stu's calculator

[Stephen Claypool]

Man i hate to bug u even more but. Im actually using a 150 gr broadhead and a 100gr insert that i think is supposed to be added in on the footing. Also im using 3-5" feathers. Sorry really wish i could use the program myself.

[Flying Dutchman]

The four feathers was my mistake, I will correct that. The weight of the inserts goes into the weight-insert box.

This is how the Eastons come out. With the given information, I end up with a .300 shaft.

     

This gives you a high FOC, but also a very heigh weight of 13,3 grains per pound (GPP)

I took the liberty to see if I could end around the 10 gpp. I used here 5575 Goldtip Traditionals, very strong arrows with a woodprint. I used them a lot and they are virtually indestructable, as long as you don't shoot at rochs or brick walls. Besides of that; Goldtip has a very convenient weight-insert system.I used here the standard insert of 14,6 grains and a 150 grains broadhead.
I would pefer the set-up with the Goldtip Traditional! The ideal weight of around the 10 GPP and still a FOC of almost 15%. This should give you a great flight!

     

[Flying Dutchman]

BTW:

Goldtip Traditionals have a shaftlenght of 30,3 inches. If you put this value into Stu, you end up with 67,8 lbs, which is as close as you can get!
No need for shortening the shaft, you just have to glue the inserts in. For this I would advise a two component 24 hours epoxy. 3rivers sells it and once I used it, I never looked back!

If you have anymore questions....shoot!  

[Stephen Claypool]

Thank You so much for your time dutchman. I appreciate you helping me out. Im not sure i understand though. The way i read the chart i would need a 67-70# bow for either of those arrows set ups to work. Am i reading it wrong? What exactly Are the arrow dynamic spine boxs saying?

[Flying Dutchman]

Yes, you are reading wrong. You have your rated bow weight, in this case 48 lbs. When filling in all the different boxes, you come to a certain dynamic spine, in your case 67,4.

So you are shooting a 48 lbs bow with a dynamic spine of 67,4. The dynamic spine is determined by several factors, such as how much centercut your bow is, what kind of bow you have, your drawlengt and so on. When everything filled in correctly, you come to the dynamic spine value of your bow.

The whole idea of Stu is finding an arrow, which has the same dynamic spine as your bow has. The tow black boxes should be as close as possible, at least 2 lbs.

In your case I gave you two different arrows: the easton Axis .300 and the Goldtip traditional 5575.
The dynamic spines of both arrows match up perfectly with that of your bow. The only difference is that they have a different point-weight. I would prefer the Goldtip solution as I told you already.

The spine is called dynamic because you can't measure it on a tester. i.e. when you use a heigher point weight, your arrow will be less stiff. However, when you put the arrow on a spine tester, you won't notice any difference. You will notice this only while shooting. Hence the term: Dynamic. Capiche?
In Stu you can virtually "tune" your arows, by adding weight, making the shaft shorter/longer as you can see in the boxes.

So four yor bow of 48 lbs you can use both arrows

[Stephen Claypool]

Capiche!
Thank you so very much.
I guess the part that threw me off was the bottom dynamic spine box where it said "required pounds". I already have a dz of the fmj .300 shafts that i use to use w/ my 70# compounds, so i will build them and play. Also i will take you advise on the gold tips and build a lighter 10gpp shaft too. Thanks again for all your help.

[Flying Dutchman]

No thanks and let me know how it ends!

[Stephen Claypool]

Will do bud.

[yeager]

Steve and Dutch,

I also use FMJ 400's with 100 grain brass inserts. Therefore,  you put ZERO in the insert box and in the footing box you put "YES" and in the two boxes below the "yes box" you put 1.4 for the length and 100 for the weight.  Yes, HIT inserts act as a footing so the insert box, like I said would be left blank.

I ran the numbers and with Easton FMJ 400's, 150 point weight, 18 grain nock end weight, and 3x5 fletching, the arrow length of 28 11/16" would come to an arrow dynamic spine of 67.5 vs an arrow dynamic spine required of 67.4.

Hope this helps and answers any questions.  In the instructions it gives a good example of how to figure out footing numbers.

[yeager]

I just ran the numbers with FMJ 340's and an arrow length of 30 1/4" would give a dynamic spine of 67.2 vs 67.4 required.   The FMJ 500's with all the same input numbers would require an arrow length of 27 -27 1/4" which is probably too short for you.

[Flying Dutchman]

You are right yeager, buth the differences between filling in as "footing" or "insert" are very small, we are talking about 1 lbs or so.

Nevertheless, you are right.

[ranger 3]

Stephen, you can down load Open Office for free and it works good.
 http://download.openoffice.org/other.html

[Stephen Claypool]

Ok yeager thanks for your time.
From what i read the hit insert was supposed to be in the footing box, but i didnt know it would make that much of a difference.


Ranger thank you too, but i already downloaded open office the other day.Unfortunately im not smart enough to figure it out.

Flying dutchman. I tried the .300s today set up like we talked about except i didnt cut them yet. They bare shafted well and actually grouped w/ some .400's i set up the same way. This is all new to me and getting very confusing. In another thread i started everyone is telling me the 300's are way to stiff so ill try the 400's for now and see where that gets me. Thanks for taking the time.

[metsastaja]

Some of you really need to read the instructions.
there is misinformation here regarding how to treat inserts longer then .90 inches and how correctly calculate inserts as footings.


Here is the direct link to the instructions in pdf format.

   Instructions for using Stu\\'s Calculator

[Flying Dutchman]

Stephem,

if the 400's perform well, use them!