Primitive Archer
Main Discussion Area => Bows => Topic started by: lonbow on May 13, 2017, 03:09:04 am
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It´s generally said that bows should be stiff at the tips for reducing limb vibration. But I´ve already seen some warbows that actually bend slightely at the tip area (I´m writing about a continuation of the bend to the tips and not about whip tillered bows). One of the bows was an original from the Mary Rose and some reproductions I´ve seen do also have bending tips. So I wonder why it was done. Was it made like that for reducing the stress on other parts of the limbs and for reducing mass at the tips? Is there actually more limb vibration? Are there other bow designs like weaker longbows or flatbows that could actually benefit from a design with bending tips? Is the design only appropriate for bows with long limbs? (There probably would be bad energy storage for short bows because of the bigger angle bethween the limb and the bowstring).
Do you have any experience and thoughts about that topic?
Thanks in advance,
lonbow
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Too many vague questions. What do you mean by tips... there is so little leverage near the tips that they seldom bend visibly over the last 3" or so. You are unlikely to have seem Mary Rose Bows with their tips bending as they only flexed a few.
Or do you mean recuved tips? Which can either be stiff or flexing.
One needs to be very explicit in your terminology and explanations if you want meaningful answers.
IMO Warbows are generally arc of a circle tillered so each point is bending equally, (with a slight stiffening at grip and extreme tip).
The problem is that optimum designs depends on so many factors and what you are trying to achieve. Are you trying to:-
Shoot an arrow as far as possible.
Make a smooth accurate long lasting bow.
Shoot a heavy arrow at armour.
Make a bow that is easily carried in the brush and is accurate and powerful for short range hunting.
The other problem is that theoretical optimum designs may only suit modern materials so you can't copy a modern Olympic recurve using a stave and expect it to work (yes I've tried !)
There are too many subtle differences to even generalise. I used to think the Mollegabet design with stiff levers was bonkers, so I thought I should build one... pound for pound draw weight wise it is one of my best bows for flight shooting.
Bottom line, try 'em and see!
A good way to experiment is to re-tiller old bows and see if you improve them :)
Del
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a slight bend would probably shoot ok,,and certainly reduce the mass,,
making a bow of similar design,, and shooting through a chrono, would answer most questions,, )-w(
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There's a lot of really good info in TBB 1 on this. I know the authors have rethought some of that book, but I believe what is written about this topic is sound.
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I have always believed that one of the big reasons stiff tip bows tend to perform a little better is because they have less limb to vibrate which is one of the biggest losses in any bow modern or primitive. Either way I don't think it makes a huge difference. If you need the extra bending limb to avoid set I would use it.
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Yes, the Möllegabet design is a really good one with a very long and stiff tips. A friend makes Möllegabet bows out of osage and they are fast and have zero hand shock. So actually I didn´t intend to generalise.
My thought was just that there might be some bowdesigns with special characteristics which would work as good or even better with slightly bending tips (where you still have very little bend over the last 3-4 inches). In the book "Weapons of Warre" you can find a picture of an original Mary Rose bow flexed (page 625) and I do believe to see some little bend quite close to the tip area (Thanks by the way for mentioning that book in your video, Del :) ). On victorian bows (for example from Richard Head longbows), there is less bend close to the tips. Is the difference of the tiller due to the different amount of stress on the material or are there other reasons for it, like a sometimes very low arrow mass compared to the draw weight for warbows. A 1000 grain arrow shot from a 150 lbs warbow makes only 6,7 ggp and one of the lighter arrows from the Mary Rose with a weight of let´s say 695 grain makes less than 5 ggp for the same bow. That´s so low that reducing the mass of the limbs could have a greater effect on arrow speed than energy storage. Ore are there other reasons for the different tiller?
Maybe I should try different tillering profiles one day for bows of the same draw weight ;)
lonbow
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Leaving the last 6 inches slightly stiff gives a nice smooth draw because it reduces the string angle. That's good for a relatively short hunting bow.
Elb's are usually longer and the string angle is not an issue.
Jawge
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That sounds evident!