Arrow trajectory or speed on different weight bows

[K. Mogensen]

I have a question that I've been wondering about for a while.

You have 2 bows that are exactly the same in every aspect except draw weight, one is 60#'s and the other is 40#'s. If you shoot an arrow that is 10 GPP out of each bow, will the speed or trajectory be the same? Even though the 60# bow is heavier and more "powerful" the arrow would be 200 grains heavier.

Again, both bows are exactly the same, and the arrows are exactly the same.

Just curious.

[wtpops]

Ive had that question rolling around in my head also. You would think you would end up with the same speed and trajectory.

One thing that would be different would be the momentum = speed X weight.

Lets say both are shooting 165fps:

40# bow...
400grains X 165 fps = 66,000

600 bow....
600grains X 165 fps = 99,000

Am i over thinking this        man this stuff is fun.

[SAM E. STEPHENS]

Im not sure think I should go buy 2 new bows and see for myself.,,,,,,,Sam,,,,,,,,
 Thanks guys I knew I needed some new bows

[smilinicon]

I have a 36 and 51 pound BW PL longbow. I shoot 12.3 gpp arrows and both shoot 160 fps.

[oxnam]

Originally posted by SAM E. STEPHENS:
Im not sure think I should go buy 2 new bows and see for myself.,,,,,,,Sam,,,,,,,,
 Thanks guys I knew I needed some new bows

That is what I was thinking also.

[McDave]

Assuming arrows from both bows have the same initial velocity, the heavier arrow will have a higher downrange velocity, due to its higher momentum, which will enable it to overcome wind resistance better than the lighter arrow.  Imagine shooting a soda straw out of one bow and a 500 grain arrow out of another bow, both at an initial velocity of 200 fps.  The soda straw won't go very far compared with the 500 grain arrow.

[GREASEMAN]

I think the answer lies in stored foot lbs  of each bow regardless of poundage.Refer to ACS website for the math calculation.Many times a lighter weight Bow could be the better choice because of stored ft#'s of energy

[Bjorn]

The answer is 'yes' as borne out by smilinicon and many others in lots of testing.

[wtpops]

Originally posted by GREASEMAN:
I think the answer lies in stored foot lbs  of each bow regardless of poundage.Refer to ACS website for the math calculation.Many times a lighter weight Bow could be the better choice because of stored ft#'s of energy

This is true but we are assuming that both are the same.

[hvyhitter]

For all practical purposes it seems about the same to me. I have a 60# predator that I shoot 580gr 2020s with and a 70# predator that I shoot 680gr 2219s with and both shoot about identical out to about 30 yds. I usually shoot one one day at a shoot and the other another or change bows on different courses the same day just to shoot them both. I just point and shoot and dont seem to need to change my aim.

[Friend]

Interesting discussion - While it seems we are splitting hairs and that I don't shoot accurate enough at distances far enough to make a difference; the down range penetration enhancement at my maximum hunting range is personally of interest.

Something a little off subject that would interest me would be to have some perspective on the velocity impact based on arrow design. Have two identical arrow wts.,well tuned, shot with one having normal FOC and the other Ultra-EFOC being shot from the same bow. Readings to be taken for initial velocity and downrange ~25 yards.

I just know that I was unable to follow a tuned 12 gpp.. 32% Ultra-EFOC bare shaft arrow down range to 25 yards. After the initial kick, the arrow flight was invisible to my poor old eyes.

Something else unexpected was that I could take the same 350 spine arrow(6.7 gpi) from 245 up front at 25% EFOC up to 400 up front at 32% Ultra-EFOC and hit a 2” spot at 20 yards.  The two ways that I have best been able discern best tuning these high FOC shafts is by after the initial kick the shaft actually disappears from my sight and I am unable to follow the arrow down range to a target at 25 yards. This observation occurs,for my poor eye sight, around the Ultra-EFOC range. My final determination is always with broadheads.

[Bowmania]

Back from my darker days, concerning KE, the gain from 50 to 60 was more than the gain from 60 to 70.  It seemed that 60 pounds was about your max gain in performance per pound of draw.  That was with round wheels though and your talking about bows and not compounds, so I have no idea, but I would guess the 60 pounder is the max at efficiency and at 40 speed would be quite a bit less.

Bowmania

[Looper]

I think that within hunting distances, yes, they should be close to being the same.  It is a good idea to have a couple of bows with the same arrow trajectory.  A light one, to work on your form, and a heavier one to hunt with.

[Ragnarok Forge]

I shoot a 40 lb R/D longbow and a 55 lb R/D longbow from the same bowyer.  My arrows are 10.85 gpp for each bow.  They have the same point of impact out to 35 yards after that the lighter arrow looses momentum and hits lower.  I set them up for hunting and target during the off season.  My goal being to have the same point of impact with all bows I shoot.

[3arrows]

yes,this is why the old timers use mostly 45# for hunting with sharp 2 blade broadhead.