Primitive Archer
Main Discussion Area => Bows => Flight Bows => Topic started by: JNystrom on September 05, 2017, 02:01:54 am
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I've made some personal progress in flight shoots, passing modest 250m ( 273 yards) multiple times with shortbows of 18-23" draw. The best being ironically with my weakest bow of 43 pounds, 22-23" draw and 54" ntn rowan flatbow (1" of reflex) of 275 yards.
Anyways, while making multiple flight arrows and testing them I came to think, is there some thing with the point weight I haven't figured out? All my past arrows have been pointless.
My arrow balance point has allways varied, and i have tested from 1,5" forward to 1,5" backward balance point.
The world of flight arrows feels like a huge sea of possibilities... I hope i have enough time and enthusiasm to try all! :D
What has been a treasure for me the past days to soak in information about flight gear, has been this grayson collection site. https://as-file.col.missouri.edu/fmi/webd#Grayson%20Objects
Use quest account, do a search and type in description field "flight" and you will find hundreds of gear from the golden flight era of 1930-1980.
Resemblance with the amount of arrows between the 1900's guys and Monus? ;)
Here is where i noticed, that allmost every arrow has a point weight! So there is something really important in them. What is it??
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Those are pretty good distances. Your balance point is about what I found to work best. Getting an additional 3" of draw length would help to get past 300 yards. I have used no point and small points and did not find any advantage to having a point. I also found that an arrow weight of around 275 to 300 grains worked best for a 50# bow. I think the best distance I ever got was around 330 yards. Here are some of the regular flight arrows I have made
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But if working balance point area is 3", its reeeeally wide "good point". Could it be that shooting to headwind, forward balance works, when shooting to backwind, backward balance works? I haven't still figured that much difference with the balance point. Maybe when i get some decent yards under the arrows...
Those are really nice looking arrows. What is the fletching size in those 275-300 grains weights?
Thing with the point is that it really makes a difference with the expected lifetime of the arrow, my soft pine/spruce arrows tend to slowly break from the point. I have somehow fixed this with heattreating the ends and putting a superglue coat. For example it would be really annoying to break good arrow before competition.
I try to make bows with longer draws, its just that i like my bows short and heavy. I have a wych elm static 90 degree recurve, 60# @23" and 55" long. It just has 3 inches of reflex and it is a selfbow.
I hope these new records we just heard from the salt flats boost the enthusiasm towards flight shooting! I have many thoughts and questions that i would like to share. As you might noticed! :D
We really need some Monus arrows presented here!
edit: length of the elm recurve was 55", not 59".
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Here is a link to some information on the Turkish flight arrows.
http://www.turkishculture.org/lifestyles/turkish-culture-portal/turkish-flight-arrows-554.htm?type=1
I have found that the bulbous nock appears to give greater distance, possibly cleaning up the air flow around the back of the arrow? Having the fletching as far back as possible as per the pictures is a good idea.
The ivory points that they used are that small that it would only be a small increase in weight compared to no point. The main function I guess is more to strengthen the end of the arrow and allow them to be shaped better than wood alone.
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Nice points, they make perfect sense. Bulbous nock and sharp taper at the end. The sharp taper might be the thing.
It's common knowledge that point needs to be more like a bullet, than really sharp. But the ivory will surely hold it's form better than wood itself. So after all the effort you put into the arrow, you actually get to shoot it again.
I have read that article many times, but didn't pay that much attention to the nock end. Do you construct your nock with two pieces of wood like in the article? Or just sand it to its shape.
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nice performance :)
it is my understanding that weight forward of center might let you get by with smaller/less fletching, and the fletching is only there to create drag, your enemy when shooting for distance.
I have experimenting mostly with atlatl darts though, and do not know if some recommendations can be extrapolated to arrows.
10 to 15 percent FOC seems to be enough, although some archers seem to go to extremes
having the FOC created by a distributed mass in the front half of the projectile seems to work better than just adding weight to the tip. I think this has something to do with where the dynamic flexing happens (slightly off topic).
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It is true that arrows with FOC let you use smaller fletchings, but they also make the arrow drop shorter. There's no gliding effect of back balanced arrow. I wish i got to see Monus arrows with some information and dimensions...
The 10-15% FOC is way too much in flight arrows, in my opinion. The most i would do is 5%. If you look at the turkish arrows, all of them are more than -5% FOC, so quite the opposite.
Distributed mass in front is worth trying. Many of those museum arrows from the record guys are footed with hardwood.
