up differently with different setups. While Javi's rig and arrows won't produce much of a difference given a 20fps drop, someone elses might. In which case, it would be a good idea to use speed nocks to gain that extra 5 fps. Why? Because maybe you can get another 5-10 fps elsewhere, then another 4 fps with a lighter string, then again 3 fps with a drop away... all culminating in a 20-25 fps boost (or 15-20, or 25-30, or 22-24, or whatever... etc). 

In and of itself, 5 fps isn't much. But 5 fps here, 5 fps there, and eventually you have something that might make a difference with your setup. With certain arrows and/or bows, this could pay off enough to warrant the use of speed nocks and whatever else helps squeeze those few fps. 

A quick point of clarification, all my above posts were ultimately addressing the fact that pure calculations won't _necessarily_ tell you whether or not your rig could appreciate that gain in speed. Look back to my original post and you'll see that I'm an advocate of testing over calculations. Hence why I made it a point to state that I didn't disagree with Javi's numbers as I was under the impression he came upon those figures through live testing.


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## Spotshooter2 (Oct 23, 2003)

If you use the same arrows, vanes , weights of arrows the drop can be calculated very accurately otherwise software programs like On Target wouldnt be able to accurately give you a reliable sight tape. But obviously they do work so obviously you can predict the drops.


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## Target Tony (Mar 3, 2003)

Burly Hall did a real world test of a bow that shoots 280 and a bow that shoots 310. this is all on video tape by the way. the differance in those 2 speeds and a 2 yard error in yardage was 1 1/2 inches.

so if you shoot for a center 10 and you miss it by 2 yards, you will hit 1 1/2 inches lower than with a bow that shoots 310 fps. 

of course this is only good for IBO shoots. also local shoots where no one checks how fast your bow is shooting.. NFAA and ASA have a 280 speed limit.


Shoot Strong
Tony


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## Top Cat (Jun 22, 2002)

Target Tony said:


> Burly Hall did a real world test of a bow that shoots 280 and a bow that shoots 310. this is all on video tape by the way. the differance in those 2 speeds and a 2 yard error in yardage was 1 1/2 inches.
> 
> so if you shoot for a center 10 and you miss it by 2 yards, you will hit 1 1/2 inches lower than with a bow that shoots 310 fps.
> 
> ...


 Thanks Tony, you saved me the trouble of getting out my video. 
1 1/2" is a big difference as far as I'm concerend. What distance did Burly do that test at?
ASA is 280 fps. IBO 280 fps or 5 gpp. I think in IBO any speed gain you can get is worth it. 2 fps here and 3 fps there add up after a while. Shoot the FASTEST bow you can shoot accuratly 

bowhuntrrl, I would like to commend you for not losing your cool when responding to the posts of Miles Gloriosus. We could use more of the self control you showed on these threads :thumbs_up


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## silverback (Jan 20, 2005)

CoppertoneSPF15 said:


> A quick point of clarification, all my above posts were ultimately addressing the fact that pure calculations won't _necessarily_ tell you whether or not your rig could appreciate that gain in speed. Look back to my original post and you'll see that I'm an advocate of testing over calculations. Hence why I made it a point to state that I didn't disagree with Javi's numbers as I was under the impression he came upon those figures through live testing.


Well, the thread is about speed nocks, and how much of a difference they make.
We are talking about the speed they will add, which is under 10fps.
You are talking about a different subject.

Javi's point was the difference was so small, he couldn't tell.
If that is the case, then experimenting is useless, because human error is too high. You can't determine if the difference is the result of human error or the different configuration.

Sure if you change the rules of the game (by adding 5 fps here and 5 fps there), your argument is valid, but I thought this thread was about speed nocks and less than 10fps difference.
Since that is the subject I was talking about, I think the calculation will still be accurate for the difference between the arrows.

