MJL927

At the bowjackson webpage, what do you put in the virtual mass(grains) field when calculating the arrow speed? It says to enter a number between 0-500. What exactly is this field looking for??

The other option is to go with bow efficiency(in %). Where in the world do you determine that??

-Mike

biggunz.45-70

the best way to determine arrow speed is to chrono your arrows. I've found different bows react to change in arrow weight much differently than others. Most pro shops will have a chronograph you can use.

MJL927

<BLOCKQUOTE id=quote<font size=1 face='Verdana, Arial, Helvetica' id=quote>quote:<hr height=1 noshade id=quote>the best way to determine arrow speed is to chrono your arrows. <hr height=1 noshade id=quote></BLOCKQUOTE id=quote></font id=quote><font face='Verdana, Arial, Helvetica' size=2 id=quote>

&lt;sarcasm&gt;Well...DUH!!!&lt;/sarcasm&gt;

I fully realize that a chrono would be the only way to know exactly what my own bow is doing. I simply want to play around with the formulas to make better educated guesses as to how a bow and arrow combination would work. It could be a great tool to help one with tuning of the bow, arrow selection, bow selection, etc.

-Mike

ACLakey

I would suggest downloading the trial of The Archery Program. You can enter you're bow and exact setup and play around with arrow setup combinations. It has a cool trajectory calculator in it as well. I have found the results to be very close to what the chrono says.


Andrew

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Derbytown

MJL927, here ya go. This will get ya in the ballpark on what speed your bow is shooting. I got this off of the Ederbow web site, so don't flame me if you dson't think it's accurate. I found it to be fairly close to my actual arrow speed.

&quot;Arrow Speed Chart from Eders Magazine:
Looking to discover how fast your arrows are shooting but don't have access to a chronograph? Well it's easier to figure out than you might think:This simple table will get you in the ball park. First, shoot your bow at a target from 20 yards using your 20 yard pin. Mark the center of the group. Next, shoot at the same target from 40 yards, aiming at the same point, but again using your 20 yard pin. Mark the center of the second group. The distance between these two marks will tell you your approximate speed.Distance between 20 and 40 yard groups (inches) Approx. Arrow Speed (fps)
28.7= 220
24.2= 240
20.6= 260
17.7= 280
15.5= 300
13.6= 320
12.8= 330&quot;

Hope this helps. At least it's something to play around with. Be safe.
Shoot Straight
Derbytown <img src=icon_smile_big.gif border=0 align=middle>

BGfisher

Derby, forget the chart on Eders. I used it and then chrono'd the bow. Or should I say I already knoew my bow speed and checked the chart against the chrono. This thing isn't even close. The chart has my bow 30 fps faster than the chrono. And the chrono is right.

sajackson

MJL,

The virtual mass or efficiency for a given bow(if he has tested them) can be gotten from a Norb Mullaney bow report out of Bowhunting World magazine. Bow & Arrow hunting magazine had similar testes but I haven't seen that mag in a awhile.

The speed charts are heavily biased by launch angle of the arrow which varies enough from archer to archer to render the results very inaccurate.

MJL927

Well, thanks all for the info. Sounds like the formula is really not worth it after all. My intention was to just &quot;play&quot; with the numbers in an effort to compare different arrow shafts and point weights. Thought maybe that could help me make more informed selections. I guess the ole trial-and-error method still reigns king!

-Mike

TheArcheryProgram

MJL927-

Try downloading my trial of 'The Archery Program'. If you put in your bows specs it will calculate your velocity very accurately, and from here you can do exactly what you just desribed wanting to do! Change the arrow weight, diameter, fletch etc and see what will happen.
It is a fully functional 15 day trial....give it a try!

Happy Shooting!

Tony Virnoche



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>>>---The Archery Program--->>>

MJL927

Tony,
Thanks. I downloaded the program. Works great.
-Mike