Author Topic: Bow design and development  (Read 35949 times)

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Offline BowEd

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Re: Bow design and development
« Reply #180 on: November 12, 2018, 10:06:36 am »
I see.2 and 1/2" beyond 28" is pushing it for sure.A little more width and thinner would have helped I bet,but sinew would do the trick I'm sure but just on the working limbs.
BowEd
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Ed

Offline BowEd

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Re: Bow design and development
« Reply #181 on: November 12, 2018, 10:11:19 am »
That's what I was saying earlier.More refinement of a design to get it better.
BowEd
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Ed

Offline Stick Bender

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Re: Bow design and development
« Reply #182 on: November 12, 2018, 12:57:47 pm »
I guess you made my point for me I have a whole corner of the bow room that need refinement....lol but a lot can be said about working with one design and taking it as far as you can go refining it but there is no way you can find a design or a book that's going to tell you that , like a friend of mine says you need to make the bow to find out , but for me in all wood bows the ones that seem to hold up with good speed & good hunting durability  are the slightly reflexed long leaver bows , I like the shorter sexier looking ones but they never hold up for my long draw with out sinew , I think the slightly reflexed self long bow is over looked a lot and if built right is with in 10 fps of there counter parts for me !
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Offline avcase

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Re: Bow design and development
« Reply #183 on: November 12, 2018, 03:46:43 pm »
I was waiting for my turn at the range the other night and was looking at the bows. Not counting the compounds every bow there(except mine) was a FG recurve.( I can be a little slow sometimes ;D ;D) Ignoring the FG part all the designs were deflexed recurves. Not one FG longbow and I know they made them when I was a kid. This got me thinking that somewhere in the past bow making companies must have done a lot of testing of various designs and all decided to make basically the same design. There must be a lot of data squirrelled away on the effect of various tests. Does anyone have access to any of this stuff? I realise that FG data won't be directly transferable to wood but a good design is a good design.

I go back and forth between natural material bows and glass bows. I don’t know if there is much data squirreled away for glass bows.  Most glass bow builders tend to copy prior designs as a starting point and this gets them something that works well and reliably most of the time. I feel the primitive bow builders have a much better understanding of materials and design because they have to. The wood bow builder has to design their bows much closer to the limits of the materials in order to achieve similar levels of performance.

So why do most glass bows look very similar to one another?  It is because they are very economical to build this way. All you need is a fixed thickness of glass on the back and belly, a decent core with a constant taper, and a tried and true recurve profile, and you end up with a decent performing bow that should last almost forever.  Performance with 10ggp arrows and 28” draw length doesn’t vary much from the best to worst. The deflexed limbs help make the bows easier to string. There are also various standards in place (for example AMO) which standardizes some features of the bow limbs. For example, it standardizes the string length relative to the limb length, and this limits the design possibilities for those manufacturers who conform to these standards.  There are other formal and informal standards for takedown bows that help insure interchangeability of various manufacturers limbs and risers.

Some bow builders try to get a bit of an edge over others by experimenting with materials and taper rates in their bow limbs. Carbon fiber doesn’t guarantee a boost in performance.  Most designs that report an increase in performance are pushing carbon much closer to its durability limits than their original glass designs.  For example, there was a trend for awhile to make high performance compound bow limbs using carbon, but the limbs were a disaster when it came to durability. Now, the pendulum has swung the other way and short glass limbs are used to store the energy. This combined with big cams takes full advantage of the capability of glass to store tremendous energy in bending. The idea is similar to using the material of horn and sinew to store energy and a large stiff and light wooden ear or throwing arm to perform a similar role as a cam.

Glass is able to store much more energy in bending for its weight than unidirectional carbon. But unidirectional carbon is a much more efficient structural material (better stiffness to weight) than glass. A bow requires the materials to store energy in bending and provide structure to hold the limb shape and control bending, so the two materials have their pluses and minuses. A carbon limb requires more limb length to store energy in bending. This allows room for more energy robbing vibration modes which counteract some of the advantages carbon has.

