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constraint Element

Constraint

Namespace: Empty

Schema: Empty

Type
Parents
Children
NameOccurrencesDescription
Sequence Sequence
      Element referenceEndConditionUID[0, 1]

Reference to the uID of the segment end condition variable to which a profile of constraintSettings is provided

      Element endConditionRatio[0, 1]

Vector indicating the ratios of the constraintSettings profile with respect to the provided referenceEndCondition, ranging from 0 to 1. If this vector is defined, the provided constraintSettings are expected to be vectors with the same length providing ratio-value pairs. Example: for referenceEndCondition <range><z> (i.e.: flown distance in z direction of the segment), a vector of <CAS> and <machNumber> is provided to define a climb profile.

      Element continuity[0, 1]

Defines how to interpret the parameter lapses within the segment: discrete steps (C0 continuity) or linear interpolation (C1 continuity)

      Element calibratedAirSpeed[0, 1]

Calibrated airspeed within the segment. If a vector is provided, a constraint profile is defined with respect to the <referenceEndCondition> using the <endConditionRatio> vector.

      Element machNumber[0, 1]

Mach number within the segment. If a vector is provided, a constraint profile is defined with respect to the <referenceEndCondition> using the <endConditionRatio> vector.

      Element climbAngle[0, 1]

Climb angle within the segment. If a vector is provided, a constraint profile is defined with respect to the <referenceEndCondition> using the <endConditionRatio> vector.

      Element rateOfClimb[0, 1]

Rate of climb within the segment. If a vector is provided, a constraint profile is defined with respect to the <referenceEndCondition> using the <endConditionRatio> vector.

      Element stepClimbSpecificExcessPower[0, 1]

Specific excess power within the segment (e.g.: for defining minimum SEP to remain after step climbs have been performed).

      Element stepClimbAltitudeDifference[0, 1]

Altitude difference of each step climb

      Choice Choice[0, 1]
            Element heading

Flight heading at the end of the segment in compassAngle with reference to true North [deg]. If a vector is provided, a constraint profile is defined with respect to the <referenceEndCondition> using the <endConditionRatio> vector.

            Element turnAngle

Total change of heading angle during segment (a full turn is 360 degrees) [deg]. If a vector is provided, a constraint profile is defined with respect to the <referenceEndCondition> using the <endConditionRatio> vector.

      Element rateOfTurn[0, 1]

Rate of turn within the segment [deg/s]. If a vector is provided, a constraint profile is defined with respect to the <referenceEndCondition> using the <endConditionRatio> vector.

      Element thrustSetting[0, 1]

Thrust setting for derated engine as fraction of max. Thrust (e.g.: for powered descents, deceleration not at IDLE, manoevres). If a vector is provided, a constraint profile is defined with respect to the <referenceEndCondition> using the <endConditionRatio> vector.

      Element acceleration[0, 1]

Rate of velocity within the segment. If a vector is provided, a constraint profile is defined with respect to the <referenceEndCondition> using the <endConditionRatio> vector.

      Element loadFactor[0, 1]

Load factor experienced during segment. If a vector is provided, a constraint profile is defined with respect to the <referenceEndCondition> using the <endConditionRatio> vector.

      Element altitude[0, 1]

Constant altitude of the segment. If a vector is provided, a constraint profile is defined with respect to the <referenceEndCondition> using the <endConditionRatio> vector.

      Element prioritySetting[0, 1]

Priority setting indicating which constraint is preferred within the segment. If a vector is provided, a constraint profile is defined with respect to the <referenceEndCondition> using the <endConditionRatio> vector.

Attributes
NameTypeRequiredDescription
Attribute externalDataDirectorySimple Type string
Attribute externalDataNodePathSimple Type string
Attribute externalFileNameSimple Type string
Remarks

Specification of performance constraints.

Constraints allow vectors of double values to define parameter lapses within a mission segment. The example below illustrates this by means of an exemplary climb profile of a conventional airliner, in which multiple physical and regulatory speed constraints are simultaneously specified over several altitudes (e.g., to account for the crossover altitude):

Example climb constraints using parameter lapses
Copy
<endCondition>
    <positionGeo>
        <altitude relationalOperator="ge" uID="altClimb">10058.4</altitude> <!-- FL330 -->
    </positionGeo>
</endCondition>
<constraint>
    <referenceEndConditionUID>altClimb</referenceEndConditionUID>
    <endConditionRatio>0.0;0.303</endConditionRatio> <!-- FL0, FL100 -->
    <continuitySetting>discrete</continuitySetting>
    <CAS relationalOperator="le">128.61;154.33</CAS> <!-- 250 [kt], 300 [kt]-->
    <machNumber relationalOperator="le">0.78;0.78</machNumber>
    <prioritySetting>velocity</prioritySetting>
</constraint>

From FL0 until FL100, the vehicle should fly at a velocity less than or equal to CAS = 250 kt or M = 0.78. In this first segment at low altitudes, the constraint on CAS is triggered.

From FL100 until FL330, the vehicle should fly at a velocity less than or equal to CAS = 300 kt or M = 0.78. In this second segment, the vehicle starts by increasing velocity until 300 kt, the constraint on maximum machNumber triggers from the crossover altitude onwards

See Also