# 📐 L2 Spec — Aeroacoustics — Lighthill analogy (jet/airframe noise) Mismatch-Only Spec
**ID:** `L2-270-001` · **Status:** ⊙ Testnet (genesis catalog)
**Parents:** ⬆ Principle [`L1-270`](/artifact/l1/L1-270)
> **🎯 Tolerance (ε):** expression
> **⚖ Difficulty score:** 0.48 · **Delta tier:** 5
> **⛓ On-chain block:** 41554053
---
## 1. Domain Ω
**Type:** `range`
| Parameter | Unit | Range |
|---|---|---|
| M jet | — | 0.1 – 2.0 |
| N les | — | 1000000 – 10000000000 |
| N mic | — | 4 – 256 |
| Snr db | dB | 0 – 40 |
| Freq hz max | — | 100 – 50000 |
| Refraction error | — | 0.0 – 0.2 |
| Observer pos error | — | 0.0 – 0.05 |
| Les resolution error | — | 0.01 – 0.3 |
| Source region trunc error | — | 0.0 – 0.3 |
## 2. Tolerance (ε)
**Type:** `fn`
```
1.5 + 20.0*les_resolution_error + 15.0*source_region_trunc_error + 10.0*refraction_error
```
## 3. Difficulty
| Property | Value |
|---|---|
| Difficulty score | 0.48 |
| Delta tier | 5 |
## 4. Fingerprint
`792a8c918bb2a42c8da8202117cb5c76a54d1d7ea0ce160691a0a345dbd66235`
## 5. On-chain Registration
- **Chain hash:** `0x5c986d641f028313e03c211cced40ba1fa38742625013b3cf29bed1bc0538f1a`
- **Chain tx hash:** `0xc4168b5a0605d11df6910a8463a7fd782d04ed5cb6d3790748b73279387a025b`
- **Chain block:** `41554053`
---
## File Mapping
This bundle consists of: `L2-270-001.md`, `L2-270-001.json`.
| File | Role | How to regenerate |
|------|------|-------------------|
| `L2-270-001.md` | Source of truth — edit this | Human or LLM |
| `L2-270-001.json` | Structured metadata for the registry | LLM regenerates from the sections above |
**Prompt for your LLM after editing this Markdown:**
> Read the attached Markdown. Regenerate the sibling `.json` so every field matches.
> Preserve the schema documented in the rows above.
> Output each file in its own fenced code block tagged with the filename.
> Output only the JSON object.
_This Markdown was auto-synthesized from the catalog row for `L2-270-001`._
_Edit it, regenerate the JSON, and submit at [/submit](/submit) to claim the artifact._