Primitive Archer
Main Discussion Area => Horn Bows => Topic started by: sleek on September 12, 2016, 09:12:21 pm
-
It has become my mission in the hobbie to make self bows of the same length ntn, same draw weight and same draw length as horn bows while achieving the same kenetic energy. In the arrow. I believe it can be done and will be covering everything from flight bows to war bows. I will be recreating in a self bow the brace and full draw profile as best as I can of each style.
I dont plan on building any horn bow style I cant get stats on such as ntn length, draw weight and length, and fps of what grain arrow. Fd charts would also be nice. So, if you have a horn bow, and want to help me out, I would love all that information as well as brace and full draw pics.
My wood of choice will be osage, only because it heat bends so well. I think other woods such as elm would be more suited but, availability and workability come in play.
I will be posting links here to the threads I build them on so the bows are all easily referenced and found. I hope thats ok?
-
I'll be keeping an eye on this thread, this will be interesting and exciting to see.
-
I don't think my horn bow would be very difficult compared to some others, it's something like 55ntn, 60# and only draws max to 30 but best to 28-29. I could give you full stats some time this week, including f/d curve, reflex when unstrung for days and just unstrung after shooting.. not a speed demon due to the heavy ears but not too slow either.
The problem is, I don't have a chronograph.
I think you'd have to get wood as good as what Mikke has used... or mikekeswick's hazel.
-
I don't think my horn bow would be very difficult compared to some others, it's something like 55ntn, 60# and only draws max to 30 but best to 28-29. I could give you full stats some time this week, including f/d curve, reflex when unstrung for days and just unstrung after shooting.. not a speed demon due to the heavy ears but not too slow either.
The problem is, I don't have a chronograph.
I think you'd have to get wood as good as what Mikke has used... or mikekeswic's hazel.
Force draw chart is fine. No chrono is needed absolutely.
-
There are some incredible statistics online. I seriously doubt you can even come near the speed of the heavy weight horn bows.What you are trying to do is definitely possible if you limit your draw weight, say under 60 pounds. Good luck.
-
There are some incredible statistics online. I seriously doubt you can even come near the speed of the heavy weight horn bows.What you are trying to do is definitely possible if you limit your draw weight, say under 60 pounds. Good luck.
You may be very right. It will be interesting to see at what weight horn and sinew passes wood in performance.
-
As i think about your point more, I think my first goal should be matching the fd curve of the bow I am imitating. Then the bows will differ in how the materials ability.
-
There are some incredible statistics online. I seriously doubt you can even come near the speed of the heavy weight horn bows.What you are trying to do is definitely possible if you limit your draw weight, say under 60 pounds. Good luck.
But, Joe Gibbs shot a swiss yew and a tatar hornbow. Both 180lb. They shot around the same fps with a 63.3g (976.7 grains) arrow, though the horn bow had been strung for a long time..?
-
String a longbow for a week and see what fps it gives you! Bear in mind that hornbows were never really designed for extra heavy arrows (apart from a few designs like the Manchu etc). Longbows however due to their heavy/slow moving limbs are.
Sleek - I like your style but you are trying to match an oranges performance with an apples. No wood will make a Turkish shaped bow that is comparable. Horn/wood/sinew can store more energy per mass than any wood.It is impossible as the materials are just too different. You could make a bow that is 'similar' but not the same. Look at big a steel bridge then try to make the same bridge out of stone.
-
Mike, I appreciate your opinion. I cant say about energy per mass. I dont plan on calculating that. I am only going off of draw length, weight, and ntn length along with braced and drawn profiles. I dont know if wood can match horn and sinew when compared to mass and energy storage. Seems a stretch for certain.
However, I do intened to either do it, or prove it cant be done. As far as Kenetic energy to tje arrow goes, I did come very close to your 48" horn bow with an osage, though it did use sinew. But that does show horn isnt needed.
