More arrow speed drivel... Trajectory chart
12-12-2007, 11:22 PM
#62
Nontypical Buck
Join Date: Oct 2006
Location: Kansas
Posts: 3,288
RE: More arrow speed drivel... Trajectory chart
Well shoot firethem there charts cant be right, because I have at least 5 self proclaimed experts a year tell me that their bows shoot dead flat from 0 to 50 and shoot groups this bigall day longat 80 yards (I am holding my hands together with a 2" circle formed in between them). Oh, and they always end with, "I chit you not"
12-13-2007, 12:49 AM
#63
Join Date: Feb 2003
Location: Blissfield MI USA
Posts: 5,293
RE: More arrow speed drivel... Trajectory chart
I'm not sure anyone is telling you your chart is mathematically off as far as the numbers go. I think what they are trying to say is that every set up is different and that type of a chart in no way mimics what the trajectory of a given bow or set up will be.
If you take two shooters that shoot the same bow with the same arrows at the same speeds things can be different. Peep height, anchor points, sight radius, type of sight ( multiple pin/single movable pin), how you center the pin in the peep and other factors can effect how things will really work.
I have used the arrow drop method to calculate speed several times on different set ups. Sometimes it is close, sometimes it is isn't. Sort of like using the wingspan method to determine draw length.
Your simple program and chart also do not take into account for what arrow you are using. The dia., length, weight, fletching type and size all effect the actual trajectory of the arrow. Does your chart represent a 30 inch aluminum arrow that weighs 500 grns with vanes or does it represent a 25 inch small diameter carbon arrow that weighs 300 grns with 5 inch feathers on it? It really does make a difference.
Here is calculator that is a bit more accurate and it is free as well. It just doesn't let you put in the zero range, it goes strictly off drop.
Jacksons ballistic calculator
Paul
If you take two shooters that shoot the same bow with the same arrows at the same speeds things can be different. Peep height, anchor points, sight radius, type of sight ( multiple pin/single movable pin), how you center the pin in the peep and other factors can effect how things will really work.
I have used the arrow drop method to calculate speed several times on different set ups. Sometimes it is close, sometimes it is isn't. Sort of like using the wingspan method to determine draw length.
Your simple program and chart also do not take into account for what arrow you are using. The dia., length, weight, fletching type and size all effect the actual trajectory of the arrow. Does your chart represent a 30 inch aluminum arrow that weighs 500 grns with vanes or does it represent a 25 inch small diameter carbon arrow that weighs 300 grns with 5 inch feathers on it? It really does make a difference.
Here is calculator that is a bit more accurate and it is free as well. It just doesn't let you put in the zero range, it goes strictly off drop.
Jacksons ballistic calculator
Paul
12-13-2007, 04:15 AM
#64
Join Date: Dec 2006
Location: Treasure Lake DuBois,Pa.
Posts: 1,571
RE: More arrow speed drivel... Trajectory chart
ORIGINAL: quiksilver
310 fps Zeroed @ 27 yds
10 20 27 30 40 50
+3.1 +2.50 -1.6 -10 -20.8
310 fps Zeroed @ 27 yds
10 20 27 30 40 50
+3.1 +2.50 -1.6 -10 -20.8
I would assume that the very small difference is arrow wt. I have 377gr. arrow input @310 fps @ 27 yrds.
12-13-2007, 04:35 AM
#65
Join Date: Dec 2006
Location: Treasure Lake DuBois,Pa.
Posts: 1,571
RE: More arrow speed drivel... Trajectory chart
ORIGINAL: archer58
Correct w/i a fraction.
I would assume that the very small difference is arrow wt. I have 377gr. arrow input @310 fps @ 27 yrds.
ORIGINAL: quiksilver
310 fps Zeroed @ 27 yds
10 20 27 30 40 50
+3.1 +2.50 -1.6 -10 -20.8
310 fps Zeroed @ 27 yds
10 20 27 30 40 50
+3.1 +2.50 -1.6 -10 -20.8
I would assume that the very small difference is arrow wt. I have 377gr. arrow input @310 fps @ 27 yrds.
