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So I actually stumbled across that page on Cinnabar Bow myself, and found the numbers...... surprising lets say. So I actually contacted Bamboo Archery Malaysia to ask for more information. What they provided me allowed me to create force draw curves and a more complete picture of the bow's performance. Long story short, the numbers on Cinnabar Bow don't reflect the bow's actual performance data as supplied by Ronald Chong. What you see on that website is probably just an error.

This is what I produced with the data supplied:

https://www.facebook.com/CustomThumbRin … 1280064464

Typically only the Manchu  bows can produce >100% efficiency if looking at KE output divided by #s at full draw. They accomplish this with very long draw lengths and a remarkably flat draw curve due to high early draw and the lever effect of those big siyahs late in the draw. They simply store vastly more energy, relative to their full draw poundage, than other bow types however are quite inefficient at converting it to arrow energy. Hence their high GPP. Any other bow you see reporting numbers near 100% efficiency (again KE output/poundage at full draw) be VERY suspicious. This is particularly true of Turkish bows with their short draw lengths and high brace heights; they're comparatively efficient relative to other bow styles with very light arrows, but store a lot less energy than other bow types.

Data for one of Peter Dekker's Manchu bows:
https://www.facebook.com/CustomThumbRin … mp;theater

So I'm using that analysis on geoarcher's data because that is all the data I have. That said, the analysis is still actually perfectly valid. Let me explain why.

Adam Karpowicz actually has his own analogous metric to this one. While we divide kinetic energy output by poundage at full draw, he divides kinetic energy stored by poundage at full draw. While slightly different, really, they're trying to look at similar things. Dividing energy stored by poundage at full draw tells you how efficient the bow is at storing energy with a ratio that allows fair comparison across a wide range of different poundage/power level bows. This was probably chosen by him because, as a bowyer, he was more interested in comparing how efficiently his bows generate stored energy. Now contrast this to "my" metric, energy output over poundage at full draw. (I should note I was unaware of Adam's metric at the time I came up with mine) Less interested in energy storage efficiency, I was more interested in practical bow efficiency.

So lets take a quick example here. You're looking to shoot some particular arrow with a certain power. If you were infinitely strong, it wouldn't matter, as you could simply buy ever more powerful bows until you achieved that terminal energy. Being a human of finite strength though (I assume) you can't achieve that, so you look for a bow that, relative to the maximum draw weight you can hold, produces the highest kinetic energy output. So this is the best metric for you, and it allows level comparisons of bows of vastly different draw weight.

But wait, there is more. So if you integrate a force draw curve and divide the energy output by the energy stored, you do get the bow's actual efficiency. (more or less, you're excluding various sources of loss that aren't the bow's fault) But then what? This has limitations though, because in some respects it is the special olympics of comparisons as it allows everyone to compete on their own level. That means bows inefficient at storing energy get to be compared to bows efficient at storing energy on level footing, as they only are asked to ever spit out as much energy as they stored in the first place. While all the bows I tested in my analyses and most of the bows seen here are highly reflexed so store a comparatively large amount of energy, this is not universally true. Take an English longbow which, when unbraced, is only roughly straight. Or take wood selfbows from a variety of arid climates, like Nubia/Egypt, which are highly deflexed and hold little or no string tension at brace height. (someone correct me, last I looked, years ago, it was still a debate whether they were braced under tension at all) These bows would store comparatively little energy as early draw weight is very low. So say they were, hypothetically, capable of 75% efficiency. (I genuinely have no idea how efficient they are) Would it be fair to compare one to a composite bow which also is capable of 75% efficiency? What if the ratio of stored energy to poundage at full draw of the composite bow was 1.05 whereas the arid climate selfbow was a mere 0.68? (again, just a shot in the dark) Probably not. And then you look at the outer limb mass of these selfbows next to a short slick efficient composite. Is stored energy over poundage really fair? Unless you plan to shoot extremely heavy arrows with both, again probably not. So now we compare energy output over poundage at full draw. And that is it, that is where the rubber meets the road: how much energy can this bow spit out for an archer of a given strength.

I hope that all made sense.

*edit*

I stumbled on something and didn't want to double post:
http://www.cinnabarbow.org/marinerbows/scorpius.html

So I like short, fast, and efficient bows. (obviously) This jumped out at me though, 210fps with a 416 grain arrow on a 30" draw 40#s.

So the most efficient bow in Adam Karpowicz's set of inhumanly efficient Turkish bows managed 94% efficiency shooting a 23GPP arrow. If you divide energy output over poundage at maximum draw for that particular setup, you get .932.

A 416 grain arrow traveling at 210fps is 40.75 foot pounds..... from a 40# bow drawn 30". That gives you an efficiency ratio of 1.02. Turkish style bows, what with their higher brace heights (which this has) and shorter draws (which this also has) are disadvantaged in this metric, as they store less energy. My Spitfire, which is quite efficient at storing energy with its strong reflex, low brace height, and long draw, pulls 43#s at 31" and has stored 46 foot pounds of energy. So lets give this bow the benefit of the doubt, and say that it is storing as much energy as a lower brace height longer draw bow. So shooting a 10.4GPP arrow that'd be 88.6% efficient.

