constraint Element

Constraint

Namespace: Empty

Schema: Empty

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

Reference to the uID of the segment end condition variable

      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

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

      Element machNumber[0, 1]

Mach number within the segment

      Element climbAngle[0, 1]

Climb angle within the segment

      Element rateOfClimb[0, 1]

Climb angle within the segment

      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]

            Element turnAngle

Total change of heading angle during segment (a full turn is 360 degrees) [deg]

      Element rateOfTurn[0, 1]

Rate of turn within the segment

      Element thrustSetting[0, 1]

Thrust setting for derated engine as fraction of max. Thrust (e.g.: for powered descents, deceleration not at IDLE, manoevres).

      Element acceleration[0, 1]

Rate of velocity within the segment

      Element loadFactor[0, 1]

Load factor experienced during segment

      Element altitude[0, 1]

Constant altitude for the segment.

      Element prioritySetting[0, 1]

priority setting indicating which constraint is preferred within the segment

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
<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