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Jugs line up in front of target

Jugs lined up in front of target

It’s time for Part II of the arrow penetration testing!  The entire article including Part I and Part II can be found here:  Arrow Penetration Testing: Real Bows, Real Arrows, Real Results

While the first section dealt with penetration through one jug and measuring the exit velocity, this part takes a look at shooting through six jugs and what it takes to stop the arrows.

The equipment for this round is identical as the first, with the exception that I added a FOB as the fletching.  I had first started with fletchings, but they were ripped off fairly quickly.  For round one I removed the fletchings to avoid inconsistencies in fletching contact, but decided to go with the FOBS for round two because the arrows fly better with them.  Both FOBs took virtually no force to come off the back end of the arrow.

 

Chronograph speeds of both arrows

Chronograph speeds of both arrows

Before doing penetration testing, I adjusted both arrows to have nearly identical FOCs with the FOBs.  The final weights were 322 and 579 grains.  Next I checked how they both tuned through paper.  With nearly perfect bullet holes in paper, I was ready to get some speeds using the chronograph.

Five shots with both arrows were fired to check the speed and all shots were very consistent, within +/- .1 FPS.  The lighter arrow averaged 318.9 fps and the heavier 242.3 fps.  Summarizing the weights, speeds, kinetic energy and momentum:

322 Grains 579 Grains
Initial Velocity 318.9 242.3
Initial Momentum 0.456 0.622
Initial KE 72.62 75.41
Penetration of the 322 grain arrow

Penetration of the 322 grain arrow

With all the initial setup and testing out of the way, it was time to do some shooting and make a mess!  I had twenty-four jugs saved up for testing, all of them from the same manufacturer and identical in every way.  This gave me enough for two shots through six jugs for each arrow.  All shots where taken from 5 yards away as this gave me enough room to kneel and line up the jugs as perfectly as possible (and to have the camera at the side in a good position.) Each of the two shots for each arrow had nearly identical results, so I feel they are valid so far as this type of testing is concerned.

The 322 grain arrow was first.  As can be seen in the picture, the arrow was stopped by the jugs with about 1 1/4″ protruding from the first shot and 1 3/4″ from the second shot.  As can be seen, I shot the jugs near the bottom of the flat section because that was the most consistent part of the plastic.

Pentration of the 579 grain arrow into target behind

Penetration of the 579 grain arrow into target behind

Next up was the 579 grain arrow.  Both shots resulted in the arrow penetrating all of the jugs and ending up about six to eight inches into the target behind.

The heavier arrow performed significantly better in penetration and I’m not certain even seven jugs would have stopped it.  I’ll save up some more and will repeat the test with eight jugs in the future.  That’s a lot of milk, but I think my family is up to it!

Observations

As expected, the heavier arrow performed significantly better in penetration through a combination of fluid and solid media.  The testing in this case was highly dominated by the fluid and as described in the Heavy vs. Light Arrows: Downrange Speed and Power article, faster objects will always experience a higher deceleration force that slower objects, all else being equal.  Also, it’s important to note that the heavier arrow in both Parts I and II had significantly more kinetic energy an momentum.

Just for kicks and grins…

Disclaimer:  the following pictures are not indicative of a controlled scientific experiment, but rather a “fun” test that others have done and I wanted a comparison too.  Shown is the penetration of the test arrows into and through two phone books.  Notice the consistency of the heavier arrow out-penetrating the lighter arrow.  Each set of shots was done on the same horizontal plane of the phone book, however the third set of shots shows how badly the phone books had deteriorated (though the comparative results are nearly the same.)

You can tell which is the heavier arrow by looking at the field point; the heavier has a slightly longer section behind the identical point section.

Phone book shot 1

Phone book shot 1

Phone book shot 2

Phone book shot 2

Phone book shot 3

Phone book shot 3

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