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!!!!

2011 Foot Bow - Version 2.0

Fortunately, I am not starting from scratch for my 2012 bow.  Shortly after I came upon Alevekiu's bows, I couldn't resist the temptation to try shooting the foot bow class at the Salt Flats.  At first, I figured that the best approach was simply to string up and shoot the Alevekiu bows.  Given a modern string and top notch arrows, it should shoot better than it ever has before.  Even better, it could help lend some credibility to Alevekiu's distance claims.  Unfortunately, I quickly found that the release mechanism and rails were very sensitive and unforgiving to the arrows I already had.  The arrows, nock, fletching all had to be perfectly fitted in order to make it work.  Otherwise, clean arrow flight was impossible and the chance of a misfire almost guaranteed.  A few test firings into a foam target with a light set of limbs and I realized it was going to take a lot more work to get these bows shoot ready than I had time for.

I needed to come up with another plan. I borrowed one of Alevekiu limb holders and built a new set of limbs for it.  I built a new chassis and discarded the crossbow rail arrow guides in favor of a suspended arrow rest.  The trigger system was new also and required three iterations before I has something I was happy with.  The first was based on a compound mechanical release but I was disappointed with how clean it loosed the arrow and I was concerned about the durability of the release with the heavy draw of a foot bow.  I'd shoot an arrow and it would come out tail high.  Without changing anything, the same arrow on the next shot would come out tail low and sideways.  This just wouldn't do.

The second release was based on Alevekiu's crossbow style release, but it wasn't a very forgiving system either.  I found it was going to take some work to get this one figured out and I didn't have the time.

The third attempt was based off a latch release from a truck hood.  A little cutting and grinding and I had something that I was finally thrilled with.  It worked much like the hood & loop releases that I used with my hand bows.

The next problem was the arrow rest.  The arrows are often shorter than the bow is drawn so what is the best way to handle this?  Many issues can arise just from the action of dragging the arrow backward across the arrow rest.  The arrow can pop off the string leading to a dry fire, or it can pop off the arrow rest leading to a misdirected arrow into the bow or shooters foot.  I had to do something different.  My solution was to develop a carriage system so that the arrow and rest were drawn together.  It worked great and was easy to tune.  I had a bow resembling a shooting machine where all I had to do was pull back hard and as soon as it hit a predetermined draw point it fired.  AWESOME!

There was no time left to do much more with it, I quickly packed up and drove to Bonneville.  Once there, I ran into one major shortcoming.  I didn't have a bow press to string this contraption!  The set of limbs I built had a pretty light draw weight for a foot bow but it was not light enough to use conventional stringing techniques.  I managed to string it using a combination of clamps, muscle, and stubbornness in the hotel room the night before the shoot.  I heard a disturbing "tick" and a small puff of dust come from somewhere but didn't see any visible issue.  I was a little worried since I had dropped the bow earlier which left a pretty nasty ding in one of the limbs.  Yet it drew back and seemed OK so "game on".

Out at the flats, I took the bow out for a few 300-400 yard test shots at partial draw with some heavy slow shooting arrows. It worked great and I was having a blast!  It was time to take it to the shooting line and try a full round.  My first shot was with my heaviest flight arrow and I set the trigger to go off at about 2/3rd draw.  I pulled back and the bow fired but instead of a clean "thwack!" it let out the most horrible sound.  The bow unstrung itself and I hadn't a clue as to what happened.  I checked my feet to make sure I hand no new holes there.  Next looked over the bow.  A quick check and I found that one of the nocks sheared off the limb tip where I had not shaped it properly.  Too big of a hurry.  Oh well, there was time for another round after lunch.

I shaped a new nock groove and struggled with the stringing again.  My friend James came to rescue and we just about had it restrung when the limb emitted a strange sound and I saw pieces of it go flying across the salt in different directions.  I looked at James and he had a look of shock on his face. Fortunately, he was more surprised than hurt.  Too bad for the bow however.  My chances of shooting foot bow in 2011 were over.

