Aerospace
Quantity kinds in aerospace (TAS, CAS, geopotential altitude etc.)
Units and quantities common in aerospace engineering.
See: isqx._citations.ICAO
GROUND_TRACK = HEADING['ground_track']
Direction of the aircraft's velocity vector relative to the ground.
PRESSURE_ALTITUDE = ALTITUDE['pressure']
Pressure altitude, as measured by the altimeter (standard pressure setting 1013.25 hPa).
DENSITY_ALTITUDE = ALTITUDE['density']
Density altitude, as measured by the altimeter.
GEOPOTENTIAL_ALTITUDE = ALTITUDE['geopotential']
Geopotential altitude, as measured from mean sea level.
GEOMETRIC_ALTITUDE = ALTITUDE['geometric']
Altitude measured from mean sea level (e.g. via GNSS).
Height above the reference ellipsoid.
Height above ground level (radio altimeter).
ENERGY_HEIGHT = LENGTH['energy_height']
Specific energy expressed as a height.
MEAN_AERODYNAMIC_CHORD_LEADING_EDGE_POSITION = CHORD[
"mean_aerodynamic", "leading_edge"
]
Longitudinal position of the leading edge of the mean aerodynamic chord.
MEAN_GEOMETRIC_CHORD = CHORD['mean_geometric']
Mean geometric chord (Standard Mean Chord).
ASPECT_RATIO = Dimensionless('aspect_ratio')
TAPER_RATIO = Dimensionless('taper_ratio')
FINENESS_RATIO = Dimensionless('fineness_ratio')
Ratio of length to maximum diameter for a fuselage or body.
Angle between the chord line and the relative wind vector.
Angle between the relative wind vector and the plane of symmetry.
CRITICAL_MACH_NUMBER = MACH_NUMBER['critical']
DRAG_DIVERGENCE_MACH_NUMBER = MACH_NUMBER["drag_divergence"]
ZERO_LIFT_DRAG_COEFFICIENT = DRAG_COEFFICIENT['zero_lift']
LIFT_INDUCED_DRAG_COEFFICIENT = DRAG_COEFFICIENT[
"lift_induced"
]
OSWALD_EFFICIENCY = Dimensionless(
"oswald_efficiency_factor"
)
Span efficiency factor.
PITCHING_MOMENT_COEFFICIENT = Dimensionless(
"pitching_moment_coefficient"
)
ROLLING_MOMENT_COEFFICIENT = Dimensionless(
"rolling_moment_coefficient"
)
YAWING_MOMENT_COEFFICIENT = Dimensionless(
"yawing_moment_coefficient"
)
PRESSURE_COEFFICIENT = Dimensionless("pressure_coefficient")
SKIN_FRICTION_COEFFICIENT = Dimensionless(
"skin_friction_coefficient"
)
LIFT_SLOPE = Dimensionless('lift_slope')
Change in lift coefficient per unit angle of attack (per radian).
STANDARD_ITEMS_WEIGHT = AIRCRAFT_MASS['standard_items']
Mass of standard items used in aircraft weight-and-balance.
Equipment and fluids that are not integral to a particular aircraft and do not vary between aircraft of the same type. Examples include unusable fuel and fluids, engine oil, toilet fluid, emergency equipment, galley structure, and supplementary electronic equipment (FAA AC 120-27F, Appendix A.31).
BASIC_WEIGHT = AIRCRAFT_MASS['basic']
Basic weight, a load-control starting weight. Also known as Basic Empty Weight or Fleet Empty Weight.
Includes fixed equipment, system fluids, unusable fuel, and configuration equipment including galley structure (IATA AIDM). It is the aircraft empty weight adjusted for variations in standard items (FAA AC 120-27F, Appendix A.2).
OPERATING_ITEMS_WEIGHT = AIRCRAFT_MASS['operating_items']
Aggregate mass of operating items (OI) included in dry operating weight.
Personnel, equipment, and supplies necessary for a particular operation but not included in the basic empty weight. These items may vary for a particular aircraft. (FAA AC 120-27F, Appendix A.23)
EASA Air Operations requires the operator to determine the mass of operating items and crew members included in dry operating mass.