12-13-2007, 06:04 AM
#66
Giant Nontypical
Join Date: Feb 2003
Location: HENDERSON KY USA
Posts: 6,634
RE: More arrow speed drivel... Trajectory chart
ORIGINAL: quiksilver
310 fps Zeroed @ 27 yds
10 20 27 30 40 50
+3.1 +2.50 -1.6 -10 -20.8
310 fps Zeroed @ 27 yds
10 20 27 30 40 50
+3.1 +2.50 -1.6 -10 -20.8
So it looks like if you had a 25 yard "0" that the trajectory within the 30 yard range is VERY close and that is using a 40 fps slower arrow.
Those 40 and 50 numbers are extremely close as is,you could tweak the "0" and have pretty close(not exactly)to the same setup with 40 fps slower arrow.
I believe my point is pretty clear.Again,I never said there wasn't a difference but 40 fps is alot but the trajectory isn't nearly as different as one would think.
This just shows you don't need to nitpick for every ounce of speed.
I do like matt/pa,I shoot whatever arrow I want and whatever the speed HAPPENS to be is what it is.I don't worry with it because I know it is neglagable.
12-13-2007, 07:35 AM
#67
Dominant Buck
Join Date: Feb 2003
Location: land of the Lilliputians, In the state of insanity
Posts: 26,274
RE: More arrow speed drivel... Trajectory chart
ORIGINAL: quiksilver
Tfox - you've already pointed out why you're getting different "real world" results than the ballistics calculation: Your bow is pointed "up" when it goes off. You're talking about a 3 yard misjudge with human error...and acting lke it's some kind of smoking gun that your slower arrow only drops and extra 1/2"over 3 yards at 40 yards...Think about whatyou're telling me...if 20 fps makes1/2" of difference over 3 yards, using the 40 YARD PIN. Try it with the 20 yard mark... See if it's still 1/2". HINT: It won't be.
Math doesn't lie. You can sit here and swear on your mother's grave that your arrow only drops 1" between 20 and 30 - no skin off my back bro. But I've shot enough to know that these calculations are fairly accurate - but you have to understand what the numbers are actually saying, and how that relates to the real world- and then how to manipulate the results.
Boy, you and Smartie Artie sure do get jacked up over a little physics. Like I told him- instead of complaining that it's wrong - get out your calculator and show me where I'm wrong.
Tfox - you've already pointed out why you're getting different "real world" results than the ballistics calculation: Your bow is pointed "up" when it goes off. You're talking about a 3 yard misjudge with human error...and acting lke it's some kind of smoking gun that your slower arrow only drops and extra 1/2"over 3 yards at 40 yards...Think about whatyou're telling me...if 20 fps makes1/2" of difference over 3 yards, using the 40 YARD PIN. Try it with the 20 yard mark... See if it's still 1/2". HINT: It won't be.
Math doesn't lie. You can sit here and swear on your mother's grave that your arrow only drops 1" between 20 and 30 - no skin off my back bro. But I've shot enough to know that these calculations are fairly accurate - but you have to understand what the numbers are actually saying, and how that relates to the real world- and then how to manipulate the results.
Boy, you and Smartie Artie sure do get jacked up over a little physics. Like I told him- instead of complaining that it's wrong - get out your calculator and show me where I'm wrong.
Not trying to stir the pot, but you are right, and you are wrong. Math doesnt lie, but the chart is calculated as an Ideal machine in ideal situations. Which is nothing more than the math.
Its not taking in account the friction coefficient of said fluid medium and the respective materials of said arrows. Also, it is ignoring inertia. It is simply the math of a projectile in respects of its velocity with no concernfor mass, shot in a vacuum. I feel this is where all the discrepancy is coming from here.
12-13-2007, 07:45 AM
#68
Giant Nontypical
Thread Starter
Join Date: Feb 2003
Posts: 5,716
RE: More arrow speed drivel... Trajectory chart
Yes, Tfox, but if you're playing thosegames with the trajectory - you'd behunting with a bow that hits over 3" hot inside 20 yards (where most actual hunting shots are taken, for me at least). I'll admit that if you fudge your zero out to 27 yds,your trajectoryisn't so bad at 310 (that's still smokin', as far as hunting setups go), but as you drop down under 275, you start to see the numbers getting out of whack pretty fast. I never said that you had a "bad" trajectory. I just said that if you zero at 20 yards, this is what it will be. It is what it is.
