wave-drag-area-rulelisted

# Wave Drag and the Whitcomb Area Rule (aerodynamics/high-speed/wave-drag-area-rule) Use when the task is transonic wave drag: the Whitcomb area rule, cross-sectional area distributions, the Sears-Haack minimum-drag body, and drag divergence in high-speed configuration design. ## Domain quick reference - Whitcomb area rule (1952): at transonic speeds the zero-lift wave drag of a wing-body combination depends mainly on the streamwise distribution of the total cross-sectional area (fuselage plus wing and nacelle contributions), not on the details of the individual components. The rule follows from the equivalence between the aircraft and an equivalent body of revolution. - Area-rule shaping: where the wing adds area, the fuselage is pinched so the total area distribution stays smooth; the coke-bottle waist. The pinch at a station is S_fuselage = S_target - S_wing, computed with area_rule_fuselage_area. area_rule_deviation gives the RMS distance of an actual distribution from its ideal smooth target; a rougher equivalent body costs more wave drag. - Sears-Haack body: the minimum-wave-drag body of revolution for a given length and volume (Haack 1941, Sears 1947). Radius r(x) = r_max * (4 * (x / L) * (1 - x / L))^(3/4), zero at both ends and r_max at the midpoint. This is the shape the total area distribution should approach at transonic speeds. - Volume: V = (3 * pi^2 / 16) * r_max^2 * L. A 15 m body with a 0.54 m maximum radius holds about 8.1 m^