Launcher exploded-cutaway art — generation recipe (FROZEN)

The house recipe for the exploded-stage cutaway of a launch vehicle — a richer companion to the single pencil anatomy sketch. Locked with Marko 2026-08-02 after the Saturn V anchor (v3). Match it exactly so the batch reads as one hand and sits happily next to the existing /images/anatomy/* cutaways.

The look = the watercolor cutaway style of the shipped anatomy set (apollo-csm, cassini): watercolor + ink-wash on aged graph paper, warm metallic, margin physics equations, vintage agency markings.

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0. Golden rules (this is where drift dies)

1. Model: always nano_banana_pro. Aspect: 3:2. Resolution: 2k.
2. Always pass the per-launcher structural SVG sketch as the reference image (medias:[{value, role:"image"}]). It carries the composition, the stage count, the exact engine counts, and the labels. Text alone will not hold them.
3. PROPORTION IS THE THING WE GOT WRONG TWICE — do not repeat it.
   • Each exploded stage is a TALL, SLENDER cylinder at its real aspect (S-IC ≈ 4:1, upper stages ≈ 2.5:1). Never short-and-fat / squat.
   • Segments follow the same proportion as the assembled reference stack at left — they are the same rocket pulled apart, not re-drawn boxes.
   • The prompt MUST keep the clause: "preserving the tall-and-narrow proportions of every stage (do NOT make them short or fat)."
4. Composition (all three, every time):
   • Left: a small assembled reference rocket in true proportion + a tiny human silhouette (1.8 m) beside it + a total-height dimension line. This is the size anchor.
   • Right: the pieces exploded apart in two columns so each is large + un-squished (big stages in one column, upper pieces/payload in the other).
   • Every stage cut open to show its LOX + fuel tanks; engines drawn at the base in the exact count; fairing/payload + boosters where the vehicle has them.
5. Vintage, free-to-use agency markings. Lean into the retro NASA "worm" and "meatball" (and each agency's period logo) — public-domain era markings, flags, stencilled serials. More of that = more awesome (Marko).
6. QC every render against the Saturn V anchor + the anatomy set before committing. Wrong engine count or squat stages → regenerate.

1. The palette / background

Aged cream graph paper with foxing/ink-splatter; warm muted metallic (brass, steel, copper); handwritten annotations + thin ruled leader lines; faint physics equations in the margins; vintage scientific-sketchbook / editorial-infographic aesthetic. (Same family as the watercolor anatomy recipe in anatomy-art-runbook.md §2 — this is the exploded, multi-stage extension.)

2. The locked prompt template (swap the [bracketed] parts)

Exploded technical cutaway illustration of the [VEHICLE] rocket, watercolor and
ink-wash on faint aged graph paper, exposed internal structure. Follow the
reference layout EXACTLY, preserving the tall-and-narrow proportions of every
stage (do NOT make them short or fat): at far left a small assembled
scale-reference rocket in correct proportion with a tiny human figure beside it
and a '[HEIGHT] m' dimension line; the stages exploded apart in two columns,
each stage a TALL SLENDER cylinder cut open to reveal its tanks with the engines
drawn at the base. Exposed internals: propellant tanks, turbopumps, engine
bells[, strap-on boosters]. Handwritten engineering annotations, thin ruled
leader lines, dimension lines, faint physics equations in the margins,
ink-splatter wash clouds, warm muted metallic palette (brass, steel, copper on
cream paper), vintage scientific sketchbook / editorial infographic aesthetic.
Vintage [AGENCY] markings (retro logo, flag, stencilled serials). KEEP the
engine counts exact ([PER-STAGE COUNTS]), the cut-open [PROPELLANT] tanks, and
every label legible and in place: [LABELS]. A warm hand-painted sketchbook
cutaway — not a flat vector chart, not photorealistic.

3. Pipeline

1. node scripts/essays/build-cutaway-sketches.mjs — data-driven from src/lib/orbital/launcher-engines.ts (stages, engine counts, arrangement, boosters) + engine-registry.ts (propellants). Emits one structural SVG + PNG per launcher to docs/wip/essay-diagram-sources/launcher-cutaways/.
2. Upload each PNG (media_upload → PUT → media_confirm), generate with the template above (up to 8 concurrent, poll job_status sync:true), 2 credits each.
3. Download raw PNG → original-assets/launcher-cutaways/<id>.png (committed backup) → resize webp to static/images/anatomy-exploded/<id>.webp (sharp().resize(1600).webp({quality:86})).
4. Wire into the fleet DETAIL tab alongside the pencil anatomy (a second view, not a replacement). Generated art → no provenance row (Orrery-original).

4. Where things live

Thing	Path
Structural sketches (input)	docs/wip/essay-diagram-sources/launcher-cutaways/*.svg
Generated originals (backup)	original-assets/launcher-cutaways/*.png
Served display images	static/images/anatomy-exploded/*.webp
Sketch generator	scripts/essays/build-cutaway-sketches.mjs
Reference anchor	Saturn V v3 (saturn-v-exploded) — the north star

5. Manual exceptions — do NOT regenerate these from the generator

The build-cutaway-sketches.mjs generator encodes ONE model: an in-line tandem stack (cylindrical stages atop each other, tank split + engine bells per stage, one representative booster, a fairing+payload cone on top). That is correct for ~70% of the fleet but structurally WRONG for vehicles that deviate. These 7 were hand-authored from corrected prose (2026-08-02), anchored to the Saturn V for style, and passed NO generator sketch. Re-running the generator for them would reintroduce the wrong geometry — edit the prose instead.

id	Why the generator is wrong	Corrected to
space-shuttle-stack	Side-mount, not a tandem stack	Orbiter (3× RS-25) + External Tank (no engines) + 2 SRBs, exploded
soyuz	Strap-ons cluster around the core, not stacked	Korolev cross — 4 conical boosters around Blok-A core
vostok-k	Same, + spherical capsule not a fairing	Korolev cross + spherical Vostok capsule
voskhod-11a57	Same cluster	Korolev cross around the core
titan-ii-glv	Flew a bare capsule, no fairing	Bare Gemini capsule on top, no clamshell
atlas-lv-3b	Bare capsule + escape tower, no fairing	Mercury capsule + escape tower, stage-and-a-half
mercury-redstone	Bare capsule + escape tower, no fairing	Mercury capsule + escape tower, single stage

The corrected prose for each lives in the git history of this session; regenerate from that, not from a generator sketch.