Data Gathering Complete!

finished

after finishing the last arrow for her science project

For nine different sessions the older one has been flinging arrows at the target and collecting data for her science project.  After the spreadsheet counted down the last arrow, she was pretty happy.

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Yumi

At the range this weekend, we got to see the end of an indoor 3D tournament and then an unusual archer shooting a yumi

Wikipedia informs us that:

Yumi () is the Japanese term for a bow. As used in English, yumi refers more specifically to traditional Japanese asymmetrical bows, and includes the longer daikyū (大弓) and the shorter hankyū (半弓) used in the practice of kyūdō and kyūjutsu, or Japanese archery. The yumi was an important weapon of the samurai warrior during the feudal period of Japan.

I think this yumi was probably close to nine feet long.  The archer was close to 6’4″.  It was bamboo and full of natural features.  I suspect his bow was made locally, maybe even in the Boulder area.  What’s interesting about the Japanese bow making craft is that it is passed on in a documented inheritance.

 

December Rotational

The December rotational is in the books.  This rotational was slightly more agitated – it’s hard to schedule anything in December, the shooting times were not released until very late, and this tournament overlapped with Junior Dream Team.

For the little one, it was her last shoot as a yeoman.  She also got the 8:00 AM start, 7:00 AM check-in.  She has become pretty good friends with other yeoman recurve and barebow shooters.  Nearly all of them will be ending their yeoman (or “yo-women” as it is called in our house) status.

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Buddies

Her shooting was a bit erratic, but she was still doing pretty well.  She ended up with a slightly lower score compared to the November shoot and ended up with a second place medal.

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The older one got the 4:00 PM start with of course the transitionary check in at 3:00 while the other session is nearly finished.  She shot well, getting past her scores in November, but not quite to her combined 450 goal.

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Crowded place for bows.  Recurves take up a lot of space.

It was a day when her normal coaches were not around so she wore her favorite combo – galaxy skater skirt, Wonder Woman quiver belt, and Star Wars “vans”.

Her second half was not as good as her first, but she kept her form nearly throughout.

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Shooting face to face with her teammate

Archery Science – Arrows and Fletchings

The older kid has chosen to study the affect of fletchings on arrow flight.  Her simple goal is to examine the results of feather fletchings and plastic fletchings for indoor shooting.  Her project includes shooting a lot of arrows which is underway.  Her paper has been submitted to her teacher.  You can read it here.

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Second Indoor Shoot – Younger Edition

She has returned to the sport.  She couldn’t make the first indoor shoot because of another sport conflict.  For this tournament, scheduling was a bit strange.  The older one shot at 08:00 and she shot at 16:00.  All in all, I was at the range from 07:00 to 20:30.  A long day of being any type of archery parent.

Both sisters are on the same team which is focused on slightly older kids – Cadet and Juniors for the most part.  I would say that her team is also aligning around recurve with only a small number of kids shooting compound or barebow.  Other teams in our area have different niches and demographics.  She is the only Yeoman on her team and although it doesn’t bother her much at practice or on team night, it is sort of odd to show up at a tournament and not know anyone.  Thankfully, another club (from the hosting archery range) had plenty of Yeoman.  You can see them in the green shirts while the younger one is waiting for her line to shoot.  Yeoman tend to start in barebow too, so a lot of kids on the yeoman side are shooting barebow.  This archer is of course shooting recurve with her hand-me-down kit including a riser, ILF limbs, stabilizer, and sight; all not normally seen for the Yeoman class which is dominated by wooden risers and knock down limbs.  She is sporting her new archery Puma shoes (not officially archery shoes, but good for archery according to KiSik Lee).  She also likes her family to wear Puma shoes in support.

She made friends quickly with two girls from the green team – one a barebow shooter and the other a recurve shooter.  They became good enough pals that she has a holiday party invite waiting and a new FaceTime friend.  (This tournament is just about an hour travel distance and both girls are probably further away than the range).

Her scores seem to be a natural extension of where she left off last indoor season.   In the first 30, she shot 228.  In the last 30, she shot 200.  I could see that the event was beginning to grind on her – a lot of arrows, new friends, and shooting when she is normally getting ready for bed.  She persisted and came home with a first place finish and two new friends.  I don’t know which she is more excited about.  She’s already asked about next month’s tournament.

Formula Limbs: Extracting Value

In a previous post, Formula fittings are compared to ILF. In this post, a deeper dive into the Formula limbs.

A 2009 Hoyt product catalog introduced the system

NEW PARALEVER MOUNTING SYSTEM

The Formula limbs innovative, all-new cross-carbon multi-laminates work in concert with the Paralever Mounting System and extended limb design to reshape the limb stress curve for unmatched smoothness before the shot. The Paralever mount also manages vibration after the shot, with more than 40% less limb stress in the critical riser interface area. The result: increased smoothness in the clicker zone and a substantial velocity advantage with ultimate accuracy. The Paralever mount also further reduces limb alignment tolerance, allowing for rock-solid alignment stability and 0.005” increment adjustment capability using the ultra-reliable Hardlock alignment module.