You said 5 fps by itself is not much, but several 5 fps gains are. Javi was putting into context what 5 fps means. It is obvious that several changes will be significant, but we were talking about only 1 change.
It appeared that you were arguing it was significant by itself.
We were talking about a 5-7 fps difference, not 20-30.
Of course I would agree that the calculation for 20-30 will not be as accurate.
Kind of like the idea behind calculus and Riemann sums. Several small linear approximations can be helpful.
If you are looking at a small interval, the linear approximation can be quite accurate.
Increase the range, and the accuracy is not there.


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## JAVI (Jun 19, 2003)

Top Cat said:


> Thanks Tony, you saved me the trouble of getting out my video.
> 1 1/2" is a big difference as far as I'm concerend. What distance did Burly do that test at?
> ASA is 280 fps. IBO 280 fps or 5 gpp. I think in IBO any speed gain you can get is worth it. 2 fps here and 3 fps there add up after a while. Shoot the FASTEST bow you can shoot accuratly
> 
> bowhuntrrl, I would like to commend you for not losing your cool when responding to the posts of Miles Gloriosus. We could use more of the self control you showed on these threads :thumbs_up


Please remember that the test Burly shows is only valid for the bow and the arrow he shot during the test...As are the tests I ran... another setup will give different results... even changing the same vane from offset to helical will change the results... Even changing the FOC of the arrow will change the results... there are simply too many variables to use one example as the gospel....

I suggest you test the theory for yourselves.... Sometimes the cost of the extra FPS isn't worth the effort...

By the way.... I'm not saying don't use speed nocks... they do work and help in many ways... I'm just saying that to spend the time tuning them to gain 5fps is not worth the effort....

Almost forgot.... Some of you guys take this WAAAAAAYYYYYYY to SERIOUSLY.... It's just a game....:thumbs_up


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## silverback (Jan 20, 2005)

JAVI said:


> Almost forgot.... Some of you guys take this WAAAAAAYYYYYYY to SERIOUSLY.... It's just a game....:thumbs_up


Probably right, but it's how engineers have fun.:wink:


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## Top Cat (Jun 22, 2002)

Just a GAME? Just a GAME you say?  
You mean I have been spending all this money and all this time practicing and all this time trying different things to help me gain some kind of advantage over other shooters, and now I find out it's only a GAME 
Thats the last straw. I'm going to quit worring about this stuff every wakeing moment and just go shoot and have fun.  
Thanks Javi:wink:


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## RCL (Apr 23, 2004)

JAVI said:


> Almost forgot.... Some of you guys take this WAAAAAAYYYYYYY to SERIOUSLY.... It's just a game....:thumbs_up


You meen I bought a sharpie and signed all these crispies for nothing? 

:wink: :darkbeer: :wink:


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## CoppertoneSPF15 (Mar 14, 2006)

silverback said:


> Well, the thread is about speed nocks, and how much of a difference they make.
> We are talking about the speed they will add, which is under 10fps.
> You are talking about a different subject.
> 
> ...



In all my posts, neither the points I made nor the argument I was gearing toward has changed. It seems what you just posted was more a less a summary of what I've been talking about this entire time. 

I'm pretty sure it was easily seen that my original response was to Mike Glorisus post as I even went ahead and quoted his post. Whether there was a bit of thread hijacking there or not, the intent and subject were quite clear. 

I think the above posts made by Tony and Javi citing cases of live testing supports what I have been getting at. Javi's test case with a drop from 300fps to 280fps was far different that the one Tony mentioned. 310fps to 280fps isn't the same thing but it think it's quite obvious that the two cases were comparable and the difference experience was significant. 

BTW, even if this is thread jacking.... 

HAPPY EASTER! Our Lord has risen!


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## CoppertoneSPF15 (Mar 14, 2006)

As an aside, Riemann sum, linear approx, whatever... it's been a LONG while since I did freshman/sophmore math. Regardless, I do recall that the basic kinematic equation used in calculating drop has the acceleration/deceleration term multiplied by a time squared component. Moreover, the deceleration term itself (Drag force) is related to velocity by an exponential factor. That's a exponential factor times an exponential factor, making for the most significant contributor to calculating drop. The largest contributing portion of the equation can *never* be assumed by a small approximation. Whatever engineering discipline you're speaking from, this is without exception. I'm sure you can look up the basic equations on Wikipedia. 

