# SR-71 model provenance

Aircraft geometry and texture: Emmanuel Baranger (helijah), FlightGear Lockheed-SR71.
Upstream notices list 2007, 2020, 2022, and 2026 revisions. See source/Read-Me-current.txt.
License: GNU General Public License version 2. The full text is in COPYING.

Source downloaded 2026-09-10 from the FlightGear FGAddon repository, revision 21535:
https://svn.code.sf.net/p/flightgear/fgaddon/trunk/Aircraft/Lockheed-SR71/
Repository browser:
https://sourceforge.net/p/flightgear/fgaddon/21535/tree/trunk/Aircraft/Lockheed-SR71/

Cockpit and exhaust submodels downloaded 2026-09-12 at revision 21560.
Their AC3D meshes, textures and XML placement references are included under source/.

## Changes by Codex, 2026-09-10–12

- Converted AC3D polygons into triangulated glTF 2.0 geometry, preserving the
  authored texture coordinates and crease-angle surface normals.
- Converted the coordinate system to Three.js Y-up with the nose toward negative Z.
- Grouped authored surfaces into ten educational assemblies; bilateral parts
  separate outward independently. The forebody is clipped at an illustrative
  display section. This is not an aircraft maintenance disassembly sequence.
- Excluded the deployed parachute and duplicate HDR glazing. Landing gear remains
  extended as authored. PBR materials replace FlightGear's renderer-specific materials.
- Added the authored pilot panel and individual instruments, seat, cockpit shell,
  canopy lining, and 16 pairs of nozzle petal surfaces per engine. XML placement
  transforms are baked into the exported geometry. Dynamic simulator animations
  and instrument readings are not evaluated.
- The pilot seat source explicitly says "Based on F14b seat" (source/Interior/Seat/seat.xml).
  This interior is a simulator representation, not an exact SR-71 cockpit reconstruction.
  The rear crew station is incomplete.
- No internal engine, fuel, or structural systems are represented.

## Texture changes, 2026-09-13

- Removed the USAF and U.S. AIR FORCE lettering and star-and-bars insignia
  from the exterior texture for the requested unmarked finish. The edited
  texture is included as texture.png and embedded in sr71.glb.
- Used built-in image editing to restore dark paint in four marking regions,
  composited into the original atlas. Pixels outside those regions are unchanged.
  Geometry, UV coordinates, red outlines and author credit are preserved.
- The original editable FlightGear texture remains in source/texture.xcf.gz.
  The unmarked finish is an exhibit adaptation, not a claim that every SR-71
  flew without national markings.

The derived model and conversion script are provided under GPL-2.0.
The source archive contains the original mesh, editable texture source, texture,
source notices, license, and converter. Rebuild from the project root with:

    npm install
    node scripts/convert-sr71.mjs

Requires Node.js and the project's Three.js dependency. The converter writes
public/models/sr71/sr71.glb and conversion-report.json.

## Engineering references

Smithsonian National Air and Space Museum, Lockheed SR-71 Blackbird:
https://airandspace.si.edu/collection-objects/lockheed-sr-71-blackbird/nasm_A19920072000
NASA, Design and Development of the Blackbird: Challenges and Lessons Learned:
https://ntrs.nasa.gov/citations/20090007797