Consider a light, single-engine, propeller-driven airplane similar to a Cessna Skylane. The airplane weight is 2950 lb and the wing reference area is 174 ft². The drag coefficient of the airplane CD is a function of the lift coefficient CL for reasons that are given in Chapter 5; this function for the given airplane is CD = 0.025 + 0.054C2L .

a. For a steady level flight at sea level, where the ambient atmospheric density is 0.002377 slug/ft³, plot on a graph the variation of CL , CD, and the lift-to-drag ratio L/D with flight velocity ranging between 70 ft/s and 250 ft/s. 

b. Make some observations about the variation of these quantities with velocity.