How do you perform a drag breakdown analysis for an aircraft?

Drag breakdown analysis separates total drag into components: Skin friction drag using flat plate correlations adjusted for form factor; Pressure (form) drag from integrated CFD pressure distributions; Induced drag from Trefftz plane analysis or lift-dependent methods; Wave drag using CFD or area-rule based estimates; Interference drag from junction regions; and Excrescence drag from antennas, gaps, rivets. Methods include CFD component breakdown, wind tunnel testing with different configurations, and bookkeeping using semi-empirical methods (DATCOM). Results guide design improvements by identifying major contributors.