Mid range trajectory

[jhansen]

Swamp,
I have to agree with Don.  Go shoot some heavy slow arrows and some lighter faster ones.  I think where I've been getting confused by your theory is the idea of "point on" which is something I never do.  The arrow is somewhere below my line of sight and I never see the point.  If I were to do that I'd be changing focus constantly between the tip of the arrow and the target.  Some target archers do this but I don't.  I limit my effective range to 20 yards on any living game animal.  I focus on where I want the arrow to hit and let my brain do the calculations based on experience gained from many shots released at an unknown range out to 20 yards.  With an arrow of about 10 grains per pound of draw weight the trajectory will be such that at out to 20 yards I can hold center of mass and get a killing shot on the heart/lung area of a deer.  When my game is a rabbit or a squirrel, I'll either get a clean kill or a complete miss.  I'm okay with either one.  If I'm really hungry I'll break out the .22 rifle.

Regardless, your idea of a slow heavy arrow having a lower arc at a point-on range of 30 yards is just plain wrong.  This is akin to the "point blank" range in rifle shooting.  A faster bullet wins there every time too.

Sorry,
John

[reddogge]

I'd like to do a shooting experiment like swampthing did but I don't have a bale big enough to do it.  I'd like the distances calculated every 5 yards from his or anyone's point on distance.  I believe the highest point of the arc is not the mid range but more towards the target due to increased acceleration in the beginning and less acceleration and more drag at the end.

In other words the inches over the target will be less from 5-10 yards from the bow than 20-25 yards from the bow so the arc is not a perfect parabola peaking at exactly midpoint of your point on.

Does this make sense?

[Rattus58]

Originally posted by reddogge:
I'd like to do a shooting experiment like swampthing did but I don't have a bale big enough to do it.  I'd like the distances calculated every 5 yards from his or anyone's point on distance.  I believe the highest point of the arc is not the mid range but more towards the target due to increased acceleration in the beginning and less acceleration and more drag at the end.

In other words the inches over the target will be less from 5-10 yards from the bow than 20-25 yards from the bow so the arc is not a perfect parabola peaking at exactly midpoint of your point on.

Does this make sense?

Looking at a low coefficient bullet at 500 fps (the lowest I can compute)and a 50 yard zero (again the shortest distance I can compute), mid-range trajectory is highest at 30 and 35 yards. I used a 6" scope height to illustrate this for myself and it points out that bullet or bow, if you sling something at a target, it will necessarily have a curved arc to the target.

You are, in my opinion, correct in your assumptions that the midrange is going to be beyond the halfway point, but as the old (before ballistic calculators) systems implied, mid-range is just that, mid-range, not specifically half way but close enough for government work without the budget.

While I was playing games with myself in the neibhors guava patch years ago with wood arrows, I come to conclusion that it didn't matter that midrange was 4 yards beyond halfway or 6 yards beyond halfway, they still got tangled up with lower hanging branches... The only way to have solved that pesky parabola, was to increase the speed of the slingee... and alas... the desired limitations of the longbow prevail and I moved on to clearer pathways.

Not to be disagreeable, but you are correct in the reduced acceleration towards the target, but that isn't a result of increased drag. Drag is a function of speed in air and as the arrow slows down, so too does the drag effect or coefficient might be proper... the increased drag at the launch being greatly of influence of the decelerated values later on...

As for arrow acceleration, I'm not certain, but I think that once the arrow leaves the string, acceleration is fini... and thus it's all deceleration from there I think.

Aloha...  :cool:

[Rattus58]

Originally posted by Rattus58:
 

Originally posted by reddogge:
I'd like to do a shooting experiment like swampthing did but I don't have a bale big enough to do it.  I'd like the distances calculated every 5 yards from his or anyone's point on distance.  I believe the highest point of the arc is not the mid range but more towards the target due to increased acceleration in the beginning and less acceleration and more drag at the end.

In other words the inches over the target will be less from 5-10 yards from the bow than 20-25 yards from the bow so the arc is not a perfect parabola peaking at exactly midpoint of your point on.

Does this make sense?

Looking at a low coefficient bullet at 500 fps (the lowest I can compute)and a 50 yard zero (again the shortest distance I can compute), mid-range trajectory is highest at 30 and 35 yards. I used a 6" scope height to illustrate this for myself and it points out that bullet or bow, if you sling something at a target, it will necessarily have a curved arc to the target.

You are, in my opinion, correct in your assumptions that the midrange is going to be beyond the halfway point, but as the old (before ballistic calculators) systems implied, mid-range is just that, mid-range, not specifically half way but close enough for government work without the budget.

