Heavy vs. light.......oh boy...........

[HumbleHunter]

Howdy guys!
I haven't been online much cause of poor internet connection. However, I have a question for you guys that know more then I.

Heavy Vs. Light for penetration......oh boy

Test that I did:
50lb Recurve,
405 Grain Arrow,
530 Grain Arrow,
Same arrow Dia.
Same tip Dia.
Same distance from target.

Target being 1/2" ply board stood up on fence.

The 405 Grn. arrow way way way OUT penetrated the heavier 530 Grn. arrow.

The 405 had around 24" of penetration through the board!
While the heavier 530 grn. arrow only had around 12"  of penetration.

I have read Dr. Ashby's articles and believe what he writes. I just can't figure out why the lighter won. I shot at least 5 shots with both weights and the lighter won every time. Once it even went through the ply wood 15" then 1/2" into a 2x4.......I am baffled guys, Can someone explain this???!!!!

[woodslinger]

My guess is one arrow is tuned for the bow and one isn't.

[HumbleHunter]

howdy woodslinger!!!
Yes actually the 530 grn. is tuned (bare shafting) while the 405 grn. is alittle bit stiff.

[robtattoo]

Waaaaaay too many variables when shooting into wood.

In no particular order, you've got; different densities, grain orientation, broadhead rotation in relation to the grain, moisture difference, broadhead sharpness, bevel pitch on the broadheads, broadhead tip shape + probably a ton of stuff I can't think of!

If you want to test penetration comparisons, do it on meat. That's what you're shooting at & that's what broadheads are designed to hit.

[sloaf]

The reason heavier arrows penetrate better in general is the the transfer of energy is more efficient into the heavier object.  Example at 500 grains your getting back 80% of the energy you put into the bow and at 400 grains your only getting 75%.  The lighter arrow may be flying like a bat out of hell but the heavier arrow is carring more energy.  There can be exceptions to this though depending on bow design and how far in extreme you go.  At some point a heavier arrow won't gain you any more efficiency and you'll lose energy.  KE is a decent representation of penetrating ability but momentum is probably a better way to measure penetrating setup.  This can be a difficult topic for anyone without some physics background.  Dr Ashby's study is a great resource and very sound science from what I've read.    Clear as mud for most folks.

[HumbleHunter]

Thank you guys for yall's posts.

Sloaf, I also agree momentum is the better way to measure penetration. I've done the math with both momentum and KE and it proves the heavier arrow should be better. However, I can't wrap my mind around why the lighter arrow did better on the board. How could one know when too much is too much on weight?

Robtattoo, Yes Sir, I understand that the board isn't "consistent" enough for a scientific study and that meat would be way better. If I can get a chance I will test that as well. However, I do not see that the board's variables would create such a consistent outcome. Not one set did the heavier arrow win. I am using field points by the way not broad heads sorry, I forgot to mention that.


Keep um coming fellows!!!! Thanks, HH

[mcgroundstalker]

Don't want to take the wind from your sails but I don't think a sheet of 1/2" plywood speaks for penetration. The faster/lighter arrow, as it breaks through the plywood, has less time for the vibration of the sheet to stop your shaft. The heaver/slower one has more time to do the same thing. That's That! IMO

... mike ...

[HumbleHunter]

huh....that's interesting.
Well, lets look at this. What if I shoot at game (hogs, dogs, and deer) and place a not so perfect shot and hit bone......maybe rib or one of the shoulder bones. Wouldn't that be alittle closer like 1/2" plywood vs. meat? IF that's the case, and wood is closer to bone then meat is.......even if it is a "timing" issue........I'd like to know.

[The Vanilla Gorilla]

Maybe if you tried single beveled fieldpoints you'd get better penetration!    

I kinda agree with Robtattoo. Density of plywood can change in fractions of an inch. You probably need to be shooting into something that has more of a uniform density...Like the tailgate of your brothers truck.  Doh!

See ya in 3 weeks!

[mcgroundstalker]

Shoulder bones will stop an arrow quick. That's why "timing the shot" is a big issue. Arrows are not bullets. Shot placement is key. Relaxed, feeding game will let a well placed arrow pass thru them. From a quiet bow mind you. Where a deer looking at you will move like lightning as you loose an arrow. THIS may become a poor hit with little penetration whatever the arrow weight.

... mike ...

[HumbleHunter]

Hey, Camo! What's up bud?
Yeah, tail-gate not a good idea, everyday all day. lol

And I agree too about plywood not being consistent. BUT.....wouldn't the lighter arrows have to hit the same variables as the heavier arrows? AND......if that's the case how could the lighter arrows not ONCE hit a variable in the plywood that would cause it to LOSE to the heavier???? Huh??? uh??? HUH????? lol You're dad fixed up now with this GT's?

