Speed vs Cast

[Precurve]

I joined an indoor 3-d winter league recently that has targets from 10-40 yards.  I haven't shot that far since mid-summer, so was doing some practicing at the range this weekend with my standard brand of recurve with Osage limbs, and a new A&H ACX that I recently bought.  The recurve is exactly 10lbs heavier in draw than the ACX, and the arrows with target tips I'd tuned for the bows are 8.6 for the recurve and 8.55 for the ACX.  I shoot the recurve perfectly out to about 30 yards, but the arrow drops off drastically after that.  It's really noticeable; like it hits a wind shear.  The ACX shoots just where I look at any distance, and seems to be very flat all the way out to the far targets.  I ran them through the store's chrono after my shooting session and both bows were within 3-4 fps of each other (the ACX is faster).  

I remember talking to Mike Steliga, owner of Bruin Archery at a shoot back in 1991 and he mentioned that while my Jim Brakenbury Legend wasn't super fast it did have great cast.  I asked him what he meant as I've always thought speed and cast were one in the same, but he claimed a bow's ability to maintain downrange speed and good flight characteristics was different from the raw speed measured at the release and varied by bow design and limb woods used. I thought this sounded like an old wives' tale, but now I'm having second thoughts.  Is there something to this?  (By the way I wasn't using Turbo-feathers on either arrow, just regular LW Trueflights.)

Dave

[mmgrode]

Once the arrow leaves the bow, it's on it's own. The bow cannot affect the arrow after it's left the bow.  If a given arrow is propelled from two different bows at the same speed there will be absolutely no difference between the arrows in downrange speed. Mass is mass. It's all about the law of conservation of energy.  How could a guy put more "energy" into the same arrow going the same speed?  Now, will there be a difference in propulsion/efficiency between bow designs of the same weight?  Definitely!
 Good flight characteristics are based on proper tuning and arrow design relative to the bow, not the bow by itself.  Granted some are easier to tune(cut past center recurves vs. selfbows), but once the arrows are tuned this is not an issue.

Good hunting, Matt

[Bjorn]

Matt has it right. Guess you know which bow to shoot-you are likely seeing the effect of that 4 fps. I find the same with my ACS too it shoots where I look-but I don't always know just where I was looking! LOL!

[Otto]

Those old "rocket assisted" arrows have great cast.

[oops sorry]

The arrow that recovers quickest will have higher retained velocity. While those arrows are fishtailing they are burning velocity off. Where was the chrono? Before full recovery or after?

[mmgrode]

Otto- ROTFL   Now that's funny right there!    Where can I get a hold of some of those!        :D  

oops- We were assuming tuned arrows, not fishtailing ones. The same mass is still moving at the same speed.

[oops sorry]

I never argue with the law of conservation of energy. I have been formost among those conserving energy for as long as possible. I assumed that the arrows from each bow had the same drag coefficient so if they were launched at the same speed, then one must have been in paradox a bit harder or longer than the other...can't see any other way there would be difference in cast.

[Str8Shooter]

You weren't shooting at Buck Rub, were you?

[Kingstaken]

I was in there until Rich mentioned "drag coefficiency"...    
But 3 to 4 feet does make a difference and with a ACS, the recovery is faster allowing for more energy and more distance covered.
You say one bow is 10#'s heavier. Do you think or better yet are you sure your coming to full draw with the heavier bow?
I know guys who say they shoot "X"mount of #'s, yet when I see them shoot they short draw by as much as 5". Big difference.
Also, a bigger brace height will give more cast.

[traditional beagle]

I agree with oops. With identical arrows and identical speed, they will fly the same. The arrow does not know what bow shot it. There has to be a difference in the way the arrow leaves the bow. Hard to see with the eye. One of the arrows is leaving the bow with less oscillation.

[oops sorry]

You could try putting the chrono at 3' and at 30' and see if there is a discrepancy showing up at the longer range....I don't do things like that since I shot my chrono. oops sorry!

[Boneyard Bowhunter]

Maintaining down range speed and accuracy depends on arrow weight. A heavy arrow will be less critical to wind and will more efficient. It will loose a lesser percentage of speed even though it starts out slower. A bow that is more efficient will be faster with both heavy and light arrows.

[McDave]

In general, I think that arrows shot at the same speed and angle will travel different distances from different bows, since there are so many forces acting on the arrow other than the main force pushing it toward the target:

--One arrow will be better tuned for the bow than the other, so will have less oscillations and therefore will travel further.

--Different arrows will have different drag and momentum depending on fletching, points, arrow shaft diameter, weight and finish.

--If arrows are tuned identically well for two different bows, but one bow is more centershot than the other, the arrow from the more centershot bow will travel further because it will have less paradox than the other, which is probably another way of saying that it will recover quicker, as was mentioned before.