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My experience with atlatl darts has been a pleasant way to see how aerodynamics effect dart design changes. Short ranges and low velocities make for easy observations, and I do not expect the 10% FOC for darts should be applicable to flight arrows.
Actually, FOC calculations should be replaced with an examination of Cp, (center of pressure) when looking at flight characteristics over varying velocities, as the Cp of an arrow changes with velocity, while FOC is an arbitrary approximation based on the length of the projectile, but does not consider the shape of the projectile.
Hardwood footings would seem to allow a smaller diameter profile for a more centrally balanced shaft.
Have you been able to examine the taper or barrel profiles of some turkish flight arrows?
A simple explanation of Cp, can be found here https://www.grc.nasa.gov/WWW/K-12/rocket/rktstab.html
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I agree with Willie's comment about the center of pressure. The center of balance doesn't mean much without knowing the center of pressure of an arrow. A negative FOC arrow will still fly stable with little or no fletching as long as the center of pressure remains rearward of the center of balance.
It is also interesting how the center of pressure moves depending on the speed of an arrow. A marginally stable arrow might fly just fine right out of the bow, but suddenly turn and fall from the sky as soon as it slows down enough that the center of pressure has moved ahead of the CG.
Back to the original question, I always put a light point on my arrows made of metal, bone, or horn just to protect the arrow from impact. It isn't necessary for much else that I know of.
Alan
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Guys I just came from the flats. My broadhead arrows were 27-29 inches in length. I put a 20" tapper on the arrows. My balance point was between 11-13" from my broadhead points. My fletchings was way too big . I managed 200 yds out of arrows weighing 450-500 grains from 50 pound selfbow. 20 short of record. I will be working on points and fletchings on that set of arrows and moving mass around in other arrows for more distance. Maybe y'all can do the math on what I just gave ya. I can't I will tell ya. Arvin
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Well, that center of pressure was a new thing! Of course everyone has experimented it somehow, but it's good to have right definition for it. So do you have a way to calculate the cp while making arrows, avcase? The string method in the end of the Willie's article should work, but if you say it changes with speed....
Like in many things, testing works, for you too, Selfbowman!
About the arrow points, avcase, how do you shaft those small bone/antler/horn points? I have seen the wedge style, but I have found it hard to do. Maybe i just need some practice.
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There is a trade off with fletching size vs balance point. I've seen some crazy arrow flight with small fletchings and balance point about 1/8" FOC (not one of my arrows) but it went about 40 yards, turned hard right and nose dived, then, just before it hit the ground it climbed and resumed a normal flight, eventually landing about 40 yards right of the initial line !.... scary :o
Mind most of my flight arrows have been for warbows, and I've turned small brass points to give a bit of weight. Tricky arrows, cos a warbow is fairly wide at the grip (approx 40mm)
Warbows aren't very well suited to flight shooting with V light arrows... mind I'm willing to hear any suggestions :)
Everyone knows a bullet point is better, for bullets... but is that really true at the velocities we are talking about? And at what scale is a bullet point a bullet point? E.G, With gradual taper as in barrelled arrow, how thin do you go before rounding it off to a bullet point...?
It's hard to determine the critical factors, and obviously that's why people build shooting machines. Unfortunately I've lost the test ground near me >:(
Del
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While back I hit 279 yards with lilac shortie 49", ~75# @19 with 4" brace height and 40mm wide handle. So its doable, you just need to have the arrow bend past the handle! Hah..
My yard calculations were wrong in the opening post, i hit 280 yards with the 43 pound rowan. Problems with yards, problems with inches!
The point-thickness variable is shady as you said, i have shot equally decent distances with almost blunt heads and sharp heads.
Turks had 3mm at the base of pile.
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There is a trade off with fletching size vs balance point. I've seen some crazy arrow flight with small fletchings and balance point about 1/8" FOC (not one of my arrows) but it went about 40 yards, turned hard right and nose dived, then, just before it hit the ground it climbed and resumed a normal flight, eventually landing about 40 yards right of the initial line !.... scary :o
Mind most of my flight arrows have been for warbows, and I've turned small brass points to give a bit of weight. Tricky arrows, cos a warbow is fairly wide at the grip (approx 40mm)
Warbows aren't very well suited to flight shooting with V light arrows... mind I'm willing to hear any suggestions :)
Everyone knows a bullet point is better, for bullets... but is that really true at the velocities we are talking about? And at what scale is a bullet point a bullet point? E.G, With gradual taper as in barrelled arrow, how thin do you go before rounding it off to a bullet point...?
