# Jet Twin: FOSS provenance

> What we can fold into lucid.rodeo for a Noyron-*shaped* jet-engine design loop,
> and what we cannot (because it is closed).

## The honest answer on Noyron

**[Noyron](https://leap71.com/noyron/) is proprietary.** LEAP 71's Large Computational
Engineering Model (thermal rules, manufacturing logic, rocket/heat-exchanger CEMs) is
customer-only. They have said publicly they are *considering* open-sourcing parts; as of
2026 that has not happened. We do **not** ship or reverse-engineer Noyron.

What LEAP 71 *has* released as FOSS:

| Artifact | License | Role |
|---|---|---|
| [PicoGK](https://github.com/leap71/PicoGK) | Apache-2.0 | Voxel geometry kernel (C++/C#) |
| [ShapeKernel](https://github.com/leap71/PicoGKShapeKernel) | Apache-2.0 | Shape helpers on PicoGK |
| [HelixHeatX](https://github.com/leap71/LEAP71_HelixHeatX) | Apache-2.0 | Worked heat-exchanger CEM example |

PicoGK is the **geometry** half of the Noyron stack, not the thermodynamics. Useful later
for printable cooling channels / casings; not the twin's live cycle engine.

## FOSS thermodynamic / design stacks we *can* fold in

| Project | License | Fit for lucid.rodeo |
|---|---|---|
| **[NovaTurbo AI](https://github.com/axonyxquantum/novaturbo)** | MIT | Closest Noyron-inspired FOSS: Brayton stations, micro-turbojet geometry, Three.js UI, NSGA-II. **`brayton.js` here is a browser port of their `brayton.py`.** |
| **[OpenMDAO/pyCycle](https://github.com/OpenMDAO/pycycle)** | Apache-2.0 | Serious NASA-lineage jet cycle analysis (NPSS-inspired). Next upgrade path for off-browser / Worker fidelity (CEA or tabular thermo). |
| **[Huracan](https://github.com/alopezrivera/huracan)** | GPL-3.0 | 0-D airbreathing architectures (turbojet / turbofan / turboprop). Strong for multi-spool teaching; GPL means keep it out-of-process or as a cited sibling, not copy into Apache/MIT pages. |
| **[T-MATS](https://github.com/nasa/T-MATS)** (NASA) | NASA Open Source | MATLAB/Simulink turbomachinery. Offline validation, not browser. |
| **CoolProp / Cantera** | permissive | Real-gas / CEA-adjacent properties when we leave the ideal-gas cold/hot γ split. |

## What this twin claims (SkyLab grade)

- **Grade: APPROXIMATE.** Ideal-gas Brayton, cold/hot γ, component isentropic efficiencies,
  ISA atmosphere, throttle as ṁ + TIT schedule. No blade CFD, no spool inertia, no combustor
  chemistry network.
- **Provenance on HUD.** NovaTurbo MIT Brayton + ISA; Noyron named as inspiration only.
- **420-code law.** Consistency, not proof; the HUD says where it simplifies; kill the twin
  before it teaches a false number as exact.

## Suggested fold-in roadmap

1. **Now (shipped):** browser Brayton digital twin + controls (`/skylab/jet-twin/`).
1b. **Cinema (shipped):** WebGL2 set piece (`/skylab/jet-twin/cinema.html`) driven by the same Brayton solve. Visuals are **ILLUSTRATIVE** (procedural mesh, volumetric exhaust, bloom). Not CFD, not Noyron.
1c. **Dual-rotor audio (shipped):** Web Audio (`jet-audio.js`) prefers **NASA Langley** recorded jet noise + fan-tone auralization loops (`audio/`, see `ATTRIBUTION.md`). Compressor layer ↔ fan tones, turbine/exhaust ↔ recorded jet, core rumble ↔ synth-with-LFO; playbackRate/gains follow shared spool ω / Ve / TIT. Synth blade-pass fallback if samples fail. **ILLUSTRATIVE** staging of real source material, not a certified auralization of this micro-turbojet. No NASA endorsement.
1d. **Sound PWA (shipped):** phone-first installable app at `/skylab/jet-twin/sound/`: sound only, no animation; offline shell + cached NASA samples via service worker.
1e. **Turbo Sound suite (shipped):** multi-version sound-only hub at `/skylab/turbo-sound/` (jets + tuner / supertruck / tractor / farm truck). Jets: NASA packs + Brayton. Vehicles: on-device OfflineAudioContext render with single / twin turbo / supercharger and exhaust notes. Pressure-sensitive throttle pad on all decks.
2. **Next:** pyCycle Worker or offline proof for CEA/tabular cross-check; link from HUD.
3. **Geometry lane:** PicoGK / HelixHeatX patterns for cooling-channel / casing generation
   (separate tool; Apache stack), fed by twin station heat loads.
4. **Design loop:** NovaTurbo-style NSGA-II or a thin Pareto over thrust / TSFC / mass,
   still graded APPROXIMATE until CFD-calibrated.