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The Mad Scientist
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Discussion Starter · #1 ·
There are 2 ways to make any bow faster, store more energy or deliver more of the energy you already have to the arrow with a higher efficiency. Efficiency is expressed as a percentage of the energy imparted to the arrow vs the stored energy (KE). While efficiency can be important when the ACS-RC came out I asked John Harvard about the lower than average efficiency and he said stored energy trumps efficiency. He's right of course, but by how much? Based on Blacky's tests (@ 9 gpp) the ACS longbow shoots 200 fps, and the ACS-RC shoots 198, so basically identical. While the RC stores more energy the LB is at 85.9% efficiency, the RC is 81.1%. The best I found in Blacky's tests was a Morrison longbow at 87%. This means that a sizable portion of the energy you put into the limbs is lost to vibration, limb/string oscillation, and noise (it has to go somewhere). Less wasted energy would mean a faster arrow, and perhaps a quieter bow too. But the quest for speed has been mainly through limb shape changes more than anything else leading some to question if conventional RC limbs are dead.

When I posted about lateral stability (TS) and draw weight I was looking to see if this affected efficiency. Turns out it does as adding TS adds weight and possibly width, which reduces efficiency. Then I noticed my EBF limbs shot the same speed as my fiberglass Palmer in Blacky's test, and my Palmer was actually more efficient (82.5% vs 84.5%). This has to be the limb design as fiberglass weighs more than carbon fiber (CF). I wondered how fast my Palmer could it be if it was made out of modern materials, keeping everything else the same (very little torsional stability as is the case with all glass bows). It would be faster than the EBFs and just as accurate for sure!

Not everyone likes the feel of a super RC, especially those who don't use draw checks (like hunters). I had trouble consistently finding my anchor because the flat DFC (low increase in draw weight) of a super RC gives little physical indication of drawing at the end. Plus the high initial higher draw weight might be an issue for some. This begs the question, why no super high tech conventional limbs designed for hunting?

All else equal recurves (RC) can never match the efficiency of a longbow ( LB) as the limb length is longer (it's curved) so it's heavier and has more air resistance, it needs more torsional stability (TS) which also adds weight, and the string is longer which adds weight too. A super RC will always be less efficient than a conventional RC, the limbs are even longer, they need a lot more TS and the string is also longer (more weight and air resistance). This is also true because whatever materials and methods used make a super RC can be used in a conventional RC, so the conventional limb will always be more efficient. There is no free lunch, more stored energy (KE) comes at a price. But (so far) KE trumps efficiency, so they shoot faster. JP clocked the EBFs at 194 fps, Hex 6 at 201 and Hex 7 at 209. The fastest RC limbs on the planet are 15 fps faster at 10 gpp than my EBFs, which sounds like a lot but that's only a 7% increase in speed (14% inc in KE though).

But is this really a fair comparison? My EBFs are based on a target limb, but is all the TS too much robbing efficiency? Or can the limb design be tweaked (like the fiberglass Palmer) for all out speed? I've owned Hex 5 and 6 limbs, they are very light, noticeably lighter than my EBFs so they had efficiency in mind too, but nowhere near what could be achieve in a conventional RC limb. Going by Borders data for the Covert Hunter (204 @ 9 gpp at 50#, 1.17 se/pdf) the Hex 7 efficiency is only 71.1%. That's the price paid for those big energy storing hooks.

Border uses very expensive exotic materials in their Hex 7 limbs, but what if they specifically designed a conventional RC hunting limb using the same materials? I know they have a CX limb, but that is a target design and likely a compromise between TS and speed. You could give up a bit on some of the target priorities like the extra TS and go for max efficiency, AND lower the brace height (another reason why super RCs are faster). The EBF limbs are 82.5% efficient, if you got that to 90% you would be at 203 fps, so only 6 fps slower than a Hex 7 and 2 fps faster than a Hex 6!. Drop the BH to 6.5" and slim up the tips (less air resistance) and you are almost in the same ballpark.

I think there is a market for conventional RC limbs for those who don't like the feel of a super RC, but want an all-out hunting limb. This would be cheaper too and gives us more options. If you like the let-off feel go for the super RC. Actually that's perhaps the biggest benefit of the design. All the current top end conventional RC limbs are designed for target shooters. So how about a conventional ACS-RC, or a CX designed for hunting that is more focused on performance (speed) than ultimate accuracy? It might not be as fast as a super RC but that's not the point. It might be the best balance of all the attributes needed for a top of the line hunting limb.

We will never know how much the shape of a limb affects speed until someone builds matching limbs of different shapes. Bigger hooks are faster, but not by as much as the stored KE would suggest. And there is a limit to how far you can go with a super RC design as efficiency loss and KE gained will converge to a point where bigger hooks will mean a loss in performance even if they store more KE. Eventually someone will figure out the perfect shape for a hunting limb, or perhaps the choice will be based on draw feel (smoothness). It seems like all the top target limbs are very similar in shape and construction, that's no coincidence.
 

