WHY are short bows slower?

[nclonghunter]

Just reading some this makes me wonder if the right question was asked. My understanding has to do with mass of bow and compression and tension woods. A long bow has narrow limbs and thinner vs. a shorter bow with wider limbs. I believe in The Bowyers Bible they actually weigh the bows to find the correct mass. Point is a short bow will shoot the same as a long bow if mass and design are correct.  I would say some short bows shoot faster than long ones if design is better and vice verse. If you have a bow that is slow then look at the design of it, that's where the difference is. I will say after you get to a certain length or shortness, you will be getting lower or greater than the "perfect mass" and design for a bow. If you can get a Bowyers Bible it will explain it far better than I can.
 

[Marc St Louis]

Trying to sort this out while my short irons are still in the fire:

Say there are two well designed bows, one 66" the other 56". The 66" is straight and the 56" is reflexed enough to have a similiar F-D curve. However, it seems that even with less mass and no stack the short bows don't shoot faster. I can only guess that their less mass is cancelled out by the less leverage, correct? Is that the trade off or am I missing something else?

Thanks in advance, hopefully the next set of sticks I finish will be able to shed some light as well

Is this an assumption or empirical data?

[George Tsoukalas]

I take that back. The bow I described will most likely break or be under drawn for its sort life. I do not like short bows. Can you tell? Jawge

[gmc]

Can you post a picture of the unbraced profile and tiller of this slow "shorter" bow? Just curious, apart from giving up a little accuracy, the speed in comparison is too close to argue with.

[Jesse]

I gotta say horse bows can hold their own in the speed department. As far as accuracy I prefer a longer bow. Besides extreme designs though I would say that @ a 28" draw the longer bows outperform noticeably for me. ------------ Not empirical data  

[Ryano]

Short relative to what?  For a given draw length, there is an optimum bow length (or range of lengths) for maximizing the speed of the arrow.

I agree 100%

[Kegan]

Whoops, guess I was too vague !

I don't have any bows to compare personally. But, looking at the numbers of well made bows out there and comparing the speed, they're all shooting more or less the same. My question is:

If a short bow has the same FD curve as a longer bow, but less mass, why is it NOT faster? Many of the well made bows all shoot around the same regardless of length. So if the short bow has less mass, it must be giving something else up and that is why they all shoot the same if well made.

The Mass principal helps show that all bow designs if well executed can shoot the same. I want to know why a bow with less mass is not faster than one with more mass. The more massive bow being longer, he only thing I see different- and this also form TBB vol. 4- being the longer, more massive bow has leverage to compensate for its mass. I wanted to know if there are things I'm missing or not aware of as well?

I guess "WHY aren't short bows faster?" would have been a better title. I'm trying to understand some of the physics behind all these awesome bows for reference. Just wnat to know how they 'tick'

[bow-toxo]

Trying to sort this out while my short irons are still in the fire:

Say there are two well designed bows, one 66" the other 56". The 66" is straight and the 56" is reflexed enough to have a similiar F-D curve. However, it seems that even with less mass and no stack the short bows don't shoot faster. I can only guess that their less mass is cancelled out by the less leverage, correct? Is that the trade off or am I missing something else?

Thanks in advance, hopefully the next set of sticks I finish will be able to shed some light as well

Howard Hill said ”The more a bow limb is bent, the faster it returns”. No one has mentioned the arrows. They have to be shorter for a short bow, and of course thinner for the sams draw weight as a longbow. They don’t have the mass to shoot a heavy arrow, therefore less penetration, but should shoot faster if the arrow length is proportional to the bow length.

[Traxx]

No one has mentioned the arrows. They have to be shorter for a short bow, and of course thinner for the sams draw weight as a longbow.

I assume then,that you are not familiar with the Archery,of the West coast Native people and how they applied it to their shooting.

[RyanY]

Kegan, I think your assumption that a short bow with the same FD curve shooting slower is wrong. The reason short bows don't shoot as fast as long bows is because they don't store energy as well so they have Different FD curves. If you have a short and long bow, same general design, pulling the same draw weight at the same draw length, the shorter bow will store less energy. If you could make a short bow store as much energy as a longbow, I imagine it Would shoot faster because of lower mass, if designed well enough to do so.

[Kegan]

Kegan, I think your assumption that a short bow with the same FD curve shooting slower is wrong. The reason short bows don't shoot as fast as long bows is because they don't store energy as well so they have Different FD curves. If you have a short and long bow, same general design, pulling the same draw weight at the same draw length, the shorter bow will store less energy. If you could make a short bow store as much energy as a longbow, I imagine it Would shoot faster because of lower mass, if designed well enough to do so.

That's exactly what I thought, but so far I've yet to see one that does shoot faster. Most of the examples of well made short bows (60" or less) all seem to shoot as fast as a longer bow. Even with FG, the short bows are not shooting the pants off their longer- and heavier- couonterparts. Even Asiatic recurve replicas, shooting same GPP and draw length, don't put some well designed longbows to shame.

It seems that if you have a bow that will survive with less mass and store more energy, it will be faster. Given the same length between two bows that seems very true, but when you reduce mass by shortenning the whold design the resulting short bow now seems to shoot about the same. Why is that? Why is it not faster?

[gmc]

I don't think you can compare the FD curve in your example as being the same as they will store energy differently. If we are talking about working vs. nonworking handles, the nonworking porition removed to achieve the shorter length, lower overall mass (which I think we are) then it will still take the same amount of working mass on both designs to deliver. The FD curve of the shorter bow will show a lower "early" draw weight but the longer power stroke of the shorter bow will make up a lot of ground in the end. It has been my my experience that the end result in speed is marginal in comparison between the two.

Designing for a slight bend in the handle section, holding the inner 3rd a little more rigid on the shorter bow, has delivered a faster result for me. I can use the best of both worlds, utilizing more working wood within a shorter length. The tiller is somewhere between circular and elliptical, and I find these bows are shorter and faster within the realm of what I build.

As you can tell, I do have a bias towards shorter bows and this is just my opinion based on what I've experimented with as shorter, faster bows, I do find intriguing.

[bucksbuoy]

In theory shorter limbs should be faster. Longer limbs have more cast, better penetration, and longer range. I just think there are so many factors and variables that you cant change one without affecting another. Another thing Ive noticed is that most woods have a general window of speed and tend to shoot that speed no matter how the bow is built, to a degree, as long as it is built reasonably well. Hickory, osage, yew maybe around 150 fps? Maple, elm, other less dense woods around 190?

[NTD]

Another thing Ive noticed is that most woods have a general window of speed and tend to shoot that speed no matter how the bow is built, to a degree, as long as it is built reasonably well. Hickory, osage, yew maybe around 150 fps? Maple, elm, other less dense woods around 190?

WHAT???

[Traxx]

Ill second that,WHAT???