In the flight_model config file, there is an [AIRPLANE_GEOMETRY] section that describes the airplane geometry for the purposes of flight behavior. Changing it does result in changes in the flight behavior of the aircraft, regardless of what the visual model looks like.
Here are just a few excerpts from the section on the wings:
wing_area = 193.75 ; Wing area S (SQUARE FEET)
wing_span = 39.89 ; Wing span b (FEET)
wing_root_chord = 6.5 ; Wing root chord croot (FEET)
wing_camber = 1 ; (DEGREES)
wing_thickness_ratio = 0.05 ; Local thickness is local_chord(x)*wing_thickness_ratio, x = lateral coord
wing_dihedral = 6.5 ; Dihedral angle Lambda (DEGREES)
wing_incidence = -2 ; Wing incidence (DEGREES)
wing_twist = 0 ; Wing twist epsilon (DEGREES)
oswald_efficiency_factor = 0.731 ; Wing Oswald efficiency factor e (non dimensional)
wing_winglets_flag = 0 ; Has winglets true/false
wing_sweep = 1.7 ; Wing sweep (DEGREES)
wing_pos_apex_lon = -14.41833 ; Longitudinal (z) position of wing apex w.r.t reference datum (FEET)
wing_pos_apex_vert = -1.2 ; Vertical (y) position of wing apex w.r.t reference datum (FEET)
And here are are some TABLES used to describe some flight geometry and behavior:
elevator_elasticity_table = 0:1, 40:1, 250:0.33
aileron_elasticity_table = 0:1, 40:1, 250:0.33
rudder_elasticity_table = 0:1, 40:1, 250:0.33
elevator_trim_elasticity_table = 0:1, 40:1, 250:0.33
lift_coef_aoa_table = -3.15:0, -0.8:-1.323, -0.4:-1.107, -0.2:-0.809, -0.1:-0.508, 0:0.168, 0.20:1.389, 0.23:1.521, 0.26:1.637, 0.29:1.412, 0.31:1.279, 0.4:1.072, 0.8:1.341, 3.15:0
drag_coef_zero_lift_mach_tab = 0:0.000, 0.5:0.000, 0.55:0.000, 0.6:0.100, 0.65:0.200, 0.7:0.243, 0.75:0.286, 0.8:0.329, 0.85:0.371, 0.9:0.414, 0.95:0.457, 1.0:0.500, 1.1:0.264, 1.5:0.025
SUMMARY
So this supports Willis’ statement that the visible geometry isn’t necessarily used for flight calculations. Take a look at the flight_model config file and you will be struck by the amount of detail it contains about the aerodynamic detail you would need for that. We know that people have made odd shapes fly, and I agree with Willis. They probably have flight geometry described in the config file, and the visual model is just that – visual.