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250 pounder attempt

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rudderbows:
I spoke with Marlon tonight about the 250 pounder. he had some very good info and insight about heavy bows from an archers perspective.  Seems a person who shoots a bow is under compression normall BUT  that is why when they shoot a seriously heavy bow there is allot more compression and issues arrise from it. . This means the archer has to reach out alot farther to push against the compression necissary for a full draw  at 30-31 32 33 etc. He explained it allot better than I am right now. . he thought that numbers around 200 maybe slightly more and maybe slightly less were just about what flesh and bone can take and not much more no matter how strong an archer was. never occured to mem that the muscles and bone joints had limitations like that from compression. .  I may end up shooting te 250 pounder from a mechanical device. Marlon was very gracious to start working up to a 200 pound Boo backed ipe bow I am going to attempt to build for him,. I would really love to see an arrow fly from a really big bow.

RyanY:
I understand what he's saying but I don't think that drawing a 250# bow is in the realm of impossibility. I could be wrong but I'd like to find out more about the amount of force muscles and bone can take. If my memory is correct I believe that an average adult femur can withstand up to 2000# of force.
Also I understand if you leave me out rudderbows.  ;)

ChrisD:

--- Quote from: ryoon4690 on December 12, 2009, 04:28:14 am ---I understand what he's saying but I don't think that drawing a 250# bow is in the realm of impossibility. I could be wrong but I'd like to find out more about the amount of force muscles and bone can take. If my memory is correct I believe that an average adult femur can withstand up to 2000# of force.
Also I understand if you leave me out rudderbows.  ;)

--- End quote ---

True - but probably not relevant. Long bones are designed to take loads along their long axis and are strong that way but markedly weak when exposed to much smaller loads across the long axis - thats why they break in that situation. The issue with drawing bows really is one of leverage and force multiplication with the key question being 'what can the rotators of the shoulder handle at their points of insertion when drawing really heavy bows?'. These muscles arise from the scapula directly and that in turn is stabilised by muscles arising from the spinous processes of the vertebrae. Picture a shortish muscle rotating the proximal end of a long lever like the humerus and you get some idea of the mechanical disadvantage that these muscles are under. The forces at work drawing 40lb bows are said to be huge (I have them somewhere and I'll look them up). I very much suspect that Marlon is right in thinking that 200lb bows or so would provide in or about the physiological limit where the moorings of the tendon insertions would tear free from their bony anchor.

Chris

RyanY:
That makes sense. I mean there has to be a limit eventually to what the body can take. I guess I'd need to see some information about it before I really truly believe that 200#'s is the limit but I also understand that I'm stubborn and really want to think the human body is capable of much more. I mean even though the mechanical forces around the rotator cuff are at a disadvantage wouldn't stresses of around 1000# for a bench press cause a failure for those muscles involved? I'm not saying you guy are wrong, in fact you're probably right, I just don't want to believe it.  ;)

rudderbows:
Ryan,  I fully intend on following through with sending a heavy duty bow to you. I appreciate your willingness to give it a try.  Between you and Marlon I am betting we will learn allot here.  I am already learning allot.
--- Quote from: ryoon4690 on December 12, 2009, 04:28:14 am ---I understand what he's saying but I don't think that drawing a 250# bow is in the realm of impossibility. I could be wrong but I'd like to find out more about the amount of force muscles and bone can take. If my memory is correct I believe that an average adult femur can withstand up to 2000# of force.
Also I understand if you leave me out rudderbows.  ;)

--- End quote ---

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