parasite-draglisted

Use when the task is drag buildup, zero-lift drag estimation, the wetted-area method, skin-friction coefficients, form factor, interference factor, or equivalent skin-friction coefficient in a preliminary drag assessment. Estimate the parasite (zero-lift) drag of a fixed-wing aircraft with the component buildup method: compute the flat-plate skin-friction coefficient from the Reynolds number for laminar and turbulent flow, apply the form factor and interference factor to each component, convert the wetted area into a drag coefficient, and sum the wing, fuselage, nacelle, and tail contributions into the total parasite drag. Also back out the equivalent skin-friction coefficient from the total wetted area and the total drag. Trigger: parasite drag, zero-lift drag, skin friction, wetted area, form factor, interference factor, drag buildup, Reynolds number.
ashfordeOU/aero-agent-skills · ★ 0 · AI & Automation · score 78

Install: claude install-skill ashfordeOU/aero-agent-skills

# Parasite Drag Buildup (aerodynamics/drag-polars/parasite-drag) Use when the task is estimating the zero-lift (parasite) drag of an aircraft by the component buildup method: flat-plate skin friction, wetted areas, form factors, and interference factors for the wing, fuselage, nacelle, and tail. ## Domain quick reference - Parasite drag is the drag at zero lift: skin friction, pressure drag from separated or thick boundary layers, and miscellaneous excrescences. It is the CD0 term of the parabolic drag polar CD = CD0 + k * CL^2. - The buildup method sums per-component drag coefficients: CD_i = Cf * FF * Q * S_wet_i / S_ref Cf is the flat-plate skin-friction coefficient, FF the form factor, Q the interference factor, S_wet_i the wetted area of the component, S_ref the reference area, and CD_parasite = sum of all CD_i. - Flat-plate skin friction depends on the Reynolds number Re = rho * V * L / mu (density, speed, length, viscosity): laminar Cf = 1.328 / sqrt(Re); fully turbulent Cf = 0.455 / (log10(Re))^2.58. With transition at Re_tr the mixed value is Cf = Cf_turb(Re) - (Re_tr/Re) * (Cf_turb(Re_tr) - Cf_lam(Re_tr)). - Wetted area is the surface actually in contact with the flow. A first-order wing estimate is S_wet = 2 * S_exposed * (1 + 0.2*t/c); fuselage and nacelle wetted areas come from body dimensions. - Form factors inflate the flat-plate value for the component shape: wing/tail FF = 1 + 2*(t/c) + 100*(t/c)^4; fuselage FF = 1 + 60/(l