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on the efficency values quoted in our documentation.

they are based on fingershot. with string silencers and 5" 3 fletchshafts and16 strand flemish twist string.

not triggershot.

not a 12 strand string.

and not a string silencer free.

this is actually how the bow would be shot from a tree stand
not centreshot out the box...
 

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now.... id like to hear what you think is a hunting limb...

your palmer is as fast as your extreme bfs. but your extremes can not only take game. but also take 90meter scores.
 

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and your last paragraph... I dont understand where you make your assumption.
the cv series is of EXACTLY the same construction as the hex6.

so it is possible to check out the difference shape makes.
same with the hex 5 and cx series.
or the early hex4 and tx series.
 

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The Mad Scientist
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Discussion Starter · #6 ·
Sid - My point is you (and other bowyers) have yet to optimize a conventional RC for hunting purposes! Now that we have carbon and foam there are more gains to be had with efficiency, and a bit more with limb design as illustrated by my fiberglass Palmer. Not everyone wants or needs to shoot 90 meters, so there's no need to design for that. We want max speed and decent accuracy. If the CVs are the same as a Hex 6 the TS is way overkill, and you said that adding TS takes away performance. So the CVs are not optimum for a hunting bow, IMO.

The problem is you won't allow anyone to test your bows so we can have a fair comparison. FWIW Blacky uses a 16 strand Flemish string with a mechanical release on a shooting machine. Even with a few more FPS with a mechanical release the efficiency of the Covert Hunter would still be in the low 70% range. I would love to see what a CV has for numbers, but you didn't include them in your own comparison, I think you used a PSE limb. Why not?

My fiberglass Palmer with pretty bocote veneers on the limbs tested at 196 fps, vs. the EBF at 194 with the same SE/pdf of 0.91. How can that be if carbon is so superior? What would it be if you built it for all out speed, would it be knocking on the door of the Hex 7? This is the value of real test data, not only for us but for bowyers too (bragging rights). I've always looked at Blacky's test for the DFC (SE) and efficiency, not just the speed rating. THAT to me is the mark of a well designed limb.

I'm not a speed freak, but being a draw length challenged hunter I need all the KE I can get, and since KE is directly related to speed that's why we talk speed. But not everyone can shoot a super RC, some of us like conventional limbs but even with these new materials bowyers ignored optimizing a conventional limb and instead focused on geometry instead. It works, but we won't know by how much until someone puts in the same level of effort with a conventional limb. My guess is the difference will be at most 5 fps, but with cheaper limbs and less noise (and maybe a bit more stability).

It was a smart move introduce the Hex 7 limbs on the Covert Hunter rather than a target bow. That implies you know what hunters want, so do the same thing with a conventional limb. But I want the first one (if you will agree to sell it to me)!
 

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Sid - My point is you (and other bowyers) have yet to optimize a conventional RC for hunting purposes! Now that we have carbon and foam there are more gains to be had with efficiency, and a bit more with limb design as illustrated by my fiberglass Palmer. Not everyone wants or needs to shoot 90 meters, so there's no need to design for that. We want max speed and decent accuracy. If the CVs are the same as a Hex 6 the TS is way overkill, and you said that adding TS takes away performance. So the CVs are not optimum for a hunting bow, IMO.

The problem is you won't allow anyone to test your bows so we can have a fair comparison. FWIW Blacky uses a 16 strand Flemish string with a mechanical release on a shooting machine. Even with a few more FPS with a mechanical release the efficiency of the Covert Hunter would still be in the low 70% range. I would love to see what a CV has for numbers, but you didn't include them in your own comparison, I think you used a PSE limb. Why not?

My fiberglass Palmer with pretty bocote veneers on the limbs tested at 196 fps, vs. the EBF at 194 with the same SE/pdf of 0.91. How can that be if carbon is so superior? What would it be if you built it for all out speed, would it be knocking on the door of the Hex 7? This is the value of real test data, not only for us but for bowyers too (bragging rights). I've always looked at Blacky's test for the DFC (SE) and efficiency, not just the speed rating. THAT to me is the mark of a well designed limb.

I'm not a speed freak, but being a draw length challenged hunter I need all the KE I can get, and since KE is directly related to speed that's why we talk speed. But not everyone can shoot a super RC, some of us like conventional limbs but even with these new materials bowyers ignored optimizing a conventional limb and instead focused on geometry instead. It works, but we won't know by how much until someone puts in the same level of effort with a conventional limb. My guess is the difference will be at most 5 fps, but with cheaper limbs and less noise (and maybe a bit more stability).

