Flight Arrows

[avcase]

DC, Your systematic approach should serve you well.  A well tuned arrow makes a big difference.

I have an article in my files somewhere written by one or the leading flight archers of the 1970’s. I recall that he used a test where he measured the buckling force on his arrows. But it may have been different thing because the arrows were shot with a release through a keyhole type riser.

I used to sort my flight arrows by their natural vibration frequency.  It requires good organization and good note taking in order to get something out of it.

Alan

[DC]

How would you measure the frequency?

[avcase]

How would you measure the frequency?

Usually, I balance the arrow near my ear and tap it. This will emphasize a higher pitch 4th mode harmonic, but I can clearly hear it. The frequency it rings at is a function of its distribution of stiffness and mass.

Alan

[DC]

Oh good one thing I can forget. I've got hearing aids.

[DC]

Alan, I think it was in the build a long you mentioned pinching feathers to decide if they were good for flight arrows. Have you arrived at a legal species to use? Can a feather be too floppy/soft?

[DC]

Does the cock fletch have to be 90°to the string? I want to try some vellum fletching but the arrow has a horn insert in the nock end that is 90° to the string(right where i want the cock fletch to be) and it will be very difficult to cut a groove for the fletch in that thin piece of horn.

[avcase]

Alan, I think it was in the build a long you mentioned pinching feathers to decide if they were good for flight arrows. Have you arrived at a legal species to use? Can a feather be too floppy/soft?

I have had success with various pheasant tail feathers and smaller waterfowl feathers. I used to have some Guinea fowl feathers that worked pretty well too. I used to sort through a lot of feathers to find a few precious ones that were exceptionally stiff and thin.  The shape and size of the feather is pretty important to combat flutter. My best mimic the shape of the typical Turkish flight arrow. I make the height about the same as the diameter of the arrow shaft.

It has been too long since I have been able to devote time to the natural material flight categories. It seems like vanes from thin vellum parchment should work better.  Ivar Malde used vanes made from some kind of durable hand made paper for his 600+yard record. Adam Karpowicz also uses this kind of vane for his horn bow flight arrows and they work great.  The only thing I found which could be better is vanes made from very high quality water buffalo horn. They seemed very promising if you can avoid contact with the bow.

Alan

[DC]

I've been making shafts out of various woods. I have a 25" Hemlock with a .700 deflection, 2 lbs @ 22" That flies well so I'm trying to duplicate that in different wood to see if I can get a smaller diameter. So far I've tried Hemlock, Doug Fir, Ocean Spray, Sitka Spruce, Beauty Bush and Cotoneaster. (PS and Black Walnut) All of them except the OS ended up with close to the same diameter. The OS was getting to close to the pith to continue reducing and it still weighs 470 some grains. The weights were similar too with the Hemlock being the lightest at 213 grains. Should I be seeing a bigger difference? Did I happen to pick woods with a similar weight/stiffness ratio? I finally get to go shoot them this weekend so that may tell me something. I do have one OS arrow that I cut out of a stave so it has no pith. I can reduce it more but it weighs almost as much as the bow so I don't think OS is the answer. It just seems that it doesn't really matter what wood I use. Can you see something I'm doing wrong?

[willie]

Should I be seeing a bigger difference? Did I happen to pick woods with a similar weight/stiffness ratio?

arrow stiffness changes fast as diameter increases. on a bigger order of magnitude than if you optimize material stiffness.

on the other hand, diameter imposes its own aerodynamic penalties that cannot be avoided.

[DC]

I thought that the idea was that you can use a denser, stiffer wood and so reduce the diameter and end up with the same weight and spine in a skinnier package but it's looking like dimensions trump density. At least as far as stiffness is concerned.

[mmattockx]

I thought that the idea was that you can use a denser, stiffer wood and so reduce the diameter and end up with the same weight and spine in a skinnier package but it's looking like dimensions trump density. At least as far as stiffness is concerned.

Stiffness is proportional to the 4th power of the diameter, so it is vastly more influential than material. If you double the stiffness of your material (which is hard to do with wood) then the diameter only drops to 84% of the original diameter.


Mark

[willie]

the 4th power of the diameter

that seems decisive enough to just work with whatever Dfir, hemlock. spruce, larch or pine has a reasonably high stiffness:density ratio.  one criteria might be how well your choice survives impacts.  oven dried wood might be too brash in spite of stiffness gains. I think I read where different woods were tested for brashness/impact in the aircraft spruce alternative paper. Also some interesting comparisons at the end of the paper.
  https://ntrs.nasa.gov/api/citations/19930091423/downloads/19930091423.pdf

Do the records in the class you wish to enter show any arrow specs? knowing more about the typical arrow may help you choose whether the lightest possible arrow is actually better than a heavier one that might carry further in spite of a lesser initial velocity.

[DC]

I took a half dozen arrows to the field today. All my new low spine were too low spine. They came out of the bow sideways so 35# 28" no tips is too light. It's looking like 50# spine is what I need even with no tip weight. I had made 6 arrows all little different were and there and they all shot within a few yds of each other. No joy there.
What does a tail wind do to arrow flight? Mostly I'm wondering about the difference between heavy and light arrows. Like will a heavy arrow benefit more from a tail wind or vice versa.
I did shoot a PB at about 260 yds with a Hemlock 37# spine 312 grain arrow. The wind had changed to cross wind by then. I think it was just a 50# bow instead of a 40# bow.

[Badger]

DC, at 260 yards you are still not getting good distance so I wouldn't use those arrows as a model. Anything under 300 yards you are not getting good flight. Your bow is fast enough to hit 400+yards with decent arrow flight.

[DC]

Yeah, I was shooting against hunting bows and was only 20 yds past them. I was getting very poor launch I think. How much can the launch affect the distance? Somehow I just can't see anything that will get me out to 400 yds. Even if I changed a half dozen things that got me 10 yds each I'm still short.