Main Discussion Area > Horn Bows
Composite Longbow
Digital Caveman:
I just found gemsbok horns online, surpassingly inexpensive, how would those hold up?
mmattockx:
--- Quote from: bownarra on December 11, 2020, 12:49:32 am ---Also you can't make the limbs all that wide because of the poisson effect.
--- End quote ---
Can you explain why the Poisson effect would be a problem on this style bow as opposed to other styles of bow?
--- Quote from: bownarra on December 11, 2020, 12:49:32 am ---I will post a picture if you want.
--- End quote ---
That's a silly question, of course we want pictures.
Mark
sleek:
Whats the poison affect?
scp:
I would love to see a composite bow with less than 14 inch long working limbs and more than 14 inch long siyahs.
mmattockx:
--- Quote from: sleek on December 11, 2020, 11:31:40 am ---Whats the poison affect?
--- End quote ---
Poisson, named after French mathematician Simeon Poisson. It is the effect where a material changes dimension perpendicular to the direction it is loaded in. Think of pulling on a rubber band, as it stretches in length it gets narrower in width. Also, when you squash a rubber block it expands in width.
This affects bows with wide, flat limbs because the back is being stretched while the belly is being compressed. This means the back surface is trying to get narrower while the belly wants to get wider. The end result is the limb cups towards the back when bent. You can easily see the effect by drawing a bow with wide rectangular section limbs on the tillering tree and putting a straight edge across the back of the limb.
Mark
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