How is the aircraft drag polar constructed?

Drag polar (CD vs CL) built from components: Parasite drag (CD0) - Friction and form drag at zero lift, Component buildup (fuselage, wing, nacelles, empennage, misc.), Calculated from wetted area and form factors; Induced drag (CDi) - Drag due to lift, CDi = CL2/(pi*AR*e), where e is Oswald efficiency (0.75-0.85 typical); Compressibility drag - Wave drag above critical Mach, significant for transonic aircraft; and Trim drag - Drag from trim load on horizontal tail. Analysis methods: Conceptual - Component wetted area with empirical coefficients; Preliminary - Panel methods, CFD for pressure drag; and Detailed - Full CFD (RANS), validated with wind tunnel. Drag polar form: CD = CD0 + k*CL2, where k = 1/(pi*AR*e). Accurate drag prediction is critical: 1% drag error = significant fuel burn difference. Flight test validates and tunes drag models. Drag reduction focus: laminar flow, winglets, smooth surfaces.