[Flyboy718]

Need an arrow recommendation for a Pearson Colt 62" 28# @ 28", I am drawing 29" so about 30ish#. What do you recommend for both an aluminum shaft and carbon shaft?

 

[rraming]

http://www.arrowsbykelly.com/Spine_Charts.html

Wouldn't it more rewarding to figure it out yourself - bookmark it

 

[Flyboy718]

rraming:

Thanks, I have looked at the spine charts and know that I need 1816/1916 shaft...I thought someone may be shooting a similar setup and could give me an account of what shaft/point weight combo they may be shooting.

On the other hand...here is another question: For a given shaft, such as an 1816, how much does the deflection increase per inch of shaft beyond 28"?

 

[Warbow]

Well, my oly Recurve is 28# at 30" and I shoot full length 29" to back of point 1716s with 125 grain tips. I can get them to tune to the recurve, but they are a bit stiff. I would think 1816's could be too stiff for your set up with no way to weaken them past 125 grain points, but the 1716's can take lighter points to stiffen them up.

 

[Viper1]

Flybow -

Full length (29") 1716s with glue-n points, if screw-ins, max out at 100 gr. Use a rest, and the arrow being shorter than your DL won't be a problem. If it really bugs you, go to full length (30.5") 1816s, with a heavier head, but expect a performance hit.

Good luck with the Colt.

Viper1 out.

 

[Flyboy718]

Ok, 1716's it is.

For a given shaft, such as an 1816, how much does the deflection increase per inch of shaft beyond 28"?

 

[Warbow]

For a given shaft, such as an 1816, how much does the deflection increase per inch of shaft beyond 28"?

Well, the deflection for the material is the same, that is "static spine" is measured as deflection from a consistent span, either 26 or 28 inches depending on the standard. It is dynamic spine that changes with arrow length.

 

[Viper1]

Flyboy -

What WB said; dynamic spine varies roughly 5# / inch for aluminums.

Viper1 out.

 

[Flyboy718]

?

So the shaft has the same static spine at say...29 1/2" as it does at 28" ?

 

[Viper1]

Flyboy -

So the shaft has the same static spine at say...29 1/2" as it does at 28" ?

Yup.

Viper1 out.

 

[Warbow]

So the shaft has the same static spine at say...29 1/2" as it does at 28" ?

Well, yes. But static spine is a standardized measurement of a material's flexibility. Static spine doesn't change with arrow length any more than the diameter of the arrow changes with arrow length. Static spine is used as part of a way to **estimate** how a an arrow will behave dynamically, under acceleration. It is dynamic spine that you really care about.

 

[Viper1]

Flyboy -

So the shaft has the same static spine at say...29 1/2" as it does at 28" ?

Yup.

Viper1 out

 

[Flyboy718]

Dynamic Spine...

And only way to change dynamic spine is to change point weight?

 

[Warbow]

And only way to change dynamic spine is to change point weight?

If you have an arrow of a given flexibility, static spine, there are two basic ways to increase the dynamic spine, similar to making it "more whippy". Put more weight on the tip and make it longer--or both.

 

[Viper1]

Flyboy -

And only way to change dynamic spine is to change point weight?

Nope.

Head weight
Tail-end weight
Shaft length
Degree of centershot
Brace height
String material / no. of strands / add-ons
Weight (weight adjustable/ILF bows)
Draw lenght
Assorted user errors

The dynamic spine if an ar arrow is defines as it's amoint of flex as it leaves the bow (paradox). All of the above, plus others, I'm sure will affect that.

Viper1 out.

 

[Flyboy718]

What are the differences in static spine and dynamic spine?

 

[Warbow]

What are the differences in static spine and dynamic spine?

Static spine is a static measurement of flexibility. It is a static measurement of a material's property, like arrow diameter. Dynamic spine is how an arrow behaves under acceleration.

You can get in an initiative idea of how this works. Imagine if you had a 6 foot length of 1" PVC water pipe. If you waved it around it would flex a bit. No imagine if you put a 3 pound lead weight at the far end, and then waved it around. The pipe would act much more whippy and flex more, even though the static qualities of the pipe have not changed.

 

[Flyboy718]

ok

so static spine basically becomes dynamic spine once the arrow is in motion...or maybe static spine is the base or beginning point of a certain spine, then once the arrow is in motion it is then called dynamic spine. Can dynamic spine be measured then...seems as though only static spine can be measured.

 

[Warbow]

so static spine basically becomes dynamic spine once the arrow is in motion...or maybe static spine is the base or beginning point of a certain spine, then once the arrow is in motion it is then called dynamic spine. Can dynamic spine be measured then...seems as though only static spine can be measured.

The way archers measure dynamic spine is by testing how well their bow and arrow combination works, by shooting through paper to see if the arrow is traveling straight through or at an angle, buy shooting unfleched bare shaft arrows and seeing if they land straight in to the target or if they land pointing in an angle, left or right, or by comparing the grouping of bare shafts relative to fletched shafts.

OL Adcock has a good, simple section on bareshaft tuning.

 

[Flyboy718]

I am pretty good at tuning my arrows to different bows; I have a good understanding of the concept. I am just trying to get better at selecting the correct shaft to begin the tuning process, namely I would like to be able to get pretty close to what my arrow length and point weight combos should be for a given setup. The tuning charts are not always correct...some bows are cut past center and some are not. Bows that are cut past center and relatively light poundage like to have stiffer than normal shafts put through them for example.