positioningType

A positioning translates a section of a component, e.g. a wing or a fuselage, in the coordinate system of the component. Instead of Cartesian coordinates, the translation is given by a length and two angles, so that span, sweep and dihedral of a wing can be set directly. The positioning does not rotate the section.

Positioning vector

The positioning vector v is the y-axis scaled to the length L, rotated by the sweepAngle φ about the z-axis towards positive x, and then by the dihedralAngle ν about the x-axis towards positive z:

v = L (sin phi, cos phi cos nu, cos phi sin nu)

A positive sweep angle thus points the vector backwards, a positive dihedral angle upwards. With both angles equal to 0, the vector points along the y-axis. For a fuselage, whose sections follow the x-axis, a sweep angle of 90 points the vector along the x-axis.

The dihedral angle is the angle of the vector in the front view (y-z plane). The sweep angle is the angle between the vector and the y-z plane; in the top view, the vector appears more strongly swept if the dihedral angle is not 0.

Construction of a positioning vector of length L from the y-axis rotated by the sweep angle phi about the z-axis and by the dihedral angle nu about the x-axis, and a chain of positionings A, B, C in which positioning C starts at the end of positioning B although section B is additionally translated

Figure (a) constructs the vector: the y-axis is first rotated by φ in the x-y plane and then by ν about the x-axis.

Chain of positionings

Without fromSectionUID, the vector starts at the origin of the component coordinate system. With fromSectionUID, it starts at the end of the positioning of the referenced section, so that positionings form a chain, e.g. from the root over the kink to the tip. The translation of the referenced section does not move this start point; the chain connects the ends of the positionings only. The origin of a section lies at the end of its positioning plus its own translation.

Figure (b) shows a chain in the top view. Section B is additionally translated by its transformation, and positioning C still starts at the end of positioning B.

Each section is positioned by at most one positioning, i.e. no two positionings reference the same section in toSectionUID.
A section referenced by fromSectionUID is positioned itself, i.e. it is the toSectionUID of another positioning.
The positionings of a component do not form a cycle.

Example

The positionings of the wing shown in wingType: the root section stays at the origin, and the kink and tip sections are each positioned from the previous section.

<positionings>
    <positioning uID="Wing_root_positioning">
        <name>Root positioning</name>
        <length>0</length>
        <sweepAngle>0</sweepAngle>
        <dihedralAngle>0</dihedralAngle>
        <toSectionUID>Wing_root</toSectionUID>
    </positioning>
    <positioning uID="Wing_kink_positioning">
        <name>Kink positioning</name>
        <length>6</length>
        <sweepAngle>20</sweepAngle>
        <dihedralAngle>6</dihedralAngle>
        <fromSectionUID>Wing_root</fromSectionUID>
        <toSectionUID>Wing_kink</toSectionUID>
    </positioning>
    <positioning uID="Wing_tip_positioning">
        <name>Tip positioning</name>
        <length>9</length>
        <sweepAngle>28</sweepAngle>
        <dihedralAngle>6</dihedralAngle>
        <fromSectionUID>Wing_kink</fromSectionUID>
        <toSectionUID>Wing_tip</toSectionUID>
    </positioning>
</positionings>

Chain of positionings from root to tip

Attributes

Name	Type	Use	Description
`@externalDataDirectory`	`xsd:string`	optional	Directory of the external data file
`@externalDataNodePath`	`xsd:string`	optional	Path of the node inside the external data file
`@externalFileName`	`xsd:string`	optional	Name of the external data file
`@uID`	`xsd:ID`	required	UID

Child elements

Name	Type	OccurrenceHow often the element may appear at this place. The schema writes it as minOccurs and maxOccurs on the declaration.	Description
allThe children below may appear in any order. Each may appear at most once.
`name`	`stringBaseType`	[1..1] required	Name
`description`	`stringBaseType`	[0..1] optional	Description
`length`	`doubleBaseType`	[1..1] required	Length of the positioning vector [m]
`sweepAngle`	`doubleBaseType`	[1..1] required	Rotation of the positioning vector about the z-axis towards positive x, applied before the dihedral angle [deg]
`dihedralAngle`	`doubleBaseType`	[1..1] required	Rotation of the positioning vector about the x-axis towards positive z [deg]
`fromSectionUID`	`stringUIDBaseType`	[0..1] optional	Section at the end of whose positioning the vector starts. If missing, the vector starts at the origin of the component coordinate system.
`toSectionUID`	`stringUIDBaseType`	[1..1] required	Section translated by the positioning

positioningType

Attributes

Child elements

Used by

In a dataset · 7 paths

In the schema · 1 declaration