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Horn bows and stacking
gfugal:
--- Quote from: sleek on January 29, 2018, 12:06:03 pm ---A bow could be built with tips thay shoot straight down, creating 0 degrees string angle, and still have leverage as long as the nock is at or above the back of the bow.
--- End quote ---
What do you mean by 0° string angle? It all depends on your reference point.
here you have three separate reference points (1st which is verticle, probably in reference to the handle, 2nd reference point doesn't make sense to me but apparently it's been used in discussion before in the other thread on the bow forum, 3rd reference point is in reference to the tip of the limb which happens to be horizontal in the picture I drew). It also depends on where the string is and I have three potential string locations (1 verticle, 2 most like what we see, and 3 exactly horizontal to the tip). The colored angle arcs belong to one of the three reference points: blue to the 3nd (tip), orange to the 2nd, and purple to the 1st (handle). In all of these situations, I can only think of one that would have a string angle of 0° and that is a verticle string in reference to the verticle plane of the handle. But even in that situation the leverage does not equal 0 just because that string angle is 0°. while it is 0° in reference to the handle it is 90° in reference to the tip which gives a lot of leverage. So the fact that the bow isn't linear, but a curved arc really throws stuff like this off since there are so many potential reference points.
I personally like to think of string angle in reference to the tip, but the handle could work too. I downright don't get why you would use a diagonal reference point that seems to be hovering theoretically in space not connected to anything.
sleek:
Im glad you are giving this some thought. I will reply with pictures of what I am talking about when i get home. Im on a cross country trip right now, be home tomorrow.
gfugal:
--- Quote from: sleek on January 29, 2018, 11:55:19 am ---I disagree very respectfully. I believe it has everything to do with leverage and i believe I can prove it.
Simply putting the long post i made, the bigger the gap in distance, between the string nock, and the back of the bow, the more leverage. It has ZERO to do with string angle. String angle is a bi-product not a cause of leverage.
--- End quote ---
Yes the larger that gap the greater the leverage. This is what I was saying before when I was talking about the length of the lever, it's not just about string angle. But I think I was (and maybe you too) confusing leverage and torque. I was also misusing the word fulcrum before.
You get more leverage when you have a longer lever length from tip to the fulcrum. Greater leverage gives you more torque. More torque is what we want because we can get more stored energy with less effort on our part (greater speeds for the same draw weight). But leverage is not the only thing that affects torque. The direction of the force is also important. In this simple example, that doesn't translate well to the bow, the best direction for torque is perpendicular to the lever arm. if we imagine the thing applying this force is a string, then you can think of it as string angle. Thus, in this case, the optimal string angle is 90°. As you can see both levers may have the same string angle but the lower lever will move much easier with less force due to its leverage. likewise, you could have a different string angle than 90° with the same leverage, as depicted by the different colors, but again just because the string angles are the same between the two does not mean the torque is. So yes you're right, string angle may not be as important as leverage. But string angle is not the bi-product of leverage. leverage is independent of the direction the force is applied. Torque is not independent, but leverage is. In the lower image, the limb has great leverage regardless of either of those three potential string angles. Those three separate string angles could all potentially happen too so, therefore, it is not dependent on how long the lever is. So the amount of torque is a byproduct of the combination of leverage and force. The amount of force applied to the lever is a byproduct of string angle. It's also true that changing the lever shape on the limb may change the string angle (maybe this is what you're referring too). I agree with that. By changing the shape to increase the lever length and thus the leverage you may also change the string angle, but theoretically, they are independent things as depicted in my image.
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