A lightweight parachute is being designed for military use. Its diameter (D) is 24ft, and the total weight (W) of the falling payload, parachute, and equipment is 230lbf. The design 'terminal settling speed' Vt of the parachute at this weight is 18ft/s. A one-twelfth scale model of the parachute is tested in a wind tunnel. The wind tunnel pressure and temperature are the same as those in the prototype, namely 60 degrees Farenheit (F) and standard atmospheric pressure.
a. Calculate the drag coefficient of the prototype. (Hint: at terminal sttling speed , weight is balanced by aerodynamic drag.)
b. At what wind tunnel speed should the wind tunnel be run in order to acheive dynamic similarity?
c. Estimate the aerodynamic drag of the model parachute in the wind tunnel?