New Flight Arrows

There is much more to flight shooting than simply driving out to a dry lake bed, drawing back a heavy bow, and magically breaking a new record. Shooting a bow can't happen without arrows and it can't be done with the kind of arrows produced commercially.  Even the tiniest available target or hunting arrows are too large and heavy with too much aerodynamic drag to be competitive for flight shooting.

Due to the trackless design of my bow, my new arrows will need to be a minimum of 14" in length through 17" long. I'm using 4mm diameter high modulus carbon fiber solid rod for the arrow shafts and stainless steel for the points and nocks. Based on past experiences, I have found that the highly alkali salt at Bonneville eats aluminum and attacks the zinc in brass in little time, so I made the switch to stainless steel.

My machining capabilities are pretty limited, but I will try to make up for that with a little extra patience. I had planned to build as many as 36 new foot bow arrows before the US Nationals in August, but quality trumps quantity in this area. I'd be happier with three great arrows than have a hundred pretty good ones. 

Here's some pictures of the process:

Marking Carbon Rod for Cutting

Cutting the Carbon Rod Lengths Using a Dremel Cutoff Blade

Tapering the Ends of the Rods to Receive the Points and Nocks

Making Nocks - Drilling 1/8" Dia Stainless Tube

Roughed Out Nocks

Drilling an Inverse Cone Into 1/8" Solid Rod to Form Points

Simple Jig to Guide and Center the Bit to Drill the End of the Stainless Rod

Showing Drilled Point to Match the Conical Carbon Shaft End

A bunch of Arrow Shafts and Nocks Ready to be Glued in place

Long draw, short arrow

It is easy to concentrate on arrow speed  but put off figuring out how to get a consistent clean shot.  It is hard to do and takes time. The ideal projectile is short, stiff, and not forgiving of errors.  The ideal draw length is much longer than the arrow, so it is no surprise that a little misalignment would send an arrow out of the bow tumbling end over end.

George Alavekiu struggled with getting clean arrow flight and wrote about it often in his letters. In one of the letters is a statement that these bows could shoot over 2500 yards if the arrow would just come out clean. In these letters is lots of interesting correspondence with target crossbow shooter Gil Frey.  Gil recommended a trackless design with a D-loop on the string to help solve the issue.  For whatever reason, George did not follow through with this advice and kept with the standard crossbow arrow tracks and release claw.  I believe it was driven by his need to shoot very short arrows made of steel.  George tried putting arrows under the arrow tracks in an effort to keep them from jumping out but these approaches only resulted in modest improvements.  A few years back, I decided against arrow tracks when I tried test shooting George's old bows and found it was probably only an occasional lucky shot that gave him his best distances.  I am sure the majority of the shots resulted in sideways arrows and relatively poor distances.  I feel the same is true for Harry Drake's foot bow record.

I don't live anywhere near a place where I can actually flight shoot, so the next best thing is to test shoot into a soft target to prevent damage to the arrows.  I use a form of paper tuning because I can't actually see the arrow leave the bow.  The piece of paper sits out on a long stabilizer-like support and I analyze the size and shape of the holes left by the arrow to determine if the arrow is leaving the bow perfectly straight, or if it is point up or down, or side to side.  If the bow was shooting perfect, I would expect to see a single circular hole left in the paper with each successive arrow going through the same hole.  

For the test arrows, I am using very short steel and composite arrows that are as little as 7-1/4 inches long.  The shorter the arrow and longer the draw, the less forgiving the bow will be of errors in the tuning and set-up.   I figure if I can get consistent flight with these short arrows, then it should be much easier to get clean flight with the 14-16 inch long arrows that I plan to use at the Salt Flats this August.  To complicate the issue even further, my test arrows vary in geometry and weight.  I rarely have build my flight arrows completely uniform.  Some are heavier than others.  Some are a little stiffer than others.  The competition limits the amount of arrows we can shoot, and there is not a lot of time to figure out which arrow design is the perfect match for the bow that I will be shooting.

The test bow limbs that I am using are much lower in draw weight than the bow limbs that I will be using in August.  I am often test shooting this contraption in my house, and I want to limit the possible damage to the bow, arrow and living room if something goes wrong at over 700 feet per second!  The test bow limbs limit the arrow speeds between 300 and 400 feet per second, which is much more manageable.  So far, I have several hundred test shots on a single set of bow limbs without any sign of failure. The arrow rest and release are both mounted to a sliding "carriage" so that I can draw the short arrow back farther than the length of the arrow.  This also reduces the chances that the arrow pops off the rest or off the string as the bow is drawn.  My goal is to be able to achieve consistent and clean flight with an arrow drawn nearly twice as far as the arrow is long!

