From Runway to Orbit: Reflections of a NASA Engineer by Ken Iliff, 2004.From
Appendix D: Aircraft Nomenclature
This appendix shows four views of an aircraft and the variables that engineers use to describe aircraft flight. It is hoped that the reader interested in learning more about aircraft flight will find geometric definitions useful.
| ALPHA: | Also α, also angle of attack, the angle between the relative wind and the longitudinal axis of the body, x-z plane, deg. |
| AN: | Acceleration normal to the body axis, positive upwards, g. |
| AX: | Acceleration along the body axis, positive forward, g. |
| BETA: | Also β, also angle of sideslip, angle between the relative wind and the longitudinal axis in the x-y plane, deg. |
| Flight Path Angle: | See GAMMA |
| g: | Gravitational acceleration. |
| GAMMA: | Also 'Y, angle between the flight path and the local horizon, deg. |
| L: | Rolling moment, ft - lbf. |
| Local Horizon: | Local "level" reference plane. |
| M: | Pitching moment, ft - lbf. |
| N: | Yawing moment, ft - lbf. |
| p: | Roll rate, deg/sec. |
| PHI: | Also φ, roll attitude angle rotation, angle between the wings and the local horizon, deg. |
| Pitch Attitude: | See THETA. |
| q: | Pitch rate, deg/sec. |
| r: | Yaw rate, deg/sec. |
| Relative Wind: | "Wind" vector established by flight path vector. |
| THETA: | Also θ, Angle between longitudinal body axis and the local horizon, deg. |
| x: | Along the longitudinal body axis. |
| y: | Lateral with respect to the body axis system. |
| z: | Vertical with respect to the body axis system. |
NOTE: The wings are in the x-y plane, the vertical tail center plane is in the x-z plane.
Fig. D-1. Diagram showing longitudinal terms with aircraft climbing.
Fig. D-2. Diagram showing longitudinal terms with aircraft descending.
Fig. D-3. Diagram showing directional terms.
Fig. D-4. Diagram showing lateral terms.
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