# Turbojet CAD reconstruction

Open **index.html** for the offline interactive preview. Open **cad/Turbojet.FCStd** in FreeCAD 1.1 for the editable model. The original README.txt is preserved.

## What was delivered

41 separate PartDesign bodies, grouped under one main App::Part assembly and two App::Part subassemblies: 24 stationary components and 17 rotor components. The 16 compressor blades are integral pad features in the compressor body; the 12 turbine blades are separate parts. The manifest is exports/parts.csv. Each body has native sketches and Pad, Pocket or Revolution history. There are no mesh-only CAD bodies.

The main assembly is 265 mm long with a maximum 126 mm diameter. Units are millimetres and the shaft axis is global Z. These dimensions, the part allocation and detailed geometry are original reconstruction choices, not dimensions recovered from the video.

## Edit and rotate

1. Open cad/Turbojet.FCStd. Expand the main assembly and either subassembly.
2. Expand a body. Double-click its sketch to edit the profile, or select its Pad/Pocket/Revolution to edit length or angle in the Data properties. Annulus sketches expose radius dimensions. Polygon blade and meridian sketches, off-axis injector circles and flow-port circles remain underconstrained; they are deliberately editable, not production drawings.
3. Select the **Rotor** subassembly and edit **Motion → RotorAngle**. Its placement expression rotates all 17 rotor parts about Z together. Zero resets the assembly.
4. For animation, use Macro → Macros, navigate to scripts/AnimateRotor.FCMacro and execute it. Execute again to stop. The macro advances 3 degrees every 50 ms: illustrative animation, not operating RPM. It stops if the active document changes.
5. Toggle the casing/liners with the Space key to inspect interiors. The HTML preview also offers casing visibility, single-part isolation, orbit, zoom, pause and angle controls.

App::Part containers and a placement expression provide deterministic hierarchy and motion. This is **not** a FreeCAD Assembly-workbench joint solution, and there are no claimed solved mates, contact dynamics or flexible components. The saved file opens without custom Python proxy classes. Editing major geometry may require updating other sketches or regenerating the project; this is not a fully relational engine configurator.

## Files and reproducibility

- cad/Turbojet.FCStd: native editable master.
- exports/Turbojet_complete.step: complete 41-solid exchange model; STEP does not retain feature history or the native container hierarchy.
- exports/TJ-*.step: 41 individual part exports in assembly coordinates.
- exports/parts.csv: numbered bill of materials with one row per body.
- index.html: standalone viewer with geometry and Three.js 0.160.1 embedded; no runtime network connection required. Adjacent download links need the folder structure.
- scripts/build.py: rebuilds geometry and all STEP/mesh/BOM exports using the FreeCAD bundled Python executable. It overwrites generated deliverables; save manual edits under another name first.
- scripts/Preview.FCMacro: applies visibility/colors and captures a native preview. Its root path targets this project folder.
- scripts/make_viewer.py: regenerates the standalone viewer.
- scripts/verify.py and scripts/test_viewer.py: geometry/exchange and browser checks.
- verification/: machine-readable results, logs and screenshots.

Rebuild on this machine with the Python executable in C:/Program Files/FreeCAD 1.1/bin, passing scripts/build.py. Then run scripts/verify.py using the same executable. Run make_viewer.py with regular Python, and run Preview.FCMacro in FreeCAD to restore the presentation. The browser test requires Playwright and its Chromium runtime. Three.js is MIT licensed; its embedded library header is retained and the license is provided in scripts/THREE-LICENSE.txt.

## Source evidence and reconstruction boundary

Reference: [GPT-6 Astra on CAD (SolidWorks 2026) with MecAgent](https://www.youtube.com/watch?v=Se0etN27I6Y). The local README and retrieved video description state 41 parts, two subassemblies, one main assembly, a 57-minute generation run, editable features and remaining sketch constraints. These are the source author's claims; this reconstruction does not verify their generation process or timing.

The downloaded 23-second video was inspected using frames at 1, 5, 9, 13, 17 and 21 seconds (sources/contact_sheet.jpg). It shows a tapered housing, visible internal rotor, individual sketch/feature editing and an assembly overview. It does not provide a complete dimensional specification or usable engineering drawing set. No English subtitles were available. The supplied geometry is an interpretation of that visual concept, not an exact copy of the original SolidWorks project. FreeCAD was already installed; no SolidWorks installation was found in the inspected Program Files listing. No MecAgent account or credits were used.

## Engineering limitations

This is an educational CAD and motion study, **not manufacturable, flightworthy or safe to run**.

- The compressor uses extruded swept-planform blades, not designed three-dimensional compressor aerodynamics. The diffuser ports and stator vanes are illustrative. No pressure ratio, mass flow, compressor map, thrust or efficiency is claimed.
- The annular liners lack a designed dome, dilution/primary holes, flame stabilisation, igniter, cooling and fuel manifold. Injector tubes do not constitute a fuel system.
- The turbine blades have simplified constant-section geometry and no engineered roots, cooling passages or attachment method. Blade-to-disk attachment is not mechanically resolved. Shaft-to-disk torque transfer, bearing retention and rear support are unresolved.
- Rings represent bearings without rolling elements, seals or lubrication. Fasteners, assembly access, balancing, thermal growth and manufacturing tolerances are not engineered.
- Material colors are visual identifiers. There is no validated alloy selection, temperature rating, stress, fatigue, creep, rotor-dynamic or containment analysis.
- Clearance tests use rigid nominal CAD at sampled angles; they do not prove continuous-motion clearance, safe hot running or tolerance robustness. No combustion, CFD, FEA or physical testing was performed.

## Verification

The CAD build asserts 41 valid, positive-volume single-solid bodies and checks rotor motion at 0, 30, 90, 180, 270 and 360 degrees. The reopening test confirms 41 valid native bodies and 41 valid STEP solids, with no invalid document objects. Rotor/stationary common-volume checks at 0, 15, 30, 45, 60, 75 and 90 degrees found no intersections above 0.01 mm³ after the blade-tip correction. Static/static connections and rotor/rotor attachment integrity are not certified by that test. See the JSON reports for exact results.