Bow Testing 2023 / 2025

[simk]

I sometimes bring my shooting machine to the bow fair in Eigeltingen and request all bowmakers to bring their fastest bows. Rules are: 40# bow +/- a few #. I then measure exact drawweight and pick the arrow that brings the bow closest to 8gpp. Then shoot it on the machine. The results were published in the German "Traditionell Bogenschiessen" Mag.

In 2023 we wanted to test just "longbows" according to IFAA which also includes D/R profiles as long as they fully stretch out at brace. The "winning" bows were a classic 66" Longbow made from yew, maple and bamboo and a D/R glassbow which both measured same speeds. Wooden bows are brown, glassbows blue.

[simk]

In 2025 we dropped the restriction on "longbows" and allowed any bow. We had a compound bow (dark blue), recurves, longbows and asiatic bows made from glass (light blue), some of the most sophisticated carbon-superrecurves (grey) - beneath selfbows (light brown), wood composites (medium brown) and horn-sinew wood composites (dark brown). The weather was very hot and humid which certainly affected the performance of the horn-sinew composites. I never build my bows for max speed or flight - I do sell my bows and not want them to come back to me. Durability and successful target-shooting are the main goals. With 3d bows I'm looking for a little more speed than 20y target shooting. Hunting bows must be short and tough in the first place.
 

[Tuomo]

Great tests, and very good wooden bows! Hopefully you will continue these in the future.

Testing different bows at the same time and with the same setup is the best and really the only way to get accurate speed measurements, because only then are the results truly comparable.

Were the wooden bows new or used?

[willie]

The "winning" bows were a classic 66" Longbow made from yew, maple and bamboo and a D/R glassbow which both measured same speeds.

nice test and study. can you comment on the side profiles of the top 10% of wood bows?

previous research has led me to believe that a deflexed recurve of moderate proportions.   (plus and minus 30mm or so) should be up there and hold their own against more radical bent wood designs.

[simk]

Yes Tuomo, do only trust your own numbers  Maybe there will be another test in 2027. Next year I will have the visitors build a bow with me at the fair.
The fast bloodwood bow was pretty new. I dont even have a pic - passed it to the new owner right after the testing. The Yew/maple/bamboo was maybe shot 200 arrows. The fast yew selfbow was the same as in 2023....because I was interested in how much it lost.... a loss of 1fps is pretty good...the bow was regularly shot in these 2 years.
Willie: The laminated boloodwood semi-recurve had a similar profile like pics 1 & 2 - just less deflex aka set  and was 64.5" ntn - the one on the pic is even shorter and the osage took clear set - nevermind, this is a fine bow to shoot.
The laminated yew maple bamboo was a classic asl longbow, 66"
The yew selfbow was from a natural deflex stave, somewhat 66" - its my personal selfbow
The  next was a osage recurve this year, classic recurve, pretty pronounced and steep hooks, not mine, no pic.
Hickory backed bows always perform poor. Its a massive difference to the same bow backed with boo.   
cheers

[simk]

found pics from the bloodwood build on the phone - that was probably from the start of the tillering process - the limbs pull straight later at fd.

[willie]

Willie: The laminated boloodwood semi-recurve had a similar profile like pics 1 & 2 - just less deflex

The laminated yew maple bamboo was a classic asl longbow, 66"

so not much deflex needed to place high on the list?   
Was there any deflex out of the handle with the clasic ASL?

[simk]

wiellie: I glue these up with no deflex but i think they are on the edge. a lot of strain on the inners. but beautyful shooters. They are very light in mass, 400-450gramms. narrow like 34mm. but it only works with the very best material - and bloodwood is pretty stubborn at taking set. then rather chrysals away spontaneously. as you see the osage took plenty set. it probably shows what would have been be the best amount of deflex for the glueup. you can put more and more reflex into a wooden bow but they always settle in to where they want - at least with me. I would suggest glueing in a little deflex. Probably should make one new slightly deflexed caul for me as well. A little deflex out of the grip is always a + I'd say. It also allows you to make the bow a little shorter  than straight bow. The asl is straight out of the grip. maybe the tapered powerlam makes it looks a little deflex. 

