"Slow" Bows with Heavy Arrows

[PistolPete]

Hi all,

I'm looking for some technical information here. I've heard some theories that certain types of bows, like a Hill-style, can shoot heavy arrows as well as bows that are much faster with light arrows. For example, let's say we have bow A and bow B, which pull the same weight; is it actually possible that with say 8 GPP bow A is 20 fps faster, but with 14 GPP they shoot the same speed?

I've heard lots of stories of this type of "catch-up" effect, but has anyone actually documented it?

Pete

[SL]

I believe the faster bow will alway be faster. If its more efficient with a light arrow it will be more efficient with a heavy arrow as well.

[Orion]

I Agree with SL. The faster bow will always be faster as the arrow leaves the bow.  However, a light arrow will slow down quicker than a heavier arrow so there may come a point/distance where the heavier arrow overtakes the lighter arrow.

[Jim Wright]

I have shot Dan Toelke "Super Ds" for a good while now. I have noticed that through a chronograph with 8 or 9 to 1  arrows they were 7-10 f.p.s. slower than some friend's recurves but with 12 to 1 arrows shot very close to and in some instances faster.

[McDave]

I tend to agree with Jim.  I believe different bow design features will favor light or heavy weight arrows.  In some cases, it might be possible that bow A, that shoots a light weight arrow faster than bow B, might shoot a heavy weight arrow slower than bow B.  This would have to be determined by testing.  I think this would be more likely to happen if the speeds between the two bows were close to begin with.  For example, if bow A shot a 350 grain arrow 180 fps and bow B shot the same arrow at 175 fps, it might be more likely that bow B would shoot a 500 grain arrow faster than bow A than it would be if the initial difference were 10 fps.

[A Lex]

I hope I can answer this the way I see it, not quite sure how to actually word it, but I'll have a crack.

As I understand it, a very light arrow does not "absorb" as much energy from the bow as a heavier arrow will. It may not be as an efficient combination as the same bow with a heavier arrow. However, there will be an optimum point for every bow and arrow weight combination.

It may be splitting hairs, but as long as the bow the arrow is launched from is well designed, well made, has good string, and the shooter has a good consistant release and good form etc etc, in theory a heavier arrow (to a point) makes the bow more efficient. This generally means a slight increase in arrow speed.

I think McDave has answered it well, and as he also said, "this would have to be determined by testing".

Good question though.

Enjoy being outside.....

Best
Lex

[PistolPete]

All interesting theories - and this might be a good question for Toelke, since he makes both types of bows.

Jim, that is the kind of testing and data I was curious about, and that is the effect I was asking about. Thank you. Now I am even more curious.

[Jim Wright]

Dan would certainly be a good source of information on the subject. To your comment about a bow being well designed , well made and having a good string, Dan's bows shine there. I am a shameless fan but all the Toelke models go through a very extended and precise r&d period before they are ever produced and I have owned quite a number of them. In addition to being superbly crafted from beautiful woods, every one of them had another quality that I believe is a major reason his bows have been received so well by so many and that is that they are efficient. And that is why they do not jolt your hand upon release and they are so ridiculously quiet, the stored energy in the drawn bow is channeled into the released arrow. 

[Orion]

John Havard, who used to co-own A&H archery and is now working with Dryad, has done a lot of testing along these lines.  It was he I was paraphrasing when I offered that a bow that shoots a light arrow fast will also shoot a heavier arrow fast(er) relative to another bow. Stated another way, if it's faster than another bow when shooting the same lighter arrow, it will also be faster than that bow when shooting the same heavier arrow.

For example, as noted, a longbow might extract more energy out of a heavier arrow, but it will not become a speed demon when shooting a light arrow.  Likewise, a recurve that shoots a light arrow fast isn't necessarily going to propel a heavier arrow with as much velocity, but likely still faster than a longbow of the same weight. 

Regardless, I agree with McDave.  There are lots of myths in archery.  Would like to see someone do some more testing on this one.

[mahantango]

Physics is physics.

[Stumpkiller]

Physics is physics.

There you have it.

Shoot the heaviest draw you can shoot accurately with an arrow heavy enough to poke out the backside of a deer and let the rest of the world go by.

[kat]

Physics is physics.

There you have it.

Shoot the heaviest draw you can shoot accurately with an arrow heavy enough to poke out the backside of a deer and let the rest of the world go by.

X2

[PistolPete]

Physics is physics.

There you have it.

Shoot the heaviest draw you can shoot accurately with an arrow heavy enough to poke out the backside of a deer and let the rest of the world go by.

X2

Great advice. Not helpful here in the least. Good luck this year.