All of these numbers strike me as a little difficult to swallow, particularly for a glass bows since, these days, the most efficient bows use carbon and for good reason. I don't suppose anyone has gotten their hands one one of these bows and can provide some data?

*edit2*
Just found on their facebook page:
"50# @ 28" = 57" @ 30"" (ref. https://www.facebook.com/bambooarchery/ … 496827919)

While not totally dramatic stacking, it hardly is indicative of an unimaginably fat force-draw curve that'd store unusual amounts of energy. Amusingly, it also seems to match the Grozer almost perfectly.

I would love to test my my hypotheses on these bows, but given their expense and my general disinclination to shoot very heavy arrows, I see them as too much of a novelty to invest the money necessary for a reproduction or even a Mariner.

That takes nothing away from anyone else who enjoys them though. If our goal were simply efficiency at all costs, wheelie bows typically offer vastly superior performance as well as having a high tolerance for low mass projectiles. But then why not move to a crossbow? And from there, why not a firearm? So I enjoy these bows as a protest against some level of technology, if that makes sense. I suspect similar reasoning applies for most people.

Finally posted chrono data. Unsurprisingly, the Korean bows are significantly more efficient, both per pound and relative to their total stored energy, than the Grozer. I strongly suspect that, either the Grozer bows used in these competitions are special/modified, or technique plays a larger factor in range than bow performance, because I find it highly implausible that the Grozer would become more efficient with lighter arrows or that with its significant performance disadvantage it could outshoot one of these carbon Korean bows.

https://www.facebook.com/permalink.php? … ry_index=0

That is an immense amount of data right there. I'm struggling to get my mouth around it though, so to speak. The scatter is huge. And what does that even mean? Variability in methodology, different bows with vastly different performance? I haven't the foggiest.

I do have a couple questions though:

For the compounds, I presume poundage is the bow's nominal poundage, meaning hypothetically peak poundage?

As for the rest, is poundage at 28", or full draw, or something else?

I have always wondered about the numbers generated by Adam Karpowicz. Really, they seem staggeringly, almost implausibly, good. Just so we're all looking at the same stuff:

http://www.atarn.org/islamic/Performanc … h_bows.htm
http://www.atarn.org/islamic/Performanc … _table.htm
http://www.atarn.org/islamic/akarpowicz … _tests.htm

Just to pull out a specific example, he claims to have shot a 203 grain arrow at 357.1fps from a 125# bow drawn to 27-7/8". That is 57.495 foot pounds. And he claims that was 48% efficient. That means his bow would have to be storing less than 120 foot pounds of energy. Now in NONE of my tests did any of my bows have a ratio of less than 1 for foot pounds energy (stored)/peak draw force. If you do go into his table though and try to extrapolate/cross check his math, to be fair to him, everything does appear to be within a rounding error of correct. And sure, he'll gain some efficiency from having his bows fairly rigidly mounted, and gain some from his fast draw-shoot machine, and maybe gain some elsewhere that I'm not thinking of. The punchline though is that, his bows still seem almost inhumanly efficient. Even if you subject them to arrow energy output/poundage at max draw they seem unreasonably well off, particularly given their short draw lengths. Sure that makes them look a little more human, clearly his bows are comparatively poor at storing energy relative to their maximum draw weight, but even still..... *shrug*

I hope you don't mind, but as I'm prone to I wanted to rub a little math on your raw data to make it more digestible. Thankfully, you provided the information necessary for one of my simplest and also favorite analyses: poundage held efficiency, which is the kinetic energy of the arrow divided by the poundage of the bow at full draw. It is important to note that this ONLY works to compare bows shot with identical draw lengths. Draw a bow further or shorter and this falls apart, as it generally benefits long draws and penalizes short ones, but also can throw a real curve ball if a bow stacks badly for example.

You noted in your discussion, for example, that you intended to work on your Saluki Damascus. Surprised then you'd be that, based on this analysis, it was the second most efficient bow you tested.

I do want to be clear though that this measure of efficiency also has limits, so people should be careful not to too broadly apply it especially when it comes to potentially condemning various manufacturers for what some may perceive as a performance deficit.

I see I've come across a member of Chris' fan club......

I think this is where I should step aside. No ill feelings toward anyone.

I would say it looks different from the bow you pictured in a number of respects. Most pertinent in this case is that, at least to my eyes, the deflex appears different.

Easiest solution is just to put all the bows on my bow rack and take a side-on picture so you can compare all the profiles simultaneously. Note how perfectly the profile of the spitfire matches that of the Kaya. I'd also like to point out that, in terms of looking like an actual horn bow, the Hwarang is the only one that is even close. Far from regretting buying it, it is one of my favorite bows. I wouldn't discourage anyone from buying one. It really is a different animal from the ~200$ Korean carbon wunderbows.