Autopsy

I always return from a flight shoot with lots of energy and enthusiasm for flight shooting and next year's plans.  But before doing jumping in, I performed a thorough autopsy on the failed 2011 bow.  Here's what I learned.

What Went Wrong:

1. The Alevekiu limb holder I used did not allow for precise adjustment of the limbs.  I could use wedges underneath the limbs to adjust the limbs in and out, but this is not very user friendly and requires numerous wedges to get the perfect tiller.  George Alevekiu's solution was to build dozens of fixed limb holders of various lengths and limb angles.  This required complete dis-assembly and reassembly of the bow just to change the limb angle.  It also takes up a lot of space in the shop!
2. One set of limbs is not enough.  When pushing these bows to the limit, something always will go wrong.  For example, when I dropped the bow at the hotel parking lot, it put a pretty good ding in the outer limb and could have ended the chance to shoot the bow at all.  To my surprise, I found the damage suffered from the drop wasn't the root cause of the shattered bow limb.
3. One can never be too careful with the glue joints.  I used a very strong but very thin epoxy to laminate the limbs.  I also was in a big hurry on the limb that failed and did not mix enough epoxy to get the job done so I took a shortcut and spread it as thin as possible.  Much of the limb delamination is clean, indicating a glue starved joint.  In addition, the glass set around the shop for a couple of years before I used it.  A couple passes with sandpaper and thorough cleaning wouldn't have hurt either.
4. The nock has to be very robust!  The nocks on the limbs I built were very narrow and string grooves carved very shallow compared to the limbs George Alevekiu used.  I now realize that there is a very good reason for this when shooting such light arrows out of heavy draw bows. The string slams the nocks extremely hard at near dry-fire speeds and must be able to withstand the forces.
5. Most important, the bow must be safe and easy to string and tune.

Small Sample of George Alevekiu's Foot Bow Limb Holders

Delaminated 2011 Bow Limb

Broken 2011 Limb Set.  Note sheared off nock on lower set.

 

What Went Right:

1. The retractable arrow rest and release carriage worked great!  It provided a very stable platform that diminished the concern that the arrow could dislodge from the string or arrow rest while drawing the arrow back.  This was a huge improvement from first foot bow.  It also solves the problem of to drawing an arrow farther than the arrow is long.
2. I felt very comfortable my trigger and release system.  It was very precise and consistent and tunable.  It's a keeper.
3. The brush arrow rest worked well although but needs more more precise left-right and up-down adjustment. I was very happy that none of my test arrows showed damaged fletching due to contact with the bow or arrow rest on release.  This was a first!

That catches us up with the past.  Time for the present.  Next, I'll go into detail step-by-step detail on how I take these lessons learned and apply it to my 2012 attempt.  Ready?  Yahoooo!!!!