# hunting arrow weight



## Pinefarm (Sep 19, 2000)

I'm comparing that to when I used lighter draw weights, but heavier arrows and 125-145gr heads in the old days vs the lightest carbons and 85gr heads.


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## gashogford (Jul 5, 2008)

Old school Carbon Express Terminators Selects 450 grains with includes 100 bh. They pack a punch!


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## GRUNDY (Jun 18, 2005)

I've always been perplexed by the light arrow high KE mentality. A light arrow will dissipate energy quite fast when it strikes an object. A heavy arrow will store more energy due to its higher mass. This is evidenced by how quiet your bow can get when you start upping arrow weight.

Here is the best link to finding out all about arrow penetration and lethality. Its been done by a compound and longbow shooter for a very long time on many different kinds of African game, including controlled tests on dead animals. Its alot of reading and sometimes quite mathmatical, but very enlightening. It will have you trying to make your arrow as heavy as possible.

Enjoy... http://*************/ashby/Momentum%20Kinetic%20Energy%20and%20Arrow%20Penetration.htm


Brian


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## GRUNDY (Jun 18, 2005)

Unfortunately MS.com does not like the link. I will try again... Please type this into you browser with out the spaces. 

W W W . t r a d g a n g . c o m / a s h b y /

You'll be glad you did!

Brian


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## Michihunter (Jan 8, 2003)

GRUNDY said:


> I've always been perplexed by the light arrow high KE mentality. A light arrow will dissipate energy quite fast when it strikes an object. A heavy arrow will store more energy due to its higher mass. This is evidenced by how quiet your bow can get when you start upping arrow weight.
> 
> Here is the best link to finding out all about arrow penetration and lethality. Its been done by a compound and longbow shooter for a very long time on many different kinds of African game, including controlled tests on dead animals. Its alot of reading and sometimes quite mathmatical, but very enlightening. It will have you trying to make your arrow as heavy as possible.
> 
> ...


Mass does not necessarily determine how fast kinetic energy will dissipate but it is a factor in momentum which in laymens terms is "the amount of force it takes to stop an object in one second"". Kinetic energy in laymens terms is the "amount of force required to stop the object over a distance of one foot". Whether you have 70 ft-lbs with a light arrow or 70 ft-lbs with a heavy arrow the energy is equal. Sorta like the age old question what weighs more, a ton of feathers or a ton of lead. Here's the truth of the matter- http://www.tap46home.plus.com/mechanics/downrange.htm

For a better read by an actual Physicist you need to read Joe Tapleys Topics on Bow Mechanics. Ashby's work is a good read but unfortunately there are a lot of innaccuracies in his contentions. In fact if you are thoroughly familiar with Dr. Ashby, you'll know that he has a ton of contradictions that he himself has admitted to and has attempted to correct in his latest works. I give credit where credit is due and Dr. Ashby is certainly deserving of that for the time and work he has spent doing this research. It is invaluable for sure.


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## Michihunter (Jan 8, 2003)

Here's a great example of what I mean regarding Ashby's inaccuracies and penchant to use them to prove a point: 

Ashby states:


> A baseball weighs 5.12 ounces (that&#8217;s 2240 grains) and can be thrown in excess of 95 mph (which is 139.33 feet per second). It has 96.5 foot pounds of kinetic energy. It actually strikes much harder than a heavy hunting arrow at &#8216;traditional bow&#8217; velocities, but I can't really see hunting buffalo with a fast ball! Kinetic energy determines how hard the baseball strikes; it has no direct bearing on how well it penetrates.As with the baseball, a tuning fork, once struck, has high kinetic energy (it can shatter a crystal wine glass), but has almost no momentum. It would make a darn poor weapon against an animal of even modest size!


Well of course it doesn't. It's a blunt object that has non penetrating properties. It is not designed to penetrate. Take that same weight and same speed and make it into an arrow and tell me now how it will do in penetrating a buffalo. There's a ton more of these in his writings which makes it hard for anyone with a physics background to take him as serious as some seem to do


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## Pinefarm (Sep 19, 2000)

Grundy,
I've read that before and it's really great info. Just with my backyard tests, my 500gr arrows don't come close to my 675gr arrows. I'm been playing around with weight tubes and aquarium air tubing and so far the results are impressive, and the bows also become scary silent.
I'm thinking that a good 2 blade and about an 800gr arrow out of my longbows and recurves at 15-18 yards will be a super combination.

Another good read, although I think a Steelforce double bevel cannot be beat...

http://www.bowhunters.org.au/phpBB3/images/bowhunting/Why Single-Bevel Broadheads.pdf


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## Michihunter (Jan 8, 2003)

Pinefarm said:


> Grundy,
> I've read that before and it's really great info. Just with my backyard tests, my 500gr arrows don't come close to my 675gr arrows. I'm been playing around with weight tubes and aquarium air tubing and so far the results are impressive, and the bows also become scary silent.
> I'm thinking that a good 2 blade and about an 800gr arrow out of my longbows and recurves at 15-18 yards will be a super combination.
> 
> ...


