// Define the X-33 class
class X33 : public VESSEL4 {
public:
// Constructor
X33(OBJHANDLE hObj, int flightmodel);
// Flight model override function
void clbkSetClassCaps(FILEHANDLE cfg);
// Flight model update function
void clbkPreStep(double simt, double simdt, double mjd);
private:
// Private variables for spacecraft dynamics
double mass;
double fuel;
VECTOR3 CoM;
VECTOR3 CoP;
VECTOR3 thrust_vector;
double thrust_magnitude;
double Isp;
double Cd;
double Cl;
double As;
double Ar;
double bank_angle;
double pitch_angle;
double yaw_angle;
double altitude;
// Private functions for spacecraft dynamics
void update_dynamics(double simt, double simdt);
void compute_forces_moments();
};
// Constructor
X33::X33(OBJHANDLE hObj, int flightmodel) : VESSEL4(hObj, flightmodel) {
// Set initial values for private variables
mass = 27000.0;
fuel = 18000.0;
CoM = _V(0, 0, -5.6);
CoP = _V(0, 0, -4.2);
thrust_vector = _V(0, 0, -1);
thrust_magnitude = 300000.0;
Isp = 330.0;
Cd = 0.3;
Cl = 0.3;
As = 330.0;
Ar = 160.0;
bank_angle = 0.0;
pitch_angle = 0.0;
yaw_angle = 0.0;
altitude = 0.0;
}
// Flight model override function
void X33::clbkSetClassCaps(FILEHANDLE cfg) {
VESSEL4::clbkSetClassCaps(cfg);
// Set vessel mass and empty mass
SetEmptyMass(mass - fuel);
SetSize(10.0);
// Define propellant resources
AddPropellantResource("LH2", fuel);
// Define thruster groups
CreateThrusterGroup("main", 1, &thrust_vector, true, Isp, Cd, Cl, As, Ar);
}
// Flight model update function
void X33::clbkPreStep(double simt, double simdt, double mjd) {
// Update spacecraft dynamics
update_dynamics(simt, simdt);
// Calculate forces and moments acting on spacecraft
compute_forces_moments();
// Update spacecraft state
VESSEL4::clbkPreStep(simt, simdt, mjd);
}
// Private function to update spacecraft dynamics
void X33::update_dynamics(double simt, double simdt) {
// Update vessel velocity and position
VECTOR3 vel = GetRelativeVelocity();
VECTOR3 pos = GetRelativePos();
VECTOR3 acc = GetGravityRef()->GetAcceleration(GetPosition());
SetRelativeVel(vel + acc * simdt);
SetRelativePos(pos + vel * simdt + 0.5 * acc * simdt * simdt);
// Update vessel attitude
bank_angle += GetControlSurfaceLevel(AIRCTRL_BANK, 0) * simdt * 10;
pitch_angle += GetControlSurfaceLevel(AIRCTRL_PITCH, 0) * simdt *