OPERATING_EMPTY_WEIGHT = AIRCRAFT_MASS['operating_empty']
Operating empty weight (OEW).
The basic weight plus operating items excluding usable fuel and payload.
Whether crew/crew baggage and catering/service items are included depends on the manufacturer or operator.
This term is typically used interchangeably with the dry operating weight
DRY_OPERATING_WEIGHT = AIRCRAFT_MASS['dry_operating']
Dry operating weight/mass (DOW).
Total mass of the aircraft ready for a specific type of operation, excluding usable fuel and traffic load (EASA Air Operations, Annex I, 2025/133(41)).
This term is typically used interchangeably with the operating empty weight. It typically includes crew/crew baggage, catering/service equipment, potable water and other operator-specific items (IATA AIDM).
PAYLOAD = AIRCRAFT_MASS['payload']
Mass carried as payload. Typically includes weight of occupants, cargo and baggage (FAA-H-8083-1B, GAMA).
TRAFFIC_LOAD = AIRCRAFT_MASS['traffic_load']
Operational traffic load.
Load carried in addition to dry operating mass, including passengers, baggage, freight/cargo and, where applicable, ballast or other non-revenue load (EASA Air Operations, Annex I, 2025/133(120)).
ZERO_FUEL_WEIGHT = AIRCRAFT_MASS['zero_fuel']
Total aircraft mass excluding usable fuel (ZFW).
RAMP_WEIGHT = AIRCRAFT_MASS['ramp']
Aircraft mass before taxi, normally including the fuel expected to be consumed before takeoff.
TAKEOFF_WEIGHT = AIRCRAFT_MASS['takeoff']
Aircraft mass at the start of the takeoff roll.
LANDING_WEIGHT = AIRCRAFT_MASS['landing']
FUEL_MASS_FLOW_RATE = MASS_FLOW_RATE['aircraft', 'fuel']
Rate of fuel-mass consumption.
TAXI_FUEL = _FuelRole('taxi_fuel')
Fuel expected to be used before takeoff (CAT.OP.MPA.181(c)(1)).
TRIP_FUEL = _FuelRole('trip_fuel')
Fuel required from takeoff, or an in-flight replanning point, to landing at the destination aerodrome (CAT.OP.MPA.181(c)(2)).
CONTINGENCY_FUEL = _FuelRole('contingency_fuel')
Fuel required to compensate for unforeseen factors (CAT.OP.MPA.181(c)(3)).
ALTERNATE_FUEL = _FuelRole('alternate_fuel')
Fuel required from the destination to the destination alternate, or the prescribed destination holding amount when no alternate is required (CAT.OP.MPA.181(c)(4)).
FINAL_RESERVE_FUEL = _FuelRole('final_reserve_fuel')
Fuel calculated at holding speed at 1500 ft above aerodrome elevation, subject to the prescribed reciprocating- or turbine-engine minimum duration (CAT.OP.MPA.181(c)(5)).
ADDITIONAL_FUEL = _FuelRole('additional_fuel')
Fuel required for the critical fuel en-route-alternate scenario after a consumption-increasing aircraft failure when the other specified components are insufficient (CAT.OP.MPA.181(c)(6)).
EXTRA_FUEL = _FuelRole('extra_fuel')
Fuel carried for anticipated delays or specific operational constraints (CAT.OP.MPA.181(c)(7)).
DISCRETIONARY_FUEL = _FuelRole('discretionary_fuel')
Fuel required at the commander's discretion (CAT.OP.MPA.181(c)(8)).
TANKERING_FUEL = _FuelRole('tankering_fuel')
Supplementary fuel carried for operational reasons (for example, to offset higher fuel price at the destination).
AIRCRAFT_LOAD_INDEX = Dimensionless('aircraft_load_index')
Dimensionless load-distribution index used in weight-and-balance.
CENTER_OF_GRAVITY_MAC = Dimensionless(
"center_of_gravity_mean_aerodynamic_chord"
)
Centre-of-gravity position as a fraction of mean aerodynamic chord.