It's hard to determine the critical factors, and obviously that's why people build shooting machines. Unfortunately I've lost the test ground near me >:(
Del
Many years ago when I had more interest in flightbows I had the idea of buying some 22 caliber spire point bullets and melting the lead out of the copper jacket then using the empty jacket for points
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Another reason I put a point on my "Primitive" arrows is that I build a lot of split-cane arrows and self-bamboo arrows, and it requires some kind of point to finish it off. For the split-cane and self bamboo arrows, the point has a tang that is inserted into a hole at the end of the arrow shaft. For solid wood arrows, I've drilled the end of the shaft to accept a tang, or created a conical shape on the end of the arrow shaft that matches an inverted conical shape drilled into the point. I leave a slight shoulder on the point and smooth out the transition to the arrow shaft with hide glue that I sand down. This is followed by a few coats of shellac, which is polished smooth, and a final polish of carnuba wax.
Alan
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I feel the point shape is less critical than other factors for a high performance flight arrow. However, the ideal shape should resemble the rounded nose shape of a 747 jet airplane, but this may be a relatively small factor as long as it is nicely rounded over. Sharply pointed shapes work best for supersonic projectiles, which is far beyond the speeds of the fastest flight bows. One of the worst performing flight arrow shapes that I have experience with are arrows that have a very long needle-like sharp point.
I don't have a very good method to analyze the center of pressure with my Primitive flight arrows. I do a little better job of this with my non-Primitive footbow arrows, by observing how they sink and shoot underwater. I can do this with arrows made of carbon and stainless steel components, but not with an arrow made of Primitive materials.
Probably the best advice I can recommend is to mark all your flight arrows with a permanent serial number and keep a log of how the arrows perform with different bows and shooting conditions. I observed some interesting things when I started doing this. First, I found that I had two or three arrows that were consistently the longest flyers, even if shot from radically different bows using radically different shooting styles. For example, I have one or two arrows that I found were used to set records for Modern Longbows 35 & 50lb), English Longbows(35 & 50 lb), and Primitive bows (35 & 50lb). Second, the arrows that matched the classic Turkish flight arrow geometry with the maximum thickness in the rear 1/3rd of the arrow were never my best performers. I have better luck with this shape if shot backward with the point where the nock should be, and nock where the point should be. Third, my high FOC arrows fly very consistent, but have not been the farthest flyers for whatever reason. They do seem to drill a deeper hole in the ground, but that is about it. Fourth, it is very important to pay a lot of attention to the fletching. Thick turkey feathers are the equivalent air-brakes.
Alan
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Great, thanks! I will try that.
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Hope I am not going too far off topic, as this is not much about points anymore, but there are some good observations being shared in this thread about aerodynamics that I would like to follow up on. There might even be some erroneous statements also. I have to question my own assertation that the Cp moves in relation to the CG as the arrow slows down. The lift and drag forces that act at the Cp on the lever arm are reduced as velocity diminishes, thus lessening the ability of the arrow to restore itself to efficient flight, if disrupted, but I cannot see why the length of the lever arm would have reason to change.
A few different questions have been on my mind.....
1. what is the gliding effect that JNystrom mentions?
2. why did the reproduction turkish arrows that Alan made, fly better backwards?
3. why do high FOC arrows nose dive more at the end of the flight?
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Well I would say do to gravity and the heaviest part of arrow will have tendency to fall faster, the fletchings will create drag against the heavy end . What goes up must come down. I don't know about the rest. Arvin
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I was wondering if this could be a reason to use a minimum of concentrated mass in the point. Its my experience that if shooting over the chrono, same weight arrows tend to be faster if having no steel arrow head. So it might influence acceleration?
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Well I would say do to gravity and the heaviest part of arrow will have tendency to fall faster, the fletchings will create drag against the heavy end . What goes up must come down. I don't know about the rest. Arvin
The mass of an object doesn't effect the speed at which it falls (in a vacuum), so it's only drag and position of the balance point that makes it fall point first. If the centre of mass is only just front of centre and you put the fletchings just behind the point it would fall nock first >:D ;)
I say one arrow shot a few times that flew completely wild, veering sideways, nosediving the suddenly climbing again before eventually settling to a more normal flight on a path about 46 degrees right of the line of aim.
My guess was it's centre of mass was too close to the geometric centre (about 1/8").
It wasn't an arrow that I'd made.
Del