Fletching Shootoff - Shoot Your Favorite, It Really Doesn't Matter

Introduction

During the winter of 2011/12 I built a shooting machine to help answer fundamental questions about arrow trajectory without the complications of human error in shot placement.  The machine was portable and was clamped to two saw horses to provide a convenient base.   The machine worked well in my 11 yard indoor range, but moved ever so slightly after each shot making longer range experiments difficult.   This winter I decided to fix the stability problem by constructing a sled out of old 2x8" lumber to permanently mount the shooting machine.  Using the upgraded base, I now have a shooting machine capable of evaluating arrow performance at ranges over 30 yards.  In this post I use a shooting machine to compare the target groups of six different arrows made from carbon shafts with different fletchings and tips.  

As a bit of background, the reader is directed to the excellent post by Michael Larson,  Fletching Review: speed, drop, ease of use and more comparing the flight speed and drop of arrows made with an array of fletching materials.   Larson's results show the predicted effect of arrow mass on arrow speed - heavier arrows fly slower from the same bow.   His data also shows that differences in fletching design does effect the drag on the arrow.  These effects may be quantified through the trajectory calculators detailed in my previous post.  However, Larson was not able to evaluate the target groups of his test arrows because he did not have a shooting machine.   This post is a start at correcting that problem.

Methods

A PSE Stinger bow with a 60# draw weight  was mounted in my home-built shooting machine detailed in my previous shooting machine post.  The bow used a drop away rest to avoid fletching contact for all arrows tested.  Test arrows were built on twenty nine inch Cabela's Stalker Extreme or Carbon Express Mayhem Hunter shafts with NAP Quickspin, Bohning Blazer, or Duravane four inch vanes, and were tipped with 100 or 142 grain field points.   Details on the specific arrow combination are provided in Table 1. Arrows were fletched using commercially available four degree straight or helical fletching jigs.  Careful cleaning of the arrow shafts was critical for proper adhesion of the fletching.  Tests were performed on three or more arrows of the same design.  All arrows were spin tested before being used in the study, and arrows that landed     Figure 1.  Shooting Machine used in tests

 more than 50% away from a testing group were eliminated from the analysis       

Figure 2. Arrows used in testing.   See Table 1 for details.


Table 1.  Arrow Construction and Testing Details

 Arrow      Shaft Vane Tip     Weigt (grains) Speed (ft/s)
A     Stalker Extreme Duravane 4" 100 gr       410 235
B Stalker Extreme Blazer 100 gr 398 239
C Stalker Extreme Blazer Helix 100 gr 398 239
D Stalker Extreme Quickspin  


 100 gr 398 239
 E Mayhem Blazer 100 gr 398 239
 F Mayhem    Blazer Helix 100 gr 398 239
 G Mayhem           Quckspin     100 gr 398     239
 H Mayhem Blazer144 gr  442 227

Figure 3 shows the typical shot pattern from the shooting machine at 35 yards.  Between groups of arrows the target was shifted to the left.  Very little variation is observed between arrows shooting the full range of fletching types.    In many cases the arrows shafts were touching for shots within a test group.   Individual arrows did shoot poorly due to poor fletching or a bent shaft and were eliminated from the trial (these arrows are not shown in figure 3.)  

Calculations of the arrow trajectory were performed using Technical Archery’s trajectory calculator.   These calculations used a finite difference approach to model arrow flight as a function of arrow speed, launch angle, and aerodynamic drag. An Excel spreadsheet to implement these calculations is attached to the end of this post.


                     Figure 3. Shot Patterns at 35 yards.

Results

Arrow speed for the 398 grain arrows was 239 ft/s measured using an ArrowSpeed RADARChron.   The speed of the 442 grain arrows was 227 ft/s in agreement with the predicted speed  calculated from the conservation of kinetic energy.

(1)

Equation 1 may be used to calculate the change in arrow speed for arrows of different total mass due to changes in fletching or tip mass  

The figures below show the target groups of the different sets of arrows defined in Table 1.  The Blazer fletching on Cabela's shafts shot a respectable group of less then one inch at 35 yards (Figure 4.)   Similar results were obtained with with the same shafts fletched with with Quickspin fletchings as shown in Figure 5.   One type G arrow was also shot with this group with indistinguishable results.   With these vanes both arrow shafts perform equally.  It is important to note that fletching arrows with the Quickspin vanes was more difficult than fletching with any other material because the nib on the top of vane interferes with the fletching clamp.

 
Figure 4.   Shooting Results for Arrow B - Blazers on Cabela's Stalker Extreme

Figure 5.   Shooting Results for Arrows D and G fletched with Quickspins

Figure 6.   Shooting Results for Arrows E (Mayhem) and A (4" vanes on Cabela's)

Figure 6 shows a nice group with Carbon Express Mayhem arrows fletched with Blazer or Quickspin vanes.   These two vane types did not make a difference in the flight of these shafts.  However, the effect of increased fletching mass on the A arrow is obvious in Figure 6.  Arrow A (yellow vanes) is 12 grains heavier.   Based on the increased mass and decreased velocity of arrow A, the trajectory calculator predicts the arrow will fly 1.2 inches low.  This is what is observed in these tests.  You can download the full trajectory calculator at the bottom of this post if you want to test the effect of different arrow masses on flight trajectories.   Figure 7 shows this effect when the 100 grain field tip on arrow E is replaced with a 144 grain tip to make arrow H.


Figure 7. Effect of adding 44 grains to tip weight on Arrow E to make Arrow H.

The trajectory calculator predicts a 4 inch drop and this is what is observed within the errors of the group.

Finally, Figures 8 and 9 show the effect of a poor fletching job or a slightly bent arrow.   The circled arrow consistently flies low by 4 inches at a range of 35 yards.   This is a clear example of why it is important to test all of your arrows before a hunt.  The anomalous arrow was not visibly different, but consistently flew low and left compared to the rest of the group.  


Figure 8. Anomalous Arrow placement (yellow ring)

Figure 8. Repeat Shot of Anomalous Arrow (yellow ring)

What about the effects of arrow tips?

This last photo shows the effect of switching from 100 grain field tips to Rage, three blade, 100 grain mechanical tips.  The switch to mechanical tips had no noticeable effect on arrow flight.   If you miss the deer at 35 yards, don't blame it on the arrows or tips.

Figure 9.  Arrow group after switching field tips for three blade, mechanical broad heads.   Shooting distance is still 35 yards. Notice the different arrow types and the helical fletch on the Stalker Extremes.

Lessons Learned

A shooting machine is a great tool for evaluating arrow flight under controlled conditions.  With the exception of "damaged" arrows, all of the arrows tested were capable of 1.5 inch groups at 35 yards irrespective of arrow shaft or fletching.  Vane weight did influence arrow trajectory, but not arrow group size.   Arrow prices can vary a lot and these tests indicate that you don't always get better performance from a more expensive arrow, at least when shooting field tips or mechanical broad heads.  In my opinion, if you want to invest in arrows, consider purchasing a good quality fletching jig to keep your current arrow fletching in top flight condition.  If you are fletching your own arrows avoid the Quickspin vanes because they are significantly more difficult to fletch - at least with the equipment generally available.   


OOPS!  Refletching the arrow will not solve this problem!

February 2013.


Ĉ
Whitney King,
Jan 27, 2013, 5:33 PM
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