Basic jist of all this is that the velocity term is the last thing you want to assume with a linear approximation in this case. If you can agree that 20-30 fps is significant, 5-7 fps is just as important in terms pure calculations. But like I've said already and have continued to touch on, punching in some numbers into a computer software is not the way to go here. I never said you *can't* calculate drops, but I did say that you can't _always_ predict it accurately. Throw on the speed nocks and shoot some arrows. That will tell you whether the extra speed will help or not. If you have read my posts carefully, you'll see that this was, has been, and still is my point. I don't know how to better communicate this.


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## silverback (Jan 20, 2005)

Ok, I thought we had given this up. 
A linear approximation is used to approximate curves... not lines (otherwise it would not be an approximation, it would be the actual result).
That was exactly my point, it is the basics of calculus.
Over a small interval, you can approximate a curve by the secant line.

Anyway, my point was that assuming there is no diffence in drag for a 5 fps difference is *analagous* to using a Riemann sum to calculate integrals.
So, you are complaining that I don't read your posts carefully...
I said "Of course I would agree that the calculation for 20-30 will not be as accurate.
_Kind of like the idea behind calculus _and Riemann sums. Several small linear approximations can be helpful." The second sentence was referring to the Riemann sums, not speed equations; it was an analogy.

Anyway, if the drag difference is significant, then a broadhead, with more surface area, a different shape, etc. would always drop more than a field point.
Why can people tune their bows (with 90° nock settings) and get identical broadhead and field point POI? Because the arrow is not going fast enough for it to matter. Otherwise, broadheads would always hit lower.

For what it is worth, I also have an engineering degree. So I appreciate your advice on looking up equations in Wikipedia.

I am done with this thread... I apologize if I got off topic.

*BTW Hayman, thanks for the test. Now I don't feel so bad about taking the speed nocks off my bow. They're probably not in the right place anyway.
Great test! *:thumbs_up


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## CoppertoneSPF15 (Mar 14, 2006)

silverback said:


> For what it is worth, I also have an engineering degree. So I appreciate your advice on looking up equations in Wikipedia.


If it seemed that my suggestion was insulting, I apologize as that was never my intent. It's only been a scant few years since I've gotten my aero degree but I couldn't regurgitate 90% of the basic flow equations. Suggesting Wikipedia was only to say you can easily verify or dispute what I had to say about term relations. I was citing off memory as I mentioned in the post and am always proned to error when doing so. I did not mean it to be derogatory, perhaps I should've worded it differently.



silverback said:


> Anyway, if the drag difference is significant, then a broadhead, with more surface area, a different shape, etc. would always drop more than a field point.
> Why can people tune their bows (with 90° nock settings) and get identical broadhead and field point POI? Because the arrow is not going fast enough for it to matter. Otherwise, broadheads would always hit lower.


The largest drag count on an arrow will almost always be around the fletching minus the extreme case of say a 0.2 inch fletch (random example). This is why I spoke mostly on fletch variations when discussing significant drag hits. Using broadhead vs field tip comparison to discount drag effects on an average arrow is like getting hit by a train, volleyed 100 ft across the tracks into a spikey palm tree, then complaining how your toe hurts from stubbing it on a rock. 

The broadhead does incur more drag on the arrow vs a field tip and it probably does always hit lower. Just not enough to notice. More important here is likely the difference in weight of the broadhead to field tip. In this case, I'd be more concerned with FOC and how that plays into the picture than the drag. Or, any wind planing in less than desirable weather.


