Overview
ISO 1151-6:1982 - Terms and symbols for flight dynamics - Part 6: Aircraft geometry defines the fundamental notions and symbols used to describe an aircraft’s geometry for flight-dynamics studies. Published by ISO/TC 20 (Aircraft and space vehicles), this part of the ISO 1151 series standardizes how to reference aircraft components, axes, dimensions and limit angles used in theoretical analyses, experiments and data exchange. It clarifies the aircraft reference plane, reference axis system, reference points, and the idea of a componentized aircraft (fuselage, wing, empennages, etc.). The document includes figures and is intended to provide consistent terminology rather than a full shape-definition system.
Key topics and requirements
- Aircraft decomposition: Treats the aircraft as an assembly of main parts and components (basic, fixed, movable) and defines how to identify and describe them.
- Reference systems and points: Specifies the aircraft reference axis system (XR, YR, ZR), component reference axis systems (Xi, Yi, Zi), and reference points used to locate parts and features consistently.
- Settings and geometric state: Defines the setting of components and main parts (position and orientation relative to other parts or to the aircraft reference axes) and the geometric state of the aircraft, including movable surfaces.
- Overall dimensions: Gives formal definitions for overall length, width and height and corresponding ground dimensions when the aircraft rests on a horizontal plane.
- Ground limit angles: Defines extreme angular positions the aircraft can assume on the ground (lift-off/touch-down cases), including assumptions about undercarriage and contact points.
- Component descriptions: Covers generalized definitions for fuselage, aerodynamic surfaces, wing and empennages and prescribes the use of figures to illustrate terms.
- Notation and symbols: Recommends consistent symbols for coordinates, differences and axis rotations used in flight-dynamics work.
Practical applications
- Establishes a common language for flight-dynamics analysis, wind-tunnel test configuration reporting and computational modeling.
- Ensures consistent reference axes and dimensions for calculation of aerodynamic coefficients, stability and control parameters.
- Supports aircraft design, systems integration (e.g., high-lift or variable-sweep mechanisms), ground-clearance and undercarriage design studies.
- Useful for preparing test reports, simulation inputs, and interoperability between design, analysis, and certification teams.
Who should use this standard
- Aerospace and aerodynamic engineers
- Flight-dynamics analysts and simulation developers
- Wind-tunnel and flight-test personnel
- Aircraft designers and systems integrators
- Regulatory and certification specialists requiring unambiguous geometry definitions
Related standards
ISO 1151 is a multi-part series; relevant companion parts include:
- ISO 1151-1 (reference surfaces and motion relative to the air)
- ISO 1151-2, -3, -4, -5 (motions, derivatives, stability/control parameters, measurement quantities)
Keywords: ISO 1151-6, aircraft geometry, flight dynamics, reference axis system, ground limit angles, fuselage, wing, empennage, overall dimensions, geometric state.