[Tuomo]

Hickory backed bows always perform poor. Its a massive difference to the same bow backed with boo.   

Very interesting find! Why is that? Why would a hickory back be a poor choice? Does it take tension set (assuming that’s even possible)?

[willie]

Hickory backed bows always perform poor. Its a massive difference to the same bow backed with boo.   

Very interesting find! Why is that? Why would a hickory back be a poor choice? Does it take tension set (assuming that’s even possible)?

lots of different kinds of hickory here in the US, and densities vary widely. Lumber grading is mostly by appearance rather than structural strength. https://www.extension.purdue.edu/extmedia/FNR/FNR-285-W.pdf
A bowyer sourcing top end hickory in the states would most likely not source from the lumber retailers.

[Tuomo]

Willie – please define what you mean by “top-end hickory,” either from a bowyer’s perspective or specifically as a backing material. Quality alone is not a sufficient reason, because it does not directly affect bow speed. If a finished bow functions well and has no problems, then the wood quality is adequate.

The most important parameters are strength, elastic modulus, and density. One possible reason is that hickory, on average, has a lower elastic modulus relative to its density than bamboo. As a result, a finished bow is heavier (in physical weight) compared to a similar bamboo-backed bow.

[willie]

A bowyer could cut logs from healthy trees of the desired species ( dense and high moe) and have boards milled to spec and air dried instead of kiln dried.

No suprise that Simk finds bamboo to out perform hickory, although saying

always perform poor. Its a massive difference

makes me think there is better moe hickory to be had, or a different thicknesses to better match the very dense bellywoods. Maybe Simk can say more about what he worked with.

[simk]

Willie: I do not have a good explanlation for these findings. The only thing I could think of is that hickory maybe has more strectch than boo and thus does not "stress" the belly lamiante like bamboo does. However this idea does not fit into virtual-bow-logic as there is no stretch parameter. My "stretch" must somehow be connected to MOE and here the differences betwween boo and hickory are not so big....yes boo is a little stiffer.

Other - maybe related - question: Why do we have different stress on back and belly if we bend a piece of wood?

[Tuomo]

Willie: I do not have a good explanlation for these findings. The only thing I could think of is that hickory maybe has more strectch than boo and thus does not "stress" the belly lamiante like bamboo does. However this idea does not fit into virtual-bow-logic as there is no stretch parameter. My "stretch" must somehow be connected to MOE and here the differences betwween boo and hickory are not so big....yes boo is a little stiffer.

Other - maybe related - question: Why do we have different stress on back and belly if we bend a piece of wood?

I think the main reason is that different wood and grass species have different rheological properties, and therefore their viscoelastic behavior differs. For example, hickory is well known to perform excellently at very low humidity but is generally sluggish at high humidity. Its intrinsic properties vary with conditions (both external and internal). Additionally, viscoelastic material properties are time-dependent. A well-known example of this is that with a fast release we obtain a higher arrow speed than with a long anchor at full draw. Thus, the main reason lies in the intrinsic material properties, which we do not know well enough and which are difficult to model accurately. In practice, we must rely on measured data. For example, the measured difference between hickory and bamboo backing is both interesting and important.

The second question "Why do we have different stress on back and belly if we bend a piece of wood?". In theory, a homogeneous, symmetric bending beam should have identical absolute values of tensile and compressive stresses within the elastic range. However, in a bending bow there is also an axial force (a force in the direction of the bowstring), which affects the stress distribution by introducing additional compression force. As a result, the compressive strain is higher than the tensile strain, and this effect is also modeled in VirtualBow. In reality, there are additional material and geometrical factors that influence the stress distribution, each contributing its own effect, but which are difficult to model.