Computational Engineering Static-Test Specification

Year 10 Reactivity Rocket Project · v0.2

Published

May 8, 2026

TA-04 · Vendor copper combustion chamber · Phase 3 prediction

Article TA-04 Within envelope Ethanol Option H · Monolithic 21% O₂ (air)

The viewer below renders the prediction the Computational Engineering workstream delivers before the vendor’s pressurised burn. The numbers are computed in the browser by a one-to-one JavaScript port of helios_rocket_static_test::predict_vendor_burn. The chamber is fabricated and tested off-site by a licensed vendor — students do not attend in person.

Crate-only two-stage extension

The Rust crate now includes an additive two-stage dual-mode propulsion study for review outside the Year 10 program artefacts. It generates a reusable air-augmented booster front, an expendable glide-and-terminal front, and a composed system Pareto set under the parts-and-vendor services cost model. The emitted prediction sheet is rust/helios_rocket_static_test/predictions/two_stage_interceptor_pareto.md.

Current result: at least one composed design reaches the AU$5-15k cost-per-intercept target. The solver finds a nozzle split: the reusable Stage 1 front uses Options B/C for reuse life and authority, while the recommended expendable Stage 2 uses Option A for cost floor.

Chamber 3D model TA-04 · Cu · vendor-built

t = 0.0 s

Construction: Propellant: O₂ enrichment: 21%

Section view TC ports

Live prediction helios_rocket_static_test v0.2.0

Test article: TA-04
Chamber type: Monolithic Cu
Propellant: Ethanol
O₂ enrichment: 0.21 (air)
Chamber volume: — L
Copper mass: — kg
Nozzle expansion ratio: —
Peak chamber pressure: — kPa
Peak thrust: — N
Peak wall T (throat): — °C
Safety status: —

Time series P(t) · F(t) · T(t)

Pressure (kPa, ÷4) Thrust (N × 100) T throat (°C) T exit (°C) T inlet (°C)

Can 35% H₂O₂ supply the O₂ for the ethanol burn?

This is the headline stoichiometric question students answer in lab report 1 after running their H₂O₂ rates calibration. The JavaScript below is a one-to-one port of helios_rocket_static_test::stoichiometric_check. Move the sliders to vary the ethanol burn flow rate or the H₂O₂ concentration and see when the project’s premise becomes feasible.

Stoichiometric Check 2 H₂O₂ → 2 H₂O + O₂ · C₂H₅OH + 3 O₂ → 2 CO₂ + 3 H₂O

Ethanol burn (g/min): 0.50 H₂O₂ concentration:

Ethanol mass flow: — g/min
O₂ demand for burn: — mL/min @ STP
O₂ produced per mL H₂O₂: — mL/mL
H₂O₂ flow required: — mL/min
Feasible at school scale?: —

“Feasible at school scale” is defined as H₂O₂ flow under 20 mL/min — roughly what a separating-funnel + flask rig can manage stably. Above that, the rates lab can’t realistically supply the oxidiser for the designed burn, and a stronger H₂O₂ concentration or a different oxidiser (LOX, compressed O₂) is needed. The Walter rocket’s choice of 80% H₂O₂ in 1937 is exactly this engineering reasoning at full scale.

Two construction options on the same prediction model

The Manufacturing team chooses between Option H (monolithic 3D-printed copper, Leap71 pattern) and Option L (laminated 2D+1 copper stack, 1940s cavity-magnetron pattern) based on vendor quotes. Both are vendor-built; both are copper; both are within the safety case.

The 3D viewer toggle above shows what each looks like geometrically. The thermal model differs only in time constant — the laminated stack has ~15% longer time constants due to interfacial resistance between brazed copper layers. Visible in the time-series chart when you switch.

What this Rust crate models

Input	Effect
Propellant: LPG vs Ethanol	Lower Heating Value (46.0 vs 26.8 MJ/kg) → chemical power → thrust
O₂ enrichment fraction (0.21 → 1.0)	Higher flame temperature → higher wall T, modest thrust boost
Chamber type: Monolithic vs Laminated	Time constant for wall T
Geometry	Chamber volume, throat area, expansion ratio, copper mass

What this Rust crate does NOT model

The model is deliberately educational, not predictive of vendor performance. It does not include:

Real combustion chemistry (CHEMKIN-style kinetics)
Real-gas effects in the nozzle
Detailed CFD of the chamber
Material fatigue, repeated burn cycling, or thermal cycling fracture
Vendor’s actual pressure-cert envelope (placeholder 2000 kPa)

The vendor’s CFD and test data supersede this model. Our predictions are a before-the-test sanity check, not a design optimisation.

