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A New Bow of Radical Design, Construction and Performance
Part 3 of 9

It may also be shown that the length of the draw when the string of the new bow is at right angles to the limb is given by the equation.

formula09 (1K)

Where the letters have the same significance as before. If B = 16", l = H = 4", D will equal 24.7". This is an increase in the draw of 43 per cent over that for 1 and 2.

A model of the new type as shown in Fig. 6 was constructed and the force plotted as a function of the draw. (Curve 2, Graph 2). The stress or force on the tips was also plotted and is shown on the same graph by curve 4. A model of type 2 was made having exactly the same dimensions, but shaped as shown in Fig. 2 (a). The reflex was made such that at full draw, the stress in the limbs was the same as for type 6. Curves 1 and 3, Graph 2, give the drawing force and the force on the tips respectively as functions of the draw. The stress as shown by curve 3 starts at a value of 41 pounds and increases to 86 pounds, while the stress for type 6 starts at 18 pounds and rises to the same value, 86 pounds.

065_small (20K) 066_small (19K)
Graph 2 Graph 3

The work that may be obtained from type 2 is equal to the area bounded by the curve 1, the line CE and the line EF. The point (A) on curve 1 shows the position at which the string is radial to the arc formed by the limb. It is not considered good practice to draw the bow farther than this point, although it is done in flight shooting. The work that may be done by type 6 is equal to the area bounded by the curve 2 and the lines DE and EF. This area is much larger than that for type 2. The point (B) on curve 2 shows the position where the string is at right angles to the limb. This bow may therefore be drawn still farther than the point D. In this comparison, it is assumed that when fully drawn, type 2 is bent in the form of a circle. In practice this would not be the case after the pull passes the point A on curve 1. (Graph 2). In order to pull this bow to a point corresponding to point C, the string would be pulling in such a direction that the bow would bend more near the handle. It is very doubtful if this type bow could be drawn this far.