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A New Bow of Radical Design, Construction and Performance
Part 2 of 9

Many of the Asiatic bows have both of the foregoing features. These bows are highly reflexed and are also fitted with curved tips. The Turkish bow is an example of this type of construction and is shown in Fig. 4. The force-draw curve for this style bow is convex upward as shown by curve 3, Graph 1. The work that can be obtained from this bow is much greater than can be obtained from the other styles having the same holding force. On the other hand, the fiber stress is also much greater. Using bows of this style, the Turks have shot arrows over 800 yards. A substantial amount of this increase in cast was due to the fact that they used a composite bow of horn for the belly, maple for the core and sinew for the back. Due to the high clastic limit of these materials, they were able to make their bows very short. This made them ideal for flight shooting.

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There is one more form of construction that has often been used. In order to construct the highly reflexed limbs, it was necessary to use two or more layers. (a composite form of construction). In cases where the limbs were made of a single piece of wood, they could not be highly reflexed so they were often set back at an angle with the handle as shown in (a) Fig. 5. Pitching the limbs back at an angle gave the bow more potential energy in its braced position and thus made the force-draw curve more convex upward. These bows also have higher fiber stresses.

The style of bow to be described is shown in Fig. 6. The bow in its unbraced position is shown in (a). The limbs are set forward at an angle instead of backward as in type 5, and are highly reflexed. When this bow is braced (b), it is not necessary to have much potential energy in order to obtain a desirable force-draw curve. When the bow is fully drawn, the limbs are approximately straight as shown in (c) and the string makes an angle of 90 degrees with the limb. Such a construction permits the use of very short limbs with relatively long arrows. Curve 4, Graph 1, shows the pull force as a function of the draw. This curve is more convex upward than any of the others. This improvement is due to the advantageous angle that the string makes with the limb. In all of the other styles, the ends of the limbs arc soon bent forward and toward each other so far that the string is in a radial position. It is not considered advisable to pull these bows farther than this position. A simple mathematical consideration will show that the length of draw for types 1 and 2 which brings the string to the radial position is given by the equation,

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Where B is the length of each limb and L is one half the length of the handle and H is the bracing height. If B = 16", L = 4" and H = 4". D will equal 17.3 inches. This formula is quite accurate and takes into consideration the bracing height, the length of the handle and the manner in which the bow bends. The last two terms are rather small and to a great extent off-set each other so that a very good approximation is given by the formula D=.98B.