Arrow Penetration

[NYBuckHunter27]

Does a heavier grains per inch arrow necessarily mean more penetration?

[orion]

yes/no/maybe?

A lot of other variables but if all else is equal except weight, then yes you will get deeper penetration

[fasteddie]

Anything I have read says that the heavier arrow will penetrate more than a lighter arrow .

 

http://archeryreport.com/2011/03/arrow-penetration-testing-real-bows-real-arrows-real-results/

[dbHunterNY]

yes.... you need to consider all other things equal though. 

 

if the head, shot location, bow, or anything else is different then you have to factor that in too.  weight doesn't trump everything else.  the only exception I can think of is if you had lower draw weight/slower bow/ lesser KE to work with and hit a solid leg bone or spine.  then a light arrow versus a heavy arrow would be pretty much the same as it's prematurely stopped by a very solid object.  shooting through ribs or most of the shoulder blade and the answer is still yes.

[grampy]

All other things being equal,the heavier arrow will penetrate more than the lighter arrow.

[Doc]

Yeah, back when arrow speed became the altar at which archers worshipped, this argument had its heyday. All the armchair physicists came out of the woodwork and began calculations and tests and eventually decided on the archery truth that the heavier arrow penetrated more than the light fast arrow. It's not immediately obvious because speed gets involved too in the energy fomulas. But in spite of that, it is the mass weight that rules the day on impact and penetration. Proven both mathematically and empirically.

 

Of course if you really want to get into it all, there are other factors at work such as broadhead design, bow and arrow tuning, and bow draw weight and other factors. Don't expect the old Browning serpentine broadhead to help out penetration. And don't expect an arrow that enters at an angle to the shot direction to help penetration a bunch. And don't expect a 35# draw weighted bow to deliver as much penetration as a 60 pounder. Ha-ha ..... flu-flu fletching won't max out your penetration either .... lol.

[Bow Addict]

A heavier arrow will retain it's kinetic energy down range better than a light arrow.

[NYBuckHunter27]

whats considered a heavier arrow? 8-9 GPI or 10+ GPI?

[Grizz1219]

Yes

[dbHunterNY]

whats considered a heavier arrow? 8-9 GPI or 10+ GPI?

 

it depends on the arrows spine everything else when equating GPI.  if your shaft is sized correctly say with a .300 - .350 spine then 10+ grains per inch is heavy.  closer to 8 gpi is light and 9+ gpi is about average.

[Lawdwaz]

Easy answer....... Would you rather get hit with a ping pong ball or a golf ball?

[dbHunterNY]

A heavier arrow will retain it's kinetic energy down range better than a light arrow.

 

....as it has more momentum (mass X velocity) and so down range is carries more of it's speed.  kinetic energy is 0.5 X mass X velocity X velocity.

[Jeremy K]

Easy answer....... Would you rather get hit with a ping pong ball or a golf ball?

Speaking from experience, I would much rather the ping pong ball.

[Lawdwaz]

[NYBuckHunter27]

Easy answer....... Would you rather get hit with a ping pong ball or a golf ball?

 

i knew someone could put it in simple terms for me...

[Bow Addict]

whats considered a heavier arrow? 8-9 GPI or 10+ GPI?

A 500 grain arrow is going to penetrate better than a 350 grain arrow.

[Hock3y24]

U use a 440 grain finished arrow with nap thunderheads, got through deer like butter and still fly fast.

[Doc]

Easy answer....... Would you rather get hit with a ping pong ball or a golf ball?

When I was a young-un, I worked at Olympic park at the golf ball driving range. I learned about getting wacked with a golf ball when I tried retrieving some of the balls while we were still open. I would have been a lot happier if they had been knocking out Ping-Pong balls ..... lol. Some of those guys were pretty good at hitting what they aimed at when they had a live moving target out there. I am a quick learner, and never repeated that stunt.

[NFA-ADK]

My 340's go slower than my 400's and both penetrate about the same.  Heavy arrow shots slower and a light one shoots faster, both have about the same KE and are a pain in the neck to pull out of 3D unless you lub up the tips. 

 

If the speed was the same for both arrows then the heavy arrow has more KE.

[JimMac]

plug in some numbers and see , speed , ke

 

http://www.backcountrybowhunting.com/articles/calc/

 

 

[Doc]

plug in some numbers and see , speed , ke

 

http://www.backcountrybowhunting.com/articles/calc/

Interesting!  I'm not sure how reliable this calculator is, but I did find a threshold where when you plug in a ridiculously high arrow weight (something like 700gr) you can get the energy lessening because of a resulting drop in speed. Apparently there is a sweet spot where the arrow weight with a given set-up will get the maximum energy. So there are limits as to where adding more arrow weight will actually lessen energy.

 

Also, I have to assume that the values given are at initial launch, since there are no distances factored in here. Probably they were trying to eliminate such variables as air drag of vanes and such. But it would have been great if distances had been added into the calculations.

 

I kind of like this little calculator. It gives some interesting stuff.

[Trial153]

Something to keep in mind in the Ke & Momentum calculations.... Because mass is the only variable that stays the same it has the most influence on the equation.

An arrow looses velocity as soon as it clears the string, however the mass remains constant....

[phade]

These discussions are always entertaining, frustrating at times, and people come out of the woodwork.

 

I think the biggest point to clarify is "why is this being asked?"

 

There's a balance to everything - most people shoot whitetail deer and maybe turkey. As a point to that, most people do not need to shoot logs, they can shoot a middle of the road weight and still get the penetration they need. I shoot around a 400 gr arrow combo with an expandable 1 3/8" BH at a realistic 255-260 fps. Sometimes I also use a 1" fixed BH (STs). I sit right around 60lbs KE. I could most certainly up that weight, and I could most certainly lower it. I've found that this is a good middle ground for me. 

 

If I were to be chasing elk or bigger game, I'd likely move to a fixed head and look at upping my arrow weight.

 

 

[NYBuckHunter27]

These discussions are always entertaining, frustrating at times, and people come out of the woodwork.

 

I think the biggest point to clarify is "why is this being asked?"

 

There's a balance to everything - most people shoot whitetail deer and maybe turkey. As a point to that, most people do not need to shoot logs, they can shoot a middle of the road weight and still get the penetration they need. I shoot around a 400 gr arrow combo with an expandable 1 3/8" BH at a realistic 255-260 fps. Sometimes I also use a 1" fixed BH (STs). I sit right around 60lbs KE. I could most certainly up that weight, and I could most certainly lower it. I've found that this is a good middle ground for me. 

 

If I were to be chasing elk or bigger game, I'd likely move to a fixed head and look at upping my arrow weight.

 

Basically I'm looking to be able to use a two inch cut mechanical broad-head with correct penetration. I have a 60lb bow at about 28.5 draw so i know my bow with current arrows at 8.1 GPI is shooting them at about 268 fps, but i'm wondering if a arrow in the 9+ GPI range is needed....

[NFA-ADK]

I have the same draw length with about 270 fps using a 400

Beeman ICS Hunter pro at 8.1 GPI

You should have no problems with penetration.