-
Two bows looking alike at brace and full draw does not mean they will have the same amount of stored energy.It's what the tension is on that string throughout the draw from the get go that's the difference in stored energy.It begins with the design and unbraced profile and integrity of materials used.Not paying attention to mass per draw weight is a mistake also when going against horn bows.
Comparing KE between bows using different weight arrows on each bow is not an accurate or true test of 2 bows.
-
Well, reckon ima need mass specs too then.
-
Biggest problem will be availability of data. I dont think im going to make mass a goal, but will be happy to measure it when done for comparison. I do plan on shooting similar arrows in weight to compare KE. I dont want efficiency of one bow to skew the results of another by not comparing grain weight arrows. Of course, that limits me to basically k owing a person with a horn bow to get that info from.
As to your point on brace and full draw profile, I know the unbraced is 1/3 the equation. But that will be the only variable I work with to make the brace and full draw effective profiles for these bows. Add to the variable, frontal profile as well. I want to recreate horn and sinew with wood only and allow myself the variables I have based on only " Thats how I wanna do it."
-
The amount of energy per mass that the materials can store and their elastic limits are the factors that will determine what shape bow you can make.
Bear in mind that 48 inch is overly long for a Turkish bow. 42 - 44 inch being the average and the limbs only bend over a 12 inch section...My 48 incher could be drawn to 30 with no ill effects.
When I say that you can't make a wooden bow the same or really even close to a Turkish bow I not guessing! The materials are not capable of it. It could be proved with numbers but....that isn't necessary! If (and i'm sure you can with sinew to stop splinters lifting) you manage to get one to stay together it will be a heavily overstrained bow that will not perform well....there is no way around it.
Don't you think that IF it could be done it would have been done?!? How long have people been making bows? How long have people known the properties of wood through experience of working with it? If it was possible to make a comparible bow out of wood why did the Asiatic peoples even bother to make hornbows?
I suggest you try to make some broadhead flight bows. I made a whole batch of them a few years ago and they taught me a lot about what you can get out of a wooden bow. The best performers are always the ones that get to full draw with low set and haven't ever been overstrained. Making a great wooden bow is about learning to finesse your way upto full draw and keeping the wood 'fresh' along the way. My best wooden bow was a b.locust r/d recurve. Nothing extreme apart from short , sharp recurves, about 2 inch overall reflex and that thing is smoking fast and it looks nothing like a hornbow.....because the materials used are totally different....they can't look the same. Material properties are what determine design and you simply can't separate the two. Think about the analogy I made above regarding the bridges.....;)
-
I was just reading Tim Bakers "Bow design" chapter(around page 50) last night and I think he claims that the side profile of the "used and unbraced" bow will determine the energy storage. Doesn't matter whether it's all wood or sinew or horn, as long as the unbraced shape and draw weight are the same and the bow actually survives the bend, the energy storage will be the same. Are we disputing that?
-
Why don't you try making the identical bow in horn and self wood yourself that way you can keep as. any of the other variables the same as you can and then compare the results?
Although a true test would also require making a horn bow to self bow specs to compare? Like a horn ELB design? It seems like the differing designs are to bring forth the potential of the differing materials
-
Horn takes way too much work to do that with. But i have seen a few large ones built.
-
Maybe partner with a horn bow builder then? You each make two to identical specs, one design favoring wood the other horn?
-
sleek...I'd hate to be accused of trying to stop you from doing what you wanna do and the way you wanna do it.
You really don't need a horn bow maker to get this done.There is plenty of info out there a person can get.Comparing curves,designs, and statistics etc. if accurately done.You seem to know what that's all about already or should have a good idea about it to go on an adventure like this.Then it's just a matter of making the bows like you said.
-
Sorry if I spoke out of turn I wasn't trying to say he shouldn't do it his way. Just thought it might be interesting to see tha same design made with different materials
-
Sorry if I spoke out of turn I wasn't trying to say he shouldn't do it his way. Just thought it might be interesting to see tha same design made with different materials
Your point was valid. No worries on what you or anyone has said. I just need to do what I can to make me happy and satisfied with my results, and be sure to be honeat about what they really represent. Problem is, I could never do a complete scientific test with hard fast results. So I will get close as I can within my level of interest, and make bows.
