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A New Bow of Radical Design, Construction and Performance
Part 5 of 9

Having shown the advantages of the new type 6 bow, attention will now be called to its disadvantages. This bow as well as types 2 and 4 must be constructed of laminations if they are to be highly reflexed. During the process of drawing, there is a force tending to separate the back from the belly, whereas in all the other types this force is one of compression. In types 2 and 4 there is this same tendency for the back and belly to be separated during the act of bracing, but before fully braced the force changes to one of compression. It may therefore, in some cases, be necessary to use external wrappings or binders to hold the back and belly together. The new bow is not, in general, as stable as the others. But since it is necessary to make it wider in order to increase the weight, the stability will be improved. There is some question as to the effect of the new bow on the romance of archery. We are so accustomed to seeing a bow take a graceful bend as it is drawn that it looks odd, to say the least, to see bows with their limbs straightening as the archers draw them.

A method of constructing suitable limbs for the new type bow will be described. The principle involved is applicable to other bow limbs as well as to any flat spring.

069-01_small (4K) 069-02_small (5K) 069-03_small (4K)
 Click for a larger image   Click for a larger image   Click for a larger image 

If two thin strips 35 and 36 of wood, for example, are clamped at one end as shown in Fig. 7 and the free ends are deflected a distance No as shown in Fig. 8, the fiber stresses in the two strips will be approximately equal. The deflection in either strip at any point P1 on the section A—A' is proportional to the deflection No, and to the distance from the neutral plane of the strip. We may therefore write

formula10 (1K) (10)

where N1 is the deflection at P1, K1 is a constant of proportionality, y is the distance of P1 from the neutral plane of the strip 36 and t is the thickness of the strip.