calculate_responses2¶

Source: userfiles/SSBJ/subsystem2/calculate_responses2.py

Response calculation module for SSBJ Subsystem 2 (Aerodynamics).

This module provides aerodynamic calculations for the Supersonic Business Jet (SSBJ) problem.

Attribution: This file contains code derived from the DMDO framework by Ahmed Bayoumy, originally published under the GNU Lesser General Public License v3.0. Ahmed H. Bayoumy, the copyright holder of the original code, has granted permission to distribute this derived file under the GNU Lesser General Public License v3.0. Source: https://github.com/Ahmed-Bayoumy/DMDO/blob/DEV/tests/SBJ/SSBJ_Aerodynamics.py Relevant original functions: calculate_drag_polar(), poly_approx()

Modifications from the original: - Refactored from class SSBJAerodynamics to standalone functions; removed auxiliary methods (SBJ_aerodynamics_opt(), print_results(), init()). - Constants, coefficients, and state variables are passed as function arguments instead of class attributes. - poly_approx() decoupled from instance state (self.Z, self.ESFp, etc.). - Removed the if CLo[0] > 0 branch in calculate_constraints() (only the CLo[0] > 0 case is retained). - Adverse pressure gradient (calculate_drag_polar()): the base argument of poly_approx() is set to the fixed baseline thickness-to-chord ratio (tc = 0.05) to match NoHiMDO (SBJ_constraint_dragpolar.m). The DMDO port reused the local thickness_to_chord_ratio for both the base and the evaluation point (base == new), which collapses the response surface to a constant and makes the constraint inert. Using the fixed baseline as the base restores a live constraint that responds to the local t/c design variable. (DDO's aerodynamics subsystem only has access to its own local t/c, not the shared/target copy NoHiMDO passes as tc, so the baseline design value about which the response surface is fitted is used instead.) - Engine-scale-factor drag factor Fo1 (calculate_drag_polar()): the base argument of poly_approx() is set to the fixed nominal ESF baseline (engine_scale_factor = 1.0, i.e. the initial local design value) instead of reusing the current engine_scale_factor for both base and evaluation point. The DMDO port used base == new, which collapsed Fo1 to the constant Ao and made the ESF term in CDmin inert. Using base != new restores an Fo1 (and hence a minimum-drag coefficient) that responds to the local engine_scale_factor design variable, mirroring the adverse-pressure-gradient (tc = 0.05) fix above. - Added type hints to function signatures. - Added Google-style docstrings. - Added explanatory inline comments and physical units (e.g. [ft], [lb], [deg], [-]) throughout to document the design variables, responses, and intermediate quantities.

Functions¶

poly_approx(S, S_new, flag, S_bound)

Second-order polynomial response-surface approximation (SSBJ surrogate).

Fits a quadratic about the base point S and evaluates it at S_new, returning a dimensionless correction factor. NOTE: if S_new == S the normalized shift is zero and FF collapses to the constant term Ao (i.e. the factor becomes independent of the input).

Args:

S: Base (reference) values.
S_new: Evaluation-point values.
flag: Per-variable slope/shape mode selector.
S_bound: Per-variable bound used to fit the polynomial.

Returns:

FF: Dimensionless correction factor [-].

calculate_drag_polar(tail_sweep_angle: float, wing_moment_arm: float, tail_moment_arm: float, thickness_to_chord_ratio: float, wing_sweep_angle: float, wing_aspect_ratio: float, wing_surface_area: float, tail_aspect_ratio: float, tail_surface_area: float, total_weight: float, engine_scale_factor: float, wing_twist: float, h: float, Mach: float)

Calculate the drag polar and related parameters.

Args:

tail_sweep_angle: Horizontal tail sweep angle [deg].
wing_moment_arm: Wing aerodynamic moment arm [ft].
tail_moment_arm: Horizontal tail aerodynamic moment arm [ft].
thickness_to_chord_ratio: Wing thickness-to-chord ratio [-].
wing_sweep_angle: Wing sweep angle [deg].
wing_aspect_ratio: Wing aspect ratio [-].
wing_surface_area: Wing reference surface area [ft^2].
tail_aspect_ratio: Horizontal tail aspect ratio [-].
tail_surface_area: Horizontal tail reference surface area [ft^2].
total_weight: Total aircraft weight [lb].
engine_scale_factor: Engine scale factor, ESF [-].
wing_twist: Wing twist / incidence angle [deg].
h: Altitude [ft].
Mach: Mach number [-].

Returns:

List containing [Lift [lb], Drag [lb], LDr [-], Pg [-],
CLo_wing [-], CLo_tail [-]].