1. The problem statement, all variables and given/known data An aircraft is flying straight and level at 300 kilometers per hour at an altitude where the density is 0.9kg/m^3. The ratio of lift to drag coefficients for this aircraft at this flight condition is 15. Its weight at the moment under consideration is 98,000 Newtons. The aspect ratio of the wing is 8. Wing span is 15m. Assuming spanwise efficiency of 1, what is the induced drag coefficient? Thus, what is the profile drag coefficient? What is the speed for minimum drag for the aircraft at the same altitude and weight? 2. Relevant equations V = 300 km/h = 83.3 m/s W = 98,000 N L/D = 15 AR = b^2/S so S = 28.13 m^2 e = 1 rho = 0.9 3. The attempt at a solution Lift coefficient = W/(q*S) = 2*W/((rho)*V^2*S) = 1.12 Induced drag = Lift coefficient^2/pi*AR*e = 0.0500 L/D = 15 = 0.114/Drag; Drag = 0.0747 profile drag = 0.00759-0.000515 = 0.025 Now, I know profile drag equals induced drag for minimum drag but how do I go about finding the velocity where this occurs?