# Flight Mechanics Expert

> Expert-level flight mechanics covering aircraft equations of motion, stability and control, performance, handling qualities, and flight simulation.

- Skill: `luokai0/flight-mechanics-expert` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add luokai0/flight-mechanics-expert`
- Raw SKILL.md: https://api.skillmd.com/api/skills/luokai0/flight-mechanics-expert/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: AI & ML
- Author: luokai0 (https://skillmd.com/u/luokai0)
- Updated: 2026-09-08
- Page: https://skillmd.com/skills/luokai0/flight-mechanics-expert

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# Flight Mechanics Expert

## Before Starting
1. Fixed wing or rotary wing?
2. Stability analysis or performance calculation?
3. Longitudinal or lateral-directional focus?

## Core Expertise Areas

### Equations of Motion
Six DOF: three translational and three rotational equations in body axes.
Body axes: x forward, y right, z down, aligned with aircraft.
Euler angles: roll phi, pitch theta, yaw psi relate body to inertial frame.
Linearization: small perturbation equations about trim condition.
Decoupling: longitudinal and lateral-directional motions separate for symmetric aircraft.

### Longitudinal Stability
Stick-fixed neutral point: CG location for neutral pitch stability.
Static margin: distance between CG and neutral point, positive for stability.
Phugoid mode: long period, lightly damped pitch oscillation at near constant AoA.
Short period mode: rapid heavily damped pitch oscillation, must be well damped.
Pitch stiffness: Cm_alpha negative for stable aircraft.

### Lateral-Directional Stability
Dihedral effect: roll restoring moment from sideslip, Cl_beta negative.
Dutch roll: coupled roll-yaw oscillation, must meet handling quality requirements.
Spiral mode: slow divergence or convergence, mildly unstable acceptable.
Roll mode: first order roll response to aileron input.

### Aircraft Performance
Thrust required: TR = W times CD over CL.
Maximum range: fly at maximum L over D for jet aircraft.
Maximum endurance: fly at minimum power required.
Rate of climb: RC = excess power over weight.
V-n diagram: flight envelope, structural and aerodynamic limits.

## Best Practices
- Verify trim condition before performing stability analysis
- Check handling qualities against MIL-SPEC or civil requirements
- Include flexible modes for large or high aspect ratio aircraft
- Validate simulation model against flight test data

## Common Pitfalls
| Pitfall | Fix |
|---|---|
| Wrong body axis convention | Define axes clearly before writing equations |
| Ignoring propulsion effects on stability | Slipstream and thrust line affect trim and stability |
| Linear analysis outside valid range | Check perturbation amplitudes against nonlinear effects |
| Missing ground effect in takeoff analysis | Ground effect increases L/D near runway |

## Related Skills
- aerodynamics-expert
- control-systems-expert
- astrodynamics-expert