IMO, this is where a "hunter" and a "3d shooter" will butt heads.A competitive archer willalmost never take a 6-yard shot at a moving targetfrom a 25' platform, froze solid and running on 3 hours of sleep.They only shoot at non-moving styrofoam between15 and 39 yards... For you guys, one-pin 3+" high at 13 yards doesn't seem so bad. That's where a good 3d setup becomes a bad hunting setup.
3d guys set up for the shots thatthey are most likely to encounter (i.e. - a 28 yard broadside black bear target) - and that's fair. Bowhunters set up for the shots thatthey are most likely to encounter (i.e. - a 9 yard quartering buck - walking away - with 12 seconds to get the shot off - leaning away from the tree to get a clear lane).So, along those lines, I really don't think there's anything wrong with a one-pin hunter being zeroed at 20 yards. That's where most ofmy shotsare... So... It's only natural that we use that as my baseline in the field.
You keep arguing with me here,but I'm not sure what you're arguing about. It is what it is. Every speed and trajectory has its own parabola. The slower it's going, the more drastic the curve. You can play all the games you want with where it's zero'ed, but it doesn't change the fact that the slower it's moving, the worse the trajectory becomes.
__________________________________________________ _______________________________
Paul - this chart WILL tell you what the trajectory of any given bow will be. The shaft, fletchings, bow - do NOT matter. Newton's law of falling bodies. The difference between how THIS chart can be accurate, while the "drop speed calculator" will be off is simple: This calculator accounts for your zero and trajectory. The drop calculators just run a generic "9.8 meters per second squared" calculation - working backward from how far it fell, to attain "time in flight" and plugging in the yardage numbers to get a rough guess of speed.
__________________________________________________ _______________________________
Burnie: I understand that the speed does degrade, and this chart doesn't account for it. But even if it did, the numbers wouldn't be all that much different. That's why I went out and confirmedmy ownballisticsunder "real world" conditions on my own. There are external factors that influence the numbers in both directions, and the result: it balances out fairly well. It's not exact, but it's as close as you're gonna get without wasting your life doing 30 pages of high-level physics.
__________________________________________________ _______________
Just so we're all on the same page: A few pages ago, I was the village idiot for coming up with this ridiculous ballistics table. Now that you all have had time to play with your OnTarget software and pick at it - we realize now that the table is indeed correct? But, now we're just saying that my table is unrealistic, because nobody should be out there with just a 20-yard pin.
IMO, this is where a "hunter" and a "3d shooter" will butt heads.A competitive archer willalmost never take a 6-yard shot at a moving targetfrom a 25' platform, froze solid and running on 3 hours of sleep.They only shoot at non-moving styrofoam between15 and 39 yards... For you guys, one-pin 3+" high at 13 yards doesn't seem so bad. That's where a good 3d setup becomes a bad hunting setup.
3d guys set up for the shots thatthey are most likely to encounter (i.e. - a 28 yard broadside black bear target) - and that's fair. Bowhunters set up for the shots thatthey are most likely to encounter (i.e. - a 9 yard quartering buck - walking away - with 12 seconds to get the shot off - leaning away from the tree to get a clear lane).So, along those lines, I really don't think there's anything wrong with a one-pin hunter being zeroed at 20 yards. That's where most ofmy shotsare... So... It's only natural that we use that as my baseline in the field.
You keep arguing with me here,but I'm not sure what you're arguing about. It is what it is. Every speed and trajectory has its own parabola. The slower it's going, the more drastic the curve. You can play all the games you want with where it's zero'ed, but it doesn't change the fact that the slower it's moving, the worse the trajectory becomes.
