Deer "Jumping the String"

[Kirby]

Time for sound to reach animal
(40 X 3) / 1125 = .107 seconds

Time for arrow to reach animal
(40 X 3) / 320 = .400 seconds

.400 - .107 = .293 seconds (animals time to respond)

At a little over a quarter of a second that's plenty of time for a wiley critter to flinch. He won't always get out of the way but doing what you can to reduce noise still sounds like a pretty good idea to me.

The problem is the animal drops away from the string, it cannot move faster than gravity can move it this is D = (iV * t) + (1/2a * t2) where t2 is time squared. iV is 0 so remove it.

1/2A * T2 = 1/2(9. * .293(.293) = .4m that means that at 40 yards if the animal reacts INSTANTANEOUSLY it can drop 16". Now if you figure in the fact that two things must happen, one the deer must hear the sound, and then react to the sound it is physically impossible for it to react instantaeously.

Humans(albiet slower have an average reaction time around .200) now take a highly trained individual at the peak of his reaction ability you are looking at a late teens early 20's individual with a reaction time of .160 for auditory reaction (http://biology.clemson.edu/bpc/bp/Lab/110/reaction.htm)

There is a limit to how fast a reaction can occur based purely on the biology of how impulses are sent. cut the reaction time of the human to 2/3 and you have a reaction time of .12 seconds. Now, you have a lapse time of sound being .293-.120, time of drop is now .173

4.9 * .173(.173) = .14m = .48 feet = 5.8" I have never shot a deer that had a chest less than 16'' deep. aim for the center of the deer and he drops 6'' your still gonna hit'em in the vitals.

Kirby

[mntbowhunter]

Wow Kirby! I still have trouble with my times tables. You are one edjumacuated SOB! Thanks for the exlaination thats pretty cool.

[proguide66]

Buddy of mine from alabama sent me this last Nov after hunting here in Sept....they figure it 'would have' made top 10 4X4's ever shot .....
Maybe those damned tree stands give you too much 'buildup' time..his reaction says it all...http://www.youtube.com/watch?v=mkHhCSj0MUU

[killman]

Wow Kirby! I still have trouble with my times tables. You are one edjumacuated SOB! Thanks for the exlaination thats pretty cool.

LOL that is exactly what I was thinking. Damn now my brain hurts

[Bow Walker]

Thanks Kirby - I think.

Now I gotta go out with a measuring tape, a calculator (scientific type), a huge note pad, a bundle of pencils, and a large bottle of aspirin just to test, evaluate, and confirm your findings.

I wouldn't want jess to be all over me, ya know...

[huntwriter]

No offense Huntwriter but I call BS... dont shoot for the heart... aim for the lungs... to far forward and you hit the front leg.... as for the gap between the lungs and the spine... tell yourself that space is there all you want but in reality its a good excuse for a poor shot....
I have shot 29 deer with the bow and have yet to see one visibly jump the string... aim for where you want the arrow to go... not where you expect the animal to move...
guys you are over worrying little things... get out and shoot as many good shots a day practicing and that is all you can do...as for taking longer shots dont worry about the deer dropping....just put it where you want it... pick the smallest spot on the deer side and hit it....

25 years bowhunting and 382 deer, non of them lost, all aimed for the heart right behind the elbow. It seems the "BS" worked just fine for me. When I guided and outfitted I told all my clients. "In my camp you aim low 2 inch over the brisket, right behind the elbow." the "BS" has worked. Of the 168 that had a shot opportunity 167 killed the deer, one missed completely shooting over the back because he wasn't compensating for threestand height. Having said that I might add that I hunt only from treestands which is a bit different then hunting from the ground with straight on shots.

But it's no problem you do what works for you I do what works for me.

As for the gab between the spine and lungs. have a look at this picture. (I do not post pictures on forums to which I do not outright own the copyright.)

BowWalker is right about whitetails, they are very jumpy, especially where they are subjected to heavy hunting pressure, which almost anywhere in the U.S.A.

[Bow Walker]

See where the heart is in the pic that I posted in reply #9? Aim for the heart. If the deer drops because he either hears you or sees you then you're almost sure to get the lungs.

Can't go wrong aiming at the heart.

[huntwriter]

See where the heart is in the pic that I posted in reply #9? Aim for the heart. If the deer drops because he either hears you or sees you then you're almost sure to get the lungs.

Can't go wrong aiming at the heart.

There you go. Thanks! If the deer ducks you still get a double lung shot. Aim for the lungs, deer ducks and arrow flies over the back.

Here is a video that shows in slow motion just how fast and how low a deer can duck in a split second. Archer aimed for the lungs.

[Hydrojet]

not to start trouble.....but what happens when the deer jumps.....which would mean pushing in the opposite direction of gravity so that the "a" for acceleration in kirbys equation changes and I am assuming iV is for initial velocity. If the deer can jump at a force greater than 9 m/s^2 (which I haven't seen studied for a number but to jump like they do I am assuming a difference of at least 10-12 m/s^2 as the over all acceleration in the direction of movement has to be greater than 9 to over come the effect of gravity and then some to get some air) and isn't perfectly still at the time of release you could see that 5.8" push 7" and the point of impact move down or down and forward/back which would put the arrow in leg or miss territory. Now I am no means a bow hunter and with a rifle I have only seen deer duck, look or go flop. Wouldn't it be best to still worry about the flinch due to the string noise? Or do the deer always duck?.....sorry as soon as someone brings out the physics I get excited.... hey Huntwriter....does that picture come any bigger....all I can see is a brown looking thing with horns

[Hydrojet]

That video of HW shows a 250 fps arrow so it is slower than slinky's calculation and would push Kirby and my numbers out even more.....The biggest thing I ever encountered was trying to increase my accuracy of my University labs and in the end the good ol' human error was always large enough to negate any other error and give a error probability large enough so my data and findings were within spec......We may be splitting hairs here boys and the little shake from the extra coffee that morning caused an error that would negate the rest of the effort!