Velocity of Arrow Vs Speed of Sound
08-14-2008, 12:40 PM
#11
Giant Nontypical
Join Date: Feb 2003
Location: PA
Posts: 9,085
RE: Velocity of Arrow Vs Speed of Sound
AF...i did something similar once...but was comparing bow speeds and time it takes...
reallllllly not all that different from most of the bow speeds out there...so i kinda chuckle when i hear guys say shoot a faster bow to avoid the "duck"
cant remember the numbers and have no desire to do the crunching again...it just dont make a difference with the reaction time they have...
i think too many guys shoot alert deer or make deer alert by trying to stop them for the shot....
reallllllly not all that different from most of the bow speeds out there...so i kinda chuckle when i hear guys say shoot a faster bow to avoid the "duck"
cant remember the numbers and have no desire to do the crunching again...it just dont make a difference with the reaction time they have...
i think too many guys shoot alert deer or make deer alert by trying to stop them for the shot....
08-14-2008, 12:43 PM
#12
Nontypical Buck
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Join Date: Oct 2005
Location: Iowa (Heartland USA)
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RE: Velocity of Arrow Vs Speed of Sound
Mauser, I'm not even considering trying to find a way to avoid the duck, just saying at those speeds it's amazing how quickly the deer react to the "whump" of an arrow being sent down range. I am in total awe of that quick of reaction speed.
08-14-2008, 12:45 PM
#13
Giant Nontypical
Join Date: Feb 2004
Location: Pittsburgh, PA
Posts: 7,208
RE: Velocity of Arrow Vs Speed of Sound
A while back I did some similar calculations. I arbitrarily chose the horizontal deceleration of the arrow to be 0.25 ft/s per yard travelled. And I dragged my calcs out to 50 yds, at which it takes an arrow starting at 300 fps, .51 sec to get there.
The speed of sound is 1116 ft/s. It takes .134 sec to go 50 yds. Difference in time is .376.
At 30 yds an arrow takes .294 sec & sound takes .08 sec. Difference of .214 sec.
A deer does not have less time to react the farther away it is.
The speed of sound is 1116 ft/s. It takes .134 sec to go 50 yds. Difference in time is .376.
At 30 yds an arrow takes .294 sec & sound takes .08 sec. Difference of .214 sec.
A deer does not have less time to react the farther away it is.
08-14-2008, 01:00 PM
#15
Join Date: Mar 2004
Location:
Posts: 13,082
RE: Velocity of Arrow Vs Speed of Sound
I'm confused.....How can the deer have less time to react on a further shot? At 20 yards, you state it has 3/20 of a second to react.....That's far less time that the 1/3 of a second at 40 yards, isn't it? Or have I completely misread this?
08-14-2008, 01:14 PM
#16
Join Date: Dec 2003
Location: Southeast, TX
Posts: 818
RE: Velocity of Arrow Vs Speed of Sound
Here are some numbers(speeds @ different yardages)that I pulled from a Kanga post in the Tech forum.
mobow, you're right 3/20th of a sec is less than 1/3 sec. Think of it in percent. 3/20th is 15% of a second. 1/3 is 33% of a second.
I'm sure AF's brain was hurting after calculating all that. It is interesting though and yes those suckers react fast.
The first arrow is 302gr with a FOC of 6%
The second arrow is 480gr with a 24% FOC.
Both arrows where spined perfectly for the bow.
I first shot the heavy arrow through the crono at point blank 249fps KE 66 ft/lb
Then the light arrow 299fps KE 59.9 ft/lb
Ok now for the fun.
Heavy arrow
10 yds 245 fps KE 64.1 ft/lb
20 yds 241 fps KE 62.3 ft/lb
30 yds 238 fps KE 60.5ft/lb
40 yds235 fpsKE 58.8 ft/lb
50yds231 fps KE 57.1 ft/lb
After a couple of minor tuningadjustments and resighting in for the light arrow.