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## sean (May 31, 2003)

a good ballistics chart for a particular rifle such as a mil dot master is good enough to put a bullet in a man sized torso at a thousand yards , theory or not ... and its a simple sliding scale so I imagine a ballistics program tailored to a particular set up is even more accurate if archers advantage says the difference between 280 and 300 is 1/2 '' at 50 it is or its close enough you and I wouldn't know the difference


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## CoppertoneSPF15 (Mar 14, 2006)

sean said:


> a good ballistics chart for a particular rifle such as a mil dot master is good enough to put a bullet in a man sized torso at a thousand yards , theory or not ... and its a simple sliding scale so I imagine a ballistics program tailored to a particular set up is even more accurate if archers advantage says the difference between 280 and 300 is 1/2 '' at 50 it is or its close enough you and I wouldn't know the difference


Perhaps this is the case.

Or, sometimes, perhaps not...



bowhuntrrl said:


> It's all nice to use software to calculate drop and trajectory, but I bet in the real world the difference is more significant than that. I bet 20 fps is good for 2" or more. I've used ballistic software for years. You have to remember something, it's all based on theoretical calculations and physics. It doesn't take real world effects into account. I found this out many times in the past sighting in rifles.


I find that experience often has the upper hand over speculation. So maybe, maybe not. Which is why I advocate going out and shooting arrows to best find out.


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## JAVI (Jun 19, 2003)

Wait till you've been out of school over 40 years.... then try to remember the equations....  I let the computer do my math....


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## Jorge Oliveira (Aug 13, 2004)

JAVI said:


> Wait till you've been out of school over 40 years.... then try to remember the equations....  I let the computer do my math....


Equations...
I remember something by this name...
There were numbers, letters and an equal sign in them, right?


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## silverback (Jan 20, 2005)

*OK, I lied...*



CoppertoneSPF15 said:


> The broadhead does incur more drag on the arrow vs a field tip and it probably does always hit lower. Just not enough to notice. More important here is likely the difference in weight of the broadhead to field tip. In this case, I'd be more concerned with FOC and how that plays into the picture than the drag. Or, any wind planing in less than desirable weather.


For now, assume a slick trick and an easton RPS point, they are very close to the same length... the FOC shouldn't change.

Still, if the broadhead is getting more drag, you may not be able to see the difference at 20 yds, but you would see it at 60. Right?
But by then, the arrow has slowed down a lot, and the ammount of drag would constantly be decreasing.


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## Deezlin (Feb 5, 2004)

bowhuntrrl said:


> It's all nice to use software to calculate drop and trajectory, but I bet in the real world the difference is more significant than that. I bet 20 fps is good for 2" or more. I've used ballistic software for years. You have to remember something, it's all based on theoretical calculations and physics. It doesn't take real world effects into account. I found this out many times in the past sighting in rifles.


I total agree with JAVI. I have even done some experimenting. The software calculations seem to be very accurate. There is a lot of things which can interact with an arrow, to produce flatter trajectories than the addition of speed nocks. If you can see some gain I guess, it is worth it. I am more concerned about accuracy than a few fps.

I have found that heavier arrows will at time shoot flatter than lighter ones. Now, this was shown in software and in experimentation. The heavier arrow may start out slower, but retains it speed by have more energy transfered into the arrow and by the arrow's momentum carrying that speed further down range.

The problem with speed is everything become more critical. The light weight arrows we are using in some cases will produce higher speeds. But, they become very sensitive to any deviation in FOC, overall weight or even fletching. As JAVI said, 280 is fast enough and it equalizes the playing field more.

I shoot rifles, if the data that is in the program is correct and your mechancial measuring device are correct, the results of any of these programs, are usually. I have never had one not caculate the trajectory correctly, if you have all of your real world information, correct.


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## CoppertoneSPF15 (Mar 14, 2006)

silverback said:


> For now, assume a slick trick and an easton RPS point, they are very close to the same length... the FOC shouldn't change.
> 
> Still, if the broadhead is getting more drag, you may not be able to see the difference at 20 yds, but you would see it at 60. Right?
> But by then, the arrow has slowed down a lot, and the ammount of drag would constantly be decreasing.