Honestly, my main goal is to make short horse bow size, weight, and draw length bows and get the best out of them I can. I am using horn bows as my measuring stick. Pun not intended but still humorous.
-
Understood I just didn't want to come across as arrogant.
If I understand correctly even two identical self bows from the same wood made to the same dimensions can still shoot differently but your test sounds interesting.
-
I still think the two can come way closer in performance regardless of pre-strung profile. The hand held wood bow record still stands at way over 500 yards. Same with the sinew backed wood bow.
You can look at the results from the last Wendover shoots to see how the horn bow guys are faring so far.
Part of the problem right now is that neither the wood nor horn guys are bringing their best game relative to the old ways.
-
You are probably right pat. I should like to prove you right though. And a world record would be fun to chase...
-
Many years ago I posted a recurve I had made on ATARN along with the performance I was getting. Adam contacted me about it asking for more info, I think he was surprised at how fast it was, for a wood bow.
-
You have my attention:)
-
Unfortunately it was too long ago and I don't remember much about it. I know it was a deflex static recurve but I don't remember if it was sinew backed or hard backed, I don't have the bow anymore
-
I was just reading Tim Bakers "Bow design" chapter(around page 50) last night and I think he claims that the side profile of the "used and unbraced" bow will determine the energy storage. Doesn't matter whether it's all wood or sinew or horn, as long as the unbraced shape and draw weight are the same and the bow actually survives the bend, the energy storage will be the same. Are we disputing that?
This is not true, pretty good indicator but a bow with plenty of reflex can have crappy performance. I built two bows a couple of years ago with about 12" of reflex and big recurves. It maintained most of its profile but the wood was basically crushed after a dozen or so shots and I had a mediocre performer, Thats why I now measure the draw weight at different points, sometimes a bow wont take much set but will loose weight.
-
I was just reading Tim Bakers "Bow design" chapter(around page 50) last night and I think he claims that the side profile of the "used and unbraced" bow will determine the energy storage. Doesn't matter whether it's all wood or sinew or horn, as long as the unbraced shape and draw weight are the same and the bow actually survives the bend, the energy storage will be the same. Are we disputing that?
This is not true, pretty good indicator but a bow with plenty of reflex can have crappy performance. I built two bows a couple of years ago with about 12" of reflex and big recurves. It maintained most of its profile but the wood was basically crushed after a dozen or so shots and I had a mediocre performer, Thats why I now measure the draw weight at different points, sometimes a bow wont take much set but will loose weight.
Hence the *used* and unbraced reflex would be low? ie reflex right after shooting, then unstringing
Another thing that affects the energy storage is the tiller? How close to the handle the limbs bend? And I guess also where the reflex is, closer to handle or outer limbs. Of course you can also have a bow that stores a ton of energy that shoots horrible because it's very inefficient. Manchu bows are only great at very heavy arrows - long horn bows
-
The reason Horn Bows are so good is because of their shape and design that allows for earlier energy built up in the beginning of the draw. Theoretically if you built a self bow with the same design and it holds up it would perform similarly. However, there are two problems. 1) Self-bows usually can't take that much energy without breaking or getting set. I am finishing up on a another short wood bow with only paper backing. Its 43" knock to knock and draws 45#@27". That being said it has a horrible energy storage curve because the wood just can't handle the design. It got a lot of set and string follow. If a wood bow was to compare to a horn bow it would have to be able to retain the large reflex without taking set. Now this could be because I'm using less than Ideal wood and errors in my tillering, but it still illustrates the problem. 2) the other issue is even if you were able to get the same force curve as a horn that doesn't mean it will spit out an arrow at the same speed. Some material is less efficient at transferring potential energy into kinetic energy. The only way to know is to get the efficiency ratio by taking the kinetic energy determined by the velocity and arrow mass and divide it by the stored up potential energy determined by the force curve.