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Path: SC/Disturbances
% Compute the total force and torque on a spacecraft generated by the CAD package.
Environment inputs are given in e.
The number of points generated will equal the length of the longest
transformation matrix in g or the longest member of e. If the number of
points is > 1 all other members of e and transformation matrices in g
must equal that number or 1.
The optical input is a flux vector with magnitude in watts.
The aerodynamic and optical computations optionally use shadowing.
To get shadowing you must enter the shadow and scanLines fields.
Planetary radiation assumes that the optical coefficients are zero
except for the diffuse coefficient which is 1.
The defaults are:
- AtmDens2 for the Earth, if atmosphericDensity is not entered
- AtmDens1 for the other planets, if atmosphericDensity is not entered
- Constant(['bond albedo ',e.planet]) for albedo fraction, if not entered
- Constant(['mu ',e.planet]) for mu, if not entered
- Constant(['equatorial radius ',e.planet]), if planetRadius not entered
- Constant(['black body radiation ',e.planet]) if radiation is not entered
- No aerodynamic disturbances unless v is entered
- No planetary radiation unless r is entered
- Flags computeAero and computePR override defaults
- No shadowing
- No scan display and 0 scanLines
- No plots
The output units are determined by e.units as follows:
e.units force torque
------- ----- ------
'm' N Nm
'in' lbf in-lbf
'ft' lbf ft-lbf
You first call
h = Disturbances( 'init', g, e );
This returns a handle, h, to the display. You can then call this
[f, t, m, harm, angMom] = Disturbances( 'run', g, e, h, doPlots )
multiple times.
Since version 2.
--------------------------------------------------------------------------
Forms:
e = Disturbances( 'defaults' )
h = Disturbances( 'init', g, e )
[f, t, m, harm, angMom] = Disturbances( 'run', g, e, h, doPlots )
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------
Inputs
------
mode 'init', 'defaults' or 'run'
g Spacecraft data structure
e Disturbances data structure
.units (1,:) 'm', 'in', 'ft'
.r (3,:) Distance from gravity center (km)
.v (3,:) Velocity vector in the inertial frame (km/sec)
- should include planetary rotation
.s (3,:) Solar optical radiation flux vector (watts)
.b (3,:) Magnetic field vector (T)
.planet (1,:) Will compute density and mu for various
planets
.planetRadius* (1,:) Radius of the planet (km)
.atmosphericDensity* (1,:) Density
.mu* (1,1) Gravitational parameter (km^3/sec^2)
.albedo* (1,1) Albedo fraction
.radiation* (1,1) Planet radiation (w/m^2)
* looked up by planet if not entered or 0
.tGas (1,1) Gas temperature (deg-K)
.mGas (1,1) Gas molecular weight
.tSamp (1,1) Sample time between transformation matrices in g
.shadow (1,1) 1 for on, 0 for off
.nScanLines (1,1) Number of scan lines for shadowing
.showScans (1,1) True means show the HSRCAD scan display
.computeAero** (1,1) True means compute aerodynamic torques
.computePR** (1,1) True means compute planetary radiation torques
** optional fields
h Handle to display
doPlots If true, will plot outputs
-------
Outputs
-------
f (:) Force structure or handle to display if mode is 'init'
.total (3,:) Force in ECI frame
.aero Aerodynamic
.optical Optical
.thermal Thermal
.rF Radio Frequency
.pR Planetary radiation
.al Planetary albedo
t (:) Torque structure
.total (3,:) Torque in body frame
.aero
.magnetic
.optical
.thermal
.rF
.pR
.al
.gravityGradient
m (:) Mass properties
.mass
.inertia
.cM
harm (:) Harmonic coefficients
.wf(3,:) Harmonic frequencies for force
.wt(3,:) Harmonic frequencies for torque
.f (3,:) Harmonic coefficents
.sin
.cos
.dC
.t (3,:) Harmonic coefficents
.sin
.cos
.dC
angMom (:) Angular momentum
.eCI (3,:) In the inertial frame
.body (3,:) In the body frame
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AerospaceUtils: AtmosphericCalculations/AtmDens1 AerospaceUtils: AtmosphericCalculations/AtmDens2 AerospaceUtils: CAD/BHinge AerospaceUtils: CAD/HSRCAD Common: Database/Constant Common: Graphics/NewFig Common: Graphics/Plot2D Common: Graphics/TimeLabl Common: Time/JD2000 Math: Analysis/FourierSeries Math: Linear/Cross Math: Linear/Dot Math: Linear/DupVect Math: Linear/Mag Math: Linear/SkewSq Math: Linear/Unit SC: BasicOrbit/VOrbit SC: Environs/MagField SC: Environs/SolarFlx SC: Ephem/SunV1
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