Drag coefficient values also change depending upon the area used in the calculation of the drag force. Typically, several different drag coefficients are reported. A drag coefficient calculated using the projected area of a sphere has been reported by Coulson and Richardson [24], Clift et al. [1], and Isaacs and Thodos [18], among others. Tek Dec 12, 2017 · 0.110 m, Coefficient of Drag = .75, Empty Mass of Rocket = .074 kg Fig. 7. Exploring optimal launch pressure using computational model of altitude over time of a water bottle rocket with: Volume of Bottle = 2 L, (Volume of Water)/(Volume of Bottle) = 33%, Bottle Diameter = 0.110 m, Coefficient of Drag = .75, Empty Mass of Rocket = .074 kg