Formula system components feature two riser lengths and three limb lengths for combinations ranging from 66 to 72 inches in length, and from 22 to 50 pounds measured to ATA standards.

The Formula Series Limb Dampening Bushing allows the use of accessories like the FUSE Recurve Shock Rod or even a simple Doinker suppression mount – to absorb vibration before it gets to the riser. This patent-pending feature is exclusive to the Formula Series.

The Formula Patent

ABSTRACT
A traditional archery bow includes a handle assembly, a bowstring, and at least one connection apparatus. The handle assembly includes a riser, an upper limb, and a lower limb. The upper and lower limbs each include a proximal end connected to the riser and a distal end. The bowstring extends between the distal ends of the upper and lower limbs. The at least one connection apparatus is mounted to at least one of the upper or lower limbs. An accessory such as a bushing or stabilizer may be mounted to one of the limbs with the connection apparatus.

In my view, the two distinct features are:

  1. Longer fitting compared to the ILF
  2. Limb dampening bushing

Longer Fitting

The change in geometry on the Formula limb (about 1.5 inches longer) will change the physics of the limb. The longer working segment of the limb will change the drawing and loading characteristics of the limb. In theory, the total length of the limb could be made lighter since the thick, heavy part of the limb doesn’t have to be as long. Lighter limbs will change the energy dynamics of the bow in general.How would a normal human test this? It would require Hoyt to make identical risers in both the Formula fitting and the ILF (“Grand Prix”) fitting. Then, identical Hoyt limbs in both fittings and an incredibly robotic archer shooting statistically random sessions (hot, tired, indoor, etc). This would be fantastic, but unlikely since Hoyt doesn’t produce their high end risers in both fittings. They do produce the Horizon in both fittings. As a parent of a young archer, I struggle to think about the nearly robotic archer to launch and measure the results.

Limb Dampening Bushing

From Hoyt Patent

This is the second feature of the Formula is the the threaded socket (bushing) to allow a new class of dampener to attach to the limb and absorb vibration from the limb before it hits the riser. The patent illustration shows this example:

From Hoyt Patent

This sounds logical and it would be neat to see innovation in he limb dampening space.

Photo from Bignani Archery (Italy)

And here is an archive picture of Brady Ellison shooting Formula limbs with a dampener.

Photo from Wired Magazine

You can see the dampener highlighted in yellow.  There’s a special dampener on the back of the bow shown in blue.  I suspect that might be a Doinker.

In 2017, several years after the introduction of the Formula limbs, the market should have many options. Sadly, there are not a lot of market options. Is the market voting that this technology isn’t living up to the promise?

The dampener used by Brady Ellison appears to be a Sims Limb Saver Node.  It was released in 2010.  According to Lancaster, it has been discontinued.

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The FUSE Recurve Shock Rod also appears to be discontinued.

An interesting question remains.  If you attach something like the FUSE dampener to your limb, do you only attach it to the bottom limb?  Do you shoot with this apparatus on both limbs?  Does only the bottom limb produce vibration?  I guess the advantage of the riser based stabilizer is that it can take vibrations out from both limbs.

Bottom Line

If you are chasing the top of the line riser from Hoyt, it will be a Formula fitting riser.  The Hoyt engineering team may have found a way to get straighter and lighter limbs by changing the ILF into the Formula fitting.  Any benefit you receive from the Formula fitting will be wrapped up in total engineering of the premier equipment from Hoyt.  I don’t think you will be able to say the limbs were the single secret.

Hoyt Grand Prix, ILF, Hoyt Formula – What Is the Difference?

Besides angering online archers, what is the difference between ILF, Grand Prix, and Formula limbs?

There are ILF limbs from SF Archery and Formula limbs from Hoyt.

Recurve bows are made in a take apart design. The International Limb Fitting or ILF was first designed by Hoyt in the 1980s. Before this time, manufacturers had different limb fittings that were not interchangeable. Today, Hoyt call this the ‘Grand Prix’ fitting.

ILF and Grand Prix are the same thing.

Hoyt evolved the Grand Prix design and created the Formula fitting. It is also a dovetail system. The slide-in attachment on a Formula limb is about two inches further away from the slot. As such the attachment portion of a Formula limb is about five inches while ILF is three and one half. Obviously, the physics have changed and Hoyt has probably found some benefits from this design besides a fitting that is exclusively theirs.

Formula and Grand Prix/ILF are not compatible.

Here is a Hoyt Grand Prix Horizon riser and Hoyt Formula limbs. You can see the compatible notch, but the ILF riser ends and the Formula limb is too long to attach.