There are a new breed of modern bows showing up called “Super Recurves” that use huge recurves to give force-draw curves that rival a compound. Some even show some letoff at the end of the draw. The designs are not really new. Hickman proposed a similar design for a wood bow in the 1930’s. The difference is that lighter carbon fiber designs are using interesting combinations of weaves and fiber orientation to allow the material to behave a little more like unidirectional glass (much lower stiffness, but better energy storage capability in bending). The lighter materials reduce the limb mass to the point that these can outperform most conventional designs with heavy arrows. They also do not rely on reflex to improve the force-draw curve so the limb is under very low stress when the bow is braced, which favors keeping the bending stresses under control for a carbon composite limb.  Unfortunately, the efficiency drops off so bad with lighter arrows that a conventional glass bow will run blow the Super Recurve away in a flight shoot with very light arrows. The old saying “the fastest bow with heavy arrows will be the fastest with lighter arrows” does not apply to a modern Super Recurve.

Alan

Offline DC

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Re: Bow design and development
« Reply #184 on: November 12, 2018, 03:57:45 pm »
Thanks Alan, interesting post.

Offline Halfbow

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Re: Bow design and development
« Reply #185 on: November 12, 2018, 06:55:00 pm »
Good to hear it from someone who knows a lot about the industry. :OK Interesting stuff. Thanks avcase.

Offline BowEd

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Re: Bow design and development
« Reply #186 on: November 16, 2018, 07:21:57 am »
I'm of the opinion the wooden and composite bow makers are the ones the FG makers are following in design and developement.
BowEd
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Ed

Offline Stick Bender

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Re: Bow design and development
« Reply #187 on: November 16, 2018, 03:22:27 pm »
I think your right Ed sense most designs are based on a historical design regardless of material used ,I think there are innovative and talented bowyers on both sides of the fence but there designs are all loosely based on something out of history !
If you fear failure you will never Try !

Offline Badger

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Re: Bow design and development
« Reply #188 on: November 16, 2018, 05:39:03 pm »
  the design is one thing and then you get into the bending properties of the material you are using and start addressing things like vibration and optimized reflex based on what you are working with. But I do agree that wood bowyers were a big part of the designers in modern bows.

Offline willie

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Re: Bow design and development
« Reply #189 on: November 16, 2018, 06:11:08 pm »

The old saying “the fastest bow with heavy arrows will be the fastest with lighter arrows” does not apply to a modern Super Recurve.

Alan

Interesting post Alan. Thanks.

 In reference to your closing thought, I should ask if you have seen any trends in FG bow limb development aimed towards improving designs for use with lighter arrows? 

Offline willie

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Re: Bow design and development
« Reply #190 on: November 16, 2018, 06:12:37 pm »
I'm of the opinion the wooden and composite bow makers are the ones the FG makers are following in design and developement.
:OK

Offline Stick Bender

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Re: Bow design and development
« Reply #191 on: November 17, 2018, 04:46:03 am »
When I was a kid I use to read my dad's hunting magazines & names like Ben Pearson , Dan Quinlin, Fred Bear, Howard Hill, Jack Howard , Paul Shafer, Glen St Charels eventual inspired me to make wood bows all those guys got there roots in natural material bows ,I think there big African game hunting stories inspired me too...lol  to me a bow is a bow and if I close my mind on any design or material I would have missed the boat on a lot of design keys , I think you learn a lot about bow making by studying both ,it certainly makes you understand in a hands on way what works and what doesn't !
If you fear failure you will never Try !

Offline BowEd

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Re: Bow design and development
« Reply #192 on: November 17, 2018, 09:51:59 am »
The thing about making self and composite bows is that it developes a persons' tillering skills very well IMO.
BowEd
You got to stand for something or you'll fall for anything.
Ed

Offline Badger

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Re: Bow design and development
« Reply #193 on: November 17, 2018, 10:03:22 am »
  Ed, something I have been seeing a lot of the last few years is glass bowyers using horn composite designs basically making reproductions from modern materials.  This has been going on for a long time but they are starting to incorporate features of horn composite bows more into the traditional glass bow designs which does make a lot of sense.
« Last Edit: November 17, 2018, 10:18:06 am by Badger »

Offline bradsmith2010

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Re: Bow design and development
« Reply #194 on: November 17, 2018, 11:20:28 am »
I have made fiberglass bows that shot well,, I just done enjoy grinding the fiberglass,,but feel I learned some things universal to bow making that help me with my self bows, (-_)