Starting with a spring index of C = 10, design a compression coil spring of phosphor bronze with closed ends. The spring is to deflect y = 2 in, for an applied force of F = 15 lbf and to close solid when ys = 3 in. At closure, use a design factor of 1.2 guarding against yielding. Determine the smallest-diameter wire based on preferred sizes. For the design, specify the wire diameter, the inside and outside diameters of the coil, the spring rate, the total number of coils, the free length of the spring,