Help with calculating arrow speed/energy
02-22-2002, 02:43 PM
#1
Nontypical Buck
Thread Starter
Join Date: Feb 2003
Location: Fairbanks, Alaska
Posts: 1,665
Help with calculating arrow speed/energy
I'm trying to figure out the speed and energy that my bow is producing on bowjackson. I would rather toss an arrow through a chronograph, but don't have access to one. Here's my hold ups on figuring out speed.
1) SE/PDF Ratio (~0.5-2)
2) Bow Efficiency in % Is this the let off of the bow? It is rated at 70% let off, but meets the 65% let off requirement for P&Y. What number do I use there?
3) Virtual Mass (grains) Is this arrow weight? It asks for that already, so I figure it must mean something else.
Here's my full set up.
Mathews Q2XL set at 65 pounds with 29" draw length. SL2 cam with 70% let off.
string silencers, loop and peep sight all weighing roughly 15 grains.
Beman ICS 340, 29" with 125 grain tips, total weight of 452.8-454 grains
Thanks in advance
1) SE/PDF Ratio (~0.5-2)
2) Bow Efficiency in % Is this the let off of the bow? It is rated at 70% let off, but meets the 65% let off requirement for P&Y. What number do I use there?
3) Virtual Mass (grains) Is this arrow weight? It asks for that already, so I figure it must mean something else.
Here's my full set up.
Mathews Q2XL set at 65 pounds with 29" draw length. SL2 cam with 70% let off.
string silencers, loop and peep sight all weighing roughly 15 grains.
Beman ICS 340, 29" with 125 grain tips, total weight of 452.8-454 grains
Thanks in advance
02-22-2002, 02:54 PM
#2
Join Date: Feb 2003
Location: Manitowoc WI USA
Posts: 79
RE: Help with calculating arrow speed/energy
Arctic-
I just ran all your info through "The Archery Program" I got the following results:
Speed 246.7 f/s
K.E bow = 61 ft/pnds
K.E @ 20 yards ~ 56 ft pounds
You didn't mention fletches etc so I guessed 4" vanes.
Happy Shooting!
>>>------Tony Virnoche------>>>
>>>---The Archery Program--->>>
I just ran all your info through "The Archery Program" I got the following results:
Speed 246.7 f/s
K.E bow = 61 ft/pnds
K.E @ 20 yards ~ 56 ft pounds
You didn't mention fletches etc so I guessed 4" vanes.
Happy Shooting!
>>>------Tony Virnoche------>>>
>>>---The Archery Program--->>>
02-22-2002, 03:37 PM
#4
Nontypical Buck
Thread Starter
Join Date: Feb 2003
Location: Fairbanks, Alaska
Posts: 1,665
RE: Help with calculating arrow speed/energy
Thanks TAP. Do these numbers factor into a certain type of bow? I know some bows get a lot more speed than others at the same draw length, draw weight and arrow weight.
What makes a Bowtech shoot nearly 300+fps when a similarly set up Mathews would only shoot ~247?
Oh yea, I'm shooting 4" vanes like you presumed.
What makes a Bowtech shoot nearly 300+fps when a similarly set up Mathews would only shoot ~247?
Oh yea, I'm shooting 4" vanes like you presumed.
02-22-2002, 04:05 PM
#5
Join Date: Feb 2003
Location: Manitowoc WI USA
Posts: 79
RE: Help with calculating arrow speed/energy
Arctic-
It mostly has to do with draw length, arrow weight and draw weight. Example: That bowtech you mention will not shoot your arrow @ 300 f/s with a draw of 29" and 65 pounds. Depending on the bowtech model it may infact be a little faster than your mathews because they have good BPF numbers in my program. (its an efficiency rating....my own proprietrary thingy)
I hope this answered your question,
Happy Shooting!
>>>------Tony Virnoche------>>>
>>>---The Archery Program--->>>
It mostly has to do with draw length, arrow weight and draw weight. Example: That bowtech you mention will not shoot your arrow @ 300 f/s with a draw of 29" and 65 pounds. Depending on the bowtech model it may infact be a little faster than your mathews because they have good BPF numbers in my program. (its an efficiency rating....my own proprietrary thingy)
I hope this answered your question,
Happy Shooting!
>>>------Tony Virnoche------>>>
>>>---The Archery Program--->>>