Hope you guys don't start hating me for this but once again, a myth of Dr. Ashbys is proven wrong. He contends that when a double beveled broadhead impacts with hard tissue it quits rotating. If you go to limbsaver.com and click on the slow motion videos>archery> broadhead vs beef you can clearly see several double bevel broadheads continue rotating after going through bone.


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## Pinefarm (Sep 19, 2000)

Michi,

I only said it's a good read. My tests have shown that a sharp double bevel can't be beat. I don't like single bevel's, personally. But still a worthy read and gives context to the conversations.

Try the 190gr, 2 blade, double bevel Steelforce Phat Head if you want to see something that's a bunker buster, IMHO.


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## Michihunter (Jan 8, 2003)

Pinefarm said:


> Michi,
> 
> I only said it's a good read. My tests have shown that a sharp double bevel can't be beat. I don't like single bevel's, personally. But still a worthy read and gives context to the conversations.
> 
> Try the 190gr, 2 blade, double bevel Steelforce Phat Head if you want to see something that's a bunker buster, IMHO.


I just didn't want anyone thinking it was the gospel PF. 

I actuallly went and found what I was looking for earlier. It's the papers Joe Tapley put together based on Bob Kooi's work. VERY interesting stuff if you're into the mechanics of things. Here's the link: http://www.tap46home.plus.com/mechanics/ I'd also recommend to those with decent mathematical abilities to check out this: http://www.bio.vu.nl/thb/users/kooi/


I have to add one more thing regarding downrange energy loss between light and heacy arrows which seems to be another contention that's not exactly correct: http://www.tap46home.plus.com/mechanics/downrange.htm


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## GRUNDY (Jun 18, 2005)

Well, I'm no phycisict so I can't crunch all the numbers. I also see both sides of the argument. 

All I know is that with heavier arrows, my recurves, and compound get real quiet, and the arrows hit real hard. Even had my neighbor walk over one night when I was shooting a 45# bear and asked my how much weight I was pulling cuz those arrow make quite a thump when they hit the bag target. I don't think he believed it when I told him it was a 45lber...

I guess I just lean towards a heavy arrow as long as trajectory is still decent.

B


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## Michihunter (Jan 8, 2003)

GRUNDY said:


> Well, I'm no phycisict so I can't crunch all the numbers. I also see both sides of the argument.
> 
> All I know is that with heavier arrows, my recurves, and compound get real quiet, and the arrows hit real hard. Even had my neighbor walk over one night when I was shooting a 45# bear and asked my how much weight I was pulling cuz those arrow make quite a thump when they hit the bag target. I don't think he believed it when I told him it was a 45lber...
> 
> ...


Truly there is no "right" or "wrong" answer in this equation. It boils down to a personal preference of what you as an archer choose to use amongst the MANY options that will effectively kill your game. 

In one of Tapleys statements he describes an arrow needed to penetrate armor. His opinion was that when you determine what will be enough momentum to penetrate that target, use that as your minimum goal and adjust so that your speed is at the maximum for the given weight that would produce that particular momentum. In other words if your game only needs .35 ft-seconds of momentum to consistently show a pass through, adjust your weight and speed so that you are producing the fastest arrow you can get to produce that specific momentum and you should have the optimum setup. In my mind that makes perfect sense.


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## GRUNDY (Jun 18, 2005)

Agreed.

I've tried extremely heavy arrows in my recurve, to the point where they were so heavy you could tell the penetrating qualities were not there. Speed is a factor. for sure. But I think with todays fast compounds over 300fps and modern recurves that can achieve about 200fps. There should be a general push for using an arrow that is on the "heavy side" for better results on shoulder hit game, and less than ideal arrow placement.

I also think that the Ft-s Momentum equation should trump the KE equation. But its probably more complicated to perform that calculation than the KE calculation.

Either way it's all moot, because they all seem to kill deer.

Brian


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## Michihunter (Jan 8, 2003)

GRUNDY said:


> I also think that the Ft-s Momentum equation should trump the KE equation. But its probably more complicated to perform that calculation than the KE calculation.
> 
> Either way it's all moot, because they all seem to kill deer.
> 
> Brian


Personally I think both equations should be used hand in hand equally with neither being the sole indicator of penetrating abilities. And you are absolutely right in your closing statement!!


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## GRUNDY (Jun 18, 2005)

Yup, its hard to argue the point whilst standing over yet another full pass through killed deer... Especially with todays new compounds it takes alot of the thinking out of arrow and Broadhead selection. 

Kinda too bad really, that stuff can really make you appreciate archery in a new way.

Thanks,

Brian


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