2x JetCat P70 equivalent UAV with conventional horizontal tail · baseline-to-optimized evidence with an embedded model of the actual exported mesh.
Headline values come from the optimized aircraft’s own artifacts. Every gate below carries one-line evidence and a source path; the green state is not inferred from a stage’s top-level flag alone.
This source bundle reproduces the NASA AirSTAR Generic Transport Model T-2 using only:
truth/cases/gtm-t2/inputs/design-time-input-pack.yamlNo GTM released polynomial coefficient table, lift or moment slope, neutral point, trim result, lift-to-drag result, truth observation, scorecard, or acceptance margin was read or used.
The allowed pack cites:
nasa/GTM_DesignSim, revision
9717143270144aca1f5d38d7c24c0fce678d1589The source identity is a 5.5%-scale conventional swept-wing transport with retractable tricycle gear, a conventional horizontal tail, one centerline vertical fin, and two physical turbine engines represented by one equivalent propulsion record.
The VehicleSpec carries the supplied geometry directly:
sketch.treatment is requirement. The supplied planform targets and
tolerances are encoded without widening. The fin ranges are represented by
their midpoints and half-ranges.
The input pack supplies only fuselage maximum dimensions, not section stations, so no detailed GTM loft was invented. The generic unstated-station fuselage representation is used. Wing dihedral and geometric twist are also absent from the pack; both are initialized to zero. Horizontal-tail incidence is initialized to zero as a trim design variable, not as a claimed trim answer. Tail thickness ratios remain generic conceptual defaults.
The wing uses the explicitly documented NACA 2412 surrogate. It is a model-form approximation because VehicleSpec supports only NACA 4-digit sections; it is not a GTM aerodynamic calibration.
The one EngineSpec preserves the documented equivalent of two JetCat P70 engines:
The physical installation remains two engines at x=1.097 m with lateral
offsets of +/-0.3607 m. engine.x_m preserves the supplied longitudinal mass
station. VehicleSpec has no engine count or lateral installation-coordinate
fields, so propulsion and drag still use the repository's single-centerline
equivalent-engine abstraction.
Thrust lapse and part-throttle TSFC fields are unchanged repository engineering assumptions. They are not JetCat P70 measurements and were not fitted to GTM aerodynamic data.
Allowed design-time mass facts:
Onboard research equipment is fixed aircraft equipment, not removable
payload, so mission.payload_kg is zero and the removable payload box has
zero dimensions.
VehicleSpec has no direct takeoff-mass, zero-fuel-mass, CG, inertia, or
component-station fields. The source fuel is stored exactly with
fuel_mass_mode: fixed, because this reproduction evaluates the known tank
load rather than resizing fuel to the mission duration. With the generic
open-air structure/material/gear/contingency assumptions, the unsupported
fixed equipment is represented as an aggregate
mass.systems_kg=3.202370158813779. This makes
closed_mass_breakdown(spec, 5.2253841024 kg) reproduce the supplied
20.9695752651 kg zero-fuel mass and 26.1949593675 kg takeoff mass before
mission sizing changes fuel. No unsupported systems/avionics split was
invented; the aggregate is placed in systems_kg and avionics_kg is zero.
The fuselage-tank/system station is initialized at x=1.225 m as a transparent conceptual placement near the supplied initial CG. This is not a claim that NASA documented a tank at that station. Because engine installation coordinates and the full mass tensor are not representable, the repository's component-CG buildup is not expected to reproduce the supplied initial CG exactly.
The encoded wingbox gauges, material, gear fraction, and contingency are generic conceptual-model assumptions needed by the pipeline. They are not claims about GTM construction.
The source mission is:
MissionSpec has no direct cruise-TAS field and requires a positive
cruise_cl. The encoded value 0.5286830076410565 is derived only from the
allowed mass, area, altitude, and nominal speed using
CL = W/(0.5*rho*V^2*S). It reproduces 38.6 m/s at the supplied takeoff mass;
it is not a held-out aerodynamic coefficient. cruise_mach=0.113 also
preserves the supplied nominal value.
dash_mach_cap=0.70 is the unchanged repository computational search cap,
not a GTM performance requirement or prediction.