Beginning a couple months ago, I made this bow test into a sort of a game.  I set it up and try to achieve perfect holes in the paper with a random set of arrows and draw lengths.  At first, I got pretty crazy results.  I even put a couple holes in the bow riser (see below) and this wasn't even close to using a draw length double the arrow length. 

Chaotic paper tears indicating a tuning issue

Bow Shown with arrow being drawn back

I was also getting frustrated with the durability of my arrow rests (see photo below).  They were made from thick mylar and would start to come apart after only a couple of shots. I switched to a much thinner mylar rest that is used for overhead projector transparencies and doubled them up if I needed more support.

I was able to progress to the point where I could achieve several clean holes, but this would be followed by an occasional wild flying arrow.  It took awhile, but I realized that the very short D-loop I was using was probably the main contributor.  I assume that the release loop would snag itself on the arrow nock and cause all sorts of issues.  Some of the test arrows even shows evidence of this when I would notice one ear of the nock would be bent after an erratic shot.  When I replaced the short D-loop with a longer one, the issue went away.

Mylar Arrow Rest Damage After Two Shots

Much better, three different arrows, three different draw lengths, all pretty clean holes in the paper.

Another view of the test setup with arrow nocked.

I started using post-it notes to minimize changing the paper.

I am applying a little lip-stick to the arrow point which leaves a mark in the paper so I can tell which part of the paper tear is from the arrow point, and which part of the tear is from the nock end.

Comparison of arrow length to Draw Length.

I am now able to consistently draw one of these seven inch long arrows 13 or more inches without issue.  This is a big deal given my bow does not make use of crossbow-like arrow tracks.  I'm getting more excited than ever to see what this bow will do in August!

Limb Set #28 Repair Complete

I'll continue with the status of the repairs to limb set #28. So far, the limbs had been reshaped, reglued, and the new limb tip overlays are in place. All that remains is to string them up to check the tiller and rebalance if necessary.  

Last year, I used 10-strands of Brownell Rhino for the string and I never had a failure.  10 strands plus a thin serving left little material in the 1/8" diameter arrow nocks. The new strings I made consist of only 8 strands of Rhino which I hope should hold up for at least a half dozen shots.

In the 1970's, George Alavekiu and Harry Drake were lucky if their Kevlar strings held up for two shots before blowing apart. The new more durable string materials save considerable time and add to the longevity of the limbs. 

I was a little nervous stringing and bracing the freshly repaired bow limbs.  I expected to hear a crack as the jack screws swung the limbs forward, but the only sound came from the string as the tension climbed higher and higher. I rejoiced as it reached the intended brace height. A few quick measurements revealed that the limbs were bending evenly and in perfect unison. 

Next, I carefully began exercising the limbs by drawing them back, letting down, then drawing a little farther.  I continued this process until I achieved full draw. I didn't find even a hint of uneven balance to the bend in the limbs or unusual noise.  The job is complete, successful, and I look forward to shooting these limbs again.  They may have lost as much as two pounds of draw weight, but this is less than a 1% change. In addition, they lost about a half ounce of outer limb mass during the process, which should make them easier on the strings and maybe a little quicker. 

I won't know for sure how the durability is affected until I shoot them.  At the least, the bow limbs are capable of one more shot than they would have had without the repair. 

Regroup

Following the 2013 US Nationals, I decided one of my first tasks is to repair the bow limbs that damaged with my final shot (set #28). I really liked how smoothly this set drew back and crisp it felt on the shot.  They were not of much use in the condition that they were in so I figured I had nothing to lose.

I started by carefully measuring the dimensions of the good limb, noting the thickness, width, and side profile at one inch intervals. I also measured the thickness of the back and belly glass lamination.  I fed these dimensions into my "Supertiller" bow modelling program to create a virtual version of the bow.  The damage to the limb was too severe to simply glue back together.  If the bow was to shoot again, the width profile of the outer limb will need narrowing.  I was able to use the virtual bow to develop a new width profile for the bow limbs that would have minimal affect on the tiller or way the limbs bent when drawn back and released.  I printed out the pattern and proceeded to reshape both limbs. 

I used several thin hickory laminations with a layer of glass mat between each to form the new tip overlays. I added additional overlay laminates to the sides of the limb tips with the hope that this would help counteract the high shear forces when the string slams home. 

