Centre of Pressure (Xcp) outside aircraft geometry limit even after disabling fuselage and wing-tip pressure forces

Questions, suggestions, feature requests, bug reports, feedbackCategory: QuestionsCentre of Pressure (Xcp) outside aircraft geometry limit even after disabling fuselage and wing-tip pressure forces
Aadarsh GejageAadarsh Gejage asked 5 days ago
  1. I am analyzing a fixed-wing VTOL UAV (wingspan ≈ 2.5 m) in FLOW5; the fuselage is imported as a .STEP file, and all surfaces are properly meshed with no open edges, except intentional control-surface hinge lines.
  2. The Centre of Pressure along the global X-direction (Xcp) for the whole aircraft is consistently reported outside the physical aircraft length (ahead of the nose or behind the tail). This behavior persists even after disabling both “Include contribution of fuselage pressure forces” and “Include wing-tip pressure forces” and is independent of panel density (uniform and linear density triangular panels both showing same results).
  3. Geometry orientation and reference system have been verified (global X-axis correct, origin at nose/leading edge); clarification is requested on whether Xcp outside the aircraft is expected due to CP definition at low lift, or if an additional setup or best-practice requirement should be applied.
1 Answers
André Deperroistechwinder Staff answered 2 days ago

By definition, the location of the center of pressure will go to +/- inifinity when the lift tends towards 0.
x_Cp = sum(x Fz) / sum(Fz)