The final post-hoc reproduction uses
solver.tail_lift_effectiveness_factor=0.82. It is derived from the separate
class-B NASA 14x22 horizontal-tail damage/static-margin trend (NASA
20100002211, Fig. 5) and the same-run VSPAERO wing/body neutral point. It was
added after the initial blind run failed, is printed in the report, and does
not restore validation-holdout status.
sketchThe single-fin topology, conventional horizontal tail, engine totals, payload, mission limits, and source geometry remain design requirements rather than soft inspiration.
| Requirement | Target | Predicted | Verdict |
|---|---|---|---|
| Engine | 2x JetCat P70 equivalent | 2x JetCat P70 equivalent | MET |
| Payload | 0.0 kg | 0.0 kg | MET |
| Endurance | 0.27 h | 0.58 h | MET |
| Dash | maximize; M ≤ 0.70 | 356 km/h · M 0.29 | MET |
| Configuration | sketch envelope | 2.09 m span · 25.0° sweep | MET |
Source and delivered specifications deserialize; every source-locked field is unchanged except declared trim and same-run component-stability constants.
source=yes; optimized=yes; engine requirement=yes; payload requirement=yes; reproduction frozen=yes
design.yaml · Upstream response: Correct design.yaml values or schema violations; never patch generated JSON.The exported mesh—not only the intended parameters—matches the requested aircraft.
read-back=yes; bbox=yes; mesh checks=28
optimized/geometry.json · Upstream response: Fix OpenVSP construction, section placement, or source geometry, then rerun geometry.Engine, payload, and fuel occupy non-overlapping usable volume.
fuel-volume margin 0.058 m³; engine/payload clear
optimized/geometry.json · Upstream response: Move/resize bays, increase body or tank volume, or reduce required fuel.Same-run VSPAERO wing/body/nacelle evidence feeds the declared tail model; the resulting static margin is a component-model screen, not an independent measurement.
component-model SM full 0.336; reserve 0.351 MAC
optimized/aero.json · Upstream response: Adjust wing, payload, fuel, or engine longitudinal stations; recalibrate NP only with OAS evidence.The aircraft closes lift and pitching moment at its selected wing twist or tail incidence.
tail incidence -5.055° vs spec -5.057°; CM residual 0.0000
optimized/aero.json · Upstream response: Adjust twist/tail incidence, airfoil moment, CG/wing station, or OAS-backed calibration.Wing loading remains compatible with the documented CLmax assumption.
Vstall 27.677 m/s ≤ 31.0 m/s at CLmax 1.20
optimized/aero.json · Upstream response: Increase wing area, reduce MTOW, or change CLmax only with aerodynamic evidence.Source-locked geometry clears either the minimum conceptual fin-volume screen or same-run restoring/damping derivative checks; no upper-band sizing claim or fin-sizing optimum is made.
cant-corrected fin volume Vv 0.1163 ≥ 0.02 (source-locked reproduction)
optimized/aero.json · Upstream response: Correct the source geometry or remove the reproduction claim; do not resize a source-locked fin to make the screen pass.The OAS wingbox survives the positive limit load with the encoded safety factor.
+4g failure index -0.882; CL 0.791/0.791; lift closed=yes; mass closed=yes; tip deflection 0.006 m
optimized/structures.json · Upstream response: Increase skin/spar gauge, section depth, or material capability; reduce load only by changing requirements.The closed fuel budget meets endurance and installed thrust covers modeled drag.
0.58 h; cruise/dash thrust ≥ buildup drag
optimized/aero.json + baseline/mdo.json · Upstream response: Trade fuel, mass, drag, cruise condition, wing geometry, or propulsion assumptions upstream.Source coordinates remain frozen while a separate OAS solve checks trim and structures; stability retains its declared independent-derivative or component-model evidence label.
feasible=yes; driver=yes; post-delivery verify=yes; calibration=yes; frozen=yes; 1 starts
baseline/mdo.json · Upstream response: Fix source serialization, trim/structures verification, or stability provenance; do not optimize frozen reproduction coordinates.Delivered proportions stay inside the hard identity bound and every soft-prior departure is explained.
span/L 0.81; root/L 0.15; sweep 25.0°; 0 scored shape departures; 0 total audit records
optimized/design.yaml + baseline/mdo.json · Upstream response: Fix unjustified departures or the upstream physics; never widen the hard identity bound silently.Required analytical identities and declared-scope solver checks pass, method spread is disclosed, and headline values reproduce from same-phase artifacts.
core 13/13; VSPAERO/OAS CLα ratio 0.949; NP method spread 0.196 MAC (diagnostic); report Mach 0.291 vs recomputed 0.291; MTOW report/aero/MDO 26.195/26.195/26.195 kg; L/D report/aero/MDO 9.726/9.726/9.726
optimized/validation.json + optimized/report.json · Upstream response: Use the failed validation check name to fix its upstream model or calibration.The first figure and interactive hero are rendered from the exported STL itself. The remaining figures expose the numerical story: what changed, where drag and mass live, and how close the design sits to its constraints.
