The W47 was 18 inches in diameter and 47 inches long, and weighed 720 pounds in the Y1 model and 733 pounds in the Y2 model. The Y1 model had design yield of 600 kilotons and the Y2 model had a doubled design yield of 1.2 megatons. The W47 was the first warhead with a new, miniaturized pit. The aerodynamic flare at the base provided stability of orientation during descent. Two small rocket motors were used to spin the warhead for better stability and symmetry during reentry.