Experimenting with flechings

[Fbrit]

A little self indulgence I know, but I've been playing around with fletch profiles. I shoot a compound bow that is delivering a 450 grain arrow at around the 320feet per second mark so there isn't much need to put too much angle on the fletches to impart spin (about 1°). However my findings are as follows:

1) Traditional tear drop profiles of more than 3" in length seem to be influenced by cross winds.
2) Shield cut profiles at 3" perform better in cross winds, but are quite noisy in flight with an audible 'buzz'.

Things that have been tried:

1) 6, 5, 4, 3 and two inch fletch lengths with 3" performing the best overall in all profiles.
2) Cutting the hight of the fletches down to a lower profile by gradual increments (minimum 10mm) helped with cross winds effect, but dimimished flight stability.
3) Trimming a 4" tear drop profiles to 3" with a 30° straight forward cut.

So far, the straight cut fletches have shown the best compromise of stability in cross winds and reduced (but not completely eliminated) noise. The experiments continue.

 

[JAA7]

I always wondered about that and had it in mind to try a long low fletch to minimize the 'front edge' air resistance. It also occurred to me that the nearer the nock the fletch is the smaller it needs to be, so wondered if a fletch that is higher at the font, tapering towards the nock would work well.

Wild speculation... torn shoulder tendon, so no archery.

 

[Gers32]

I fitted Bohning Zen 4" (low profile) flights to my arrows with a need to clear the bow, but the manufacturer does claim that groups are improved by fitting them. You only need to induce drag at the back, to keep the flight straight, if your arrows are straight. Perhaps flights are unnecessary and you could wrap a bit of wool around them?

 

[Fbrit]

I fitted Bohning Zen 4" (low profile) flights to my arrows with a need to clear the bow, but the manufacturer does claim that groups are improved by fitting them. You only need to induce drag at the back, to keep the flight straight, if your arrows are straight. Perhaps flights are unnecessary and you could wrap a bit of wool around them?

The reason for fletchings is to impart spin to the arrow during flight. This improves stability and accuracy especially over longer distances, because the trajectory curve is lengthend. The drag caused by the fletches is cost we pay in arrow speed. The greater the angle of the fletches, the higher the spin rate, the more stable the flight, but the slower the arrow speed due to increased drag. Therefore the compromise here is spin rate to arrow speed. Arrow speed is directly proportional to down range trajectory and accuracy,
An arrow without fletches will fly straight over short distances due to the fact that momentum of the weight of the point in relation to the arrow shaft will encourage straight flight, hence the whole theory around arrow FOC. In fact part of the bow tuning process is to shoot unfletched arrows at a 20 yard target to check for correct arrow rest alignment. Incorrect alignment will induce porpoising or dovetailing of the arrow in flight where the back of the arrow swings up and down or side to side in relation to the point which in terms results in arrows hitting the target at an angle to their trajectory.
Wrapping wool on the arrow will indeed have a stabilising effect on the arrow but will not impart spin, but will slow the arrow like a parachute. Large fletches will be more effective at stability than small ones however the bigger they are, the greater the drag and the greater the effect of cross wind. Too small and the spin rate is less effective but cross wind effect and drag is less, so a faster arrow. The technical aspects of archery are all about compromises between the benefits of one to the deficits of another.