The baseline is the aircraft as drawn; the optimizer answers what it presented. Both columns below are read from their own phase artifacts — the two phases are different aircraft and are never mixed inside one number. The delivered configuration is checked by a separate OAS solve; stability evidence is labeled by method.
| Quantity | Baseline | Optimized | Change |
|---|---|---|---|
| Wing span | 2.088 m | 2.088 m | unchanged |
| Wing area | 0.548 m² | 0.548 m² | unchanged |
| Aspect ratio | 7.95 | 7.95 | unchanged |
| Taper | 0.397 | 0.397 | unchanged |
| LE sweep | 25.0 deg | 25.0 deg | unchanged |
| Airfoil | NACA 2412 | NACA 2412 | unchanged |
| Thickness t/c | 0.120 | 0.120 | unchanged |
| Tip twist | 0.00 deg | 0.00 deg | unchanged |
| MTOW | 26.19 kg | 26.19 kg | unchanged |
| Fuel | 5.23 kg | 5.23 kg | unchanged |
| Dash speed | 356 km/h | 356 km/h | unchanged |
| Endurance | 0.58 h | 0.58 h | unchanged |
| Cruise L/D | 9.73 | 9.73 | unchanged |
| Stall speed | 27.7 m/s | 27.7 m/s | unchanged |
| Static margin (full) | 0.336 MAC | 0.336 MAC | unchanged |
| Trim tail incidence | -5.05 deg | -5.06 deg | unchanged |
Mission, topology, and proportions become a validated, version-controlled concept specification.
Fuel and MTOW close at 0.58 h; artifact geometry and OAS models establish the reference.
Source coordinates remain frozen while same-run OAS closes model calibration and verifies trim, stability, and structures.
Separate OAS and mesh-truth checks produce the 356 km/h delivered configuration.
| Start | Dash | Endurance | MTOW | Feasible |
|---|---|---|---|---|
| deterministic_reference_closure | 356 km/h | 0.58 h | 26.2 kg | yes |
| Attempt | Internal band | Evaluated full / reserve | Verdict |
|---|---|---|---|
| same-run component analysis | declared solver evidence | {"ok":true,"method":"VSPAERO hybrid: thick fuselage/nacelles + thin main wing","points":[{"ok":tr… | PASS |
Analytical identities, OAS comparisons, VSPAERO, artifact-level geometry checks, and stretch solvers test different failure modes. TACS and SU2 are shown as calibration data—not promoted into certification evidence.
| Check | Class | Observed | Reference | Verdict |
|---|---|---|---|---|
| k450 tsfc kg per kgf hr | core gate | 1.467 | 1.467 | PASS |
| breguet round trip | core gate | 7,200.0 | 7,200.0 | PASS |
| isa T sl | core gate | 288.1 | 288.1 | PASS |
| isa rho sl | core gate | 1.225 | 1.225 | PASS |
| oas induced drag vs elliptic | core gate | 0.003 | 0.003 | PASS |
| cantilever deflection identity | core gate | 0.014 | 0.014 | PASS |
| thin airfoil cm ac | core gate | {"0012":0.0,"2412":-0.05311944998613994} | {"0012":0.0,"2412":-0.047} | PASS |
| fin volume coefficient | core gate | 0.116 | >= 0.02 or passing same-run directional derivatives (source-locked reproduction) | PASS |
| fin te within body | core gate | 0.011 | <= 0.051816 m | PASS |
| hybrid component provenance | core gate | {"wing_body_np_mac":0.10846023017447082,"wing_body_cl_alpha_per_deg":0.078237979588} | serialized constants trace to converged same-run VSPAERO | PASS |
| wing mass buildup vs oas | core gate | 4.071 | 0 < wing structural mass < 20.9696 kg reference OE mass | PASS |
| vspaero vs oas CL | core gate | 0.949 | n/a | PASS |
| elevon cm delta vspaero vs oas | core gate | n/a | pitch trim control is not elevon | PASS |
| tacs artifact schema | stretch calibration | tacs | stretch; schema presence only | PASS |
| su2 convergence reported separately | stretch calibration | [false,false] | stretch; 'ok' means ran+parsed, 'converged' is the residual verdict | PASS |
Component extents, fin verticality, whole-model envelope, and root attachment are measured on exported STL files.
