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Run npx skillmds@latest add ashfordeou/trim-analysis 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.

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Which AI agents work with Trim Analysis?

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 Trim Analysis free to use?

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

Who published Trim Analysis?

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

Trim Analysis by ashfordeou — Agent Skill

Name: Trim Analysis
Author: ashfordeOU

Trim Analysis

Use when you must analyze the stick fixed trim condition of a fixed-wing aircraft: compute the trim lift coefficient from the weight, density, true airspeed, and wing area, derive the elevator deflection required to trim from the pitching moment coefficients and the elevator effectiveness, find the trim speed for a given trim lift coefficient in level flight, and check whether the total pitching moment closes at zero for the trimmed verdict. Produces the trim lift coefficient, the elevator deflection, the trim speed, and the trimmed verdict that gate the pitch trim analysis. Trigger: elevator deflection, trim speed, trim lift coefficient, stick fixed, elevator effectiveness, pitching moment, trim analysis.

ashfordeOU 5cb5c34 3 files · 10.2 KB Updated Sep 17, 2026

File contents

Trim Analysis (flight-mechanics/stability-control/trim-analysis)

Use when the task is the stick fixed pitch trim condition of an aircraft: trim lift coefficient, elevator deflection to trim, trim speed, and the trimmed verdict from the pitching moment closure.

Domain quick reference

The trim lift coefficient in level flight follows from the weight, density, true airspeed, and wing area: CL_trim = 2W / (rho V^2 S).
The pitching moment model is Cm = Cm0 + Cm_alpha * alpha + Cm_delta_e * de; the trimmed condition closes the moment at zero, Cm = 0.
The angle of attack follows from the lift slope: alpha_trim = CL_trim / CL_alpha.
The elevator deflection to trim is de_trim = -(Cm0 + Cm_alpha * alpha_trim) / Cm_delta_e.
The trim speed for a given trim lift coefficient is V_trim = sqrt(2W / (rho S CL_trim)).
Units: weight in newtons, density in kg/m^3, speed in m/s, wing area in m^2, angles in radians, moment slopes per radian. Trim requirements sit in the FAR-25 / CS-25 longitudinal stability context.

Workflow

Collect the weight, density, true airspeed, and wing area.
Compute the trim lift coefficient with trim_lift_coefficient.
Derive the elevator deflection to trim with elevator_deflection_to_trim.
Find the trim speed with trim_speed.
Check the pitching moment closure with is_trimmed for the trimmed verdict.

Pitfalls

Using the aircraft mass in kilograms where the equations take the weight in newtons; multiply the mass by g0 = 9.80665.
A zero elevator effectiveness; Cm_delta_e = 0 leaves no control authority and elevator_deflection_to_trim raises ValueError.
A non-positive lift slope; CL_alpha must be greater than zero for the alpha_trim division.
Ignoring the zero-lift angle of attack; the model here uses the simplified lift curve CL = CL_alpha * alpha.
Applying a tight is_trimmed tolerance without stating it; pass an explicit tol for the verdict.

Behavior contract (gate 3)

The trim analysis logic is exercised by the gate 3 contract test: scripts/test_trim_analysis.py against scripts/trim_analysis_logic.py (stdlib unittest, offline). Run: python3 scripts/test_trim_analysis.py

Compliance

Standards referenced, not reproduced: FAR-25 is US government work (public domain) and CS-25 is a free EASA download; the trim condition method is common static stability methodology, summary-only per standards-map.yaml.
compliance: STANDARDS-REF, gated: false.

---name: trim-analysisdescription: Use when you must analyze the stick fixed trim condition of a fixed-wing aircraft: compute the trim lift coefficient from the weight, density, true airspeed, and wing area, derive the elevator deflection required to trim from the pitching moment coefficients and the elevator effectiveness, find the trim speed for a given trim lift coefficient in level flight, and check whether the total pitching moment closes at zero for the trimmed verdict. Produces the trim lift coefficient, the elevator deflection, the trim speed, and the trimmed verdict that gate the pitch trim analysis. Trigger: elevator deflection, trim speed, trim lift coefficient, stick fixed, elevator effectiveness, pitching moment, trim analysis.license: Apache-2.0---# Trim Analysis (flight-mechanics/stability-control/trim-analysis)Use when the task is the stick fixed pitch trim condition of anaircraft: trim lift coefficient, elevator deflection to trim,trim speed, and the trimmed verdict from the pitching momentclosure.## Domain quick reference- The trim lift coefficient in level flight follows from the weight, density, true airspeed, and wing area: CL_trim = 2W / (rho V^2 S).- The pitching moment model is Cm = Cm0 + Cm_alpha * alpha + Cm_delta_e * de; the trimmed condition closes the moment at zero, Cm = 0.- The angle of attack follows from the lift slope: alpha_trim = CL_trim / CL_alpha.- The elevator deflection to trim is de_trim = -(Cm0 + Cm_alpha * alpha_trim) / Cm_delta_e.- The trim speed for a given trim lift coefficient is V_trim = sqrt(2W / (rho S CL_trim)).- Units: weight in newtons, density in kg/m^3, speed in m/s, wing area in m^2, angles in radians, moment slopes per radian. Trim requirements sit in the FAR-25 / CS-25 longitudinal stability context.## Workflow1. Collect the weight, density, true airspeed, and wing area.2. Compute the trim lift coefficient with trim_lift_coefficient.3. Derive the elevator deflection to trim with elevator_deflection_to_trim.4. Find the trim speed with trim_speed.5. Check the pitching moment closure with is_trimmed for the trimmed verdict.## Pitfalls- Using the aircraft mass in kilograms where the equations take the weight in newtons; multiply the mass by g0 = 9.80665.- A zero elevator effectiveness; Cm_delta_e = 0 leaves no control authority and elevator_deflection_to_trim raises ValueError.- A non-positive lift slope; CL_alpha must be greater than zero for the alpha_trim division.- Ignoring the zero-lift angle of attack; the model here uses the simplified lift curve CL = CL_alpha * alpha.- Applying a tight is_trimmed tolerance without stating it; pass an explicit tol for the verdict.## Behavior contract (gate 3)The trim analysis logic is exercised by the gate 3 contract test:scripts/test_trim_analysis.py against scripts/trim_analysis_logic.py(stdlib unittest, offline). Run:python3 scripts/test_trim_analysis.py## Compliance- Standards referenced, not reproduced: FAR-25 is US government work (public domain) and CS-25 is a free EASA download; the trim condition method is common static stability methodology, summary-only per standards-map.yaml.- compliance: STANDARDS-REF, gated: false.

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