Arrow speed and kinetic energy

Pydpiper · Post by **Pydpiper** » Thu Feb 22, 2007 8:11 am

I have come across a few charts for determining KE, it is always relevant to the arrow weight and speed.
So, at what distance are we measuring the speed? I am using 435 grain arrows but the speed obviously drops the farther back from the target a person gets. So when the chart is asking for arrow speed what distance is it referring to?
For example, my Exocet shoots 316 FPS at 10 yards, do I use that 316 or the speed at the distance I am shooting?

Matthias72 · Post by **Matthias72** » Thu Feb 22, 2007 8:27 am

two different things.

With the V° speed (exit speed) you measure the kinetic energy max of your crossbow (to understand the real performance respect another crossbow.

With the target speed (arrow speed during impact) you measure the kinetic energy real when the arrow hit the target. This is important to understand how many kinetic energy is necessary for penetrate on animal for example.

Pydpiper · Post by **Pydpiper** » Thu Feb 22, 2007 10:16 am

Thank you, It was your site that got me thinking of this. I recall reading that you typically do your measurements at around 3' or so?

Rebel Hog · Post by **Rebel Hog** » Thu Feb 22, 2007 12:25 pm

http://www.bowsite.com/bowsite/features ... /index.cfm

Beaver · Post by **Beaver** » Thu Feb 22, 2007 8:52 pm

If you can telll me your exact arrow weight with point or broadhead, arrow length, arrow diameter, fletch type(feather or vane), fletch length, fletch height, and if fletch is straight, offset, or helical, and your arrow launch speed, I have a ballistics program that will tell you the arrow drop and lag(speed loss) over 100 yards. I can tell you your speed, KE, and momentum at 10 yard intervals.

Pydpiper · Post by **Pydpiper** » Fri Feb 23, 2007 6:53 am

Thanks Beaver, I have that program.

I guess my question was a little more generic, I was thinking about when an article refers to kinetic energy and speed, I don't know if it is referring to the speed of the arrow as it leaves the crossbow or the speed as it hits the target.

For those who don't have access to the program it is located here: This site belongs to an active member here. This site has some in depth (very in depth) information on crossbows, ballistics and real life tests. This guy has dedicated many, many hours of testing for everyones benefit.

http://www.cacciaebalestra.altervista.o ... Main0.html