calculating speed

[jerseyhunter]

Is there a way to calculate approx. speed without a Chronograph.

[corey006]

I have tried this but never confirmed if it is very accurate or not??

http://www3.sk.sympatico.ca/ronv/whatsnew.htm

[Trebark]

Jersey,
Here are some rules of thumb, should get you close.
Every pound of draw weight increase/decrease, 2 fps increase/decrease
Every inch of draw length increase/decrease, 10 fps increase/decrease
Every 5 grains of arrow weight decrease/increase, 1 fps increase/decrease.
Start with your AMO rating of your bow, and work from that. It' s just ballpark, but it will give you some idea. AMO is rated using a 540grain arrow, 60lb draw weight, and 30 inch draw length.
I' ve been using the program call " On Target" , from www.pinwheelsoftware.com
It has a section to figure out speed, based on your setup. Using the feature called " Wild Ass Guess" , I found it to be within 2 fps of what my chrono reads. They have a free trial that you can download, and use for a couple of weeks.
Charlie