jat.forces
Class AtmosphericDrag

java.lang.Object
  jat.forces.AtmosphericDrag

All Implemented Interfaces:

EarthForceModel, ForceModel

Direct Known Subclasses:

CIRA_ExponentialDrag, ExponentialDrag, HarrisPriester, NRLMSISE_Drag

public abstract class AtmosphericDrag
extends java.lang.Object
implements ForceModel, EarthForceModel

The AtmosphericDrag class computes the acceleration due to drag on a satellite using an Earth atmosphere model that conforms to the computeDensity abstract method.

Version:

1.0

Author:

Dave Gaylor

Field Summary

double

omega_e Rotation rate of the Earth (taken from Constants.omega_e)

Constructor Summary

AtmosphericDrag(double cd, double area, double mass)
Constructor

AtmosphericDrag(Spacecraft sc)
Constructor using the Spacecraft class for parameters

Method Summary

VectorN	acceleration(EarthRef eRef, Spacecraft sc) Deprecated.
VectorN	acceleration(Time t, BodyRef bRef, Spacecraft sc) Implemented from the ForceModel interface
void	compute(Time t, BodyRef ref, VectorN r, VectorN v) Computes the acceleration due to drag in m/s^2.
abstract double	computeDensity(Time t, BodyRef ref, VectorN r) Abstract class requires the subclass to compute the atmospheric density.
VectorN	dragAccel() Return the acceleration due to drag
VectorN	partialCd() Return the partial derivative of acceleration wrt Cd
Matrix	partialV() Return the partial derivative of acceleration wrt velocity
void	updateMass(double mass) Update the mass

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

omega_e

public double omega_e

Rotation rate of the Earth (taken from Constants.omega_e)

Constructor Detail

AtmosphericDrag

public AtmosphericDrag(double cd,
                       double area,
                       double mass)

Constructor

Parameters:

cd - coefficient of drag

area - drag cross-sectional area

mass - mass

AtmosphericDrag

public AtmosphericDrag(Spacecraft sc)

Constructor using the Spacecraft class for parameters

Parameters:

sc - Spacecraft parameters

Method Detail

computeDensity

public abstract double computeDensity(Time t,
                                      BodyRef ref,
                                      VectorN r)

Abstract class requires the subclass to compute the atmospheric density.

Parameters:

ref - EarthRef object.

r - Position vector.

Returns:

Atmospheric density in kg/m^3

dragAccel

public VectorN dragAccel()

Return the acceleration due to drag

Returns:

VectorN containing the acceleration due to drag

partialV

public Matrix partialV()

Return the partial derivative of acceleration wrt velocity

Returns:

Matrix containing the partial derivative of acceleration wrt velocity

partialCd

public VectorN partialCd()

Return the partial derivative of acceleration wrt Cd

Returns:

Matrix containing the partial derivative of acceleration wrt Cd

updateMass

public void updateMass(double mass)

Update the mass

Parameters:

mass - the new mass

compute

public void compute(Time t,
                    BodyRef ref,
                    VectorN r,
                    VectorN v)

Computes the acceleration due to drag in m/s^2.

Parameters:

ref - EarthRef object.

r - ECI position vector in meters.

v - ECI velocity vector in meters.

acceleration

public VectorN acceleration(Time t,
                            BodyRef bRef,
                            Spacecraft sc)

Implemented from the ForceModel interface

Specified by:

acceleration in interface ForceModel

Parameters:

t - Time reference object

bRef - Earth reference object

sc - Spacecraft parameters and state

Returns:

the acceleration [m/s^s]

See Also:

ForceModel.acceleration(jat.spacetime.Time, jat.spacetime.BodyRef, jat.spacecraft.Spacecraft)

acceleration

public VectorN acceleration(EarthRef eRef,
                            Spacecraft sc)

Deprecated.

Returns the acceleration developed on the spacecraft at the current time and position

Specified by:

acceleration in interface EarthForceModel

Parameters:

eRef - Earth reference object

sc - Spacecraft parameters and state

Returns:

the acceleration [m/s^2]

See Also:

EarthForceModel.acceleration(jat.timeRef.EarthRef, jat.spacecraft.Spacecraft)