Bow weight and Feet per second ???

[david janssen]

I know accuracy is far more important than speed when hunting,I was just curious how many feet per second difference a bow would change from lets say for example 50# to 40# at the same draw and arrow weight.Would the 40#  bow be 10,20,30,40 etc. feet per second slower than the 50# bow ? I hope I explained this the right way. Thanks for your input.

[Shawn Leonard]

David, I am not sure of your question. If ya mean will a 50# bow shoot the same arrow faster than a 40# bow than yes. If not, all I can say is that two bows of identical design one being 40#s and the other 50#s, they will shoot an arrow the same speed all else being equal, ie. 40# bow (@28"s )shooting a 360 grain arrow at 185fps. the 50# bow (@28"s) will shoot the same 185fps. with an arrow that weighs 450 grains. 9 gpp. of draw weight. Shawn

[Blackhawk]

There is really no set rule or formula to calculate this since there are so many variables.  If I had to come up with one (based on some informal chronographing that I have done), I would estimate 3 feet per second per pound of bow weight.

With my formula, if you are getting 175 fps from a 50# bow, you would get 145 from a 40# bow if using the same arrow.  

I am sure others will have ideas different from mine...but that's what makes this fun.

[James Wrenn]

I guess it might be differant with longer draws than mine but on average I only see 1 to 2 fps differance in bow weight with the same arrow for lb of draw weight.I had much rather have an inch of draw length that 5lbs of bow weight.  

[david janssen]

I think blackhawk understands the question I asked. I wasnt sure how much slower the arrow would be if shot out of bows that are 10# diff. in weight shooting the same weight arrow. Any more opinions out there.Thanks for the input Shawn and Blackhawk.

[david janssen]

Thanks for the advice James.I only have a 26" draw and I was just curious how much slower the arrow would go if I dropped down 10# of bow weight.

[LKH]

If you are shooting the same grains per pound, I think there would be more loss going from 50 down to 40 than a straight linear graph might indicate. I base this on reasoning that the efficiency of the bow will drop with less arrow weight to absorb the bow's energy.

Conversely, if you shoot the same weight arrow out of both bows, the 40 should do better than expected.

[laddy]

A forty pound bow will most often be more efficient than a fifty, and when things get real heavy in most bow designs, the gain is minimal past 55 pounds because of increased hysteresis, at least that is how Jack Howard explained it to me.

[ChristopherO]

Last summer I took out the Chorograph out to see the difference in my Martin #10 Pioneer at 50# draw weight and my Dad's old Herter's Recurve that is nearly 48 years old.  The recurve is 44# draw weight and is basically the same length strung as the Martin longbow.  Two different bow designs of two different draw weights.  The recurve was only 2 to 3 fps slower than the heavier long (flat) bow using the same carbon arrows of about 410 grains.  
I imagine the weight of the recurve was much more efficient with those light arrows, too.

[McK]

My best estimate would be 1.5fps per lb. with moderate weight arrows. If 50lb bow shot 500gr arrow 170fps, a 60lber of the same efficiency would shoot it 185.  Assuming the same draw length with the heavier bow.
  I suppose you could shoot a 400 gr arrow from the 50lb bow and get about the same speed you would  if  you shot the 500gr arrow from the 60#er.
McK