Exactly. And based on the drag relations, as the arrow slows in speed, you'll find that the effects of interference & skin friction drag increasing diminishes, making the importance of that broadhead drag less and less. At the same time, drag experienced by the arrow becomes even more dependent on form drag, making the drag profile around the fletching an even larger percent of the overall drag. The faster the initial arrow speed, the more pertinent this becomes. If the original launch speed was say something very low like sub 150fps (just a guesstimate), the drag profile will hardly vary at all from launch to penetration. 

So much of the pay off of the boost derived from the addition of speed nocks is dependent on the rig. How fast does it shoot without speed nocks? Also then, how much oscillation is induced on the arrow if the nock travel is not straight and level? Is the bow punching bullet holes or is the arrow coming out with a slight left to right, up and down? Then there's the arrows. What kinda fletch is it? How long? How tall? Helical? And does it create noise in flight? Cause if it does, that's kinetic energy lost to sound energy, leading to more speed loss on the way to the target. If the fletch is wrinkled, nicked, etc.. that'll likely compound the problem. And there's another million and one things I haven't thought of. 

Now, if your bow is perfectly tuned, you're shooting clean target size fletch on a low tolerance spine with minimal helical or offset, field tips, than much of this above mentioned is not a concern and a small fps boost will make little to no difference. It's all dependent on your setup.


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## Target Tony (Mar 3, 2003)

Top Cat said:


> Thanks Tony, you saved me the trouble of getting out my video.
> 1 1/2" is a big difference as far as I'm concerend. What distance did Burly do that test at?
> ASA is 280 fps. IBO 280 fps or 5 gpp. I think in IBO any speed gain you can get is worth it. 2 fps here and 3 fps there add up after a while. Shoot the FASTEST bow you can shoot accuratly
> 
> bowhuntrrl, I would like to commend you for not losing your cool when responding to the posts of Miles Gloriosus. We could use more of the self control you showed on these threads :thumbs_up


Burlys tests were done at 40 yards and his missed yardage was 42 yards. 
but i dont subscribe to the need for speed thing. i would just prefer to get my yardage estimation down. :wink: 

my bow is set right at 280 fps. im going to be shooting the NFAA 3D nationals in Yankton SD and i dont need to mess around with a higher speed all summer and then change it right before i go.

if the IBO didnt have its 5 grs per pound rule, would anyone be shooting over 287 fps ? thats the ASA and NFAAs rules, 280 fps with 3% variance for chronograph error.

so why crank the bow up just to gain 2 or 3 fps or heck 10 or 15 fps. if you shoot a bunch of local shoots i guess no one would notice . but is this why the scores are so low at the ASA shoots ? 

some guys are shooting practice rounds, local shoots and club shoots at say 310 fps and then have to drop there speed to comply with ASA rules ? maybe we should just make our bow and arrow setup as forgiving as we can, shoot 280 fps and let the real game begin.:wink: 

Shoot Strong
Tony


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## sean (May 31, 2003)

Target Tony said:


> Burlys tests were done at 40 yards and his missed yardage was 42 yards.
> but i dont subscribe to the need for speed thing. i would just prefer to get my yardage estimation down. :wink:
> 
> my bow is set right at 280 fps. im going to be shooting the NFAA 3D nationals in Yankton SD and i dont need to mess around with a higher speed all summer and then change it right before i go.
> ...




Maybe they should raise the speed limit to 300 fps .... do you realy think scores would sky rocket with an increase of slightly more than 10 percent arrow speed .... my bow seems to be prety happy at 301.2


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## Target Tony (Mar 3, 2003)

i dont know if they would or not. for ASA and NFAA that extra 20 fps might get people them few extra points because there yardage was off a little.

if your only shooting IBO and local shoots then your 301 is ok. but if you go to a ASA or NFAA event then you would have to change what your comfortable with.

i just dont like to change.:wink: i think is crazy to set your bow up at say 310 fps and shoot IBOs and then have to crank it down to shoot a ASA or NFAA event.:wink: that definately has to mess with your yardage for sure.

Shoot Strong
Tony


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