__________________________________________________ _______________________________
Paul - this chart WILL tell you what the trajectory of any given bow will be. The shaft, fletchings, bow - do NOT matter. Newton's law of falling bodies. The difference between how THIS chart can be accurate, while the "drop speed calculator" will be off is simple: This calculator accounts for your zero and trajectory. The drop calculators just run a generic "9.8 meters per second squared" calculation - working backward from how far it fell, to attain "time in flight" and plugging in the yardage numbers to get a rough guess of speed.
__________________________________________________ _______________________________
Burnie: I understand that the speed does degrade, and this chart doesn't account for it. But even if it did, the numbers wouldn't be all that much different. That's why I went out and confirmedmy ownballisticsunder "real world" conditions on my own. There are external factors that influence the numbers in both directions, and the result: it balances out fairly well. It's not exact, but it's as close as you're gonna get without wasting your life doing 30 pages of high-level physics.
__________________________________________________ _______________
Just so we're all on the same page: A few pages ago, I was the village idiot for coming up with this ridiculous ballistics table. Now that you all have had time to play with your OnTarget software and pick at it - we realize now that the table is indeed correct? But, now we're just saying that my table is unrealistic, because nobody should be out there with just a 20-yard pin.
12-13-2007, 07:53 AM
#69
Dominant Buck
Join Date: Feb 2003
Location: land of the Lilliputians, In the state of insanity
Posts: 26,274
RE: More arrow speed drivel... Trajectory chart
ORIGINAL: quiksilver
Yes, Tfox, but if you're playing thosegames with the trajectory - you'd behunting with a bow that hits over 3" hot inside 20 yards (where most actual hunting shots are taken, for me at least). I'll admit that if you fudge your zero out to 27 yds,your trajectoryisn't so bad at 310 (that's still smokin', as far as hunting setups go), but as you drop down under 275, you start to see the numbers getting out of whack pretty fast. I never said that you had a "bad" trajectory. I just said that if you zero at 20 yards, this is what it will be. It is what it is.
IMO, this is where a "hunter" and a "3d shooter" will butt heads.A competitive archer willalmost never take a 6-yard shot at a moving targetfrom a 25' platform, froze solid and running on 3 hours of sleep.They only shoot at non-moving styrofoam between15 and 39 yards... For you guys, one-pin 3+" high at 13 yards doesn't seem so bad. That's where a good 3d setup becomes a bad hunting setup.
3d guys set up for the shots thatthey are most likely to encounter (i.e. - a 28 yard broadside black bear target) - and that's fair. Bowhunters set up for the shots thatthey are most likely to encounter (i.e. - a 9 yard quartering buck - walking away - with 12 seconds to get the shot off - leaning away from the tree to get a clear lane).So, along those lines, I really don't think there's anything wrong with a one-pin hunter being zeroed at 20 yards. That's where most ofmy shotsare... So... It's only natural that we use that as my baseline in the field.
You keep arguing with me here,but I'm not sure what you're arguing about. It is what it is. Every speed and trajectory has its own parabola. The slower it's going, the more drastic the curve. You can play all the games you want with where it's zero'ed, but it doesn't change the fact that the slower it's moving, the worse the trajectory becomes.
__________________________________________________ _______________________________
Paul - this chart WILL tell you what the trajectory of any given bow will be. The shaft, fletchings, bow - do NOT matter. Newton's law of falling bodies. The difference between how THIS chart can be accurate, while the "drop speed calculator" will be off is simple: This calculator accounts for your zero and trajectory. The drop calculators just run a generic "9.8 meters per second squared" calculation - working backward from how far it fell, to attain "time in flight" and plugging in the yardage numbers to get a rough guess of speed.
__________________________________________________ _______________________________
Burnie: I understand that the speed does degrade, and this chart doesn't account for it. But even if it did, the numbers wouldn't be all that much different. That's why I went out and confirmedmy ownballisticsunder "real world" conditions on my own. There are external factors that influence the numbers in both directions, and the result: it balances out fairly well. It's not exact, but it's as close as you're gonna get without wasting your life doing 30 pages of high-level physics.
__________________________________________________ _______________
Just so we're all on the same page: A few pages ago, I was the village idiot for coming up with this ridiculous ballistics table. Now that you all have had time to play with your OnTarget software and pick at it - we realize now that the table is indeed correct? But, now we're just saying that my table is unrealistic, because nobody should be out there with just a 20-yard pin.
