Project 33

C8 — Structural claim boundaries

Field	Value
Status	CONTRADICTED — Current evidence contradicts the claim or one of its requirements.
Strongest accepted evidence	MODEL ONLY
Evidence classes cited	IMPLEMENTATION, TEST PROCEDURE, ANALYTICAL
Gate reached	SOFTWARE REPRODUCTION (next: SYNTHETIC TEST)
Last review	CURRENT — snapshot recorded 2026-09-28 by tooling snapshot (no human review)

Question. Does the quasi-isotropic CFRP fin match or exceed aluminium stiffness, and does the Ti-6Al-4V hinge pin keep a factor of safety above 1.5?

Current statement. Classical laminate theory gives Ex = 56.68 GPa for the quasi-isotropic layup, below the 69 GPa aluminium comparison, so the stiffness claim is not met on modulus. A closed-form hinge-pin check gives a factor of safety of 1.88 against a 1.5 threshold. Neither is a physical test.

Requirements

ID	Requirement	Check	Bound	Observed	Result
R-C8-MODULUS	The laminate’s in-plane modulus matches or exceeds 6061-T6 aluminium (69 GPa).	machine	≥ 69.0 GPa	56.68	NOT SATISFIED (analytical)
R-C8-COMPONENT-STIFFNESS	At equal or lower mass, the CFRP fin section is at least as stiff in bending as the aluminium section it replaces.	human review	none stated	judgement, not a value	REQUIRES HUMAN REVIEW
R-C8-HINGE-FOS	The hinge pin’s factor of safety exceeds 1.5 under the 50 g deployment load.	machine	≥ 1.5 ratio	1.8847	SATISFIED (analytical)

Known contradictions

• R-C8-MODULUS
• D-015

Open questions

• The modulus result is below the comparison material (D-015); a thickness-compensation argument has not been calculated.

Discrepancies

• D-009 (OPEN) Model inputs were revised until paper targets were met
• D-010 (OPEN) No shared design point across the mass, spring, reliability, and structural models
• D-015 (OPEN) Laminate modulus is below the aluminium comparison

Assumptions

• Handbook lamina properties, ideal layup, and the stated 50 g load case represent the design.

Limitations

• Material modulus and component bending stiffness are different quantities.
• An analytical factor of safety is not a qualification test.
• Manufacturing defects and actual loads are unmeasured.
• The hinge load uses the 154 g fin whose mass conflicts with C4 (D-010).

Measurement needed to close the next gate

• A component bending-stiffness calculation for equal-mass sections, reviewed.
• Coupon or component stiffness measurement if a CFRP fin is ever made.

Pre-registered experiments

• None.

What this claim does not establish

• Any inert physical measurement: none has been accepted for this claim.
• Physical performance of any hardware.
• Flight readiness or safety for live propulsion.

Evidence

Artifact	Class	SHA-256 (first 12)	What it is
structures/fea_lite.py	IMPLEMENTATION	f8a0d02ca9d9	Classical laminate theory and closed-form hinge-pin check.
docs/EVIDENCE/C8_clt.csv	ANALYTICAL	67193424e721	Laminate equivalent moduli.
docs/EVIDENCE/C8_hinge_fos.json	ANALYTICAL	f04f43f57ff9	Hinge-pin stresses and factor of safety with inputs and load case.
tests/test_structural.py	TEST PROCEDURE	3a6078b66cfc	Laminate isotropy and regression checks.

Earlier versions (failure archive)

• evidence/archive/notes-v1/C8_clt.md — Historical C8 laminate note.
• evidence/archive/notes-v1/C8_hinge_fos.md — Historical C8 hinge note.

A change to any of these files makes the last review insufficient

• docs/EVIDENCE/C8_clt.csv
• docs/EVIDENCE/C8_hinge_fos.json
• structures/fea_lite.py
• tests/test_structural.py

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All claims · Traceability · Discrepancies · Evidence Observatory

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