A guy that I work with and I are having a little debate. He is saying that with an arrow flying at 310fps a deer will be less likely to jump the string than at let's say 280. I said that he's right in a sense. I'm saying that the "actual" time difference isn't that great to say that with 100% confidence. Does anyone know how to figure out how much time it takes for an arrow to hit a target at a given distance at any given speed? Is there an equation for such a thing?

Thanks

I'm not a math man, so forgive me if I am wrong. But if speed stays constant at 300fps, it should travel 20yds in .2 seconds at 280 it would .214 seconds. Is this correct?

Umm, you've got the formula! FPS = Feet / Seconds = Distance / Time.

At 310 fps it will take .1935 seconds to hit a target 20 yards(60 ft) away.

60/310=.1935 seconds

60/280=.2143 seconds

The speed of sound is approx. 761.21 miles per hour. Translated is equates 1116.44 fps.

The sound of your bow/arrow will reach the deer as follows:

60/1116.44=.0537 seconds

The speed of sound is roughly 3.60 times faster than the 310 fps arrow or 3.99 times faster than the 280 fps arrow. Now, all this is based on static numbers, but your velocities of your arrows will degrade over distance traveled....thus making all the above numbers completely irrelevant. But, the theory and premise are there for you.

Jason,

You aren't by chance a rocket scientist are you? That's an awefull technically correct answer and in record time. I'm impressed

Great! Thanks for the info. I have ammo in the reserves now. lol

Nope, I am a mech. engineer though. I occaisionally have my brilliant days....today is one of those days....they don't come by very often.[&:] I actually impressed myself, usually when I explain something is doesn't come out of my mouth or onto the screen anything at all like it's going on in my head....today it all came very fluidly!

The pro at our local bow shop explained the whole thing to me once. His answer was similar to that of Jason N above but included deer reaction time and the speed at which a deer can drop and then leap. I wont attempt to get into the numbers.

Bottom line, no matter what speed your arrow is traveling, deer have plenty of time to jump the string if your bow is loud enough to alarm them.

I did a similar calculation last year during gun season for a new bullet I was shooting.
12 gauge core loc'd copper solid sabot - something like 1350 fps.
Boiled down to: by the time the deer heard the shot the bullet was through him and x feet on the other side.

Now if I can only get my bow to shoot 1350fps[&:]

I don't think it's so much the bow noise, but rather the arrow noise. As the arrow approaches it gets louder. So, some deer may jump to get out of the way. I often wonder how many times, the one that jumps out of the way, has heard that sound coming at them??

Very interesting thought, Bees.
The arrow is certainly making noise in flight, especially if it is fletched with helical, shield-cut feathers, and the sound would radiate in all directions, including that of the deer.

After thinking about it for a few minutes though, it seems to me that the sound wave generated by the bowstring upon release would outrun the others since it occurred first, and it is moving over 3 times as fast as the arrow that is generating all subsequent noise.

I'll hurt my brain if I try to figure out wether the deer will hear all of the sound before the arrow strikes, but then again there is the issue of how fast the deer can react.

Having noted my own reactions to loud, unexpected noises in the past, I can attest that it only requires one instant to zero in on the source of it, not necessarily a continuous noise, if it is fairly close.