10 yds 292 fps KE 57.2 ft/lb
20 yds 285 fps KE 54.6 ft/lb
30 yds 278 fps KE 52.1 ft/lb
40 yds272 fps KE 49.7 ft/lb
50 yds266 fps KE 47.4 ft/lb
So doing the Math the heavy arrow lost 18 fps and 9 ft/lb of Ke and the light arrow lost 33 fps and 12.5 ft/lb of KE from 0 to 50 yds.
The second arrow is 480gr with a 24% FOC.
Both arrows where spined perfectly for the bow.
I first shot the heavy arrow through the crono at point blank 249fps KE 66 ft/lb
Then the light arrow 299fps KE 59.9 ft/lb
Ok now for the fun.
Heavy arrow
10 yds 245 fps KE 64.1 ft/lb
20 yds 241 fps KE 62.3 ft/lb
30 yds 238 fps KE 60.5ft/lb
40 yds235 fpsKE 58.8 ft/lb
50yds231 fps KE 57.1 ft/lb
After a couple of minor tuningadjustments and resighting in for the light arrow.
10 yds 292 fps KE 57.2 ft/lb
20 yds 285 fps KE 54.6 ft/lb
30 yds 278 fps KE 52.1 ft/lb
40 yds272 fps KE 49.7 ft/lb
50 yds266 fps KE 47.4 ft/lb
So doing the Math the heavy arrow lost 18 fps and 9 ft/lb of Ke and the light arrow lost 33 fps and 12.5 ft/lb of KE from 0 to 50 yds.
I'm sure AF's brain was hurting after calculating all that. It is interesting though and yes those suckers react fast.
08-14-2008, 01:32 PM
#17
Nontypical Buck
Thread Starter
Join Date: Oct 2005
Location: Iowa (Heartland USA)
Posts: 3,249
RE: Velocity of Arrow Vs Speed of Sound
ORIGINAL: rybohunter
A while back I did some similar calculations. I arbitrarily chose the horizontal deceleration of the arrow to be 0.25 ft/s per yard travelled. And I dragged my calcs out to 50 yds, at which it takes an arrow starting at 300 fps, .51 sec to get there.
The speed of sound is 1116 ft/s. It takes .134 sec to go 50 yds. Difference in time is .376.
At 30 yds an arrow takes .294 sec & sound takes .08 sec. Difference of .214 sec.
A deer does not have less time to react the farther away it is.
A while back I did some similar calculations. I arbitrarily chose the horizontal deceleration of the arrow to be 0.25 ft/s per yard travelled. And I dragged my calcs out to 50 yds, at which it takes an arrow starting at 300 fps, .51 sec to get there.
The speed of sound is 1116 ft/s. It takes .134 sec to go 50 yds. Difference in time is .376.
At 30 yds an arrow takes .294 sec & sound takes .08 sec. Difference of .214 sec.
A deer does not have less time to react the farther away it is.
08-14-2008, 01:45 PM
#18
Giant Nontypical
Join Date: Feb 2004
Location: Pittsburgh, PA
Posts: 7,208
RE: Velocity of Arrow Vs Speed of Sound
I don’t know what the loss of decibels over distance is, but yea it is pretty common that a loud noise close, will incite more reaction that a dull noise from farther away.
I was only number crunching for the situation that if the sound was audible and an animal was going to react, it had more time to do so from further out.
I was only number crunching for the situation that if the sound was audible and an animal was going to react, it had more time to do so from further out.
08-14-2008, 03:53 PM
#19
Join Date: Feb 2003
Location: Blissfield MI USA
Posts: 5,293
RE: Velocity of Arrow Vs Speed of Sound
I have seen deer appear to duck a shot from a muzzle loader with a bullet moving at 1800 fps, which is faster than the speed of sound. I personally have never had a deer duck a shot from a bow or a muzzle loader. I always hit right where I am aiming for, or within an inch or two.
I'm not going to say it never happens, but I bet most that say a deer ducked the shot probably miss judged the yardage or the deer was starting to move before they released the arrow. Basically they just missed.
I'm not going to say it never happens, but I bet most that say a deer ducked the shot probably miss judged the yardage or the deer was starting to move before they released the arrow. Basically they just missed.
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