# Cam 4chat

This is usually something around draw length sight extension but it's best if you measure it accurately. have to measure the distance from eye to scope to make sure it is accurate. Could you place a link to the formula you have used. Someday I will describe how it is done in a separate page.

It can also compute your other sight marks for FITA and other distances. have a good day pb Joe Tapley: Simple and pretty accurate - well done. PS: Joe, you drift program is excellent, it's amazing how good a model of arrow flight you made. Can it be tweaked to allow for sight marks where the distance between the eye and the sight pin changes (ie. ) Apostolos 20/05/07 : I think it could be tweaked for that but I have to find that piece of paper that I had all the equations written on..

Perriswood Dick 30/03/07 : I can see how the algorithm accounts for different arrow size/weight but where is limb/r1ser length and draw weight taken into account RLH Apostolos 01/04/07 : In fact, we don't care about the draw weight but only for the angle difference between the two distances. I was also thinking of doing another version that could calculate your arrow speed loss per meter given all of your sightmarks. Could you please help me figure out how to measure speed of an arrow (point blank) just with draw weight (45 lbs) and arrow weight (385 gr)?

I would like to find out my arrow's speed so I could figure out its foot-pounds of energy. ben 17/06/07 : this formula is all well and good but what arrow weight is it going off?

I am very happy to live with this minor issue, but if you ever found yourself with nothing to do sometime ........!!! Best wishes, David Morrish Harry Marx 03/09/08 : I did the same thing, but derived formula myself. Normally the arrow is shot at 42 to 47 degrees with specialist bows?

I have studied balistics but have no luck with the maths. helped me with science fair Apostolis 13/01/09 : Thank you all for your comments. I am shooting field ranges where uphill/downhill calculations depend on arrow speed. Sam S44 22/03/09 : Can you give us Yards and inches?

Tony Bakes 15/11/09 : As a keen flight archer, this is an invaluable program for seeing what differences small changes in setup will make to the speed (and hence distance) of any bow/arrow combination without having to find a field 1000m long. Bryan 02/01/10 : Very nice, is this the formulae you used S=SQRT(9.81*x*(d1-d2)/(2*h)) where S= Speed x= distance from eye to sight d1/d2= distances h= sight adjustment Anonymus 21/01/10 : ???????? what in the world is 'sight mark setting' and 'eye to sight pin'??????

I'm not in any club and I can shot when I can- which is not very much.

It also includes compensation for aerodynamic drag. Dick Baugh 10/06/08 : Comparison with Accurate Sights software: Matched at 20 and 70 yards.

This program can calculate your arrow speed, given two previously known sight marks.

The only thing you need to know is the distance from your eye to the sight pin. I am trying to make a ballistic module for bowhunters, like yours but take also Ballistic Coefficient, but I cannot find out how to calculate speed at differents distance. I used Mathematica to find the solution and it's a formula 4 lines long.

I'm not a ballistic engineer, but very curious about how you find the formula. Just to test the calculator I entered a 10cm difference between to distances - then you can see how the decceleration, gravitational and other forces start to show a non-linear relationship. Mark 25/09/09 : Robin or Locksley : The things you mention are constants for the two shots from you bow setup and your arrows. Decceleration, gravitational forces and other forces are taken into account by the formular - see my earlier comment.

JTC 26/09/09 : As an Engineer by trade, I can see how this method of calculating speed would work. for those of us who use the English system some nice converstion calculators to convert to metric.