Weight of the aircraft divided by the wing area.
Weight of the aircraft divided by the engine power.
THRUST_LOADING = Dimensionless('thrust_loading')
Thrust to weight ratio.
LOAD_FACTOR = Dimensionless('load_factor')
Ratio of lift to weight (n).
ROLL_RATE = ANGULAR_VELOCITY['roll']
Angular velocity about the body X axis.
PITCH_RATE = ANGULAR_VELOCITY['pitch']
Angular velocity about the body Y axis.
FLIGHT_PATH_ANGLE = ATTITUDE['flight_path']
Angle between the velocity vector and the horizon.
STATIC_MARGIN = Dimensionless('static_margin')
Distance between the neutral point and the center of gravity, normalized by MAC.
NEUTRAL_POINT = DISTANCE['neutral_point']
Longitudinal position of the aerodynamic center of the whole aircraft.
HORIZONTAL_TAIL_VOLUME_COEFFICIENT = (
TAIL_VOLUME_COEFFICIENT["horizontal"]
)
VERTICAL_TAIL_VOLUME_COEFFICIENT = TAIL_VOLUME_COEFFICIENT[
"vertical"
]
CONST_TEMPERATURE_ISA: Annotated[
Decimal, STATIC_TEMPERATURE(K)
] = Decimal("288.15")
TEMPERATURE_DEVIATION_ISA = STATIC_TEMPERATURE[
DELTA, OriginAt(Quantity(CONST_TEMPERATURE_ISA, K))
]
Deviation from the ISA temperature at sea level.
TEMPERATURE_RATIO = ratio(
STATIC_TEMPERATURE(K),
Quantity(CONST_TEMPERATURE_ISA, K),
)
INDICATED_AIRSPEED = AIRSPEED['indicated']
Indicated airspeed (IAS), as measured directly from the pitot-static system.
CALIBRATED_AIRSPEED = AIRSPEED['calibrated']
Calibrated airspeed (CAS), IAS corrected for instrument and position errors.
EQUIVALENT_AIRSPEED = AIRSPEED['equivalent']
Equivalent airspeed (EAS), CAS corrected for compressibility.
TRUE_AIRSPEED = AIRSPEED['true']
True airspeed (TAS), speed relative to the airmass.
CORNER_SPEED = AIRSPEED['corner']
The speed at which the maximum lift coefficient and the maximum load factor are reached simultaneously.
DENSITY_FACTOR = Dimensionless('density_factor')
Square root of local air density divided by a stated reference density.
COMPRESSIBILITY_FACTOR = Dimensionless(
"compressibility_factor"
)
Dimensionless correction factor used when relating compressible-flow airspeeds.
VERTICAL_RATE_INERTIAL = VERTICAL_RATE['inertial']
Vertical rate derived from inertial sensors/GNSS.
VERTICAL_RATE_BAROMETRIC = VERTICAL_RATE['barometric']
Vertical rate derived from barometric pressure changes.
TURN_RADIUS = DISTANCE['turn_radius']
Fuel mass flow rate per unit thrust.
Fuel mass flow rate per unit power.
BYPASS_RATIO = ratio(
ENGINE_MASS_FLOW_RATE["bypass"].si_coherent(),
ENGINE_MASS_FLOW_RATE["core"].si_coherent(),
)
ADVANCE_RATIO = Dimensionless('advance_ratio')
Ratio of freestream speed to tip speed for propellers.
ICAO_ADDRESS = Dimensionless('icao_address_24_bit')
Unique 24-bit aircraft address assigned by ICAO.
NAVIGATION_UNCERTAINTY_CATEGORY_POSITION = Dimensionless(
"adsb_nucp"
)
NAVIGATION_UNCERTAINTY_CATEGORY_VELOCITY = Dimensionless(
"adsb_nucv"
)
NAVIGATION_ACCURACY_CATEGORY_POSITION = Dimensionless(
"adsb_nacp"
)
NAVIGATION_ACCURACY_CATEGORY_VELOCITY = Dimensionless(
"adsb_nacv"
)