VSPAERO versus OAS lift-curve slope across α=[3.0, 7.0]° on the same lifting surfaces. Absolute CL has different camber fidelity; CD is intentionally not compared.
Shell mass 1.807 kg; SU2 cruise converged=no, rmsρ=-2.088.
This section preserves the details needed to challenge or reproduce the design. Values are generated from the delivered optimized YAML and same-directory stage outputs.
| Parameter | Value |
|---|---|
| Fuselage | 2.59 × 0.25 × 0.30 m |
| Wing | 2.09 m span · 0.55 m² · AR 7.95 |
| Planform | root 0.38 m · taper 0.397 · LE sweep 25.0° |
| Airfoil / thickness | NACA 2412 · t/c 0.120 |
| Twist | root +0.00° · tip +0.00° |
| Single fin | 0.40 m span · 0.0° cant |
| Propulsion | 2x JetCat P70 equivalent · 136.3 N SL |
| Fuel | 5.23 kg delivered spec |
| Structure | wingbox · skin 1.80 mm · spar 2.50 mm |
| Material | Al7050-T7451 · yield 470 MPa |
| Item | Mass | x station |
|---|---|---|
| operating_empty | 20.97 kg | 1.218 m |
| fuel_wing | 3.37 kg | 1.253 m |
| fuel_fuselage | 1.85 kg | 1.225 m |
| Python | 3.12.3 |
| OpenVSP | OpenVSP 3.51.3 |
| OpenMDAO | 3.45.0 |
| OpenAeroStruct | 2.12.0 |
| Pydantic | 2.13.4 |
| NumPy | 2.5.2 |
| Matplotlib | 3.11.1 |
name: gtm-t2
notes: Post-hoc reproduction of the NASA AirSTAR Generic Transport Model T-2. Geometry,
mass targets, equivalent twin-engine totals, mission, and requirement envelopes
come from the GTM T-2 input pack. The single centerline fin and conventional horizontal
tail are source-locked. NACA 2412 is the documented conceptual section surrogate,
not a calibration. Tail lift effectiveness is explicitly calibrated from separate
class-B NASA tail-damage evidence; no polynomial score target is embedded here.
sketch:
treatment: reproduction
hard_scale: 3.0
fidelity_weight: 1.0
span_over_length: 0.805741176
span_over_length_tol: 0.01
root_over_length: 0.145163813
root_over_length_tol: 0.008
le_sweep_deg: 25.0
le_sweep_tol_deg: 2.0
taper: 0.396781509
taper_tol: 0.03
x_le_root_over_length: 0.368702698
x_le_root_over_length_tol: 0.012
payload_bay_x_lo_m: null
payload_bay_x_hi_m: null
fuel_tank_x_lo_m: null
fuel_tank_x_hi_m: null
twist_tip_lo_deg: null
twist_tip_hi_deg: null
fin_span_m: 0.4
fin_span_tol_m: 0.03
fin_root_chord_m: 0.42
fin_root_chord_tol_m: 0.04
fin_le_sweep_deg: 38.0
fin_le_sweep_tol_deg: 5.0
fin_cant_deg: null
fin_cant_tol_deg: null
fin_x_le_m: 2.1
fin_x_le_tol_m: 0.05
engine:
name: 2x JetCat P70 equivalent
energy_source: liquid_fuel
diameter_m: 0.1372
length_m: 0.315
dry_mass_kg: 2.4
installation: external
installation_count: 2
x_m: 1.097
lateral_offset_m: 0.3607
z_m: -0.15
max_thrust_sl_n: 136.251202024
fuel_flow_max_kg_s: 0.007410599682
thrust_lapse_k_mach: 0.35
thrust_lapse_floor: 0.08
tsfc_part_a: 0.8
tsfc_part_b: 0.2
tsfc_mach_k: 0.15
min_throttle: 0.18
fuel_density_kg_m3: 800.0
nacelle_frontal_cd: 0.08
deck: null
wing:
span_m: 2.08751424
root_chord_m: 0.376085409793
taper: 0.396781508797
le_sweep_deg: 25.0
dihedral_deg: 0.0
twist_root_deg: 0.0
twist_tip_deg: 0.0
t_over_c: 0.12
airfoil: '2412'
x_le_root_m: 0.955234950997
z_root_m: -0.08