Source

The prediction model lives in rust/helios_rocket_static_test/src/lib.rs. Run it with:

cd rust/helios_rocket_static_test
cargo test                                       # 7 tests should pass
cargo run --bin initial-motor-design             # Default: Option H + Ethanol + air

For the v0.1 backwards-compat behaviour (methane + bolted steel), see git history pre-v0.2.

Purpose

This document is the human-readable companion to the VSL and Rust artifacts for the static-test project. The project remains a school-laboratory, teacher-led design exercise. The pressurised burn itself is conducted by a licensed vendor off-site; students observe by video at a safe distance only.

The computational engineering aim is to make each design decision traceable: inputs come from the Interface Control Document, predictions come from a Rust model, vendor tests produce measurements, and students reconcile prediction against evidence.

Source Artifacts

Artifact	Role
`vsl/year10-reactivity-rocket-systems.varro`	Helios VSL system-of-systems contract
`vsl/static-test-project.varro`	Helios VSL static-test project contract
`rust/helios_rocket_static_test/`	Rust prediction library and initial design demo
`interface-control-document.qmd`	Authoritative team interfaces and test article dimensions
`safety-case.qmd`	Authoritative safety controls and abort criteria
`phase-transition-gate.yaml`	Phase 2 → Phase 3 vendor handover gate

LEAP71 Translation

The LEAP71 repositories are C# and PicoGK oriented. The useful ideas for this Rust/Helios project are architectural rather than source-compatible:

LEAP71 idea	Translation in this project
Computational Engineering Models generate engineering artifacts from code	Rust model generates prediction sheets and CSV traces
Geometry kernels and ShapeKernel encode reusable shape primitives	`ChamberGeometry` encodes the test article envelope
Engineering layers sit above geometry primitives	Chemistry, thermal, safety, and evidence contracts sit above geometry
Designs should be inspectable and reproducible	VSL contracts and Rust tests make inputs, outputs, and gates explicit

References:

Scientific Coverage

Element	Project binding	Evidence
Synthesis	LPG / ethanol combustion (atmospheric demo + vendor pressurised burn)	Atmospheric flame observation, vendor telemetry, lab report
Decomposition	H₂O₂ + KMnO₄ rates calibration (3% and 6% student work + 35% teacher demonstration)	Three calibration curves; reconciliation 35% extrapolation vs measured
Displacement	Galvanic series demo (Cu, Zn, Fe in CuSO₄); Mg + HCl pop test (qualitative H₂ identification only)	Galvanic reactivity ordering; pop-test photo/video
Neutralisation	HCl + NaOH titration with phenolphthalein	Volume equivalent, lab report
Rates of reaction	The three H₂O₂/KMnO₄ controlled-variable experiments: [H₂O₂], [KMnO₄], temperature	Three calibration curves + Arrhenius activation energy; stoichiometric worked answer for the ethanol-burn feasibility check

Engineering Coverage

Discipline	Input	Output	Acceptance
Safety governance	Safety case + HoD/WHS sign-off	Phase 3 gate satisfied	Fail closed if any evidence item is missing
Manufacturing	TA-04 dimensions from ICD	Vendor RFQ + selection memo + delivered part	Geometry matches CAD; cert against spec
Materials	Cu vs Al vs steel trade-study	Cu justification + vendor spec	No unlogged material substitution
Thermal/instrumentation	Vendor TC locations (HX-D5)	Vendor’s chamber-wall T(t) traces	Locations match prediction sheet
Computational engineering	Geometry, propellant, enrichment	Markdown + CSV predictions for both H and L thermal profiles	Predictions emitted before vendor test, not after
Reconciliation	Prediction + vendor measurement	Residual explanation table	Each residual has a named plausible mechanism

Verification Commands

Run from rust/helios_rocket_static_test/:

cargo test                                 # 7 tests should pass
cargo run --bin initial-motor-design       # default: Option H + Ethanol + air
cargo run --example initial_motor          # same, via example