FiniteBurn.BurnDirection Property

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Description

The components of the thrust vector in the coordinates of the attitude system specified by the chosen AttitudeSystem.

 

For each attitude system the components are defined as follows:

 

Coordinate System

Attitude System

X-Component

Y-Component

Z-Component

Mean of J2000 (MJ2000)

0

GCI X

GCI Y

GCI Z

Velocity-Normal-Binormal (VNB)

1

Velocity

Orbit Normal

Binormal (completes the right-handed system)

Local Vertical Local Horizontal (LVLH)

2

Co-Velocity

Negative Orbit Normal

Nadir

Spacecraft Attitude

3

Spacecraft rotated to BurnDirection[0] in degrees

Spacecraft rotated to BurnDirection[1] in degrees

Spacecraft rotated to BurnDirection[2] in degrees

Geodetic

4

Geodetic X

Negative Orbit Normal

Normal to Earth's surface

UVW

5

U (Position)

V (Along Velocity Direction)

W (Orbit Normal)

RIC

6

R (Position)

I (Along Velocity Direction/"In-Track")

C (Orbit Normal/"Cross-Track")

 

Note: When the attitude system is "Spacecraft Attitude," the Spacecraft object's attitude is adjusted so that the Euler angles are temporarily set to the values specified by the BurnDirection components for the duration of the maneuver.  Each angle specified by the BurnDirection Array is evaluated in degrees and is referenced to the Spacecraft object's attitude reference frame.  The Euler sequence used to apply the BurnDirection components during the maneuver is defined by the Spacecraft object's EulerSequence property. Where applicable, individual thruster orientations defined in the Thruster object(s) are used to direct the delta-Vs.

 

In the above descriptions, the Orbit Normal is aligned with the angular momentum vector, the Negative Orbit Normal is aligned with the negative angular momentum vector, and Nadir points to the center of the Earth. The X-components of the VNB and LVLH coordinate systems, Velocity and Co-Velocity, differ by a rotation about the flight path angle. For more information on each of the coordinate systems above, see the Attitude Reference Frames page.

 

 

Timing Precision Mode

This page describes functionality in nanosecond timing precision mode.

 

Attributes

Type:

Array of number (size = 3)

Access:

read/write

Default Value:

{ 1, 0, 0 }

 

Syntax

myVariable1 = myFiniteBurn1.BurnDirection[0];

 

myFiniteBurn1.BurnDirection[0] = myVariable1;

 

See also

FiniteBurn Object

Finite Burns Guide