Aero QA Aerostructures

Aero / structures QA (OpenAeroStruct)

Read docs/guidebook/03-openaerostruct.md and 09-sizing-aero-buildup.md; execute their "Check your work" lists.

Non-negotiables for this repo:

• Every AeroPoint surface needs BOTH mesh connections (<surface>.def_mesh and aero_states.<surface>_def_mesh) — a missing wing or fallback-htail connection gives NaN or silently-wrong results from the default mesh.
• CM is about the cg input; trim work must reference the real CG from openair.mission.balance, and the flat VLM needs the thin-airfoil cm_ac added for cambered sections.
• Trim gates in aero.json: trim.converged, selected control within ~1° of spec (tailless washout, fallback-tail incidence, or elevon deflection with elevon_within_travel and twist_frozen true), |cm_residual| < 0.005, and stability.sm_full/.sm_reserve inside the mission band (measured from dCM/dCL, not the geometric model).
• Elevon trim (openair.controls, geometry.mesh.deflect_trailing_edge): trailing edge up positive; the aero-only seed gets a hinge row and a taper-prescaled z shear; dcm_ddelta_per_deg (lift-trimmed) must be positive and smaller than dcm_ddelta_fixed_alpha_per_deg; the wingbox keeps the undeflected mesh. Any spec copy turned into a synthetic test wing must reset pitch_trim_control and drop the control surfaces.
• A measured wing.sections seed already carries local LE/chord/z: its OAS surface dict must omit taper, sweep, and dihedral, and elevon deflection uses taper factor 1. Its span grid must include every section knot and reproduce section-integrated projected area. Scalar wings retain the historical OAS transforms. OAS/wingbox t/c remains uniform even when OpenVSP/Studio and geometric packing carry section-local loft t/c.
• VSPAERO's built-in stability perturbation is only 0.01°. Require stability.analysis.derivative_quality.ok: convergence factors 0.01, symmetry-noise metrics ≤ 0.02, small/large-step CLα ratio 0.90–1.10, and strict relaxed-wake residuals or a recorded fixed-wake escalation. A finite .stab table alone is not evidence. If beta symmetry noise alone fails, a recorded central ±1° beta escalation may replace only the beta cross-noise estimates; keep the small-step values disclosed and apply the same 0.02 limit. A source-locked fin below the generic Vv screen needs quality-green same-run Cn_beta > 0, Cn_r < 0, CY_beta < 0—never a resized fin.
• All plain-flap effectiveness comes from openair.aero.thin_airfoil (Glauert: τ≈0.55 at 20% chord). Never reintroduce the complementary hinge angle acos(2*x_h-1); Diana 2's V1 force scale absorbed that bug and is deliberately refused.
• Wingbox failure <= 0 at +4g is the pass criterion (KS of von Mises over allowable minus 1, safety factor 1.5). W0 excludes wing mass and OAS's internal fuel burn (keep R tiny).
• Custom NLBGS solvers must keep err_on_non_converge=True.
• Mesh conventions: num_y odd full-span; symmetric half is the LEFT wing — j=0 tip, j=-1 root; spanwise CP arrays are tip-first.