+package net.sf.openrocket.simulation.listeners.example;
+
+import java.util.List;
+import java.util.Map;
+
+import net.sf.openrocket.aerodynamics.AerodynamicCalculator;
+import net.sf.openrocket.aerodynamics.AerodynamicForces;
+import net.sf.openrocket.aerodynamics.FlightConditions;
+import net.sf.openrocket.motor.MotorId;
+import net.sf.openrocket.motor.MotorInstance;
+import net.sf.openrocket.motor.MotorInstanceConfiguration;
+import net.sf.openrocket.rocketcomponent.MotorMount;
+import net.sf.openrocket.rocketcomponent.RocketComponent;
+import net.sf.openrocket.simulation.FlightDataBranch;
+import net.sf.openrocket.simulation.FlightDataType;
+import net.sf.openrocket.simulation.SimulationStatus;
+import net.sf.openrocket.simulation.exception.SimulationException;
+import net.sf.openrocket.simulation.listeners.AbstractSimulationListener;
+import net.sf.openrocket.unit.UnitGroup;
+import net.sf.openrocket.util.ArrayList;
+import net.sf.openrocket.util.Coordinate;
+import net.sf.openrocket.util.PolyInterpolator;
+
+public class DampingMoment extends AbstractSimulationListener {
+
+ private static final FlightDataType type = FlightDataType.getType("Damping moment coefficient", "Cdm", UnitGroup.UNITS_COEFFICIENT);
+ private static final FlightDataType[] typeList = {type};
+
+ public String getName(){
+ return "Damping moment listener";
+ }
+
+ /**
+ * Return a list of any flight data types this listener creates.
+ */
+ public FlightDataType[] getFlightDataTypes(){
+ return typeList;
+ }
+
+ @Override
+ public FlightConditions postFlightConditions(SimulationStatus status, FlightConditions flightConditions) throws SimulationException {
+
+ // Save it as a flightdatatype
+
+ //status.getFlightData().setValue(type, aerodynamicPart + propulsivePart);
+ status.getFlightData().setValue(type, calculate(status, flightConditions));
+
+ return flightConditions;
+ }
+
+ private double calculate(SimulationStatus status, FlightConditions flightConditions){
+
+ // Work out the propulsive/jet damping part of the moment.
+
+ // dm/dt = (thrust - ma)/v
+ FlightDataBranch data = status.getFlightData();
+
+ List<Double> mpAll = data.get(FlightDataType.TYPE_PROPELLANT_MASS);
+ List<Double> time = data.get(FlightDataType.TYPE_TIME);
+ if (mpAll == null || time == null){
+ return Double.NaN;
+ }
+
+ int len = mpAll.size();
+
+ // This isn't as accurate as I would like
+ double mdot=Double.NaN;
+ if (len > 2){
+ // Using polynomial interpolator for derivative. Doesn't help much
+ //double[] x = { time.get(len-5), time.get(len-4), time.get(len-3), time.get(len-2), time.get(len-1) };
+ //double[] y = { mpAll.get(len-5), mpAll.get(len-4), mpAll.get(len-3), mpAll.get(len-2), mpAll.get(len-1) };
+ //PolyInterpolator interp = new PolyInterpolator(x);
+ //double[] coeff = interp.interpolator(y);
+ //double dt = .01;
+ //mdot = (interp.eval(x[4], coeff) - interp.eval(x[4]-dt, coeff))/dt;
+
+ mdot = (mpAll.get(len-1) - mpAll.get(len-2)) / (time.get(len-1) - time.get(len-2));
+ }
+
+ double cg = data.getLast(FlightDataType.TYPE_CG_LOCATION);
+
+ // find the maximum distance from nose to nozzle.
+ double nozzleDistance = 0;
+ for (MotorId id: status.getMotorConfiguration().getMotorIDs()){
+ MotorInstanceConfiguration config = status.getMotorConfiguration();
+ Coordinate position = config.getMotorPosition(id);
+
+ double x = position.x + config.getMotorInstance(id).getParentMotor().getLength();
+ if (x > nozzleDistance){
+ nozzleDistance = x;
+ }
+ }
+
+ // now can get the propulsive part
+ double propulsivePart = mdot * Math.pow(nozzleDistance - cg, 2);
+
+ // Work out the aerodynamic part of the moment.
+ double aerodynamicPart = 0;
+
+ AerodynamicCalculator aerocalc = status.getSimulationConditions().getAerodynamicCalculator();
+
+ // Must go through each component ...
+ Map<RocketComponent, AerodynamicForces> forces = aerocalc.getForceAnalysis(status.getConfiguration(), flightConditions, null);
+ for (Map.Entry<RocketComponent, AerodynamicForces> entry : forces.entrySet()){
+
+ RocketComponent comp = entry.getKey();
+
+ if (!comp.isAerodynamic()) continue;
+
+ //System.out.println(comp.toString());
+
+ double CNa = entry.getValue().getCNa(); //?
+ double Cp = entry.getValue().getCP().length();
+ double z = comp.getPositionValue(); //?
+
+ aerodynamicPart += CNa*Math.pow(z-Cp, 2);
+ }
+
+ double v = flightConditions.getVelocity();
+ double rho = flightConditions.getAtmosphericConditions().getDensity();
+ double ar = flightConditions.getRefArea();
+
+ aerodynamicPart = aerodynamicPart * .5 * rho * v * ar;
+
+ return aerodynamicPart + propulsivePart;
+
+ }
+
+}