It was a smart move introduce the Hex 7 limbs on the Covert Hunter rather than a target bow. That implies you know what hunters want, so do the same thing with a conventional limb. But I want the first one (if you will agree to sell it to me)!
I have tested Sids limbs against all comers. I own txg, cxg, hex 5, hex 6. I own or have access to all the top limbs. If you are smart limb choice has nothing to do with the numbers. It is your sight marks and the feel that make a limb.
 

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I have tested Sids limbs against all comers. I own txg, cxg, hex 5, hex 6. I own or have access to all the top limbs. If you are smart limb choice has nothing to do with the numbers. It is your sight marks and the feel that make a limb.
Truth.

Be it bow, handgun, long gun, fish rod or

my framing hammer.

Regards,

Salskov
 

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The Mad Scientist
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Discussion Starter · #9 ·
I have tested Sids limbs against all comers.
Me too, that's why I shoot Trad Tech Extreme BFs. Want to buy a set of Hex 5h MKII limbs?

But feel isn't everything is it, otherwise why brag about the CH numbers? But if you read my OP I am talking about limbs that no one has made, yet. Hopefully Sid will. If anyone can do it he can.

And btw, I don't have sight marks or care about the "feel", as long as my 10 gpp EFOC arrows hit where I am looking and I get full penetration. And my bow doesn't spook what I am shooting at. The majority of trad archers shoot stuff we'd call junk, but they seem pretty happy non the less. You know, like the guy on the header of this website. I would think a high performance limb that still looks trad will appeal to them too. But that's not my point.
 

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Hey Mat,

HERE is a link on Hank's testing of my bow. Note that the performance numbers were generated off the fingers and with Dynapuffs. Since the first testing I have changed the tuning, and increased my DL. The bow is now 55# at my new 28" DL. Current Performance numbers are as follows. 700 grain hunting arrow with 27%FOC (12.7 gpp) flies at 182 fps. My field / 3D arrow is 418 grains with 15.6% FOC (7.6 gpp) flies at 212 fps. I recently compared performance with a 70# at 28" TAC 19 / Dryad ACS CG ILF longbow. Shooting the same arrows the longbow shot 7 fps slower for both arrows despite being 15# heavier.

Now as this relates to your search for a perfect hunting bow. I went through a real struggle between these two bows. With the Longbow there was a very strong "Back Wall" as I mentioned on your other thread. I kind of liked it. Draw to my anchor, expand as hard as I liked and bam 175 fps duplicates all day long with the 700 grain hunting arrow. (10 gpp). With the SRF sight this was a pretty fool proof setup out to 20-25 yards. The long bow all set up weighed 3.2lbs.

Dressed as a target bow with sight and 24 oz of weight my 27" Max / extra short Hex 6 BB2 recurve weighs 6 lbs even. However, take off the weight and the bow is 4.5 lbs with the sight. Strung and ready to shoot the Longbow was 61" tip to tip and my recurve is 62". Guess which bow I am keeping as my one bow for all occasions?

When I worked with Sid and decided on the Extra Short limbs I knew I would be at the upper edge of the working DL range. Now at 28" DL I have the limbs comfortably maxed and I know I am getting everything I can from a bow. Despite being at the recommended max for the limbs they are still smooth, but firm, about 2.5 ppi compared to something like 5 ppi with the longbow at full draw.

My point in this long post is that the technology exists right now to configure a bow exactly the way you want. If you are seeking higher performance and a firmer back wall simply configure the bow as I have and match your DL to the max range of the limbs based on the DFC and smoothness graphs. If we are ever in the same area you are welcome to shoot the bow.

Rasyad
 

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Do you like the BFs over the Palmer ?

Is your Palmer faster than your BFs ?

There are plenty of conventional limb companies making good limbs

Hoyt

Samick

Win Win

You quote Blacky a lot

Last time he was at my house he was shooting Win Win
 

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I like what you are getting at Mat. max performance is great but I don't want a hunting bow with those huge hooks.

I think- and I'm guessing- the missing efficiency numbers are a business decision. If you could make a limb that was 10% more efficient but chanced getting a quarter of them back from customers, would you do it?

Another question; would you buy a limb that had all the attributes you mentioned- super high efficiency but came with no warranty?

It seems to me its harder making money on products that push the boundries of max performance. Companies like Sids don't get to pick and choose their customers- grin
 

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Good post Mat. To me both efficiency and stored energy are important. To much stored energy and no efficiency means the limbs are wasting energy in the form of unwanted shock and vibrations. About highly efficient and lightweight longbow limbs performing equal or better than super recurve limbs in Blacky's tests. Bear in mind Blacky used a light 9 gpp arrow with no silencers. This setup greatly favors the higher efficiency limb. But no Hunter will use that light of arrow to shoot at animals as it lacks energy and penetration. Up the arrow weight to 13 or 14 gpp, add a bunch of silencers and that's where the beauty of super recurves with their high stored energy comes in. With a heavy arrow any difference in efficiency is overshadow by the extra energy.
 

