he douglas dc-3 has a maximum velocity of 200 mi/h at an altitude of 7500 ft. each of its two engines provides a maximum of 1200 hp. its weight is 25,000 lb, aspect ratio is 9.14, and wing area is 987 ft2. assume the propeller efficiency is 0.8, and the oswald efficiency factor is 0.7. calculate the zero-lift drag coefficient for the dc-3.