2011 Foot Bow Drawn

Boom!

George Alavekiu's Foot Bows

A couple of months prior to the 2011 Flight Nationals, I stumbled upon a huge collection of foot bows for flight shooting.  After a few phone calls, the deal was sealed in a Jack-in-the-Box parking lot.  I was given several large boxes stuffed with flight archery gear.  There was so much, I could barely fit it all in my car with the seats folded down.

I got home and pulled out limb set after limb set.  Each carefully numbered with vital statistics written on them.  Limb length, working length, draw weight statistics.  No two sets were exactly alike.  Some had been shot many times, some appeared to have never been shot.  It was mind boggling.  The construction of the limbs were unmistakable.  This was classic flight shooting equipment and very well made.  I had in my possession the very systematic yet obsessed work of a brother from the past.  It was insane, yet quite moving.  In addition, there were several foot bow limb holders, release and rails.  There were also many interesting experimental hand held flight bows and older single piece foot bows.  This collection was absolutely incredible!

George Alavekiu Foot Bows - ca.1968-1969

My biggest question was "who made this stuff?"  First to mind was Harry Drake.  The construction of the limbs appeared very similar in construction to Drake flight bows that I had in my possession.  Yet, some things were just different enough that something seemed off with this assumption.  I thought they may be earlier prototypes to Drake's famous foot bow which he drove past a mile.  But Drake signed everything.  There were no names anywhere to be seen.  There are numerous notes written on the equipment and the hand writing didn't seem to match up with Drake's either.  After a few calls, I finally found the answer.  These were built by George Alavekiu!  George was pushing the envelop on flight crossbow and foot bow distances in the mid-to-late 1960's and was locked into an arms race with Harry Drake to see who was first to exceed a one mile shot.  George claimed to have exceeded a mile well before Harry Drake did. Unfortunately, George did his shooting on his own outside the sanctioned flight events after a falling out with Drake so George's distances never officially verified or recognized outside his own personal accounts.  Many have doubted the truth of his claims because of this.

Here is a link to George's story.  The details mentioned in his story matched up with the bows I acquired.  Given George's very detailed notes and record keeping, I have little doubt that George's claims are very plausible.  The design is capable of it.  The construction quality is on par with Drake's.  All the ingredients fit into place.  I'm a believer.  Enjoy!

http://www.arco-iris.com/George/alavekiu.htm

Baby Steps

Every year, I put off as much as possible until a few weeks before the competition and then it feels like I'm cramming for an exam.  The results are always are often less than spectacular as well.  Each year, I vow to do it different.  More focused, getting things done earlier, etc.  But it is kind of like knowing it's time to clean the bathroom, but thinking it can wait another day.  Days go by, and before you know it, it's just too gross to put up with anymore.

So, this year, I think I just need to break the project down into baby steps with no more than a month between each baby milestone.  Right now, it's the beginning of January which leaves about eight months to complete my ultimate arrow launching machine.  Here goes:

Goal 1 February 1, 2011
Complete a working "chassis".  This will resemble a crossbow like set up with a limb holder, arrow rest and trigger release system.

Goal 2 March 1, 2011
Using existing limb sets, complete safety systems such as foot shields and string stops.  Come up with a way to generate high speed test shots without destroying precious flight arrows.

Goal 3 April 1, 2011
Dial in limb design and complete first set of new foot bow limbs.

Goal 4 May 1, 2011
Refine system.  Generate test shots exceeding 400 feet per second.  Test durability of limb design and incorporate lessons learned into second limb set.

Goal 5 May 28, 2011
Bring foot bow to Sisters, Oregon for the local fun flight shoot.  Test shoot bow with heavy test arrows to keep them within the 700 yard boundaries of the field.