[the rifleman]

Very easy test for those that dont have a chronograph.  Just shoot a heavy arrow (12+gpp) and a lighter arrow (9-10gpp) and see which has the farther point on distance.  I too am a huge fan of Toelke bows---they are all I shoot.  Out of my 40# PIKA, as well as other bows Ive shot I have noticed that an arrow in excess of 12gpp drops like the proverbial rock after 20 yards---much more exaggerated after 25 yards.  If the heavier arrow slowed less at a certain distance i.e. retained more speed then why on earth would it fall off quicker?!

I believe adding weight beyond about 10gpp gets to be a diminishing returns proposition.  As with most things in life moderation is key and I have found that keeping within 9-10gpp gives me the best performance.  A friend once put it well---whats easier to throw a whiffle ball, a baseball, or a bowling ball?  Too much of a good thing (weight) is just that.

For those that gap shoot, spend time charting your gaps at different ranges from 10 yards back to 40 and you will notice that the arc is not even and the drop very much exaggerated closer with the heavy arrow.

[KeganM]

Performance comes from stored energy and efficiency. How much power is there versus how much the bow can put into the arrow. Heavier arrows will improve the efficiency of any bow, from selfbows to compounds (although how much can vary a lot). Stored energy is usually a function of the design and how the stick bends.

If bow A has very low stored energy but excellent efficiency (string follow bow with super-light carbon limbs, perhaps?) then it could easily be "matched" by bow B (with a lot of stored energy but low efficiency) as the GPP increases and potentially surpassed as it "runs out of steam". Likewise, if bow B is a heavy-limbed bow with lots of power it would be a nightmare to shoot with anything under 14 gpp as that thing would kick like a mule.

This sort of comparison isn't really common though as most bows that are efficient usually also have decent (or at least not subpar) stored energy, which is sort of what you'd need for the performances to eventually match. Normally, it's easy to add a little more stored energy to the efficient design and, presto, an overall better shooting bow. As Mahantango said, physics is physics.

[PistolPete]

Interesting comments, thanks. Of note is that I'm not asking if velocity ever increases as arrow weight - obviously that isn't realistic. I'm just interested in whether certain bows (straight limb) efficiency increases MORE as arrow weight increases as compared to other designs (aggressive R/D). All just for curiosity's sake.

[Ari_Bonn]

in my testing the fast bow will always be faster.    the hill style bow  will have a tighter variance over light vs heavy arrow    but the fast bow will still be faster.

[Jim Wright]

Ari, I'm not quite sure what you mean by "the fast bow". I will say again that through a chronograph my toelke Super D shot 12 to 1 arrows slightly faster than a friend's recurve with the same 12 to 1 arrows. His recurve shot 9 to 1 arrows 6-7 f.p.s. faster than my super D did.

[Ari_Bonn]

Ari, I'm not quite sure what you mean by "the fast bow". I will say again that through a chronograph my toelke Super D shot 12 to 1 arrows slightly faster than a friend's recurve with the same 12 to 1 arrows. His recurve shot 9 to 1 arrows 6-7 f.p.s. faster than my super D did.

i should have been more specific.  I wasn't really referring to recurves when i said that. Some recurves are extremely  bad when shooting a heavy arrow like "hoyts" but for the most part it still applies to them ( also shot some recurves that are slower than a straight limb).   I was reffering more to   r/d(modern trapazoid not a mild hill style r/d) vs straight limb. 

take like a light arrow i dunno say  8gpp assuming bow bows are the same weight/ length/ string type/ same shooter.   Obviously the r/d will be faster.    crank  up  to  10 and  12 gpp   the r/d will still be faster although  it will have lost more fps  than the straight limb.  the straight limb is slower overall but  more fps consistent over a large weight range of arrows(the  range is tighter).  14-16gpp  things are really starting to slow down the r/d is still faster but numbers of both bows are starting to get close.  Eventually once you get a heavy enough arrow maybe past 20 gpp   the numbers will start to overlap and the straight limb will actually be faster than the r/d  but at this point  you have such an abysmally heavy and slow arrow  its just not reasonable.   might even be sacrificing energy at that point.           

[KeganM]

A "slow" bow will only exceed a "fast" bow with a super heavy arrow if it possesses more stored energy. While some may, there are many straight limbed bows that don't (the long length gives them the smoothness and not all of them are that long). Stack points are a good indication of stored energy (or lack thereof in this case.)

As for whether some designs increase efficiency more rapidly than others with heavier arrows, that would be a 'yes'. Low-efficiency designs will benefit immensely from heavy arrows unlike more efficient designs, which wouldn't need a certain arrow weight to achieve the same efficiency. So a D/R might be performing at 60% with 8 gpp and then 75% efficiency at 14 gpp. Conversely, a straight limb bow may only be performing at 45% efficiency with 8 gpp but will move up to 70% with 14 gpp. That's a much larger change. As was mentioned, this is the reason you'll see a straight-limbed bow shoot a tighter overall fps spread across different arrow weights leaving the adage to be "they like heavy arrows best" since the speed is about the same but the noise and shock will abate significantly.

Bow design is fun stuff!