Standard Test Method for Determining the Force-Draw and Let-Down Curves for Archery Bows

This test method establishes the procedure to be used to measure the force necessary to draw an archery bow from brace height to the full draw position, and the holding force necessary to retain the bow string when the bow is let-down from full draw to brace height. The force values taken at increments of draw length are then plotted versus draw length using rectangular coordinates. The resulting curves are known as the force-draw curve and the let-down curve.

The force-draw curve is used to determine the energy that the limbs of the bow store when it is drawn. The area under the curve between the positions of brace height and full draw can be expressed as stored energy.

The let-down curve is used to determine the energy required to restrain the bowstring as the bow is let-down from full draw to brace height. The energy represented by the area under the curve can be subtracted from the stored energy in order to establish the static hysteresis of the bow system.