How do I install the Weight Estimation skill?

Run npx skillmds@latest add ashfordeou/weight-estimation in your terminal (requires Node.js), paste this page's agent-chat prompt into Claude, Cursor, or any MCP-connected agent, or download the SKILL.md file and copy it into your agent's skills directory.

Is Weight Estimation safe to use?

This skill has not completed SkillMD's automated safety review yet. SkillMD never runs a skill's scripts for you; review the SKILL.md before installing.

Which AI agents work with Weight Estimation?

This skill is tagged as working with Claude Code, Claude.ai, OpenAI Codex. SKILL.md is an open format, so most agents that read a skills directory can load it too.

Is Weight Estimation free to use?

Yes. Installing skills from SkillMD is free. This skill is licensed under Apache-2.

Who published Weight Estimation?

ashfordeOU (@ashfordeou) published this skill. Their other Agent Skills are listed on their SkillMD profile.

Weight Estimation by ashfordeou — Agent Skill

Name: Weight Estimation
Author: ashfordeOU

Weight Estimation

Use when performing class-I or class-II vehicle weight estimation: compute moments and center of gravity from component weights and arms, check the CG against the forward and aft envelope limits, and validate empty-weight fractions against typical band ranges per aircraft category. The skill supports weight and balance calculations in the FAR-25 / CS-25 certification context. Trigger: weight estimation, weight and balance, center of gravity, cg envelope, mass, weight fraction, moment, class-i, class-ii.

ashfordeOU d1815ef 3 files · 9.2 KB Updated Sep 17, 2026

File contents

Vehicle Weight Estimation (vehicle-design/sizing/weight-estimation)

Use when the task is aircraft weight estimation and weight and balance: moments and center of gravity from component weights and arms, CG envelope checks, and empty-weight fraction band checks for class-I / class-II sizing.

Domain quick reference

Moment: M = weight * arm (arm is the station distance).
Center of gravity: CG = sum(weight*arm) / sum(weight).
CG envelope: the CG must lie between the forward and aft limits.
Typical empty-weight fractions (class-I bands; validate against program data): transport 0.42-0.55, general-aviation 0.55-0.68, turboprop 0.50-0.62.
FAR-25 (14 CFR Part 25) and CS-25 set the certification context for weight and balance for transport-category aeroplanes.

Workflow

Collect component weights and arms into matching lists.
Compute the CG with cg_from_moments.
Check the CG against the forward and aft envelope limits with cg_within_envelope.
Compute the empty-weight fraction and compare it against the category band with check_empty_weight_fraction.
Confirm the deterministic checks with the contract test scripts/test_weight_estimation.py.

Pitfalls

Mismatched weights and arms lists (length mismatch) producing a wrong CG.
Zero total weight (empty or all-zero lists) dividing by zero.
Reversed forward/aft limits making every CG fail.
Using a band from one category for another category.

Behavior contract (gate 3)

The moment, CG, envelope, and band logic is exercised by the gate 3 contract test: scripts/test_weight_estimation.py against scripts/weight_estimation_logic.py (stdlib unittest, offline). Run: python3 scripts/test_weight_estimation.py

Compliance

Standards referenced, not reproduced: FAR-25 is US government work (public domain) and CS-25 is a free EASA download; both summary-only per standards-map.yaml and brief 06.
compliance: STANDARDS-REF, gated: false.

---name: weight-estimationdescription: Use when performing class-I or class-II vehicle weight estimation: compute moments and center of gravity from component weights and arms, check the CG against the forward and aft envelope limits, and validate empty-weight fractions against typical band ranges per aircraft category. The skill supports weight and balance calculations in the FAR-25 / CS-25 certification context. Trigger: weight estimation, weight and balance, center of gravity, cg envelope, mass, weight fraction, moment, class-i, class-ii.license: Apache-2.0---# Vehicle Weight Estimation (vehicle-design/sizing/weight-estimation)Use when the task is aircraft weight estimation and weight andbalance: moments and center of gravity from component weights andarms, CG envelope checks, and empty-weight fraction band checksfor class-I / class-II sizing.## Domain quick reference- Moment: M = weight * arm (arm is the station distance).- Center of gravity: CG = sum(weight*arm) / sum(weight).- CG envelope: the CG must lie between the forward and aft limits.- Typical empty-weight fractions (class-I bands; validate against program data): transport 0.42-0.55, general-aviation 0.55-0.68, turboprop 0.50-0.62.- FAR-25 (14 CFR Part 25) and CS-25 set the certification context for weight and balance for transport-category aeroplanes.## Workflow1. Collect component weights and arms into matching lists.2. Compute the CG with cg_from_moments.3. Check the CG against the forward and aft envelope limits with cg_within_envelope.4. Compute the empty-weight fraction and compare it against the category band with check_empty_weight_fraction.5. Confirm the deterministic checks with the contract test scripts/test_weight_estimation.py.## Pitfalls- Mismatched weights and arms lists (length mismatch) producing a wrong CG.- Zero total weight (empty or all-zero lists) dividing by zero.- Reversed forward/aft limits making every CG fail.- Using a band from one category for another category.## Behavior contract (gate 3)The moment, CG, envelope, and band logic is exercised by the gate3 contract test: scripts/test_weight_estimation.py againstscripts/weight_estimation_logic.py (stdlib unittest, offline).Run:python3 scripts/test_weight_estimation.py## Compliance- Standards referenced, not reproduced: FAR-25 is US government work (public domain) and CS-25 is a free EASA download; both summary-only per standards-map.yaml and brief 06.- compliance: STANDARDS-REF, gated: false.

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