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the cv series will get any hand me down technology that comes out of the hex program.
other than that. we dont see a future in conventional limbs for us.
we have a ilf hex 7 close to completion.
Since we are a target and accuracy driven company. then we will be looking to get an arrow as accuratly in the gold at 90m. the bows biggest challenge.

TS does hurt the bows performance as much as you think, but hey I suppose you will have to wait till other bowyers like palmer invest the R&D we have into making thier own laminate layup to find out what can be done with less ts in a conventional limb.
we are very very unlikely to be looking to get more out a conventional design as we think we have it pritty close. same as the bf extremes are an awesome limb. as are the W&W limbs.

but I still havent heard a good reason why super recurves need to be longer than conventional setups.
if efficency rocks your boat. I can point you to a european bowyer who from reading between the lines gets 107% efficency. and also a bunch of guys who get 95+% efficency. but then again. I would rather bave understated manufacturers numbers on output speed.
 

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This is like homework. I am so far behind on these threads by the time I get off work. This sounds very interesting but I am going to have to wait until I have time to carefully go through it.
 

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I managed to read the discussion on efficiency. Bear in mind that I get lower efficiencies than Blacky because he is using a Hooter Shooter and a release and I use numbers that are hand shot. The Hooter Shooter also allows stored energy to be calculated more accurately since you know the draw length. He mentions on his website the extra speed that he finds using a release. It is pretty significant. Efficiency is tricky since it really depends on the shooter. Blacky provide the intrinsic efficiency of the bow, which is very important. Ultimately, efficiency you experience depends on both the bow and the archer. Still, I would expect that if Blacky shows bow A to be 4% more efficient than bow B, it is probably more efficient when hand shot as well. I have been planning on retrofitting my draw board to be a Hooter Shooter. I have not had time. Maybe this summer. I have a clever neighbor that I am going to have to engage to help me.
 

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From the few reviews I have read from Blacky the speed gain from the Hooter Shooter always seem to be 5fps.

I think the speeds with a glove/tab would be more relevant to us.

I love these threads even though I understand little and like to think of Hank as our own "Blacky"!
 

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Off topic I'm afraid but the option of a more efficient string always comes to mind.

Some of the stringmaker fundis such as Rick Barbee make a string that (according to many reports) will gain you a few or more fps.
 

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I like what you are getting at Mat. max performance is great but I don't want a hunting bow with those huge hooks.

I think- and I'm guessing- the missing efficiency numbers are a business decision. If you could make a limb that was 10% more efficient but chanced getting a quarter of them back from customers, would you do it?

Another question; would you buy a limb that had all the attributes you mentioned- super high efficiency but came with no warranty?

It seems to me its harder making money on products that push the boundries of max performance. Companies like Sids don't get to pick and choose their customers- grin
People said that the Wapiti had big hooks?
People said the hex5 had a radical big hooks
People then said that the hex6 Was a radical big hook
Uukha comes out with a big hook
Uukha releases a bigger hook than its previous UX100
We release A even BIGGER hook than ever before.

The hex6 now looks small in compairson.

Id like a definition as to what is "big" and what it is thats putting you off "bigger than normal" recurves?

There have been plenty of "big" recurves before. except Big just got bigger...
So how do you define TOO big...
There is a UK bowyer here who has a near identical limb to our hex4. so times are changing, and i think big might become the new standard. inwhich case, where is big then?

As for the missing efficency numbers.
lol.
Lets see, 50lbs on your fingers, 180fps at 10gpp at 28", or 200fps at 10gpp at 28"
which one is more efficent?
now, yes. if there are 20 bows all doing 200fps at 10gpp at 28" yes, efficency might be a attribute you might be able to destinguish the wheat from the chaff.
but i dont know a bow that can shoot 200fps at 10gpp at 28" finger shot, other than the one we make.
thats 36ft/lbs vs 44.4ftlbs of energy difference with the same holding weight.
Efficency you ask?
still the same arrow. still the same holding weight...
Would you take a Prius to a Nascar race?
Would you hunt with a lower energy bow if you didnt need to.
Would you overbow yourself to get the energy and efficency when you can have more energy without overbowing your self?

My shoulder is broken, but my bow is powerfull!
I can shoot 70lbs, but i cant hold it.
why?
why not drop in draw weight, Master your bows power, by being in control of it and have more punching power than you have ever had.
We have made this bow to shoot heavy arrows. because its not speed we are after, its power...
 
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