git.gag.com Git - debian/openrocket/blob - src/net/sf/openrocket/simulation/BasicLandingStepper.java

   1 package net.sf.openrocket.simulation;
   2
   3 import net.sf.openrocket.models.atmosphere.AtmosphericConditions;
   4 import net.sf.openrocket.rocketcomponent.RecoveryDevice;
   5 import net.sf.openrocket.simulation.exception.SimulationException;
   6 import net.sf.openrocket.util.Coordinate;
   7 import net.sf.openrocket.util.MathUtil;
   8
   9 public class BasicLandingStepper extends AbstractSimulationStepper {
  10
  11         private static final double RECOVERY_TIME_STEP = 0.5;
  12
  13
  14         @Override
  15         public SimulationStatus initialize(SimulationStatus status) throws SimulationException {
  16                 return status;
  17         }
  18
  19         @Override
  20         public void step(SimulationStatus status, double maxTimeStep) throws SimulationException {
  21                 double totalCD = 0;
  22                 double refArea = status.getConfiguration().getReferenceArea();
  23
  24                 // Get the atmospheric conditions
  25                 AtmosphericConditions atmosphere = modelAtmosphericConditions(status);
  26
  27                 //// Local wind speed and direction
  28                 Coordinate windSpeed = modelWindVelocity(status);
  29                 Coordinate airSpeed = status.getRocketVelocity().add(windSpeed);
  30
  31                 // Get total CD
  32                 double mach = airSpeed.length() / atmosphere.getMachSpeed();
  33                 for (RecoveryDevice c : status.getDeployedRecoveryDevices()) {
  34                         totalCD += c.getCD(mach) * c.getArea() / refArea;
  35                 }
  36
  37                 // Compute drag force
  38                 double dynP = (0.5 * atmosphere.getDensity() * airSpeed.length2());
  39                 double dragForce = totalCD * dynP * refArea;
  40                 MassData massData = calculateMassData(status);
  41                 double mass = massData.getCG().weight;
  42
  43
  44                 // Compute drag acceleration
  45                 Coordinate linearAcceleration;
  46                 if (airSpeed.length() > 0.001) {
  47                         linearAcceleration = airSpeed.normalize().multiply(-dragForce / mass);
  48                 } else {
  49                         linearAcceleration = Coordinate.NUL;
  50                 }
  51
  52                 // Add effect of gravity
  53                 double gravity = modelGravity(status);
  54                 linearAcceleration = linearAcceleration.sub(0, 0, gravity);
  55
  56
  57                 // Select time step
  58                 double timeStep = MathUtil.min(0.5 / linearAcceleration.length(), RECOVERY_TIME_STEP);
  59
  60                 // Perform Euler integration
  61                 status.setRocketPosition(status.getRocketPosition().add(status.getRocketVelocity().multiply(timeStep)).
  62                                 add(linearAcceleration.multiply(MathUtil.pow2(timeStep) / 2)));
  63                 status.setRocketVelocity(status.getRocketVelocity().add(linearAcceleration.multiply(timeStep)));
  64                 status.setSimulationTime(status.getSimulationTime() + timeStep);
  65
  66
  67                 // Store data
  68                 FlightDataBranch data = status.getFlightData();
  69                 boolean extra = status.getSimulationConditions().isCalculateExtras();
  70                 data.addPoint();
  71
  72                 data.setValue(FlightDataType.TYPE_TIME, status.getSimulationTime());
  73                 data.setValue(FlightDataType.TYPE_ALTITUDE, status.getRocketPosition().z);
  74                 data.setValue(FlightDataType.TYPE_POSITION_X, status.getRocketPosition().x);
  75                 data.setValue(FlightDataType.TYPE_POSITION_Y, status.getRocketPosition().y);
  76                 if (extra) {
  77                         data.setValue(FlightDataType.TYPE_POSITION_XY,
  78                                         MathUtil.hypot(status.getRocketPosition().x, status.getRocketPosition().y));
  79                         data.setValue(FlightDataType.TYPE_POSITION_DIRECTION,
  80                                         Math.atan2(status.getRocketPosition().y, status.getRocketPosition().x));
  81
  82                         data.setValue(FlightDataType.TYPE_VELOCITY_XY,
  83                                         MathUtil.hypot(status.getRocketVelocity().x, status.getRocketVelocity().y));
  84                         data.setValue(FlightDataType.TYPE_ACCELERATION_XY,
  85                                         MathUtil.hypot(linearAcceleration.x, linearAcceleration.y));
  86
  87                         data.setValue(FlightDataType.TYPE_ACCELERATION_TOTAL, linearAcceleration.length());
  88
  89                         double Re = airSpeed.length() *
  90                                         status.getConfiguration().getLength() /
  91                                         atmosphere.getKinematicViscosity();
  92                         data.setValue(FlightDataType.TYPE_REYNOLDS_NUMBER, Re);
  93                 }
  94
  95                 data.setValue(FlightDataType.TYPE_VELOCITY_Z, status.getRocketVelocity().z);
  96                 data.setValue(FlightDataType.TYPE_ACCELERATION_Z, linearAcceleration.z);
  97
  98                 data.setValue(FlightDataType.TYPE_VELOCITY_TOTAL, airSpeed.length());
  99                 data.setValue(FlightDataType.TYPE_MACH_NUMBER, mach);
 100
 101                 data.setValue(FlightDataType.TYPE_MASS, mass);
 102
 103                 data.setValue(FlightDataType.TYPE_THRUST_FORCE, 0);
 104                 data.setValue(FlightDataType.TYPE_DRAG_FORCE, dragForce);
 105
 106                 data.setValue(FlightDataType.TYPE_WIND_VELOCITY, windSpeed.length());
 107                 data.setValue(FlightDataType.TYPE_AIR_TEMPERATURE, atmosphere.getTemperature());
 108                 data.setValue(FlightDataType.TYPE_AIR_PRESSURE, atmosphere.getPressure());
 109                 data.setValue(FlightDataType.TYPE_SPEED_OF_SOUND, atmosphere.getMachSpeed());
 110
 111                 data.setValue(FlightDataType.TYPE_TIME_STEP, timeStep);
 112                 data.setValue(FlightDataType.TYPE_COMPUTATION_TIME,
 113                                 (System.nanoTime() - status.getSimulationStartWallTime()) / 1000000000.0);
 114         }
 115
 116 }