_otype = otBallistic;
drag_area = 0.007;
life_timer = 0.0;
- gravity = 32;
-// buoyancy = 64;
+ gravity = 32;
+// buoyancy = 64;
no_roll = false;
- }
+}
FGAIBallistic::~FGAIBallistic() {
}
void FGAIBallistic::setWind(bool val) {
wind = val;
}
+
+void FGAIBallistic::setCd(double c) {
+ Cd = c;
+}
+
+void FGAIBallistic::setMass(double m) {
+ mass = m;
+}
+
void FGAIBallistic::Run(double dt) {
life_timer += dt;
+// cout << "life timer 1" << life_timer << dt << endl;
if (life_timer > life) setDie(true);
double speed_north_deg_sec;
double speed_east_deg_sec;
double wind_speed_from_north_deg_sec;
double wind_speed_from_east_deg_sec;
-
- // the two drag calculations below assume sea-level density,
- // mass of 0.03 slugs, drag coeff of 0.295
- // adjust speed due to drag
- speed -= 0.0116918 * drag_area * speed * speed * dt;
+ double Cdm; // Cd adjusted by Mach Number
+
+ // Adjust Cd by Mach number. The equations are based on curves
+ // for a conventional shell/bullet (no boat-tail).
+ if ( Mach < 0.7 ) { Cdm = 0.0125 * Mach + Cd; }
+ else if ( 0.7 < Mach && Mach < 1.2 ) {
+ Cdm = 0.3742 * pow ( Mach, 2) - 0.252 * Mach + 0.0021 + Cd; }
+ else { Cdm = 0.2965 * pow ( Mach, -1.1506 ) + Cd; }
+
+// cout << " Mach , " << Mach << " , Cdm , " << Cdm << endl;
+
+ // drag = Cd * 0.5 * rho * speed * speed * drag_area;
+ // rho is adjusted for altitude in void FGAIBase::update,
+ // using Standard Atmosphere (sealevel temperature 15C)
+ // acceleration = drag/mass;
+ // adjust speed by drag
+ speed -= (Cdm * 0.5 * rho * speed * speed * drag_area/mass) * dt;
+
+ // don't let speed become negative
if ( speed < 0.0 ) speed = 0.0;
+
+ // calculate vertical and horizontal speed components
vs = sin( pitch * SG_DEGREES_TO_RADIANS ) * speed;
hs = cos( pitch * SG_DEGREES_TO_RADIANS ) * speed;
speed_north_deg_sec = cos(hdg / SG_RADIANS_TO_DEGREES) * hs / ft_per_deg_lat;
speed_east_deg_sec = sin(hdg / SG_RADIANS_TO_DEGREES) * hs / ft_per_deg_lon;
- // convert wind speed (fps) to degrees per second
-
- if (!wind){
+ // if wind not required, set to zero
+ if (!wind) {
wind_from_north = 0;
wind_from_east = 0;
- }
-
+ }
+
+ // convert wind speed (fps) to degrees per second
wind_speed_from_north_deg_sec = wind_from_north / ft_per_deg_lat;
wind_speed_from_east_deg_sec = wind_from_east / ft_per_deg_lon;
-
- // set new position
-// pos.setlat( pos.lat() + (speed_north_deg_sec * dt) );
-// pos.setlon( pos.lon() + (speed_east_deg_sec * dt) );
-
-
// set new position
-
pos.setlat( pos.lat() + (speed_north_deg_sec - wind_speed_from_north_deg_sec) * dt );
pos.setlon( pos.lon() + (speed_east_deg_sec - wind_speed_from_east_deg_sec) * dt );
- // adjust vertical speed for acceleration of gravity
+ // adjust vertical speed for acceleration of gravity and buoyancy
vs -= (gravity - buoyancy) * dt;
// adjust altitude (feet)
// set destruction flag if altitude less than sea level -1000
if (altitude < -1000.0) setDie(true);
-}
+} // end Run
double FGAIBallistic::_getTime() const {
- return life_timer;
+// cout << "life timer 2" << life_timer << endl;
+ return life_timer;
}
-// end AIBallistic
\ No newline at end of file
+// end AIBallistic