Goal 6 June 14, 2011
Test first limb set to destruction or achieve 500 feet per second.  Whichever comes first.  Complete second foot bow limb set.

Goal 7 July 2, 2012
Push second set of limbs to destruction or achieve 600+ feet per second.  Whichever comes first.  Make design adjustments and complete final limb sets (plus two or three spare sets).

Goal 8 August 1, 2012
Complete flight arrows (12-24 flight arrows), strings, etc. for the flight competition at the Bonneville Salt Flats.  Add those last cosmetic touches that make the foot bow look beautiful, because we all know it will shoot much faster if it is beautiful too!

Goal 9 Last weekend of August or first weekend of September, 2012
Show up at the Bonneville Salt Flats two days early and begin distance test shots.  Dial in tuning.  Try not to lose all my precious flight arrows in the process.

Goal 10 Date of US Flight Nationals
Shoot!  Good luck to the search party who must find where the arrows land.  Ha-ha-ha-haaaa!

Goal 11 
Have fun, get some rest, and take a break from this madness!

This looks like a pretty good plan.  Let's see how it work out.

Lessons Learned Part 1

2012 will be the first time I make a pretty serious attempt at seeing what kind of distances I can get out of a foot bow.  But, I do have a couple half-hearted prior attempts that I can learn from.  I also have George Alevekiu's foot bows from the mid to late 1960's in my possession which may have surpassed the mile mark a year or two prior to Harry Drake's record breaking shots.

Version 1.0:  In 2005, I played around with a unique double bow design which showed great promise and almost limitless speed.  But, it was far too difficult to string and tune.  One string is difficult enough to deal with, but this one used three!  In addition, there was no adjustment built into the fixing of the limbs.  If one of the strings was a little off in length, it required dis-assembly of the entire bow to adjust the string length and restring the bow.  This took a lot of time and was very stressful.

The second issue is that I was attempting to shoot this in the "Conventional Foot Bow" class which disallows a mechanical release and mechanical components on the bow.  The hook-type release I devised contacted the arrow nock and I quickly realized that it could torque the arrow during drawing to the point it easily would jump from the arrow rest.  Or, the arrow would fall free from the string leading to an ultra-violent dry-fire.  Not a good thing.  One such dry-fire sent bow limbs and strings flying in all directions.  String and bow limbs flew every direction and it almost looked like some kind of confetti bomb went off.  It was so jarring that I had to double check I had all fingers and toes afterward.  The arrow flew about 1 inch.

The third issue was my overdraw and arrow rest.  The intent of this overdraw was to allow me to shoot an arrow that is shorter than the distance it is drawn back.  It had a draw lock feature built into it that held the bow at partial draw so I could nock the short carbon arrow.  As soon as I began drawing the arrow back, the draw lock automatically folded out of the way while I drew the arrow all the way back.  In 2007, I was getting ready to shoot this contraption at the US Nationals and realized that the arrow rest needed to be adjusted.  I had the arrow on the bow held at partial draw with this draw lock feature and as I was getting ready to set the bow down, the string popped off the hook.  At the same time, the arrow popped off the rest and the bow fired.  I felt a hard thump as if someone hit me on the foot with a hammer.  I looked at my foot and saw the arrow sticking clean through it.  My first thought was "I just ruined my new running shoes".  My second thought was "MY FOOT IS IN THERE!"  I quickly grabbed the arrow and yanked it free from my foot.  Of course, the arrow was covered with the alkali salt from the Bonneville Salt Flats and it burned like nothing I've felt below. 

So here I was, with a very fast bow that was hard to adjust and not very user friendly.  One of the better jokes I remember from the doctors that treated me:

Question: "How far did I shoot this time?"
Answer: "About a foot"  Hahahaha.  Ugh.

Attempt 1, Double Bow Design

"Shot about a Foot..."

What did I learn from this?
1. Don't do this again without good foot protection.
2. A fast bow is of no use if it isn't easy to shoot and tune.