User Guide — Starship Build Engineering System

1. Run the build plan (CLI)

node run.mjs

Prints, for the default target (8 vehicles/day, one 8 h shift):

• Takt — the heartbeat the line must hit (available time / demand).
• Line balance — the workstation layout (the skeleton of the work

instructions), with each station's work content, the bottleneck, line efficiency, balance delay, smoothness index, and steady-state throughput.

• Critical path — the build flow with earliest/latest start/finish, slack

per activity, the lead time, and the critical (zero-slack) path.

• Weld acceptance — Cp/Cpk/yield per weld, flagging any below the Cpk ≥ 1.33

rate-production bar.

• Fit stack-ups — worst-case and RSS variation, and whether each fits.
• DFM consolidation — part-count and assembly-time reductions.

Change the target:

node run.mjs --rate 6 --shifts 2 --hours 10

--rate vehicles/day, --shifts shifts/day, --hours hours/shift.

2. Live planner (browser)

Open public/tool.html. Drag the sliders:

• Demand / shifts / hours recompute takt and re-balance the line live. As

takt drops below the longest indivisible operation (50 min), the cycle is clamped and the bottleneck is highlighted — the signal to parallelize a station (see requiredParallelStations in src/lean.mjs).

• Weld Cpk bar re-grades each weld against your acceptance threshold.

Everything is computed in-browser from the same model; no server, no network.

3. Use it as an engineer

• Scope a new rate: set the demand to your target and read the station count

and bottleneck — that is your staffing/depth-chart and tooling driver.

• Find the lead-time lever: the critical path tells you which activity to

attack to shorten the vehicle's build; activities with slack can absorb delay.

• Gate a weld to rate: drop your measured throats into a WELD_SPECS entry;

if Cpk < 1.33 the system flags it as not capable (the Megabay 2 closeout weld in the model is intentionally marginal at Cpk ≈ 1.21 to show the flag firing).

• Check a fit before cutting metal: add a stack to TOLERANCE_STACKS; if

worst-case does not fit but RSS does, that is a candidate for a statistical tolerance with SPC backing.

4. Reproduce / verify

node verify.mjs

18 checks, each hand-checkable with a calculator (see proof/VERIFY.md and proof/REPRODUCE.md).