sections: null
tip_chord_m: 0.14922373633420458
area_m2: 0.5482951614713902
aspect_ratio: 7.947755166229314
mac_m: 0.2789834399996898
y_mac_m: 0.446751850114518
x_le_mac_m: 1.1635587600003139
x_ac_m: 1.2333046200002364
fuselage:
length_m: 2.5908
max_width_m: 0.25
max_height_m: 0.3
nose_fine_ratio: 0.22
tail_fine_ratio: 0.28
payload_bay_length_m: 0.0
payload_bay_width_m: 0.0
payload_bay_height_m: 0.0
payload_bay_x_m: 1.225
fuel_tank_x_m: 1.225
stations: null
fairings: null
vtail:
count: 1
root_attachment: derived
span_m: 0.4
root_chord_m: 0.42
taper: 0.45
le_sweep_deg: 38.0
cant_deg: 0.0
t_over_c: 0.1
x_le_m: 2.1
y_root_m: 0.0
z_root_m: 0.13
area_m2: 0.1218
htail:
span_m: 0.88
root_chord_m: 0.28
taper: 0.45
le_sweep_deg: 30.0
t_over_c: 0.1
x_le_m: 2.2
z_m: 0.1
incidence_deg: -5.057
area_m2: 0.17864000000000002
mission:
endurance_s: 960.0
endurance_required: true
payload_kg: 0.0
cruise_altitude_m: 304.8
dash_altitude_m: 304.8
cruise_mach: 0.113
cruise_cl: 0.5286830076410565
dash_mach_cap: 0.7
limit_positive_g: 4.0
limit_negative_g: -2.0
safety_factor: 1.5
static_margin_min: 0.25
static_margin_max: 0.4
reserve_fuel_fraction: 0.08
cl_max: 1.2
cl_max_basis: section
stall_speed_max_mps: 31.0
pitch_trim_control: auto
structures:
fem_model_type: wingbox
spar_thickness_m: 0.0025
skin_thickness_m: 0.0018
tube_radius_m: 0.018
tube_thickness_m: 0.0025
wing_weight_ratio: 1.35
n_spanwise: 9
n_chordwise: 3
material:
name: Al7050-T7451
E_pa: 71700000000.0
nu: 0.33
yield_pa: 470000000.0
density_kg_m3: 2830.0
G_pa: 26954887218.045113
spanwise: null
modal_calibration: []
sensor_stations: []
drag:
interference_fraction: 0.08
protuberance_cd0: 0.004
mass:
fuel_mass_kg: 5.2253841024
fuel_mass_mode: fixed
fuel_capacity_kg: null
listed_mass_min_kg: null
listed_mass_max_kg: null
listed_mass_state: null
operating_empty_mass_kg: 20.9695752651
operating_empty_cg_x_m: 1.2180642122340803
systems_kg: 3.202370158813779
landing_gear_fraction: 0.035
avionics_kg: 0.0
contingency_fraction: 0.08
flight_dynamics:
enabled: false
reference_airspeed_mps: 18.0
reference_altitude_m: 0.0
inertia: null
control_surfaces: []
aeroelastic:
enabled: false
strip_count: 48
modes_per_family: 1
frequency_min_hz: 0.5
frequency_max_hz: 30.0
frequency_points: 160
maximum_reduced_frequency: 0.3
elastic_axis_fraction_chord: 0.4
lift_curve_slope_per_rad: null
calibration_id: none
allow_diagonal_inertia_approximation: false
calibration_id: none
solver:
oas_with_viscous: true
oas_with_wave: true
optimize_maxiter: 35
optimize_tol: 1.0e-05
fd_step: 0.001
vspaero_wake_iters: 20
vspaero_convergence_factor: 0.01
su2_maxiter: 200
gmsh_lc_m: 0.08
stability_method: hybrid_component
np_shift_mac: 0.15
wing_body_np_mac: 0.10846023017447082
wing_body_cl_alpha_per_deg: 0.078237979588
cm_washout_per_deg: 0.0042
tail_incidence_offset_deg: 0.0
tail_lift_effectiveness_factor: 0.82
tail_lift_effectiveness_source: NASA 14x22 GTM horizontal-tail damage, Frink et
al. 2010, NASA 20100002211 Fig. 5; combined with same-run VSPAERO wing/body NP
elevon_effectiveness_factor: 1.0
elevon_effectiveness_source: null
n_ult: 6.0