I don't see a whole lot of 68" lam bows, any reason for that?

[bornofmud]

It seems to me like the longer the bow, the more efficient it is for a given draw weight/length. Is this incorrect? I know that most of it comes down to the specific design, but it seems like laminate longbows pretty much max out at 66" and are more commonly around 60-62".  Is there a reason for this other than a shorter bow is easier to hunt with?

Also, sorry for all the threads, I have a lot of questions! And thank you everyone for the replies! Makes this a lot easier!

[BCWV]

I'm a very new builder so a more experienced fellow will be along but here's my thoughts.
 Bow length will be determined by the shooters draw length and bow design. A shooter with say, a 28" draw, could comfortably shoot a 56" hybrid longbow but the same shooter, shooting a 62" straight longbow may feel it stacking at his same 28" draw.

[LittleBen]

Draw force curve is more favorable in a longer bow, all other things equal.

So a longer bow would therefore store more energy, but longer limbs also add more mass. So it's a balance.

Furthermore, with wood bows we're limited by the material properties, and this is likely the reason for the historic use of longer bows.
If were talking glass bows, as I assume we are, the glass as a bow building material is capable of very short compact designs and allows you to get away from the much longer (typically) wood bows.

With that said, all the Hill style bows are 66 -68" usually.

It seems to me that the more radical the R/D in the bow, the shorter the are on average, for obvious reasons.

[bornofmud]

Sorry, but what are the obvious reasons for a bow being shorter with more R/D?  Are the benefits of a R/D design negated at longer bow lengths? I get balancing the force curve with the mass of the limbs to keep the fps up though, thanks for that.

And I know about stacking as well, but stacking is less of an issue on longer bows regardless of the design, all things being equal, which to me would be more of a reason for longer bows.

And yes, it makes sense that you can make shorter bows with glass because of the properties of the material, I was just wondering if there is any benefit to smaller bows other than being easier to move with while hunting.

Basically, I want to make a bow that will provide as much stability and accuracy as possible that will be used only for target shooting, and thus the length of the bow need not be limited for use while hunting.  I was planning on a 68" r/d, but I see very very few of them, and was wondering why.

[bigbob2]

All my HH style flat laid are either 66 or 68 NTN and my Deflex/reflex is 66 NTN. I don't like the finger pinch with the shorter bows nor the 'Twitchyness' that can be an inherent part of some short bows. The longer bow is far more forgiving of any form fault in the user, but as they say horses for courses, and a heck of a lot of people are very happy with their shorter bows.

[LittleBen]

I think you're onto it that the shorter bows are really just for easier hunting.
Look at the Olympic recurve bows ... They're long. If you're shooting targets then longer is good.
More R/D typically goes with shorter bows because it reduces finger pinch, and string angle and stacking.

[7 Lakes]

There's absolutely nothing wrong with a 68" R/D longbow.  They shoot great.  

I think the reason you don't see many is because many hunters no longer "hunt" they sit in trees and "wait".     If you aren't going to sit in a tree stand or hide in a little tent a 68" bow is just fine.

[dfrois]

Just to throw a few thoughts into the mix...the size vs. mass issue must be viewed considering the properties of the material and the desired draw weight. Meaning, if we only consider, for instance, fiberglass laminated, wood core limbs, we would need thicker limbs on a long bow to reach a given draw weight, but with shorter limbs, we can get that draw weigth using thinner core wood. So, the longer limbs have more mass, not only because they are longer, but because they are also thicker, for the same draw weight.

All of this only applies to the working part of the limbs. In reality, talking about takedown recurves, hunting recurves have, in general, the same limb lengths as Olympic target limbs; it is the hunting RISERS that are shorter. Target risers are tipically 23 or 25", whereas hunting risers go from 15 to 20-21". That is where most of the size difference comes. In fact, many people use target limbs (mainly ILF) on short hunting risers, 15 to 19" long, with excellent results. And even if you look at one-piece bows, of any kind, those that have a "riser", non-bending section in the middle, have that rigid section smaller (sometimes much smaller) than the typical 25" riser of a 70" target bow.

JMHO, of course...I'm sure many, more experienced members will know far more about this than I do. If I said something wrong, please, correct me, so that we can all learn.

Thanks.

DF

[LittleBen]

I'm with everyone here on this. I didn';t mean to imply theres anythign wrong with longer bows. I own several in teh 66-72" range, and certainly will be building more. In fact I just settled a plan with a buddy of mine to build a 68" r/d takedown for him, and I'll make one for myself, I'm also working on a set of R/D longbow limbs for a takedown I already have.

I say go for it, I think those 66-68" bows shoot great

[bornofmud]

Nice, thanks for the replies everyone! Would I be right then in summing it up as: As the bow length increases you lose speed due to the extra mass to reach the same draw weight of a shorter bow, but you gain stability and ease of shot.

This brings another question up for me though.  What if you were to keep the working portion of the limb the same length as say a 62" bow with an 18" riser.  Making up the difference in riser length rather than splitting it between limb and riser length. Would this allow one to reach the same weight with the same amount of mass in the limbs?  Would it still give the benefits of a less touchy shot? Or is that governed primarily by the length and mass of the limbs with the length of the riser having more to do with string angle and possibly less hand shock due to the extra mass of the riser?   Hope that made sense haha.

[bornofmud]

Also, if the mass of the limb is greater, does this also translate to more energy being transferred to the arrow?  If so, in what way does this show up in arrow flight? I'd imagine that the speed of the arrow is dependent on the speed that the limbs recoil to their braced shape, which would be slower with a more massive limb.  However, a more massive limb would have more momentum, is that momentum somehow transferred to the arrow?

Basically I'm asking if the arrow will somehow carry that extra weight of the limbs, or if it's force is purely determined by it's acceleration, as the arrow's mass does not change depending on the bow you shoot it from haha.