[Deff]

I had a simular expierience as HH. My son and I shoot identical bows with the same carbon shafts.  Mine have weight tubes glued in the front half, brass adapters and are shot full length. Weight 740 grains.  Son's are shortened for tuning and he uses aluminum inserts. Weight 550 grains.
When shooting together into a foam block target, my arrows would make a loud thump and rock the target, his would just zip into it, but when we went to pull our arrows they would be stuck in the foam just about the same. Both of us had our arrows flying well.
I had been trying to convert Son to the Dr. Ashby inspired way of doing things but have been unable to prove that the practical difference amounts to much.
I know that I tend to shoot the heavier arrows more consistantly but Son usually outshoots me so the debate goes on.

[bm22]

if you shot both arrows into a 1 in. plate steel and the both bounce off does that mean they would penetrate the same on an animal ? If you shoot two arrows into a block target and 1 out penetrates the other by 1 in. does that mean it will penetrate the same on an animal?  no i don't thinks so.

experiments like this are fun to do but aren't very practical in compared to what happens on meat and bone.

just curious what kind of arrows are you shooting and diameter of the arrows, diameter of the field points

[sloaf]

HH the only way to know how you can maximize your efficiency is to add arrow weight in increments and graph your KE with each one. You'll see it peak and then drop off at a certain point.  I haven't done this personally because I don't want the slower arrow speed and haven't had any penetration problems with whitetails.  I've been shooting 500 grains with a 53# recurve.  As for your test results I think you need a ballistic gel to reproduce tissue penetration.

[SteveB]

Plywood is probably more consistant then a animal carcass - or even a live animal.

Until someone can come up a consistant test medium replicating the various tissues found in an animal, all tests can show are what happened with that individual that day.

Ballistic gel is not the answer either, because it enters drag into the equation nothing close to what living tissue does.

Steve

[Deff]

Just a thought --- Is it possible that the greater speed of the lighter arrows caused a bit of a "blow out" of the plywood on impact thus reducing the drag on the shaft (similar to the effect of a single bevel broadhead splitting a bone)?

[HumbleHunter]

WOW, got some attention now... Keep um coming guys, I greatly enjoy getting different opinions and experiences other then mine!!! Keep it up fellows!

Thanks to all who replyed!!!!! HH

[TNstickn]

The heavy arrow is hitting the plywood and the front is slowing down at such a fast rate that the back is oscillating to shed energy faster. The heavier arrow has more retained energy to shed. Once you get to 8-10 grains per pound I think heavier leads to poor energy transfer without stiffness to help keep your arrow straight upon impact.

Foam,layered and 3-d targets are all being designed to stop very fast, small diameter arrows by the use of excessive friction.

I shoot in an open 3-d club and all the wheelie guys get deeper penetration in the targets than I do shooting 9-11 grains per pound. Speed kills with a decent weight to it. The key is not being to lite to make penetration suffer. Less vibration/oscillation directly impacts penetration. If you could watch your test on high speed video I think you will see how much this plays into the results

[jimmerc]

i have for 35 years been doing these kinda experiments at first when i was a wheel bow shooter i wanted to prove the liter arrows would out penitrate  heavier arrows, and i shot and destroyed more arrows than i could count! found that at close range( out to 20 yards) the liter arrows did drive deeper but not much, but as the distance increases the heavier arrows took the lead every time!  now that i'm trad the same tests applied, the heavier arrows take home the meat every time~!  i shot at every thing for these tests, plywood, 1/8" alum sheets, steel drums,concreat blocks, but the best tests were hunting for 35 years and keeping logs of of every hunt,every little detail!i know there are way to many variables to all these tests, so from hunting experience i will choose heavy over lite for way to many reasons to list!! just my own opinion!

[Daddy Bear]

If maximizing penetration is a major goal for the game you seek, I look at it like this:

If you want to test maximum penetration for a water buffalo, you should probably test on a water buffalo with your hunting head and not on plywood with a field point.

If you want to test maximum penetration for an elk, you should probably test on an elk with your hunting head and not on plywood with a field point.

If you want to test maximum penetration for a deer, you should probably test on a deer with your hunting head and not on plywood with a field point.

But, if you wanted to see how far your field pointed arrow would penetrate through plywood, you probably should test on the plywood and not on a water buffalo:)

If it makes you feel better, way back in the '40s Fred Bear built a frame filled with calf's liver and using a shooting machine tested various combinations of draw and arrow weights both light and heavy for maximum penetration. These tests convinced him of his theory that 60pounds draw with an arrow of 600grains(10gpp) was near ideal for maximum penetration. The minimum arrow weight for this tested best penetration was to be no lighter than 10% less than the ideal 10gpp weight, which would be 540grains(9gpp).

later,
Daddy Bear