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General Formulas for Static Strains and Stresses in Drawing a Bow
Part 4 of 4

Making use of these formulas the values of the variables are computed for various lengths of draw and curves drawn as shown in the graph. The value of C is usually about unity so that assuming a value of unity for C, the force in pounds may be read for the string tension T, the drawing force, F, and the displacement at the bow tip, N.

The curve for N shows us the displacement of the bow tips for any draw. It should be noted that the displacement of the tip is always about one-half the total draw after the bow is about one-half drawn.

The curve for T/C shows us the tension in the string for any draw. The tension in the string is highest when the bow is at rest. As the bow is drawn the tension decreases for awhile and then increases. The total change in the tension does not amount to very much. In other words the tension remains reasonably constant throughout the full draw. This may easily be proven by placing a string balance in the string of a bow and reading the pounds tension as the string is drawn. As shown by the curve, the tension will be greatest when the bow is at rest. It will not change very much throughout the full draw. This subject will be discussed in greater detail in subsequent articles.

The curve for F C shows the force on the fingers during the draw. For a bow, the constant of which is unity, (i.e., C = 1) the force may be read directly in pounds.

Value of N, T/C and N/C vs draw
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