Yes, Tfox, but if you're playing thosegames with the trajectory - you'd behunting with a bow that hits over 3" hot inside 20 yards (where most actual hunting shots are taken, for me at least). I'll admit that if you fudge your zero out to 27 yds,your trajectoryisn't so bad at 310 (that's still smokin', as far as hunting setups go), but as you drop down under 275, you start to see the numbers getting out of whack pretty fast. I never said that you had a "bad" trajectory. I just said that if you zero at 20 yards, this is what it will be. It is what it is.
IMO, this is where a "hunter" and a "3d shooter" will butt heads.A competitive archer willalmost never take a 6-yard shot at a moving targetfrom a 25' platform, froze solid and running on 3 hours of sleep.They only shoot at non-moving styrofoam between15 and 39 yards... For you guys, one-pin 3+" high at 13 yards doesn't seem so bad. That's where a good 3d setup becomes a bad hunting setup.
3d guys set up for the shots thatthey are most likely to encounter (i.e. - a 28 yard broadside black bear target) - and that's fair. Bowhunters set up for the shots thatthey are most likely to encounter (i.e. - a 9 yard quartering buck - walking away - with 12 seconds to get the shot off - leaning away from the tree to get a clear lane).So, along those lines, I really don't think there's anything wrong with a one-pin hunter being zeroed at 20 yards. That's where most ofmy shotsare... So... It's only natural that we use that as my baseline in the field.
You keep arguing with me here,but I'm not sure what you're arguing about. It is what it is. Every speed and trajectory has its own parabola. The slower it's going, the more drastic the curve. You can play all the games you want with where it's zero'ed, but it doesn't change the fact that the slower it's moving, the worse the trajectory becomes.
__________________________________________________ _______________________________
Paul - this chart WILL tell you what the trajectory of any given bow will be. The shaft, fletchings, bow - do NOT matter. Newton's law of falling bodies. The difference between how THIS chart can be accurate, while the "drop speed calculator" will be off is simple: This calculator accounts for your zero and trajectory. The drop calculators just run a generic "9.8 meters per second squared" calculation - working backward from how far it fell, to attain "time in flight" and plugging in the yardage numbers to get a rough guess of speed.
__________________________________________________ _______________________________
Burnie: I understand that the speed does degrade, and this chart doesn't account for it. But even if it did, the numbers wouldn't be all that much different. That's why I went out and confirmedmy ownballisticsunder "real world" conditions on my own. There are external factors that influence the numbers in both directions, and the result: it balances out fairly well. It's not exact, but it's as close as you're gonna get without wasting your life doing 30 pages of high-level physics.
__________________________________________________ _______________
Just so we're all on the same page: A few pages ago, I was the village idiot for coming up with this ridiculous ballistics table. Now that you all have had time to play with your OnTarget software and pick at it - we realize now that the table is indeed correct? But, now we're just saying that my table is unrealistic, because nobody should be out there with just a 20-yard pin.
12-13-2007, 10:16 AM
#70
Join Date: Feb 2003
Location: Blissfield MI USA
Posts: 5,293
RE: More arrow speed drivel... Trajectory chart
Did you even look at the link I posted and compared it to yours? I also have Ontarget and another one on my computer and have played these scenerios over and over, as well as testing them with 4 different bows, dozens of different arrows and at ranges out to 80 yards.
I would take the time to use some better software to show the differences, but I don't know if I want to waste my time. You simply don't care, you are never wrong. It is futile trying to explain something to you. You are right and the rest of us wrong even if we have better software and decades of experience to the contrary.
Smartie Artie has probably forgotten more about archery than you think you know.
I will say it again, our 13 year old autistic kid is easier to reason with.
Paul
I would take the time to use some better software to show the differences, but I don't know if I want to waste my time. You simply don't care, you are never wrong. It is futile trying to explain something to you. You are right and the rest of us wrong even if we have better software and decades of experience to the contrary.
Smartie Artie has probably forgotten more about archery than you think you know.
I will say it again, our 13 year old autistic kid is easier to reason with.
Paul