I carefully shaped the new overlays and string grooves and smoothed and patiently blended any sharp corners or abrupt transitions.  It took a lot of patience but I was happy with the results. They looked like new again, and it was time to string them up to check the tiller and make sure it can withstand being drawn back. 

2013 US Flight Nationals

I realize I have missed sending an account of what happened at our Flight Nationals, so here it is:

US Nationals, August 31, 2013
Two of us were equipped to shoot foot bows using Alavekiu's bow limbs at the Bonneville Salt flats 2013 Flight Nationals.  James Sanchez had his beautifully made Drake-inspired foot-bow, and I had my contraption. For the first day's rounds, we disconnected the mechanical release and crossbow-like barrels to make the bows legal to shoot in the regular footbow division.  Unfortunately, nerves, and technical issues kept our distances disappointingly short. It is not as easy as it may look.

James Sanchez, Foot Bow 2013

The second day of competition had a rough start with a mishap on the shooting line. The well-being of our friends are much more important than seeing how far we can shoot arrows.  The nearest hospital is two hours away and James packed up to look after our friend.

The event continued. There was one last chance to shoot a single round of six arrows in the afternoon rounds.  I decided I should at least give it a try.  At the shooting line, I was extremely nervous and drew the first arrow a few inches short of full draw (about 13" draw on a 14" arrow) just to see if everything was working as expected. The string shattered the little Mylar arrow rest, but it fired nice and clean, better than my best expectations. 

Last shot at 2013 Nationals

I started to feel a little more confident.  With five arrows left, I figured there was little to lose.  it was time to push it to the limits to find out what the bow could do.  I replaced the broken arrow rest and took a little more care to line up the arrow and bow string.  For shot two, I adjusted the trigger to release at a 16" draw, and pulled back hard. But the bow unexpectedly released at about 12-13" draw again.  The loop on the string that the release trigger hooks into suddenly gave way, releasing before it hit full draw.






I fixed the release loop issue, reset the trigger for about a 15-1/2" draw and pulled hard again. This time everything worked perfect and the bow shot felt absolutely clean. I felt a rush of adrenaline as I knew it was going to be a long time before that arrow would find the ground. I cranked back the trigger for a 16" draw with arrow #4 and pulled hard again. I am certain arrow #4 left the bow just as cleanly as arrow #3 but the bow let out a nasty sound and the string came to rest at an awkward angle on the limbs. The high string forces of slamming the arrow down range blew the nocks off the ends of the bow limb, tore right down the right limb, and split the limb into a three pronged fork.





There were two arrows remaining to shoot, but there was no time to re-limb and re-string the bow.  The remainder of the day was dedicated to searching where those four arrows ended up.

GPS Trail Showing Arrow Search Pattern

My daughters and I hopped on the ATV and headed downrange perpendicular to the shooting line. Slow at first, then faster. Scanning at 400, 500, 600 yards. Sometimes, depending on light conditions, it is relatively easy to spot the little black arrows against the white salt from as far as 150 yards.  Sometimes it is almost impossible to see it 2 yards away. We continued on: 7, 8, 900 yards and no sign. 1000 yards, 1100, then I felt a rush of excitement as I spotted my first arrow. I marked it in my GPS then continued past 1200 yards where I spotted a second arrow and marked it in my GPS.  We slowly continued outward past 1800 yards with no sign of the other two arrows. For the next three hours, we searched the area, working our way back to the shooting line with no sign. The sun was setting and we were out of time.  An official measurement was taken of the longest found arrow at 1217 yards.  It was short of a mile and not a new record but I was ecstatic with the results!

Verification of the serial number on the longest arrow measured revealed it was from my first shot. The second, closer-in arrow, was my second shot.  It was my last two shots taken at full draw that were not found. I am certain that the last two arrows must be either farther out or they buried themselves below ground.  Regardless, these results were very encouraging that these 45 year old bow limbs are capable of mile+ shots after all. James, the ghost of George, and I will just need to return to prove it!

The next day, the broadhead events were held and we returned to the shooting area to continue the search but quickly conceded.  At the conclusion of the broadhead event the awards handed out, the ATV was packed up and competitors began leaving for home.  It was time we left too.  Overall, it was a great success.  Our girls broke three records in their classes and we had a fantastic time together as a family.  Steve Gardner broke long held records in the 50# primitive flight and broadhead classes.  Amy Haile smashed her prior 50# record.  I came away with a personal best, GPS map of the search area, and motivation to come back in 2014 to do it again! 

By the way, our injured friend set a new record of her own immediately before her incident. She is doing well and plans to shoot again this year.