While I was playing games with myself in the neibhors guava patch years ago with wood arrows, I come to conclusion that it didn't matter that midrange was 4 yards beyond halfway or 6 yards beyond halfway, they still got tangled up with lower hanging branches... The only way to have solved that pesky parabola, was to increase the speed of the slingee... and alas... the desired limitations of the longbow prevail and I moved on to clearer pathways.

Not to be disagreeable, but you are correct in the reduced acceleration towards the target, but that isn't a result of increased drag. Drag is a function of speed in air and as the arrow slows down, so too does the drag effect or coefficient might be proper... the increased drag at the launch being greatly of influence of the decelerated values later on...

As for arrow acceleration, I'm not certain, but I think that once the arrow leaves the string, acceleration is fini... and thus it's all deceleration from there I think.

Aloha...   :cool:  [/b]

I think, in thinking, that I would have used the word speed in place of acceleration in our posts...

Much Aloha...  :cool:

[Don Stokes]

Right, Rattus. Acceleration stops when the arrow leaves the string, and it's slowing down from that point on if shot level.

[Rattus58]

Originally posted by Don Stokes:
Right, Rattus. Acceleration stops when the arrow leaves the string, and it's slowing down from that point on if shot level.

I was thinking that.. Thank you....

Or Mahalo as the natives say....  

Aloha...  :cool:

[Duane Merck]

Originally posted by Don Stokes:
A faster arrow has a flatter trajectory than a slower arrow at the same range, no matter what distance they are shot. It's as simple as that. It's easy to overthink these things.

Amen...To the over-thinking part...It's a pretty simple concept!  

[Greg Skinner]

There is no question about the fact that a faster arrow is a flatter shooting arrow.  However, I have shot arrows in the 155-160 fps for so many years that if get I an arrow that is substantially lighter and faster, I shoot over everything in the 15 - 30 yard range because I am accustomed to the sight picture from shooting the slower arrow.  Thus it might seem as though the slower arrow is shooting flatter over those ranges.  The fact is that all that really matters is to shoot your bow/arrow combination enough to know the trajectory and be able to visualize that arc when making the shot.

[reddogge]

I have a friend who I shoot 3-d with and he likes very light stiff arrows like 15-35 carbons or 1913 X7s out of 45-50# bows.  Occaisionally he'll hand me an arrow and say Here, try this."  I have the same results as Greg Skinner.  I overshoot everything by a foot or two.  I guess I'm just used to the trajectory of my arrows.

[Rattus58]

Originally posted by reddogge:
I have a friend who I shoot 3-d with and he likes very light stiff arrows like 15-35 carbons or 1913 X7s out of 45-50# bows.  Occaisionally he'll hand me an arrow and say Here, try this."  I have the same results as Greg Skinner.  I overshoot everything by a foot or two.  I guess I'm just used to the trajectory of my arrows.

I'm not sure why there is any consternation about what a lighter (read faster) arrow would do when you use the same aiming device to do your shooting.

Every trajectory is based upon lobbing the bullet/arrow/marble etc. That means for most of us (and probably all of us shooting to distance)that the projectile will necessarily have to rise above line of sight.

When we shoot a lighter projectile along the initial path of a heavier arrow given the same force propelling them the lighter bullet/arrow, it will follow that path for a further distance upwards before gravity has the opportunity in TIME to bring it back to earth.

[Rattus58]

Originally posted by reddogge:
I have a friend who I shoot 3-d with and he likes very light stiff arrows like 15-35 carbons or 1913 X7s out of 45-50# bows.  Occaisionally he'll hand me an arrow and say Here, try this."  I have the same results as Greg Skinner.  I overshoot everything by a foot or two.  I guess I'm just used to the trajectory of my arrows.

I'm not sure why there is any consternation about what a lighter (read faster) arrow would do when you use the same aiming device to do your shooting.

Every trajectory is based upon lobbing the bullet/arrow/marble etc. That means for most of us (and probably all of us shooting to distance)that the projectile will necessarily have to rise above line of sight.

When we shoot a lighter projectile along the initial path of a heavier arrow given the same force propelling them the lighter bullet/arrow, it will follow that path for a further distance upwards before gravity has the opportunity in TIME to bring it back to earth.

Not being an engineer, I can't help anyone with the theory of this, but gravity I'm told is working on a feather in a vacuum at the same rate as a round ball, soo... the fast lighter arrow is falling just as fast as a heavy slow one, but being faster, is further along the trajectory before it has to start back down....

And yes... I have too much time on my hands..

Much Aloha...